Three-leg topology device, control method, inverter system and uninterruptible power supply system

Abstract

A three-bridge-arm topological device, a control method, an inverter system and an uninterruptible power supply system, the three-bridge-arm topological device realizes charging or discharging of a battery pack through a voltage conversion circuit, and charging of the battery pack can be realized without additional chargers. In addition, in the external power supply mode or the battery power supply mode, the voltage conversion circuit and the three-bridge-arm circuit participate in work, that is, all devices of the three-bridge-arm topological device participate in work. When the three-bridge-arm topological device is applied to a battery low-voltage large-current UPS system or an inverter system, the device multiplexing rate of the system can be improved, device design redundancy can be avoided, and the cost of the battery low-voltage large-current UPS system or the inverter system is reduced.

Description

[0001] This application claims priority to Chinese Patent Application No. 202010444170.4, filed on May 22, 2020, entitled “Three-arm topology device, control method, and uninterruptible power supply system”, and Chinese Patent Application No. 202020885385.5, filed on May 22, 2020, entitled “Three-arm topology device and uninterruptible power supply system”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to power supply technology, and more particularly to a three-bridge-arm topology device, control method, inverter system and uninterruptible power supply system. Background Technology

[0003] A low-voltage, high-current battery power supply system refers to a power supply system that uses a relatively small number of batteries as the battery pack. When using this type of battery pack to power a load, the power supply system can output electrical energy with low voltage and high current. Currently, common low-voltage, high-current battery power supply systems include uninterruptible power supply (UPS) systems and inverter systems.

[0004] Because low-voltage, high-current battery power supply systems use fewer battery cells in their packs, they are widely used. However, existing low-voltage, high-current battery power supply systems have low component reuse rates, resulting in higher costs. Summary of the Invention

[0005] This application provides a three-arm topology device, control method, inverter system, and uninterruptible power supply system to solve the technical problem of low device reuse rate in existing low-voltage, high-current battery UPS systems. The technical solution is as follows:

[0006] In a first aspect, embodiments of this application provide a three-arm topology device, the three-arm topology device comprising: a battery pack, a voltage conversion circuit, and a three-arm circuit; the three-arm circuit comprising: a first arm, a second arm, a third arm, a first inductor, a second inductor, a DC bus capacitor, and a first capacitor; the first arm comprising a first switch and a second switch connected in series; the second arm comprising a third switch and a fourth switch connected in series; the third arm comprising a fifth switch and a sixth switch connected in series;

[0007] The first bridge arm, the second bridge arm, the third bridge arm, and the DC bus capacitor are connected in parallel between the positive output terminal and the negative output terminal of the bus. The midpoint of the first bridge arm is connected to the first end of the first inductor, and the second end of the first inductor serves as the positive voltage input terminal of the three-bridge-arm topology. The midpoint of the second bridge arm or the negative output terminal of the bus serves as the negative voltage input terminal of the three-bridge-arm topology. The midpoint of the third bridge arm is connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the first capacitor, the second end of the first capacitor is connected to the midpoint of the second bridge arm, the first end of the first capacitor is the first output terminal of the three-bridge-arm topology, the second end of the first capacitor is the second output terminal of the three-bridge-arm topology, and both the first and second output terminals are connected to the load.

[0008] The positive terminal of the battery pack is connected to the first terminal of the voltage conversion circuit, the negative terminal of the battery pack is connected to the second terminal of the voltage conversion circuit, the third terminal of the voltage conversion circuit is connected to the positive output terminal of the bus, the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus, the first terminal of the external power supply is connected to the positive voltage input terminal, and the second terminal of the external power supply is connected to the negative voltage input terminal.

[0009] The voltage conversion circuit is used to charge the battery pack in external power supply mode and to discharge the battery pack in battery power supply mode.

[0010] Secondly, embodiments of this application provide an uninterruptible power supply system, the system comprising: an external power supply, a load, and a three-arm topology device as described in the first aspect; wherein, a first terminal of the external power supply is connected to the positive voltage input terminal of the three-arm topology device, a second terminal of the external power supply is connected to the negative voltage input terminal of the three-arm topology device, and a first output terminal and a second output terminal of the three-arm topology device are both connected to the load.

[0011] Thirdly, embodiments of this application provide an uninterruptible power supply system, the system comprising: a first external power supply, a second external power supply, a load, and a three-arm topology device as described in the first aspect; wherein, a first terminal of the first external power supply is connected to a first positive voltage input terminal of the three-arm topology device, a second terminal of the first external power supply is connected to a first negative voltage input terminal of the three-arm topology device, a first terminal of the second external power supply is connected to a second positive voltage input terminal of the three-arm topology device, a second terminal of the second external power supply is connected to a second negative voltage input terminal of the three-arm topology device, and both a first output terminal and a second output terminal of the three-arm topology device are connected to the load.

[0012] Fourthly, this application provides a control method for a three-arm topology device. In the external power supply mode, the three-arm topology device described in the first aspect controls the voltage conversion circuit to charge the battery pack via the switching switch. In the battery power supply mode, the voltage conversion circuit controls the voltage conversion circuit to discharge the battery pack. If the switching switch includes a first switch, a second switch, and a balancing component; and the third terminal of the voltage conversion circuit is connected to the fixed terminal of the first switch, the first select terminal of the first switch is connected to the first terminal of the balancing component, the second terminal of the balancing component is connected to the positive output terminal of the bus, the second select terminal of the first switch is connected to the positive voltage input terminal, the first terminal of the second switch is connected to the first terminal of the external power supply, the second terminal of the second switch is connected to the positive voltage input terminal, and the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus, then the three-arm topology device can be controlled by the following method: In the external power supply mode, controlling the fixed terminal of the first switch to connect with the first select terminal of the first switch, and closing the second switch; in the battery power supply mode, controlling the fixed terminal of the first switch to connect with the second select terminal of the first switch, and opening the second switch.

[0013] Optionally, if the balancing component is a resistor, the switching switch further includes: a third switch; the third terminal of the voltage conversion circuit is connected to the first terminal of the third switch, and the second terminal of the third switch is connected to the positive output terminal of the bus; or, the third switch is connected in parallel with the resistor. In this implementation, the three-arm topology can be controlled by the following method: in external power supply mode, the fixed terminal of the first switch is connected to the first selection terminal of the first switch, the second switch is closed, and the third switch is closed when the voltage difference between the bus and the voltage conversion circuit of the three-arm topology is less than or equal to a preset threshold; in battery power supply mode, the fixed terminal of the first switch is connected to the second selection terminal of the first switch, and the second switch and the third switch are disconnected.

[0014] Fifthly, embodiments of this application provide a control method for a three-arm topology device. In the external power supply mode, the three-arm topology device described in the first aspect controls the voltage conversion circuit to charge the battery pack via the switching switch. In the battery power supply mode, the voltage conversion circuit controls the voltage conversion circuit to discharge the battery pack. If the switching switch includes: a first switch, a second switch, and a balancing component; and the third terminal of the voltage conversion circuit is connected to the first terminal of the first switch and the first selection terminal of the second switch, the second terminal of the first switch is connected to the first terminal of the balancing component, the second terminal of the balancing component is connected to the positive output terminal of the bus, the second selection terminal of the second switch is connected to the first terminal of the external power supply, the fixed terminal of the second switch is connected to the positive voltage input terminal, and the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus, then the three-arm topology device can be controlled by the following method: In the external power supply mode, controlling the first switch to close, and the fixed terminal of the second switch to connect with the second selection terminal of the second switch; in the battery power supply mode, controlling the first switch to open, and the fixed terminal of the second switch to connect with the first selection terminal of the second switch.

[0015] Optionally, the balancing component is a resistor, and the switching switch further includes a third switch; the third terminal of the voltage conversion circuit is connected to the first terminal of the third switch, and the second terminal of the third switch is connected to the positive output terminal of the bus; or, the third switch is connected in parallel with the resistor. In this implementation, the three-arm topology can be controlled by the following method: in external power supply mode, controlling the first switch to close, the fixed terminal of the second switch to connect to the second selection terminal of the second switch, and controlling the third switch to close when the voltage difference between the bus and the voltage conversion circuit of the three-arm topology is less than or equal to a preset threshold; in battery power supply mode, controlling the third switch and the first switch to open, and the fixed terminal of the second switch to connect to the first selection terminal of the second switch.

[0016] In a sixth aspect, embodiments of this application provide a control method for a three-arm topology device. In the external power supply mode, the three-arm topology device described in the first aspect controls the voltage conversion circuit to charge the battery pack via the switching switch. In the battery power supply mode, the voltage conversion circuit controls the voltage conversion circuit to discharge the battery pack. If the switching switch includes: a first switch, a second switch, a third switch, and a balancing component; the third terminal of the voltage conversion circuit is connected to the first terminal of the first switch and the first terminal of the third switch, respectively; the second terminal of the first switch is connected to the positive voltage input terminal; the first terminal of the second switch is connected to the first terminal of the external power supply; the second terminal of the second switch is connected to the positive voltage input terminal; the second terminal of the third switch is connected to the first terminal of the balancing component; the second terminal of the balancing component is connected to the positive output terminal of the bus; and the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus, then the three-arm topology device can be controlled by the following method: in the external power supply mode, controlling the first switch to open and the second and third switches to close; in the battery power supply mode, controlling the first switch to close and the second and third switches to open.

[0017] Optionally, the balancing component is a resistor, and the switching switch further includes a fourth switch; the third terminal of the voltage conversion circuit is connected to the first terminal of the fourth switch, and the second terminal of the fourth switch is connected to the positive output terminal of the bus; or, the fourth switch is connected in parallel with the resistor. In this implementation, the three-arm topology can be controlled by the following method: in external power supply mode, the first switch is opened, the second and third switches are closed, and when the voltage difference between the bus and the voltage conversion circuit of the three-arm topology is less than or equal to a preset threshold, the fourth switch is closed; in battery power supply mode, the first switch is closed, and the second, third, and fourth switches are opened.

[0018] In a seventh aspect, embodiments of this application provide a control method for a three-arm topology device. When the voltage conversion circuit in the three-arm topology device described in the first aspect forms a bidirectional DC-DC topology by multiplexing the second arm of the three-arm circuit and the bus capacitor, the three-arm topology device can be controlled by the following method, the method comprising:

[0019] In the first stage of the external power supply mode, control the second, fourth, fifth, and eleventh switching transistors to conduct;

[0020] In the second stage of the external power supply mode, the second switch, the fourth switch, the fifth switch, and the twelfth switch are turned on.

[0021] In the third stage of the external power supply mode, the fourth switch, the fifth switch, and the eleventh switch are turned on.

[0022] In the fourth stage of the external power supply mode, the fourth switch, the fifth switch, and the twelfth switch are turned on.

[0023] In the fifth stage of the external power supply mode, the second switch, the fourth switch, the sixth switch, and the eleventh switch are turned on.

[0024] In the sixth stage of the external power supply mode, the second switch, the fourth switch, the sixth switch, and the twelfth switch are turned on.

[0025] In the seventh stage of the external power supply mode, the fourth switch, the sixth switch, and the eleventh switch are turned on.

[0026] In the eighth stage of the external power supply mode, the fourth switch, the sixth switch, and the twelfth switch are turned on.

[0027] In the ninth stage of the external power supply mode, the first switch, the third switch, the sixth switch, and the twelfth switch are turned on.

[0028] In the tenth stage of the external power supply mode, the first switch, the third switch, the sixth switch, and the eleventh switch are controlled to be turned on;

[0029] In the eleventh stage of the external power supply mode, the third switch, the sixth switch, and the twelfth switch are turned on.

[0030] In the twelfth stage of the external power supply mode, the third switch, the sixth switch, and the eleventh switch are turned on.

[0031] In the thirteenth stage of the external power supply mode, the first switch, the third switch, the fifth switch, and the twelfth switch are turned on.

[0032] In the fourteenth stage of the external power supply mode, the first switch, the third switch, the fifth switch, and the eleventh switch are turned on.

[0033] In the fifteenth stage of the external power supply mode, the third switch, the fifth switch, and the twelfth switch are turned on.

[0034] In the sixteenth stage of the external power supply mode, the third switch, the fifth switch, and the eleventh switch are turned on.

[0035] In the first stage of the battery-powered mode, the fourth, fifth, seventh, tenth, and twelfth switches are turned on.

[0036] In the second stage of the battery-powered mode, the fourth, fifth, eighth, ninth, and eleventh switches are turned on.

[0037] In the third stage of the battery-powered mode, the fourth, sixth, seventh, tenth, and twelfth switches are turned on.

[0038] In the fourth stage of the battery-powered mode, the fourth, sixth, eighth, ninth, and eleventh switches are turned on.

[0039] In the fifth stage of the battery-powered mode, the third, sixth, seventh, tenth, and twelfth switches are turned on.

[0040] In the sixth stage of the battery-powered mode, the third switch, the sixth switch, the eighth switch, the ninth switch, and the eleventh switch are turned on.

[0041] In the seventh stage of the battery-powered mode, the third switch, the fifth switch, the seventh switch, the tenth switch, and the twelfth switch are turned on.

[0042] In the eighth stage of the battery-powered mode, the third, fifth, eighth, ninth, and eleventh switches are turned on.

[0043] Eighthly, embodiments of this application provide a three-arm topology device, the three-arm topology device comprising: a battery pack, a voltage conversion circuit, and a three-arm circuit; the three-arm circuit comprising: a first arm, a second arm, a third arm, a DC bus capacitor, and a filter; the first arm comprising a first switch and a second switch connected in series; the second arm comprising a third switch and a fourth switch connected in series; the third arm comprising a fifth switch and a sixth switch connected in series;

[0044] The first bridge arm, the second bridge arm, the third bridge arm, and the DC bus capacitor are connected in parallel between the positive output terminal and the negative output terminal of the bus. The midpoints of the second bridge arm and the third bridge arm are both connected to the filter. The positive terminal of the battery pack is connected to the first terminal of the voltage conversion circuit, the negative terminal of the battery pack is connected to the second terminal of the voltage conversion circuit, and the third and fourth terminals of the voltage conversion circuit are both connected to the three-bridge-arm circuit. The filter is provided with a first external connection terminal and a second external connection terminal of the three-bridge-arm topology device, which are connected to the load in battery-powered mode.

[0045] The voltage conversion circuit discharges the battery pack in the battery-powered mode.

[0046] In a ninth aspect, embodiments of this application provide an inverter system, the system comprising: a load, and a three-arm topology device as described in the eighth aspect; in battery-powered mode, a first external connection terminal and a second external connection terminal of the three-arm topology device are both connected to the load.

[0047] In a tenth aspect, embodiments of this application provide a control method for a three-arm topology device. When the three-arm topology device described in the eighth aspect forms a bidirectional DC-DC topology through a voltage conversion circuit, the first arm of the three-arm circuit, and a bus capacitor, the three-arm topology device can be controlled by the following method, the method comprising:

[0048] In the first stage of the battery-powered mode, the second, eighth, ninth, and eleventh switches are turned on.

[0049] In the second stage of the battery-powered mode, the first, seventh, tenth, and twelfth switching transistors are turned on.

[0050] In the first stage of the battery charging mode, the second switch and the eleventh switch are turned on.

[0051] In the second stage of the battery charging mode, the first switch and the twelfth switch are turned on.

[0052] Eleventhly, embodiments of this application provide a control method for a three-arm topology device. When the three-arm topology device described in the eighth aspect forms a bidirectional DC-DC topology through a voltage conversion circuit, the first arm and the second arm of the three-arm circuit, and a bus capacitor, the three-arm topology device can be controlled by the following method, the method comprising:

[0053] In the first stage of the battery-powered mode, the second, fourth, fifth, seventh, and tenth switching transistors are turned on.

[0054] In the second stage of the battery-powered mode, the first switch, the fourth switch, the fifth switch, the eighth switch, and the ninth switch are turned on.

[0055] In the third stage of the battery-powered mode, the second switch, the fourth switch, the sixth switch, the seventh switch, and the tenth switch are turned on.

[0056] In the fourth stage of the battery-powered mode, the first switch, the fourth switch, the sixth switch, the eighth switch, and the ninth switch are turned on.

[0057] In the fifth stage of the battery-powered mode, the first switch, the third switch, the sixth switch, the eighth switch, and the ninth switch are turned on.

[0058] In the sixth stage of the battery-powered mode, the first switch, the second switch, the third switch, the sixth switch, the seventh switch, and the tenth switch are turned on.

[0059] In the seventh stage of the battery-powered mode, the first switch, the third switch, the fifth switch, the eighth switch, and the ninth switch are turned on.

[0060] In the eighth stage of the battery-powered mode, the first switch, the second switch, the third switch, the fifth switch, the seventh switch, and the tenth switch are turned on.

[0061] In the first stage of the battery charging mode, the first switch, the fourth switch, and the sixth switch are turned on.

[0062] In the second stage of the battery charging mode, the second switch, the fourth switch, and the sixth switch are turned on.

[0063] In the third stage of the battery charging mode, the first switch, the fourth switch, and the fifth switch are turned on.

[0064] In the fourth stage of the battery charging mode, the second switch, the fourth switch, and the fifth switch are turned on.

[0065] In the fifth stage of the battery charging mode, the second switch, the third switch, and the fifth switch are turned on.

[0066] In the sixth stage of the battery charging mode, the first switch, the third switch, and the fifth switch are turned on.

[0067] In the seventh stage of the battery charging mode, the second switch, the third switch, and the sixth switch are turned on.

[0068] In the eighth stage of the battery charging mode, the first switch, the third switch, and the sixth switch are turned on.

[0069] The three-arm topology device, control method, inverter system, and uninterruptible power supply system provided in this application embodiment achieve battery charging or discharging by reusing the voltage conversion circuit, eliminating the need for an additional charger. Furthermore, both the voltage conversion circuit and the three-arm circuit participate in both charging and discharging of the battery pack; that is, all components of the three-arm topology device are involved in operation. When this three-arm topology device is applied to a low-voltage, high-current UPS system or inverter system, it can improve the component reuse rate, avoid component design redundancy, and thus reduce the cost of the low-voltage, high-current UPS system or inverter system. Attached Figure Description

[0070] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0071] Figure 1 A schematic diagram of a battery-powered low-voltage, high-current UPS system provided for the present technology;

[0072] Figure 1A A schematic diagram of a battery low-voltage high-current inverter system provided by the prior art;

[0073] Figure 2 Schematic diagram of the first three-arm topology device provided in the embodiments of this application Figure 1 ;

[0074] Figure 3 Schematic diagram of the first three-arm topology device provided in the embodiments of this application Figure 2 ;

[0075] Figure 4 A schematic diagram of a second three-arm topology device provided in the embodiments of this application;

[0076] Figure 5 A schematic diagram of a third three-arm topology device provided in the embodiments of this application;

[0077] Figure 6 A schematic diagram of a fourth three-arm topology device provided in the embodiments of this application;

[0078] Figure 7 A schematic diagram of the fifth three-arm topology device provided in the embodiments of this application;

[0079] Figure 8 Current diagram of the fourth three-arm topology device provided in the embodiments of this application under external power supply mode. Figure 1 ;

[0080] Figure 9 Current diagram of the fourth three-arm topology device provided in the embodiments of this application under external power supply mode. Figure 2 ;

[0081] Figure 10 Current diagram of the fourth three-arm topology device provided in the embodiments of this application under external power supply mode. Figure 3 ;

[0082] Figure 11 Current diagram of the fourth three-arm topology device provided in the embodiments of this application under external power supply mode. Figure 4 ;

[0083] Figure 12 Current diagram of the fourth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 5 ;

[0084] Figure 13 Current diagram of the fourth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 6 ;

[0085] Figure 14 A schematic diagram of the sixth three-arm topology device provided in the embodiments of this application;

[0086] Figure 15 A schematic diagram of the seventh three-arm topology device provided in the embodiments of this application;

[0087] Figure 16 A schematic diagram of the eighth three-arm topology device provided in the embodiments of this application;

[0088] Figure 17 A schematic diagram of the ninth three-arm topology device provided in the embodiments of this application;

[0089] Figure 18 A schematic diagram of the tenth three-arm topology device provided in the embodiments of this application;

[0090] Figure 19 A schematic diagram of the eleventh three-arm topology device provided in the embodiments of this application;

[0091] Figure 20 A schematic diagram of the twelfth three-arm topology device provided in the embodiments of this application;

[0092] Figure 21 A schematic diagram of the thirteenth three-arm topology device provided in the embodiments of this application;

[0093] Figure 22 A schematic diagram of the fourteenth three-arm topology device provided in the embodiments of this application;

[0094] Figure 23 A schematic diagram of the fifteenth three-arm topology device provided in the embodiments of this application;

[0095] Figure 24 A schematic diagram of the sixteenth three-arm topology device provided in the embodiments of this application;

[0096] Figure 25 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 1 ;

[0097] Figure 26 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 2 ;

[0098] Figure 27 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 3 ;

[0099] Figure 28 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 4 ;

[0100] Figure 29 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 5 ;

[0101] Figure 30 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 6 ;

[0102] Figure 31 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 7 ;

[0103] Figure 32 A schematic diagram of the structure of the first voltage conversion unit provided in the embodiments of this application. Figure 1 ;

[0104] Figure 33 A schematic diagram of the structure of the first voltage conversion unit provided in the embodiments of this application. Figure 2 ;

[0105] Figure 34 A schematic diagram of the structure of the first voltage conversion unit provided in the embodiments of this application. Figure 3 ;

[0106] Figure 35 A schematic diagram of the structure of the first voltage conversion unit provided in the embodiments of this application. Figure 4 ;

[0107] Figure 36 A schematic diagram of the seventeenth three-arm topology device provided in the embodiments of this application;

[0108] Figure 36A Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 8 ;

[0109] Figure 36B Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 9 ;

[0110] Figure 37 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 1 ;

[0111] Figure 38 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 2 ;

[0112] Figure 39 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 3 ;

[0113] Figure 40 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 4 ;

[0114] Figure 41 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 5 ;

[0115] Figure 42 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 6 ;

[0116] Figure 43 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 7 ;

[0117] Figure 44 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 8 ;

[0118] Figure 45 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 9

[0119] Figure 46 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 ;

[0120] Figure 47 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 one;

[0121] Figure 48 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 two;

[0122] Figure 49 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 three;

[0123] Figure 50 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 Four;

[0124] Figure 51 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 five;

[0125] Figure 52 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 six;

[0126] Figure 53 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 1 ;

[0127] Figure 54 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 2 ;

[0128] Figure 55Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 3 ;

[0129] Figure 56 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 4 ;

[0130] Figure 57 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 5 ;

[0131] Figure 58 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 6 ;

[0132] Figure 59 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 7 ;

[0133] Figure 60 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 8 ;

[0134] Figure 61 A schematic diagram of the eighteenth three-arm topology device provided in the embodiments of this application;

[0135] Figure 62 A schematic diagram of the nineteenth three-arm topology device provided in the embodiments of this application;

[0136] Figure 63 A schematic diagram of the twentieth three-arm topology device provided in the embodiments of this application;

[0137] Figure 63A Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 10 ;

[0138] Figure 63B Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 10 one;

[0139] Figure 64 Current diagram of the twentieth three-arm topology device provided in this application embodiment in battery-powered mode Figure 1 ;

[0140] Figure 65 Current diagram of the twentieth three-arm topology device provided in this application embodiment in battery-powered mode Figure 2 ;

[0141] Figure 66 Current diagram of the twentieth three-arm topology device provided in this application embodiment in battery charging mode. Figure 1 ;

[0142] Figure 67 Current diagram of the twentieth three-arm topology device provided in this application embodiment in battery charging mode. Figure 2 ;

[0143] Figure 68 A schematic diagram of the twenty-first three-arm topology device provided in this application embodiment;

[0144] Figure 68A Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 10 two;

[0145] Figure 68B Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 10 three;

[0146] Figure 69 This is a schematic diagram of the twenty-second type of three-arm topology device provided in the embodiments of this application;

[0147] Figure 70 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 1 ;

[0148] Figure 71 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 2 ;

[0149] Figure 72 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode Figure 3 ;

[0150] Figure 73 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode Figure 4 ;

[0151] Figure 74 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode Figure 5 ;

[0152] Figure 75 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 6 ;

[0153] Figure 76 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 7 ;

[0154] Figure 77 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 8 ;

[0155] Figure 78 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 1 ;

[0156] Figure 79 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 2 ;

[0157] Figure 80 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 3 ;

[0158] Figure 81 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 4 ;

[0159] Figure 82 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 5 ;

[0160] Figure 83 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 6 ;

[0161] Figure 84 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 7 ;

[0162] Figure 85 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 8 ;

[0163] Figure 86 A schematic diagram illustrating the connection relationship between an LC filter and the second and third bridge arms, provided for an embodiment of this application;

[0164] Figure 87This is a schematic diagram illustrating the connection relationship between an LCL filter and the second and third bridge arms, as provided in an embodiment of this application. Detailed Implementation

[0165] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the embodiments of this application.

[0166] A battery-powered low-voltage, high-current UPS system is a type of online, small-to-medium power UPS system. This means that regardless of whether the mains voltage is normal, the AC voltage supplied to the load must be inverted by an inverter circuit. Classified by power, online small-to-medium power UPS systems typically refer to online UPS systems with power ratings between 1 kW and 3 kW.

[0167] Figure 1 This is a schematic diagram of a low-voltage, high-current battery-powered UPS system provided by existing technology. Figure 1 As shown, common low-voltage, high-current battery UPS systems currently include: charger, battery pack, unidirectional DC-DC converter, AC power supply, Vienna rectifier converter, and half-bridge inverter.

[0168] In external power supply mode (in a low-voltage, high-current UPS system with batteries, the external power supply is AC mains power; therefore, in this example, external power supply mode is AC power supply), the Vienna rectifier converter converts the AC power supplied by the AC mains power supply to DC power, the half-bridge inverter converts the DC power back to AC power to supply the load, and the charger charges the battery pack. In external power supply mode, the Vienna rectifier converter, half-bridge inverter, and charger are all active, while the DC-DC converter is idle.

[0169] In battery-powered mode (i.e., when powered by a battery pack), the DC-DC converter boosts the DC output from the battery pack, and the half-bridge inverter converts the DC back to AC to supply the load. In other words, both the DC-DC converter and the half-bridge inverter are operational. In battery-powered mode, the Vienna rectifier and charger are idle.

[0170] In other words, some components of existing low-voltage, high-current battery UPS systems are idle during operation, resulting in a low component reuse rate and thus a higher cost.

[0171] Figure 1A This is a schematic diagram of a low-voltage, high-current battery inverter system provided by existing technology. Figure 1A As shown, common battery low-voltage high-current inverter systems in existing technologies currently include: a battery pack, a bidirectional DC-DC converter, a Buck converter, and a full-bridge inverter. That is, existing battery low-voltage high-current inverter systems (i.e., bidirectional DC-AC converters) consist of three stages of converters. The Buck converter, also known as a buck converter, is used to step down the voltage.

[0172] In battery-powered mode, the DC power output from the battery pack is boosted to the bus capacitor E1 by a bidirectional DC-DC converter, and then inverted by a full-bridge inverter to output AC power to the load. In battery-charging mode, the full-bridge inverter acts as a full-bridge rectifier-PFC converter, boosting the AC power supplied by the mains AC power supply and outputting it to the bus capacitor E1. The DC power output from the bus capacitor E1 is then stepped down by a Buck converter and then used to charge the battery pack via the bidirectional DC-DC converter.

[0173] As described above, in the existing low-voltage high-current battery inverter system, the Buck converter does not participate in the operation under battery power supply mode. This results in low integration and low device reuse rate of the existing low-voltage high-current battery inverter system, leading to high cost.

[0174] In summary, the existing low-voltage, high-current battery power supply system has a low device reuse rate, resulting in a high cost.

[0175] In view of the above problems, this application provides a three-arm topology device. When the device is applied to a low-voltage, high-current UPS system or inverter system, all the devices of the device participate in the operation, whether charging or discharging the battery pack, which improves the device reuse rate of the low-voltage, high-current UPS system or inverter system and thus reduces the cost of the low-voltage, high-current UPS system or inverter system.

[0176] It should be understood that the embodiments of this application do not limit the external power supply of the battery low-voltage high-current UPS system. For example, the external power supply of the UPS system can be AC ​​mains power, DC photovoltaic power, or a combination of DC photovoltaic power and AC mains power, etc. For ease of description, the following embodiments will use AC mains power as the external power supply of the battery low-voltage high-current UPS system as an example. However, those skilled in the art will understand that the AC mains power supply involved in the following figures can be replaced by other independent external power supplies. For UPS systems with two external power supplies, the circuit connection method can be adaptively adjusted according to the actual connection method of the external power supplies in the UPS system, which will not be elaborated further.

[0177] The three-arm topology device provided in this application embodiment may include, for example, the following structures:

[0178] Structure A: The three-arm topology includes a battery pack, a voltage conversion circuit, a switching switch, and a three-arm circuit. The switching switch controls the voltage conversion circuit to charge or discharge the battery pack, ensuring that all components of the three-arm topology operate whether charging or discharging the battery pack.

[0179] The three-bridge topology provided by Structure A can be applied to low-voltage, high-current UPS systems.

[0180] Structure B: The three-arm topology includes a battery pack, a voltage conversion circuit, and a three-arm circuit, without a separate switching switch. The voltage conversion circuit can charge or discharge the battery pack, ensuring that all components of the three-arm topology operate whether charging or discharging the battery pack.

[0181] Optionally, in some embodiments, the voltage conversion circuit of the three-arm topology device shown in structure B can reuse the DC bus capacitor of the three-arm circuit, or reuse the second arm and DC bus capacitor of the three-arm circuit to realize the voltage conversion function, so as to simplify the voltage conversion circuit and further improve the device reuse rate of the three-arm topology device.

[0182] The three-bridge arm configuration provided by Structure B can be applied to UPS systems with low battery voltage and high current or inverter systems with low battery voltage and high current.

[0183] The three-arm topology device provided in this application will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0184] Structure A: The three-arm topology includes a battery pack, a voltage conversion circuit, a switching switch, and a three-arm circuit. The three-arm topology provided by Structure A can be applied to low-voltage, high-current battery UPS systems, such as low-voltage, high-current battery UPS systems with a wide range of battery input voltages, exemplarily, low-voltage, high-current battery UPS systems using lead-acid batteries. It should be understood that the battery input voltage referred to herein is the voltage output by the battery pack when the battery pack is supplying power to the load. In some embodiments, this three-arm topology can also be applied to Emergency Power Supply (EPS) systems.

[0185] Figure 2 Schematic diagram of the first three-arm topology device provided in the embodiments of this application Figure 1 .like Figure 2 As shown, the three-arm topology device may include: a battery pack, a voltage conversion circuit, a switching switch, and a three-arm circuit.

[0186] The three-arm bridge circuit may include: a first arm, a second arm, a third arm, a first inductor L1, a DC bus capacitor E1, and an LC filter. The LC filter includes: a first capacitor Co and a second inductor L2.

[0187] The first bridge arm includes a first switch Q1 and a second switch Q2, which are connected in series between BUS+ and BUS-. BUS+ is the positive output terminal of the bus, and BUS- is the negative output terminal of the bus. For example, the first end of the first switch Q1 is connected to BUS+, the second end of the first switch Q1 is connected to the first end of the second switch Q2, and the second end of the second switch Q2 is connected to BUS-. The common terminal of the first switch Q1 and the second switch Q2 is called the midpoint of the first bridge arm. When this three-bridge-arm topology is applied to a low-voltage, high-current battery UPS system, the first bridge arm can also be called the high-frequency bridge arm on the power factor correction (PFC) side.

[0188] The second bridge arm includes a third switch Q3 and a fourth switch Q4, which are connected in series between BUS+ and BUS-. For example, the first end of the third switch Q3 is connected to BUS+, the second end of the third switch Q3 is connected to the first end of the fourth switch Q4, and the second end of the fourth switch Q4 is connected to BUS-. The common end of the third switch Q3 and the fourth switch Q4 is called the midpoint of the second bridge arm. When this three-bridge-arm topology is applied to a low-voltage, high-current UPS system, this second bridge arm can also be called the bridge arm shared by the PFC and the inverter (INV).

[0189] The third bridge arm includes a fifth switch Q5 and a sixth switch Q6, which are connected in series between BUS+ and BUS-. For example, the first end of the fifth switch Q5 is connected to BUS+, the second end of the fifth switch Q5 is connected to the first end of the sixth switch Q6, and the second end of the sixth switch Q6 is connected to BUS-. The common terminal of the fifth switch Q5 and the sixth switch Q6 is called the midpoint of the third bridge arm. When this three-bridge arm topology is applied to a low-voltage, high-current UPS system, this third bridge arm can also be called the INV-side high-frequency bridge arm.

[0190] The DC bus capacitor E1 is connected between BUS+ and BUS-. That is, the first bridge arm, the second bridge arm, the third bridge arm, and the DC bus capacitor E1 are connected in parallel between BUS+ and BUS-.

[0191] The first inductor L1 is a high-frequency inductor on the PFC side. The midpoint of the first bridge arm is connected to the first terminal of the first inductor L1, and the second terminal of the first inductor L1 serves as the positive voltage input terminal AC_L of the three-bridge-arm topology. The midpoint of the second bridge arm serves as the negative voltage input terminal AC_N of the three-bridge-arm topology.

[0192] The second inductor L2 is a high-frequency inductor on the INV side. The midpoint of the third bridge arm is connected to the first terminal of the second inductor L2, the second terminal of the second inductor L2 is connected to the first terminal of the first capacitor Co, and the second terminal of the first capacitor Co is connected to the midpoint of the second bridge arm. The first terminal of the first capacitor Co is the first output terminal of the three-bridge-arm topology, and the second terminal of the first capacitor Co is the second output terminal of the three-bridge-arm topology.

[0193] The positive terminal of the battery pack is connected to the first terminal of the voltage conversion circuit, and the negative terminal is connected to the second terminal of the voltage conversion circuit. The third terminal of the voltage conversion circuit is connected to both BUS+ and the positive voltage input terminal AC_L via a switch. The fourth terminal of the voltage conversion circuit is connected to BUS-. The live wire of the AC mains power supply (i.e., the first terminal of the external power supply) is connected to the positive voltage input terminal AC_L via a switch, and the neutral wire of the AC mains power supply (i.e., the second terminal of the external power supply) is connected to the negative voltage input terminal AC_N. The first and second output terminals of the three-arm topology are both connected to the load to provide AC power to the load.

[0194] The aforementioned battery pack may include at least one battery, which can be determined based on the power of the UPS system to which the three-arm topology device is applied. For example, the UPS system may be an online UPS system with a power between 1 kW and 3 kW, or the UPS may be a battery low-voltage high-current UPS system.

[0195] The three-arm circuit involved in this embodiment is used to realize rectification and inversion functions when the three-arm topology device supplies power to the load. Specifically, it can be described in conjunction with the power supply mode adopted when the three-arm topology device supplies power to the load. Therefore, in some embodiments, the three-arm circuit involved in this embodiment can also be called a three-arm converter circuit.

[0196] Specifically, the three-arm topology device has two power supply modes: external power supply mode and battery power supply mode. Corresponding to the UPS system involved in this embodiment, the external power supply mode can be a mode where a stable AC mains power supply is provided; the battery power supply mode can be a mode where the UPS system's battery pack provides power, in which case the AC mains input may be high voltage, low voltage, have an abnormal frequency, or have no mains power input. The three-arm topology device can switch between these two modes using a switching switch.

[0197] In external power supply mode, the switch can control the AC mains power supply to power the three-bridge circuit. At this time, the three-bridge circuit operates in AC-AC mode. For example, the PFC in the three-bridge circuit converts the AC mains power input into DC power (i.e., rectifies the AC mains power input), and the DC bus capacitor E1 filters (or regulates) the DC power obtained by the PFC to obtain stable DC power. The INV of the three-bridge circuit then converts the stable DC power back into AC power and outputs it to the load to power it.

[0198] It should be noted that although the PFC converts AC to DC, this DC still contains a certain amount of pulsating AC component, which is called ripple voltage. Therefore, in external power supply mode, the DC bus capacitor E1 can filter (or regulate) the DC obtained by the PFC to remove the ripple voltage and obtain a smooth and stable DC voltage. Simultaneously, the DC bus capacitor E1 can store energy.

[0199] In external power supply mode, the switch can control the voltage conversion circuit to charge the battery pack. For example, the switch can control the voltage conversion circuit to charge the battery pack when the battery pack is at low voltage in external power supply mode. That is, charging the battery pack is achieved by reusing the voltage conversion circuit, eliminating the need for an additional charger. In this case, in external power supply mode, both the voltage conversion circuit and the three-arm circuit are involved, meaning all components of the three-arm topology are operational.

[0200] For example, the switch can control the voltage conversion circuit to be connected between BUS+ and BUS-. The voltage conversion circuit operates in BUCK mode (i.e., buck mode), and steps down the BUS voltage output from the DC bus capacitor E1 (i.e., the voltage obtained after filtering the DC power converted by the PFC by the DC bus capacitor E1) to obtain the charging voltage for the battery pack, which is then used to charge the battery pack. In this case, the battery pack serves as the output source of the voltage conversion circuit.

[0201] Reference Figure 1 In existing technologies, when using a charger to charge a battery pack, the charger needs to include a rectifier circuit and a step-down circuit. The rectifier circuit rectifies the AC power supplied by the mains AC power source to obtain DC power. The step-down circuit reduces the voltage of this DC power to obtain the charging voltage for the battery pack. This type of charger, which includes both a rectifier circuit and a step-down circuit, is commonly referred to as a flyback charger.

[0202] Because the AC power supplied by the mains AC power source has a wide voltage fluctuation range, the step-down circuit in the charger needs to achieve a wide voltage regulation range, resulting in low voltage conversion efficiency of the step-down circuit. Therefore, when using this type of flyback charger to charge the battery pack, the charger's charging efficiency is low.

[0203] In this embodiment, the BUS voltage output by the DC bus capacitor E1 is a stable DC voltage obtained through PFC rectification of the three-arm bridge circuit. Therefore, when using the BUS voltage output by the DC bus capacitor E1 to charge the battery pack, the voltage conversion circuit can be reused to step down the BUS voltage output by the DC bus capacitor E1, and there is no need to set up a separate rectification circuit. In other words, by reusing the PFC of the three-arm bridge circuit, DC power for charging the battery pack is obtained.

[0204] In addition, since the BUS voltage output by the DC bus capacitor E1 is a stable DC voltage, there is no need to use a voltage conversion circuit with a wide voltage regulation range to step down the BUS voltage output by the DC bus capacitor E1, which improves the conversion efficiency of the voltage conversion circuit and thus improves the charging efficiency of the battery pack.

[0205] In battery-powered mode, the switch can control the voltage conversion circuit to discharge the battery pack. For example, the switch can connect the voltage conversion circuit between the high-frequency inductor (i.e., the first inductor L1) on the PFC side and BUS-. In this case, the voltage conversion circuit is connected in series with the "first inductor L1 and the first arm of the three-bridge circuit forming a Boost converter circuit," achieving two-stage voltage boosting during battery pack discharge. Specifically, the voltage conversion circuit operates in Boost mode (i.e., boost mode), performing a first-stage boosting of the battery pack's output voltage. The first inductor L1 and the first arm of the three-bridge circuit form a Boost converter circuit, performing a second-stage boosting of the battery pack's output voltage. The boosted voltage is then input to the DC bus capacitor E1 of the three-bridge circuit to maintain bus voltage balance.

[0206] In UPS systems with low-voltage, high-current batteries, the battery pack outputs a lower voltage, while the load requires a higher voltage. Therefore, when this three-arm topology is applied to such a system, it needs to boost a lower voltage to a higher voltage—that is, it requires a significant voltage difference boosting process. If the voltage conversion circuit is connected in parallel with the first inductor L1 and the first arm of the three-arm circuit to form a boost circuit, and only the voltage conversion circuit is used to perform this boosting operation (i.e., using the voltage conversion circuit for a single-stage boosting process), the following problems arise:

[0207] 1. The voltage conversion circuit has a maximum boost ratio (e.g., output voltage divided by input voltage), which may result in the voltage boosted by the voltage conversion circuit using the maximum boost ratio still being less than the voltage required by the load of the UPS system with low battery voltage and high current, thus failing to meet the usage requirements of the UPS system with low battery voltage and high current.

[0208] 2. The higher the boost ratio, the lower the conversion efficiency of the voltage conversion circuit, and the greater the risk of current stress and heat loss in the voltage conversion circuit. Therefore, the above-mentioned use of a voltage conversion circuit for a single-stage boost process requires the voltage conversion circuit to perform a high boost ratio, resulting in lower conversion efficiency and higher risks of current stress and heat loss in the voltage conversion circuit.

[0209] Considering the problems associated with using a voltage conversion circuit for single-stage boosting, this embodiment of the application achieves a two-stage boosting method by connecting the voltage conversion circuit in series with a "Boost circuit formed by the first inductor L1 and the first arm of the three-arm circuit." This allows the Boost circuit formed by the first inductor L1 and the first arm of the three-arm circuit to share part of the voltage boosting operation, thereby achieving a larger boost ratio while eliminating the need for the voltage conversion circuit itself to perform a large voltage difference boosting process. The smaller the voltage difference between the input and output voltages of the voltage conversion circuit, i.e., the smaller the boost ratio, the higher the voltage conversion efficiency of the voltage conversion circuit. Therefore, the two-stage boosting method described above can improve the conversion efficiency of the voltage conversion circuit, thereby reducing the current stress risk and heat loss risk of the voltage conversion circuit, and improving the reliability of the UPS system with low battery voltage and high current.

[0210] In battery-powered mode, the battery pack serves as the input source for the voltage conversion circuit, and the output of the voltage conversion circuit powers the three-arm circuit. At this time, the first arm of the three-arm circuit operates in DC-DC mode. For example, the first arm and the first inductor L1 operate in Boost mode, and the DC bus capacitor E1 filters the boosted DC power to obtain a stable DC power. The second and third arms operate in inverter mode, converting the stable DC power into AC power and outputting it to the load to power it. Simultaneously, the DC bus capacitor E1 can store energy. In this battery-powered mode, both the voltage conversion circuit and the three-arm circuit participate in the operation; that is, all components of the three-arm topology device are involved in the operation.

[0211] It is understood that the voltage conversion circuit involved in the embodiments of this application can be any circuit with bidirectional voltage conversion function. For example, a voltage conversion circuit with soft switching, a voltage conversion circuit with hard switching, etc. The voltage conversion circuit can be a voltage conversion circuit with electrical isolation or a voltage conversion circuit without electrical isolation. For example, the voltage conversion circuit can also be called a DC-DC converter.

[0212] Figure 3 Schematic diagram of the first three-arm topology device provided in the embodiments of this application Figure 2 ,like Figure 3 As shown, for example, the voltage conversion circuit involved in the embodiments of this application may include: a first voltage conversion unit, a second voltage conversion unit, a transformer TX1, and an LC resonant cavity;

[0213] The first voltage conversion unit is connected to the low-voltage side of the transformer, and the high-voltage side of the transformer is connected to the resonant cavity and the second voltage conversion unit. The LC resonant cavity includes a fifth inductor Lik and a third capacitor Cr. It should be understood that the fifth inductor Lik can be an inductor that exists independently of the transformer TX1, or it can be the leakage inductance in the transformer TX1. That is, the fifth inductor Lik and the transformer TX1 can be independent devices, or they can be a component belonging to the transformer TX1. This application does not limit this aspect.

[0214] The first voltage conversion unit may include: the fourth bridge arm and the fifth bridge arm; the second voltage conversion unit may include: the sixth bridge arm, the seventh bridge arm, and the second capacitor E2.

[0215] The fourth bridge arm includes a seventh switch Q7 and an eighth switch Q8 connected in series, with the first end of the seventh switch Q7 connected to the first end of the eighth switch Q8. The common terminal of the seventh switch Q7 and the eighth switch Q8 is referred to as the midpoint of the fourth bridge arm.

[0216] The fifth bridge arm includes a ninth switch Q9 and a tenth switch Q10 connected in series, with the first end of the ninth switch Q9 connected to the first end of the tenth switch Q10. The common end of the ninth switch Q9 and the tenth switch Q10 is then referred to as the midpoint of the fifth bridge arm.

[0217] The sixth bridge arm includes an eleventh switch Q11 and a twelfth switch Q12 connected in series, with the first end of the eleventh switch Q11 connected to the first end of the twelfth switch Q12. The common end of the eleventh switch Q11 and the twelfth switch Q12 is then referred to as the midpoint of the sixth bridge arm.

[0218] The seventh bridge arm includes a thirteenth switch Q13 and a fourteenth switch Q14 connected in series, with the first end of the thirteenth switch Q13 connected to the first end of the fourteenth switch Q14. The common terminal of the thirteenth switch Q13 and the fourteenth switch Q14 is referred to as the midpoint of the seventh bridge arm.

[0219] The fourth bridge arm is connected in parallel with the fifth bridge arm. For example, the second end of the seventh switch Q7 is connected to the second end of the ninth switch Q9, and the second end of the eighth switch Q8 is connected to the second end of the tenth switch Q10.

[0220] The sixth bridge arm, the seventh bridge arm, and the second capacitor E2 are connected in parallel. For example, the second terminal of the eleventh switch Q11 is connected to the second terminal of the thirteenth switch Q13 and the first terminal of the second capacitor E2, and the second terminal of the twelfth switch Q12 is connected to the second terminal of the fourteenth switch Q14 and the second terminal of the second capacitor E2. It should be understood that the second capacitor E2 can be a DC capacitor used to provide filtering function so that the voltage conversion circuit provides a stable DC current when charging or discharging the battery pack.

[0221] The first terminal A of transformer TX1 (i.e., the opposite terminal on the low-voltage side of transformer TX1) is connected to the midpoint of the fourth bridge arm; the second terminal B of transformer TX1 (i.e., the same terminal on the low-voltage side of transformer TX1) is connected to the midpoint of the fifth bridge arm; the third terminal C of transformer TX1 (i.e., the same terminal on the high-voltage side of transformer TX1) is connected to the first terminal of the fifth inductor Lik; the second terminal of the fifth inductor Lik is connected to the midpoint of the sixth bridge arm; the fourth terminal D of transformer TX1 (i.e., the opposite terminal on the high-voltage side of transformer TX1) is connected to the first terminal of the third capacitor Cr; and the second terminal of the third capacitor Cr is connected to the midpoint of the seventh bridge arm.

[0222] In this voltage conversion circuit, the second terminal of the seventh switch Q7 is the first terminal of the voltage conversion circuit, the second terminal of the eighth switch Q8 is the second terminal of the voltage conversion circuit, the second terminal of the thirteenth switch Q13 is the third terminal of the voltage conversion circuit, and the second terminal of the fourteenth switch Q14 is the fourth terminal of the voltage conversion circuit.

[0223] When using Figure 3 When the voltage conversion circuit shown is charging the battery pack, it operates in full-bridge LLC resonant converter mode. That is, the second voltage conversion unit, the LC resonant cavity, and the inductor (not shown in the figure) in transformer TX1 constitute a full-bridge LLC resonant network, making the voltage conversion circuit a full-bridge LLC resonant converter. At this time, a full-bridge phase-shift control strategy can be used to control this full-bridge LLC resonant converter, enabling the leading arm of the full-bridge LLC resonant converter to achieve zero-voltage turn-on, and the lagging arm to achieve zero-voltage turn-on and zero-current turn-off. For specific operating principles, please refer to the existing technology descriptions of full-bridge LLC resonant converters; further details will not be elaborated here.

[0224] In this full-bridge LLC resonant converter mode, Q11, Q12, Q13, and Q14 are used as switching transistors, and the external diodes (also called parasitic diodes, etc.) of Q7, Q8, Q9, and Q10 are used as rectifiers. For example, a phase-shifting duty cycle method can be used to control the switching transistors in the second voltage conversion unit to turn on or off to charge the battery pack. The phase-shifting duty cycle mentioned here refers to changing the on-time of the switching transistors in the second voltage conversion unit by adjusting the phase difference between the leading and lagging arms in the full-bridge LLC resonant converter. The fixed-frequency method refers to voltage regulation control using a fixed frequency.

[0225] When using Figure 3 The voltage conversion circuit shown operates in the full-bridge secondary LC resonant converter mode when the battery pack is discharging. That is, the first voltage conversion unit of the voltage conversion circuit, the secondary side of the transformer TX1, and the LC resonant cavity constitute a full-bridge secondary LC resonant converter, realizing zero-voltage turn-on and zero-current turn-off. For the specific working principle, please refer to the introduction of the full-bridge secondary LC resonant converter in the prior art, which will not be repeated here.

[0226] It should be understood that when the voltage conversion circuit discharges the battery pack, the secondary side of the transformer TX1 connected to the LC resonant cavity is the high-voltage side of the voltage conversion circuit. When the voltage conversion circuit charges the battery pack, the secondary side of the transformer TX1 connected to the first voltage conversion unit is the low-voltage side of the voltage conversion circuit.

[0227] In this full-bridge secondary-side LC resonant converter mode, Q7, Q8, Q9, and Q10 are used as switching transistors, and the external diodes (also called parasitic diodes, etc.) of Q11, Q12, Q13, and Q14 are used as rectifiers. For example, a fixed-frequency, fixed-duty-cycle control method can be used to discharge the battery pack. Here, Q7 and Q10 are turned on simultaneously, and Q8 and Q9 are turned on simultaneously. The fixed duty cycle refers to using the same duty cycle to control Q7, Q8, Q9, and Q10, so that the conduction duration of Q7 and Q10 is the same as that of Q8 and Q9. The fixed frequency refers to using a fixed frequency for voltage regulation control.

[0228] The structure of the voltage conversion circuit described above enables soft switching. Soft-switching is a switching technique relative to hard-switching. Soft-switching technology allows the voltage of the switching transistor in the voltage conversion circuit to be reduced to zero before turn-on and the current to be reduced to zero before turn-off (i.e., zero-voltage turn-on and zero-current turn-off). This eliminates the overlap of voltage and current during the switching process, reduces their rate of change, and thus significantly reduces or even eliminates the switching losses in the voltage conversion circuit, enabling high-frequency operation of the voltage conversion circuit.

[0229] Because voltage conversion circuits with soft switching have poor voltage regulation capability. That is to say, when the voltage conversion circuit achieves voltage regulation with a large voltage difference, it can only achieve zero-voltage turn-on and cannot achieve zero-current turn-off. As a result, the voltage conversion circuit cannot achieve soft switching under all operating conditions of zero-voltage turn-on and zero-current turn-off. In other words, the voltage conversion circuit cannot operate under the full operating condition of zero-voltage turn-on and zero-current turn-off, which leads to a lower conversion efficiency than under the full operating condition, increasing the current stress risk and heat loss risk of the voltage conversion circuit.

[0230] Therefore, when the aforementioned voltage conversion circuit with soft switching is applied to the three-arm topology device provided in this application embodiment, by connecting the voltage conversion circuit in series with "the first inductor L1 and the first arm of the three-arm circuit forming a Boost converter circuit," the voltage conversion circuit can achieve a soft-switching function with a fixed boost ratio (which, for example, can achieve voltage regulation with a small voltage difference). The Boost converter circuit formed by the first inductor L1 and the first arm of the three-arm circuit achieves voltage regulation. That is, while obtaining a large boost ratio, the voltage conversion circuit with soft switching itself does not need to perform a large voltage difference boosting process. In this way, the voltage conversion circuit with soft switching can operate under the full operating condition of zero voltage turn-on and zero current turn-off, improving the conversion efficiency of the voltage conversion circuit with soft switching, thereby reducing the current stress risk and heat loss risk of the voltage conversion circuit with soft switching, and improving the reliability of the UPS system with low battery voltage and high current.

[0231] It should be understood that Figure 3 This is merely an illustration of a voltage conversion circuit with soft switching. In actual implementation, the solution of this application embodiment can also use other voltage conversion circuits with soft switching.

[0232] In addition, the above Figure 3 The first voltage conversion unit in the voltage conversion circuit shown can also be implemented using other circuit structures, and the transformer TX1, the LC resonant cavity, and the second voltage conversion unit can also be connected in other ways. For details, please refer to the descriptions of these parts in the subsequent embodiments (e.g., Figures 25 to 35 The implementation principle is similar (as described above), so I will not go into details here.

[0233] In addition, although the above Figure 3 Therefore, a voltage conversion circuit with electrical isolation is provided (e.g.) Figure 3The diagram illustrates a voltage conversion circuit with an electrical isolation implemented by a transformer. However, it should be understood that the voltage conversion circuit described in this application can be either electrically isolated or non-electrically isolated. For example, the voltage conversion circuit may have electrical isolation while the first arm of the three-arm circuit may not have electrical isolation; or, the voltage conversion circuit may not have electrical isolation while the first arm of the three-arm circuit has electrical isolation; or, the voltage conversion circuit may have electrical isolation while the first arm of the three-arm circuit has electrical isolation; or, the voltage conversion circuit may not have electrical isolation while the first arm of the three-arm circuit does not have electrical isolation, etc.

[0234] It should be noted that when the above-mentioned three-arm topology device switches from external power supply mode to battery power supply mode, or vice versa, there is a certain time difference in the mode switching (for example, there may be a time difference of X seconds from the disconnection of the mains power to the battery power supply). Therefore, within this time difference, the three-arm topology device can use the voltage stored in the DC bus capacitor E1 to supply power to the load, so as to provide stable AC power to the load and avoid the load losing power.

[0235] The three-arm topology device provided in this application uses a voltage conversion circuit to charge or discharge the battery pack, eliminating the need for an additional charger. Furthermore, both the voltage conversion circuit and the three-arm circuit operate in both external power supply and battery power supply modes, meaning all components of the three-arm topology device are active. When this three-arm topology device is applied to a low-voltage, high-current UPS system, it improves the component reuse rate, avoids redundant component design, and thus reduces the cost of the low-voltage, high-current UPS system.

[0236] The following example illustrates how the above-mentioned switch can be implemented:

[0237] Continue to refer to Figure 2 In a three-arm topology device, the switching switches may include, for example, a first switch K1, a second switch K2, and a balancing element.

[0238] The voltage conversion circuit has the third terminal connected to the fixed terminal of the first switch K1, the first selection terminal of the first switch K1 connected to the first terminal of the balancing component, the second terminal of the balancing component connected to BUS+, the second selection terminal of the first switch K1 connected to the positive voltage input terminal AC_L, the first terminal of the second switch K2 connected to the live wire of the AC mains power supply, the second terminal of the second switch K2 connected to the positive voltage input terminal AC_L, and the fourth terminal of the voltage conversion circuit connected to BUS-.

[0239] In external power supply mode, the fixed terminal of the first switch K1 is connected to the first selector terminal of the first switch K1, and the second switch K2 is closed. In battery power supply mode, the fixed terminal of the first switch K1 is connected to the second selector terminal of the first switch K1, and the second switch K2 is open. For example, the first switch K1 can be any selector switch that can be turned on or off according to a control signal, such as a double-throw relay, a bidirectional electronic switch, or a thyristor. The second switch K2 can be any switch that can be turned on or off according to a control signal, such as a single-throw relay, a one-way electronic switch, or a thyristor.

[0240] The aforementioned balancing components are used to balance the voltage between the BUS of the three-bridge arm circuit and the voltage conversion circuit in the external power supply mode, thereby preventing a large current from being input to the voltage conversion circuit at the moment when the fixed terminal of the first switch K1 is connected to the first select terminal of the first switch K1, thus enabling overcurrent protection for the voltage conversion circuit.

[0241] Continue to refer to Figure 2 In one possible implementation, the aforementioned balancing component could be, for example, a varistor RZ.

[0242] Figure 4 This is a schematic diagram of a second three-arm topology device provided in an embodiment of this application. Figure 4 As shown, in the second possible implementation, the aforementioned balancing component can be, for example, a thermistor RT with a negative temperature coefficient.

[0243] Figure 5 This is a schematic diagram of a third three-arm topology device provided in an embodiment of this application. Figure 5 As shown, in the third possible implementation, the aforementioned balancing component can be, for example, a third inductor L3.

[0244] Figure 6 This is a schematic diagram of a fourth three-arm topology device provided in an embodiment of this application. Figure 6 As shown, in a fourth possible implementation, the balancing component can be, for example, a resistor R1. In this implementation, the switching switch may further include a third switch K3.

[0245] Continue to refer to Figure 6 The third terminal of the voltage conversion circuit is connected to the first terminal of the third switch K3, and the second terminal of the third switch K3 is connected to BUS+. Figure 7 This is a schematic diagram of a fifth three-arm topology device provided in an embodiment of this application. Figure 7 As shown, in the fifth possible connection method, the third switch K3 is connected in parallel with the resistor R1.

[0246] Reference Figure 6 or Figure 7The switch shown closes the third switch K3 in external power supply mode when the voltage difference between the bus and the voltage conversion circuit is less than or equal to a preset threshold, allowing the voltage conversion circuit to charge the battery pack. In battery power supply mode, the third switch K3 is open. This preset threshold can be, for example, less than or equal to 20V, and can be specifically determined based on the operating environment of the UPS system to which the three-arm topology is applied.

[0247] For example, the third switch K3 mentioned above can be any switch that can be turned on or off according to a control signal, such as a single-throw relay, a one-way electronic switch, a thyristor, etc.

[0248] It should be understood that the second switch K2 and the third switch K3 can be the same switch or different switches. For example, the second switch K2 can be a thyristor, and the third switch K3 can be a unidirectional electronic switch.

[0249] The following is based on Figure 6 Taking the structure of the three-arm topology shown as an example, the states of each switch, each switching transistor, and the current flow of the three-arm topology under different power supply modes are illustrated:

[0250] External power supply mode: The fixed terminal of the first switch K1 is connected to the first select terminal of the first switch K1, the second switch K2 is closed, and the third switch K3 is closed when the voltage difference between the BUS+ of the three-arm topology and the voltage conversion circuit of the three-arm topology is less than or equal to a preset threshold. At this time, the voltage conversion circuit operates in Buck mode. This preset threshold can be, for example, less than or equal to 20V, and can be determined according to the operating environment of the UPS system in which the three-arm topology is used.

[0251] Figure 8 Current diagram of the fourth three-arm topology device provided in the embodiments of this application under external power supply mode. Figure 1 .like Figure 8 As shown, during the first stage of the positive half-cycle of the alternating current, the second switch Q2 and the fourth switch Q4 controlling the three-bridge arm circuit are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0252] 1. The live wire of the AC mains power supply → the first inductor L1 → the second switch Q2 → the fourth switch Q4 → the neutral wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0253] 2. BUS+ → Positive terminal of voltage conversion circuit → Positive terminal of battery pack → Negative terminal of battery pack → Negative terminal of voltage conversion circuit → BUS-, which constitutes the energy storage circuit of battery pack.

[0254] Figure 9Current diagram of the fourth three-arm topology device provided in the embodiments of this application under external power supply mode. Figure 2 ,like Figure 9 As shown, in the second stage of the positive half-cycle of the alternating current, the first switch Q1 and the fourth switch Q4 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0255] 1. The live wire of the AC mains power supply → first inductor L1 → first switch Q1 → DC bus capacitor E1 → fourth switch Q4 → neutral wire of the AC mains power supply constitutes an energy storage circuit in which the first inductor L1 and the AC mains power supply simultaneously store energy for the DC bus capacitor E1.

[0256] 2. BUS+ → Positive terminal of voltage conversion circuit → Positive terminal of battery pack → Negative terminal of battery pack → Negative terminal of voltage conversion circuit → BUS-, which constitutes the energy storage circuit of battery pack.

[0257] Figure 10 Current diagram of the fourth three-arm topology device provided in the embodiments of this application under external power supply mode. Figure 3 ,like Figure 10 As shown, in the first stage of the negative half-cycle of the alternating current, the first switch Q1 and the third switch Q3 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0258] 1. The neutral wire of the AC mains power supply → the third switch Q3 → the first switch Q1 → the first inductor L1 → the live wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0259] 2. BUS+ → Positive terminal of voltage conversion circuit → Positive terminal of battery pack → Negative terminal of battery pack → Negative terminal of voltage conversion circuit → BUS-, which constitutes the energy storage circuit of battery pack.

[0260] Figure 11 Current diagram of the fourth three-arm topology device provided in the embodiments of this application under external power supply mode. Figure 4 ,like Figure 11 As shown, in the second stage of the negative half-cycle of the AC current, the second switch Q2 and the third switch Q3 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0261] 1. The neutral wire of the AC mains power supply → the third switch Q3 → the DC bus capacitor E1 → the second switch Q2 → the first inductor L1 → the live wire of the AC mains power supply constitutes an energy storage circuit in which the first inductor L1 and the AC mains power supply simultaneously store energy for the DC bus capacitor E1.

[0262] 2. BUS+ → Positive terminal of voltage conversion circuit → Positive terminal of battery pack → Negative terminal of battery pack → Negative terminal of voltage conversion circuit → BUS-, which constitutes the energy storage circuit of battery pack.

[0263] Battery powered mode: The fixed terminal of the first switch K1 is connected to the second select terminal of the first switch K1, while the second switch K2 and the third switch K3 are disconnected. At this time, the voltage conversion circuit operates in Boost mode.

[0264] Figure 12 Current diagram of the fourth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 5 ,like Figure 12 As shown, in the first stage of the battery-powered mode, the second switch Q2 is turned on. At this time, the current flow in the three-bridge topology is as follows:

[0265] The battery pack positive terminal → voltage conversion circuit positive terminal → first inductor L1 → second switch Q2 → voltage conversion circuit negative terminal → battery pack negative terminal forms the energy storage circuit of the first inductor L1.

[0266] Figure 12 Current diagram of the fourth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 6 ,like Figure 13 As shown, in the second stage of the battery-powered mode, the first switch Q1 is turned on. At this time, the current flow in the three-bridge topology is as follows:

[0267] The battery pack positive terminal → voltage conversion circuit positive terminal → first inductor L1 → first switching transistor Q1 → DC bus capacitor E1 → voltage conversion circuit negative terminal → battery pack negative terminal forms the energy storage circuit of DC bus capacitor E1.

[0268] It should be understood that, although the above Figures 8 to 12 The current flow of the three-arm topology shown is all in the direction of Figure 6 The fourth type of three-bridge topology is illustrated as an example. However, those skilled in the art will understand that the current flow, as well as the states of each switch and each switching transistor, also apply to this. Figure 7 The three-bridge topology shown is implemented on a similar principle, and will not be described in detail here.

[0269] In addition, when adopting Figures 2 to 5 For any three-arm topology device, the states of each switch, the states of each switching transistor, and the current flow in different modes are shown below:

[0270] External power supply mode: The fixed terminal of the first switch K1 is connected to the first select terminal of the first switch K1, and the second switch K2 is closed. At this time, the voltage conversion circuit operates in Buck mode.

[0271] In this mode, the state of each switch in the three-arm topology device under external power supply mode is the same as... Figure 6 The three-arm bridge topology shown has the same state for each switch in external power supply mode. The current flow of this three-arm bridge topology is... Figure 6 The three-bridge topology shown has the same current flow in external power supply mode; see reference for details. Figures 8 to 11 The corresponding descriptions will not be repeated here.

[0272] Battery powered mode: The fixed terminal of the first switch K1 is connected to the second select terminal of the first switch K1, and the second switch K2 is disconnected. At this time, the voltage conversion circuit operates in Boost mode.

[0273] In this mode, the state of each switch in the three-arm topology device under battery power mode is similar to... Figure 6 The three-arm bridge topology shown has the same state for each switch in battery-powered mode. The current flow of this three-arm bridge topology is... Figure 6 The three-bridge topology shown has the same current flow in battery-powered mode; see reference for details. Figures 12 to 13 The corresponding descriptions will not be repeated here.

[0274] Figure 14 This is a schematic diagram of a sixth three-arm topology device provided in an embodiment of this application. Figure 4 As shown, in a three-arm topology device, the switching switch may include, for example, a first switch K1, a second switch K2, and a balancing element.

[0275] The third terminal of the voltage conversion circuit is connected to the first terminal of the first switch K1 and the first selection terminal of the second switch K2. The second terminal of the first switch K1 is connected to the first terminal of the balancing component. The second terminal of the balancing component is connected to BUS+. The second selection terminal of the second switch K2 is connected to the live wire of the AC power supply. The fixed terminal of the second switch K2 is connected to the positive voltage input terminal AC_L. The fourth terminal of the voltage conversion circuit is connected to BUS-.

[0276] In external power supply mode, the first switch K1 is closed, and the fixed terminal of the second switch K2 is connected to the second selector terminal of the second switch K2. In battery power supply mode, the first switch K1 is open, and the fixed terminal of the second switch K2 is connected to the first selector terminal of the second switch K2. For example, the first switch K1 can be any switch that can be turned on or off according to a control signal, such as a single-throw relay, a one-way electronic switch, or a thyristor. The second switch K2 can be any selector switch that can be turned on or off according to a control signal, such as a double-throw relay, a two-way electronic switch, or a thyristor.

[0277] The aforementioned balancing components are used to balance the voltage between the BUS+ of the three-bridge arm circuit and the voltage conversion circuit in the external power supply mode, thereby preventing a large current from being input to the voltage conversion circuit at the moment when the fixed terminal of the first switch K1 is connected to the first select terminal of the first switch K1, thus enabling overcurrent protection for the voltage conversion circuit.

[0278] Continue to refer to Figure 14 The sixth possible implementation is that the aforementioned balancing component can be, for example, a varistor RZ.

[0279] Figure 15 This is a schematic diagram of a seventh three-arm topology device provided in an embodiment of this application. Figure 15 As shown, in the seventh possible implementation, the aforementioned balancing component can be, for example, a thermistor RT with a negative temperature coefficient.

[0280] Figure 16 This is a schematic diagram of the eighth three-arm topology device provided in the embodiments of this application. Figure 16 As shown, in the eighth possible implementation, the aforementioned balancing component can be, for example, a third inductor L3.

[0281] When using Figures 14 to 16 For any three-arm topology device, the states of each switch, the states of each switching transistor, and the current flow in different modes are shown below:

[0282] External power supply mode: Control the first switch K1 to close, and connect the fixed terminal of the second switch K2 to the second select terminal of the second switch K2. At this time, the voltage conversion circuit operates in Buck mode.

[0283] In this mode, the state of each switch in the three-arm topology device under external power supply mode is the same as... Figure 6 The three-arm bridge topology shown has the same state for each switch in external power supply mode. The current flow of this three-arm bridge topology is... Figure 6 The three-bridge topology shown has the same current flow in external power supply mode; see reference for details. Figures 8 to 11 The corresponding descriptions will not be repeated here.

[0284] Battery powered mode: The first switch K1 is opened, and the fixed terminal of the second switch K2 is connected to the first select terminal of the second switch K2. At this time, the voltage conversion circuit operates in Boost mode.

[0285] In this mode, the state of each switch in the three-arm topology device under battery power mode is similar to... Figure 6 The three-arm bridge topology shown has the same state for each switch in battery-powered mode. The current flow of this three-arm bridge topology is... Figure 6 The three-bridge topology shown has the same current flow in battery-powered mode; see reference for details. Figures 12 to 13 The corresponding descriptions will not be repeated here.

[0286] Figure 17 This is a schematic diagram of a ninth three-arm topology device provided in an embodiment of this application. Figure 17 As shown, in the ninth possible implementation, the balancing component can be, for example, a resistor R1. In this implementation, the switching switch may further include a third switch K3.

[0287] Continue to refer to Figure 17 The third terminal of the voltage conversion circuit is connected to the first terminal of the third switch K3, and the second terminal of the third switch K3 is connected to BUS+. Figure 18 This is a schematic diagram of a tenth three-arm topology device provided in an embodiment of this application. Figure 18 As shown, in the tenth possible connection method, the third switch K3 is connected in parallel with the resistor R1.

[0288] Reference Figure 17 or Figure 18 The switch shown closes the third switch K3 in external power supply mode when the voltage difference between the bus and the voltage conversion circuit is less than or equal to a preset threshold, allowing the voltage conversion circuit to charge the battery pack. In battery power supply mode, the third switch K3 is open. This preset threshold can be, for example, less than or equal to 20V, and can be specifically determined based on the operating environment of the UPS system to which the three-arm topology is applied.

[0289] For example, the third switch K3 mentioned above can be any switch that can be turned on or off according to a control signal, such as a single-throw relay, a one-way electronic switch, a thyristor, etc.

[0290] It should be understood that the first switch K1 and the third switch K3 can be the same switch or different switches. For example, the first switch K1 can be a thyristor, and the third switch K3 can be a unidirectional electronic switch.

[0291] When using Figures 17 to 18For any three-arm topology device, the states of each switch, the states of each switching transistor, and the current flow in different modes are shown below:

[0292] External power supply mode: Control the first switch K1 to close, connect the fixed terminal of the second switch K2 to the second select terminal of the second switch K2, and control the third switch K3 to close when the voltage difference between the BUS of the three-arm topology and the voltage conversion circuit of the three-arm topology is less than or equal to a preset threshold. At this time, the voltage conversion circuit operates in Buck mode. This preset threshold can be, for example, less than or equal to 20V, and can be specifically determined according to the operating environment of the UPS system in which the three-arm topology is used.

[0293] In this mode, the state of each switch in the three-arm topology device under external power supply mode is the same as... Figure 6 The three-arm bridge topology shown has the same state for each switch in external power supply mode. The current flow of this three-arm bridge topology is... Figure 6 The three-bridge topology shown has the same current flow in external power supply mode; see reference for details. Figures 8 to 11 The corresponding descriptions will not be repeated here.

[0294] Battery powered mode: Control switches K1 and K3 are disconnected, and the fixed terminal of switch K2 is connected to the first select terminal of switch K2. In this mode, the voltage conversion circuit operates in Boost mode.

[0295] In this mode, the state of each switch in the three-arm topology device under battery power mode is similar to... Figure 6 The three-arm bridge topology shown has the same state for each switch in battery-powered mode. The current flow of this three-arm bridge topology is... Figure 6 The three-bridge topology shown has the same current flow in battery-powered mode; see reference for details. Figures 12 to 13 The corresponding descriptions will not be repeated here.

[0296] Figure 19 This is a schematic diagram of an eleventh three-arm topology device provided in an embodiment of this application. Figure 19 As shown, in a three-arm topology device, the switching switches may include, for example, a first switch K1, a second switch K2, a third switch K3, and a balancing component.

[0297] The third terminal of the voltage conversion circuit is connected to the first terminal of the first switch K1 and the first terminal of the third switch K3. The second terminal of the first switch K1 is connected to the positive voltage input terminal AC_L. The first terminal of the second switch K2 is connected to the live wire of the AC power supply. The second terminal of the second switch K2 is connected to the positive voltage input terminal AC_L. The second terminal of the third switch K3 is connected to the first terminal of the balancing component. The second terminal of the balancing component is connected to BUS+. The fourth terminal of the voltage conversion circuit is connected to BUS-.

[0298] In external power supply mode, the first switch K1 is open, and the second switch K2 and the third switch K3 are closed; in battery power supply mode, the first switch K1 is closed, and the second switch K2 and the third switch K3 are open.

[0299] The aforementioned balancing components are used to balance the voltage between the BUS of the three-arm bridge circuit and the voltage conversion circuit in the external power supply mode, thereby preventing a large current from being input to the voltage conversion circuit at the moment the first switch K3 is closed, thus enabling overcurrent protection for the voltage conversion circuit.

[0300] Continue to refer to Figure 19 In the eleventh possible implementation, the aforementioned balancing component can be, for example, a varistor RZ.

[0301] Figure 20 This is a schematic diagram of the twelfth three-arm topology device provided in the embodiments of this application. Figure 20 As shown, in the twelfth possible implementation, the aforementioned balancing component can be, for example, a thermistor RT with a negative temperature coefficient.

[0302] Figure 21 This is a schematic diagram of the thirteenth three-arm topology device provided in this application embodiment. Figure 21 As shown, in the thirteenth possible implementation, the aforementioned balancing component can be, for example, a third inductor L3.

[0303] When using Figures 19 to 21 For any three-arm topology device, the states of each switch, the states of each switching transistor, and the current flow in different modes are shown below:

[0304] External power supply mode: Control the first switch K1 to open, and the second switch K2 and the third switch K3 to close. At this time, the voltage conversion circuit operates in Buck mode.

[0305] In this mode, the state of each switch in the three-arm topology device under external power supply mode is the same as... Figure 6 The three-arm bridge topology shown has the same state for each switch in external power supply mode. The current flow of this three-arm bridge topology is... Figure 6The three-bridge topology shown has the same current flow in external power supply mode; see reference for details. Figures 8 to 11 The corresponding descriptions will not be repeated here.

[0306] Battery powered mode: Controls the first switch K1 to close, and the second switch K2 and the third switch K3 to open. At this time, the voltage conversion circuit operates in Boost mode.

[0307] In this mode, the state of each switch in the three-arm topology device under battery power mode is similar to... Figure 6 The three-arm bridge topology shown has the same state for each switch in battery-powered mode. The current flow of this three-arm bridge topology is... Figure 6 The three-bridge topology shown has the same current flow in battery-powered mode; see reference for details. Figures 12 to 13 The corresponding descriptions will not be repeated here.

[0308] Figure 22 This is a schematic diagram of the fourteenth three-arm topology device provided in this application embodiment. Figure 22 As shown, in the fourteenth possible implementation, the balancing component can be, for example, a resistor R1. In this implementation, the switching switch may further include a fourth switch K4.

[0309] Continue to refer to Figure 22 The third terminal of the voltage conversion circuit is connected to the first terminal of the fourth switch K4, and the second terminal of the fourth switch is connected to BUS+. Figure 23 This is a schematic diagram of the fifteenth three-arm topology device provided in the embodiments of this application. Figure 23 As shown, in the fifteenth possible connection method, the fourth switch K4 is connected in parallel with the resistor R1.

[0310] Reference Figure 22 or Figure 23 The switch shown closes the fourth switch K4 in external power supply mode when the voltage difference between the bus and the voltage conversion circuit is less than or equal to a preset threshold, allowing the voltage conversion circuit to charge the battery pack. In battery power supply mode, the fourth switch K4 is open. This preset threshold can be, for example, less than or equal to 20V, and can be specifically determined according to the operating environment of the UPS system in which the three-arm topology device is used.

[0311] For example, the fourth switch K4 can be any switch that can be turned on or off according to a control signal, such as a single-throw relay, a one-way electronic switch, a thyristor, etc.

[0312] In this embodiment, the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 can be any switch capable of being turned on or off according to a control signal, such as a single-throw relay, a one-way electronic switch, or a thyristor. It should be understood that the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 can be the same switch or different switches. For example, the first switch K1 can be a thyristor, while the second switch K2, the third switch K3, and the fourth switch K4 can be single-throw relays, etc. This embodiment does not limit this.

[0313] When using Figures 22 to 23 For any three-arm topology device, the states of each switch, the states of each switching transistor, and the current flow in different modes are shown below:

[0314] External power supply mode: Control switch K1 to open, switch K2 and switch K3 to close, and control switch K4 to close when the voltage difference between the BUS of the three-arm topology and the voltage conversion circuit of the three-arm topology is less than or equal to a preset threshold. At this time, the voltage conversion circuit operates in Buck mode. This preset threshold can be, for example, less than or equal to 20V, and can be specifically determined according to the operating environment of the UPS system in which the three-arm topology is used.

[0315] In this mode, the state of each switch in the three-arm topology device under external power supply mode is the same as... Figure 6 The three-arm bridge topology shown has the same state for each switch in external power supply mode. The current flow of this three-arm bridge topology is... Figure 6 The three-bridge topology shown has the same current flow in external power supply mode; see reference for details. Figures 8 to 11 The corresponding descriptions will not be repeated here.

[0316] Battery powered mode: Controls the first switch K1 to close, and the second switch K2, the third switch K3, and the fourth switch K4 to open. At this time, the voltage conversion circuit operates in Boost mode.

[0317] In this mode, the state of each switch in the three-arm topology device under battery power mode is similar to... Figure 6 The three-arm bridge topology shown has the same state for each switch in battery-powered mode. The current flow of this three-arm bridge topology is... Figure 6 The three-bridge topology shown has the same current flow in battery-powered mode; see reference for details. Figures 12 to 13 The corresponding descriptions will not be repeated here.

[0318] It should be understood that the above Figure 2 , Figures 4 to 7 ,as well as, Figures 14 to 23The switch shown is merely an example. Since there are many ways to implement switchboards, they will not be listed here in detail for applications in three-arm topologies. In actual implementation, a switchboard can be selected according to actual needs to control the voltage conversion circuit to charge the battery pack in external power supply mode and to control the voltage conversion circuit to discharge the battery pack in battery power supply mode. This will not be elaborated further.

[0319] In the above Figure 2 , Figures 4 to 7 ,as well as, Figures 14 to 23 In the example of the three-arm topology shown, the voltage conversion circuit can be any circuit with bidirectional voltage conversion capability. For example, Figure 3 The voltage conversion circuits shown are not limited in this respect.

[0320] Structure B: The three-arm topology includes a battery pack, a voltage conversion circuit, and a three-arm circuit, without a switching switch. This three-arm topology can be applied to inverter systems or UPS systems with low-voltage, high-current batteries. It should be noted that the following embodiments involve concepts or processes that are the same as or similar to those in the aforementioned three-arm topology, and will not be repeated here. For details, please refer to the description of the aforementioned three-arm topology.

[0321] Figure 24 This is a schematic diagram of the sixteenth three-arm topology device provided in the embodiments of this application. Figure 24 As shown, the three-bridge-arm topology device may include: a battery pack, a voltage conversion circuit, and a three-bridge-arm circuit. The voltage conversion circuit is connected to both the battery pack and the three-bridge-arm circuit.

[0322] The three-bridge-arm circuit includes: a first bridge arm, a second bridge arm, a third bridge arm, a DC bus capacitor E1, and an LC filter. The first bridge arm includes a first and a second switch connected in series; the second bridge arm includes a third and a fourth switch connected in series; the third bridge arm includes a fifth and a sixth switch connected in series; the LC filter includes a first capacitor Co and a second inductor L2. The first, second, and third bridge arms, along with the DC bus capacitor E1, are connected in parallel between the positive output terminal BUS+ and the negative output terminal BUS- of the bus. The midpoint of the third bridge arm is connected to the first terminal of the second inductor L2, the second terminal of the second inductor L2 is connected to the first terminal of the first capacitor Co, and the second terminal of the first capacitor Co is connected to the midpoint of the second bridge arm. The first terminal of the first capacitor Co is the first output terminal of the three-bridge-arm topology, and the second terminal of the first capacitor Co is the second output terminal of the three-bridge-arm topology.

[0323] In this embodiment, the voltage conversion circuit can achieve voltage conversion through its own circuit structure, or by reusing the bus capacitor E1 of the three-arm circuit, or by "reusing the second arm and the bus capacitor E1". Therefore, whether charging or discharging the battery pack, all components of the three-arm topology device participate in the operation, improving the component reuse rate of the three-arm topology device. When this three-arm topology device is applied to a low-voltage, high-current UPS system or inverter system, the component reuse rate of the low-voltage, high-current UPS system or inverter system can be improved, thereby reducing the cost of the system.

[0324] The specific structure and working principle of this three-arm topology device are explained below:

[0325] Structure B1: The voltage conversion circuit in this three-arm topology achieves voltage conversion through its own circuit structure. This three-arm topology is applied to battery-powered low-voltage, high-current UPS systems powered by AC mains. For example, it is a battery-powered high-current UPS system with a narrow range of battery input voltage; exemplary, it is a battery-powered high-current UPS system using lithium batteries. It should be understood that the battery input voltage referred to here is the voltage output by the battery pack when the battery pack is used to power the load. In some embodiments, this three-arm topology can also be applied to Emergency Power Supply (EPS) systems.

[0326] Continue to refer to Figure 24 In this structure B1, the three-arm circuit of the three-arm topology also includes a first inductor L1.

[0327] The first inductor L1 is a high-frequency inductor on the PFC side, and the inductors included in the filter (e.g., the second inductor L2) are high-frequency inductors on the INV side. The midpoint of the first bridge arm is connected to the first end of the first inductor L1, and the second end of the first inductor L1 serves as the positive voltage input terminal AC_L of the three-bridge-arm topology. The midpoint of the second bridge arm serves as the negative voltage input terminal AC_N of the three-bridge-arm topology. The live wire of the AC mains power supply is connected to the positive voltage input terminal AC_L, and the neutral wire of the AC mains power supply is connected to the negative voltage input terminal AC_N.

[0328] Optionally, in some embodiments, the live wire of the AC mains power supply is connected to the positive voltage input terminal AC_L via switch K5 to meet the safety requirements of the three-arm topology. It should be understood that switch K5 can be, for example, a unidirectional electronic switch, a bidirectional thyristor, etc.

[0329] The midpoint of the third bridge arm is connected to the first end of the second inductor L2, the second end of the second inductor L2 is connected to the first end of the first capacitor Co, and the second end of the first capacitor Co is connected to the midpoint of the second bridge arm. The first end of the first capacitor Co is the first output terminal of the three-bridge-arm topology, and the second end of the first capacitor Co is the second output terminal of the three-bridge-arm topology, both of which are connected to the load.

[0330] The positive terminal of the battery pack is connected to the first terminal of the voltage conversion circuit, and the negative terminal of the battery pack is connected to the second terminal of the voltage conversion circuit. The third terminal of the voltage conversion circuit is connected to BUS+, and the fourth terminal of the voltage conversion circuit is connected to BUS-.

[0331] The three-arm circuit involved in this embodiment is used to realize rectification and inversion functions when the three-arm topology device supplies power to the load. Specifically, it can be described in conjunction with the power supply mode adopted when the three-arm topology device supplies power to the load. Therefore, in some embodiments, the three-arm circuit involved in this embodiment can also be called a three-arm converter circuit.

[0332] Specifically, the three-arm topology device has two power supply modes: external power supply mode and battery power supply mode.

[0333] In external power supply mode, the AC mains power supply powers the three-bridge circuit, and the voltage conversion circuit charges the battery pack. At this time, the three-bridge circuit operates in AC-AC mode, and the voltage conversion circuit operates in BUCK mode (i.e., step-down mode), stepping down the BUS voltage output from the DC bus capacitor E1 to obtain the charging voltage for the battery pack, which is then used to charge the battery pack. In this mode, the battery pack serves as the output source for the voltage conversion circuit.

[0334] In this way, under external power supply mode, both the voltage conversion circuit and the three-arm circuit participate in the operation; that is, all components of the three-arm topology device are involved. For the technical effects of using a voltage conversion circuit to charge the battery pack, please refer to the aforementioned embodiments. Figure 2 The description uses a voltage conversion circuit to charge the battery pack.

[0335] In battery-powered mode, the battery pack serves as the input source for the voltage conversion circuit, and the output of the voltage conversion circuit powers the three-arm circuit. That is, the voltage conversion circuit discharges the battery pack. At this time, the voltage conversion circuit operates in Boost mode, boosting the output voltage of the battery pack. The boosted voltage is then input to the DC bus capacitor E1 of the three-arm circuit to maintain bus voltage balance. The first arm of the three-arm circuit operates in DC-DC mode, and the DC bus capacitor E1 filters the boosted DC power to obtain a stable DC power. The second and third arms of the three-arm circuit operate in inverter mode, converting the stable DC power into AC power and outputting it to the load to power it. Simultaneously, the DC bus capacitor E1 can store energy. In this way, in battery-powered mode, both the voltage conversion circuit and the three-arm circuit participate in the operation; that is, all components of the three-arm topology device are involved in the operation.

[0336] It is understood that the voltage conversion circuit involved in the embodiments of this application can be a voltage conversion circuit with electrical isolation or a voltage conversion circuit without electrical isolation. For example, the voltage conversion circuit can also be referred to as a DC-DC converter.

[0337] Continue to refer to Figure 24 For example, the voltage conversion circuit involved in the embodiments of this application may include: a first voltage conversion unit, a transformer, an LC resonant cavity, and a second voltage conversion unit. The first voltage conversion unit is connected to the low-voltage side of the transformer, and the high-voltage side of the transformer is connected to the LC resonant cavity and the second voltage conversion unit.

[0338] Continue to refer to Figure 24 For example, the first voltage conversion unit includes a fourth bridge arm and a fifth bridge arm. The LC resonant cavity includes a fifth inductor Lik and a third capacitor Cr. The second voltage conversion unit includes a sixth bridge arm and a seventh bridge arm. That is, the second voltage conversion unit involved in this embodiment is a full-bridge topology.

[0339] The fourth bridge arm includes a seventh switch Q7 and an eighth switch Q8 connected in series (i.e., the first end of the seventh switch Q7 is connected to the first end of the eighth switch Q8); the fifth bridge arm includes a ninth switch Q9 and a tenth switch Q10 connected in series (i.e., the first end of the ninth switch Q9 is connected to the first end of the tenth switch Q10). The fourth bridge arm and the fifth bridge arm are connected in parallel (i.e., the second end of the seventh switch Q7 is connected to the second end of the ninth switch Q9, and the second end of the eighth switch Q8 is connected to the second end of the tenth switch Q10).

[0340] The sixth bridge arm includes: an eleventh switch Q11 and a twelfth switch Q12 connected in series (i.e., the first terminal of the eleventh switch Q11 is connected to the first terminal of the twelfth switch Q12); the seventh bridge arm includes: a thirteenth switch Q13 and a fourteenth switch Q14 connected in series (i.e., the first terminal of the thirteenth switch Q13 is connected to the first terminal of the fourteenth switch Q14). The seventh bridge arm is connected in parallel with the sixth bridge arm (i.e., the second terminal of the eleventh switch Q11 is connected to the second terminal of the thirteenth switch Q13, and the second terminal of the twelfth switch Q12 is connected to the second terminal of the fourteenth switch Q14).

[0341] For descriptions of the fourth, fifth, sixth, and seventh bridge arms and the LC resonant cavity, please refer to the preceding text. Figure 3 The descriptions of the fourth, fifth, sixth, and seventh bridge arms and the resonant cavity are omitted here. In some embodiments, the above... Figure 24 The first voltage conversion unit shown can also be called a full-bridge converter circuit.

[0342] The second terminal of the seventh switch Q7 is the first terminal of the voltage conversion circuit, the second terminal of the eighth switch Q8 is the second terminal of the voltage conversion circuit, the second terminal of the thirteenth switch Q13 is the third terminal of the voltage conversion circuit, and the second terminal of the fourteenth switch Q14 is the fourth terminal of the voltage conversion circuit.

[0343] The midpoint of the fourth bridge arm is connected to the opposite-name terminal on the low-voltage side of transformer TX1, and the midpoint of the fifth bridge arm is connected to the same-name terminal on the low-voltage side of transformer TX1. The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor Lik, the second terminal of the fifth inductor Lik is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor Cr, and the second terminal of the third capacitor Cr is connected to the midpoint of the seventh bridge arm.

[0344] When this voltage conversion circuit is used to charge the battery pack, it operates in full-bridge LLC resonant converter mode. That is, the second voltage conversion unit, the LC resonant cavity, and the inductor (not shown in the figure) in transformer TX1 constitute a full-bridge LLC resonant network, making the voltage conversion circuit a full-bridge LLC resonant converter. At this time, a full-bridge phase-shift control strategy can be used to control this full-bridge LLC resonant converter, enabling the leading arm of the full-bridge LLC resonant converter to achieve zero-voltage turn-on, and the lagging arm to achieve zero-voltage turn-on and zero-current turn-off. For details on the specific working principle, please refer to the existing technology descriptions of full-bridge LLC resonant converters; further details will not be elaborated here.

[0345] When this voltage conversion circuit is used to discharge the battery pack, it operates in the full-bridge secondary-side LC resonant converter mode. That is, the first voltage conversion unit of the voltage conversion circuit, the secondary side of transformer TX1, and the LC resonant cavity constitute a full-bridge secondary-side LC resonant converter, achieving zero-voltage turn-on and zero-current turn-off. For details on the specific working principle, please refer to the existing technology for an introduction to full-bridge secondary-side LC resonant converters, which will not be repeated here.

[0346] It should be understood that when the voltage conversion circuit discharges the battery pack, the secondary side of the transformer TX1 connected to the LC resonant cavity is the high-voltage side of the voltage conversion circuit; when the voltage conversion circuit charges the battery pack, the secondary side of the transformer TX1 connected to the first voltage conversion unit is the low-voltage side of the voltage conversion circuit.

[0347] Alternatively, the high-voltage side of the transformer and the LC resonant cavity and the second voltage conversion unit can also be connected in the following ways:

[0348] Figure 25 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 1 .like Figure 25 As shown, the same-name terminal of the high-voltage side of transformer TX1 is connected to the first terminal of the third capacitor Cr, the second terminal of the third capacitor Cr is connected to the midpoint of the sixth bridge arm, the opposite-name terminal of the high-voltage side of transformer TX1 is connected to the first terminal of the fifth inductor Lik, and the second terminal of the fifth inductor Lik is connected to the midpoint of the seventh bridge arm.

[0349] Figure 26 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 2 .like Figure 26 As shown, the same-name terminal of the high-voltage side of transformer TX1 is connected to the first terminal of the third capacitor Cr, the second terminal of the third capacitor Cr is connected to the first terminal of the fifth inductor Lik, the second terminal of the fifth inductor Lik is connected to the midpoint of the sixth bridge arm, and the opposite-name terminal of the high-voltage side of transformer TX1 is connected to the midpoint of the seventh bridge arm.

[0350] Figure 27 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 3 .like Figure 27 As shown, the same-name terminal of the high-voltage side of transformer TX1 is connected to the first terminal of the fifth inductor Lik, the second terminal of the fifth inductor Lik is connected to the first terminal of the third capacitor Cr, the second terminal of the third capacitor Cr is connected to the midpoint of the sixth bridge arm, and the opposite-name terminal of the high-voltage side of transformer TX1 is connected to the midpoint of the seventh bridge arm.

[0351] Figure 28 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 4 .like Figure 28As shown, the same-name terminal of the high-voltage side of transformer TX1 is connected to the midpoint of the sixth bridge arm, the opposite-name terminal of the high-voltage side of transformer TX1 is connected to the first terminal of the third capacitor Cr, the second terminal of the third capacitor Cr is connected to the first terminal of the fifth inductor Lik, and the second terminal of the fifth inductor Lik is connected to the midpoint of the seventh bridge arm.

[0352] Figure 29 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 5 .like Figure 29 As shown, the same-name terminal of the high-voltage side of transformer TX1 is connected to the midpoint of the sixth bridge arm, the opposite-name terminal of the high-voltage side of transformer TX1 is connected to the first terminal of the fifth inductor Lik, the second terminal of the fifth inductor Lik is connected to the first terminal of the third capacitor Cr, and the second terminal of the third capacitor Cr is connected to the midpoint of the seventh bridge arm.

[0353] Figure 30 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 6 .like Figure 30 As shown, the first end of the sixth bridge arm (i.e., the second end of the eleventh switch Q11) is connected to the first opposite-name terminal of the high-voltage side of transformer TX1; the second end of the sixth bridge arm (i.e., the second end of the twelfth switch Q12) is connected to the second opposite-name terminal of the high-voltage side of transformer TX1; the first end of the seventh bridge arm (i.e., the second end of the thirteenth switch Q13) is connected to the first same-name terminal of the high-voltage side of transformer TX1; the second end of the seventh bridge arm (i.e., the second end of the fourteenth switch Q14) is connected to the second same-name terminal of the high-voltage side of transformer TX1; the midpoint of the sixth bridge arm is connected to the first end of the fifth inductor Lik; the second end of the fifth inductor Lik is connected to the first end of the third capacitor Cr; and the second end of the third capacitor Cr is connected to the midpoint of the seventh bridge arm.

[0354] Figure 31 Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 7 .like Figure 31 As shown, the first end of the sixth bridge arm (i.e., the second end of the eleventh switch Q11) is connected to the first opposite-name terminal of the high-voltage side of transformer TX1; the second end of the sixth bridge arm (i.e., the second end of the twelfth switch Q12) is connected to the second opposite-name terminal of the high-voltage side of transformer TX1; the first end of the seventh bridge arm (i.e., the second end of the thirteenth switch Q13) is connected to the first same-name terminal of the high-voltage side of transformer TX1; the second end of the seventh bridge arm (i.e., the second end of the fourteenth switch Q14) is connected to the second same-name terminal of the high-voltage side of transformer TX1; the midpoint of the sixth bridge arm is connected to the first end of the third capacitor Cr; the second end of the third capacitor Cr is connected to the first end of the fifth inductor Lik; and the second end of the fifth inductor Lik is connected to the midpoint of the seventh bridge arm.

[0355] Alternatively, the first voltage conversion unit described above can also adopt the structure shown below:

[0356] Figure 32 A schematic diagram of the structure of the first voltage conversion unit provided in the embodiments of this application. Figure 1 .like Figure 32 As shown, in another implementation, the first voltage conversion unit may include a seventh switch Q7 and an eighth switch Q8.

[0357] In this implementation, the first end of the seventh switch Q7 is connected to the first terminal of the same name on the low-voltage side of transformer TX1, the first end of the eighth switch Q8 is connected to the terminal of the opposite name on the low-voltage side of transformer TX1, and the second end of the seventh switch Q7 is connected to the second end of the eighth switch Q8.

[0358] The first terminal of the low-voltage side of transformer TX1 is the first terminal of the voltage conversion circuit, and the second terminal of the seventh switch Q7 is the second terminal of the voltage conversion circuit. In some embodiments, the above... Figure 32 The first voltage conversion unit shown can also be called a push-pull converter circuit.

[0359] Figure 33 A schematic diagram of the structure of the first voltage conversion unit provided in the embodiments of this application. Figure 2 .like Figure 33 As shown, in another implementation, the first voltage conversion unit may include a seventh switch Q7, an eighth switch Q8, and a ninth switch Q9.

[0360] In this implementation, the first end of the seventh switch Q7 is connected to the first terminal of the same name on the low-voltage side of transformer TX1, the first end of the ninth switch Q9 is connected to the second terminal of the same name on the low-voltage side of transformer TX1, the first end of the eighth switch Q8 is connected to the terminal of the opposite name on the low-voltage side of transformer TX1, and the second end of the seventh switch Q7 is connected to the second end of the eighth switch Q8.

[0361] The second terminal of the ninth switch Q9 is the first terminal of the voltage conversion circuit, and the second terminal of the seventh switch Q7 is the second terminal of the voltage conversion circuit.

[0362] In some embodiments, the above Figure 33 The first voltage conversion unit shown can also be called a three-transistor push-pull converter circuit.

[0363] Figure 34 A schematic diagram of the structure of the first voltage conversion unit provided in the embodiments of this application. Figure 3 .like Figure 34 As shown, in another implementation, the first voltage conversion unit may include: a fourth bridge arm, a fifth bridge arm, and a fourth capacitor E4.

[0364] The fourth bridge arm includes: a seventh switch Q7 and an eighth switch Q8 connected in series (i.e., the first end of the seventh switch Q7 is connected to the first end of the eighth switch Q8); the fifth bridge arm includes: a ninth switch Q9 and a tenth switch Q10 connected in series (i.e., the first end of the ninth switch Q9 is connected to the first end of the tenth switch Q10).

[0365] In this implementation, the second terminal of the seventh switch Q7 is the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch Q8 is the second terminal of the voltage conversion circuit.

[0366] The first end of the fourth bridge arm (i.e., the second end of the seventh switch Q7) is connected to the first opposite-name terminal of the low-voltage side of the transformer TX1. The second end of the fourth bridge arm (i.e., the second end of the eighth switch Q8) is connected to the second opposite-name terminal of the low-voltage side of the transformer TX1. The first end of the fifth bridge arm (i.e., the second end of the ninth switch Q9) and the first end of the fourth capacitor E4 are both connected to the first same-name terminal of the low-voltage side of the transformer TX1. The second end of the fifth bridge arm (i.e., the second end of the tenth switch Q10) and the second end of the fourth capacitor E4 are both connected to the second same-name terminal of the low-voltage side of the transformer TX1. The midpoint of the fourth bridge arm is connected to the midpoint of the fifth bridge arm.

[0367] In some embodiments, the above Figure 34 The first voltage conversion unit shown can also be called a full-bridge converter circuit.

[0368] Figure 35 A schematic diagram of the structure of the first voltage conversion unit provided in the embodiments of this application. Figure 4 .like Figure 35 As shown, if the battery pack of the three-arm topology device includes a first battery sub-group and a second battery sub-group connected in series, wherein the negative terminal of the first battery sub-group is connected to the positive terminal of the second battery sub-group, the positive terminal of the first battery sub-group is the positive terminal of the battery pack, and the negative terminal of the second battery sub-group is the negative terminal of the battery pack, then in this example, the aforementioned first voltage conversion unit may include: a fourth arm; the fourth arm includes: a seventh switch Q7 and an eighth switch Q8 connected in series (i.e., the first terminal of the seventh switch Q7 is connected to the first terminal of the eighth switch Q8).

[0369] In this implementation, the second terminal of the seventh switch Q7 is the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch Q8 is the second terminal of the voltage conversion circuit.

[0370] The negative terminal of the first battery sub-group is connected to the opposite terminal of the low-voltage side of the transformer TX1, and the midpoint of the fourth bridge arm is connected to the same terminal of the low-voltage side of the transformer TX1.

[0371] In some embodiments, the above Figure 35 The first voltage conversion unit shown can also be called a half-bridge converter circuit.

[0372] It should be understood that when implementing the voltage conversion circuit using any of the above variations, the operating modes of the voltage conversion circuit during charging of the battery pack and the operating modes during discharging of the battery pack are different from those of the voltage conversion circuit. Figure 24 The voltage conversion circuit shown is the same, so it will not be described in detail again.

[0373] Furthermore, when using a B1-structured three-arm topology, the state of each switch in the external power supply mode is related to... Figure 6 The states of the switches in the illustrated three-arm bridge topology are similar under external power supply mode. The current flow in this three-arm bridge topology is similar to... Figure 6 The current flow of the three-bridge topology shown is similar in external power supply mode; please refer to [reference needed]. Figures 8 to 11 The corresponding descriptions will not be repeated here.

[0374] Accordingly, in battery-powered mode, the states of each switch in this three-arm topology device are as follows: Figure 6 The states of the switches in the three-arm bridge topology shown are similar in battery-powered mode. The current flow in this three-arm bridge topology is similar to... Figure 6 The current flow of the three-bridge topology shown is similar in battery-powered mode; please refer to [reference needed]. Figures 12 to 13 The corresponding descriptions will not be repeated here.

[0375] Structure B2: The voltage conversion circuit in this three-bridge topology achieves voltage conversion by reusing the second bridge arm and bus capacitor E1 of the three-bridge circuit, or by reusing only bus capacitor E1. This three-bridge topology can be applied to battery low-voltage high-current inverter systems and battery low-voltage high-current UPS systems. The external power supply for this UPS system can be AC ​​mains power, PV DC power, or a combination of PV DC power and AC mains power, etc.

[0376] The following explanation and introduction will be based on the application of this structure B2 in a low-voltage, high-current battery inverter system and a low-voltage, high-current battery UPS system.

[0377] Structure B21: Applied to battery-powered, low-voltage, high-current UPS systems.

[0378] Figure 36This is a schematic diagram of the seventeenth three-arm topology device provided in the embodiments of this application. Figure 36 As shown, taking the application of this three-arm topology device to a battery-powered low-voltage, high-current UPS system powered by AC mains as an external power source as an example, the difference between the three-arm topology device shown in structure B21 and the three-arm topology device shown in structure B1 lies in the structure of the voltage conversion circuit and the connection method between the voltage conversion circuit and the three-arm circuit. The following focuses on explaining these differences:

[0379] Specifically, in the three-arm topology device shown in structure B21, the positive terminal of the battery pack is connected to the first terminal of the voltage conversion circuit, the negative terminal of the battery pack is connected to the second terminal of the voltage conversion circuit, the third terminal of the voltage conversion circuit is connected to BUS+, the fourth terminal of the voltage conversion circuit is connected to BUS-, and the fifth terminal of the voltage conversion circuit is connected to the midpoint of the second arm. The voltage conversion circuit reuses the second arm of the three-arm circuit and the bus capacitor E1 to form a bidirectional DC-DC topology to achieve bidirectional voltage conversion.

[0380] In this embodiment, the three-arm topology device also has two power supply modes: external power supply mode and battery power supply mode.

[0381] In external power supply mode, the AC mains power supply powers the three-arm circuit, and the "voltage conversion circuit, which uses the second arm and bus capacitor E1 to form a bidirectional DC-DC topology," charges the battery pack. At this time, the three-arm circuit operates in AC-AC mode, and the "voltage conversion circuit, which uses the second arm and bus capacitor E1 to form a bidirectional DC-DC topology," operates in BUCK mode (i.e., step-down mode). It steps down the BUS voltage output from the DC bus capacitor E1 to obtain the charging voltage for the battery pack, which is then used to charge the battery pack. In this mode, the battery pack serves as the output source for the "voltage conversion circuit, which uses the second arm and bus capacitor E1 to form a bidirectional DC-DC topology."

[0382] In this way, under external power supply mode, both the voltage conversion circuit and the three-bridge-arm circuit participate in the operation; that is, all components of the three-bridge-arm topology device are involved. For the technical effects of using a "bidirectional DC-DC topology composed of a voltage conversion circuit reusing the second bridge arm and bus capacitor E1" to charge the battery pack, please refer to the aforementioned embodiments. Figure 2 The description uses a voltage conversion circuit to charge the battery pack.

[0383] In battery-powered mode, the battery pack serves as the input source for the bidirectional DC-DC topology consisting of the second bridge arm of the voltage conversion circuit and bus capacitor E1. The output of this topology powers the three-bridge circuit. In other words, the bidirectional DC-DC topology discharges the battery pack. At this time, the bidirectional DC-DC topology operates in Boost mode, boosting the output voltage of the battery pack. The boosted voltage is then input to the DC bus capacitor E1 of the three-bridge circuit to maintain bus voltage balance. The DC bus capacitor E1 filters the boosted DC power to obtain stable DC power. The second and third bridge arms of the three-bridge circuit operate in inverter mode, converting the stable DC power into AC power and outputting it to the load. Simultaneously, the DC bus capacitor E1 can store energy. In this way, in battery-powered mode, both the voltage conversion circuit and the three-bridge circuit participate in the operation; that is, all components of the three-bridge topology device are involved in the operation.

[0384] It is understood that the voltage conversion circuit involved in the embodiments of this application can be a voltage conversion circuit with electrical isolation or a voltage conversion circuit without electrical isolation.

[0385] Continue to refer to Figure 36 The voltage conversion circuit involved in the embodiments of this application may include, for example, a first voltage conversion unit, a transformer, an LC resonant cavity, and a second voltage conversion unit. The first voltage conversion unit is connected to the low-voltage side of the transformer, and the high-voltage side of the transformer is connected to the LC resonant cavity and the second voltage conversion unit.

[0386] Continue to refer to Figure 36 For example, the first voltage conversion unit includes a fourth bridge arm and a fifth bridge arm. The LC resonant cavity includes a fifth inductor Lik and an inductor Cr. The second voltage conversion unit includes a sixth bridge arm. That is, the second voltage conversion unit involved in this embodiment is a half-bridge topology.

[0387] The fourth bridge arm includes a seventh switch Q7 and an eighth switch Q8 connected in series (i.e., the first end of the seventh switch Q7 is connected to the first end of the eighth switch Q8); the fifth bridge arm includes a ninth switch Q9 and a tenth switch Q10 connected in series (i.e., the first end of the ninth switch Q9 is connected to the first end of the tenth switch Q10). The fourth bridge arm and the fifth bridge arm are connected in parallel (i.e., the second end of the seventh switch Q7 is connected to the second end of the ninth switch Q9, and the second end of the eighth switch Q8 is connected to the second end of the tenth switch Q10).

[0388] The sixth bridge arm includes an eleventh switch Q11 and a twelfth switch Q12 connected in series (i.e., the first end of the eleventh switch Q11 is connected to the first end of the twelfth switch Q12). The sixth bridge arm is connected in parallel between BUS+ and BUS- (i.e., the second end of the eleventh switch Q11 is connected to BUS+, and the second end of the twelfth switch Q12 is connected to BUS-).

[0389] For descriptions of the fourth, fifth, and sixth bridge arms and the LC resonant cavity, please refer to the preceding text. Figure 3 The descriptions of the fourth, fifth, and sixth bridge arms and the LC resonant cavity are not repeated here. In some embodiments, the above... Figure 36 The first voltage conversion unit shown can also be called a full-bridge converter circuit.

[0390] The second terminal of the seventh switch Q7 is the first terminal of the voltage conversion circuit, the second terminal of the eighth switch Q8 is the second terminal of the voltage conversion circuit, the second terminal of the eleventh switch Q11 is the third terminal of the voltage conversion circuit, and the second terminal of the twelfth switch Q12 is the fourth terminal of the voltage conversion circuit.

[0391] The midpoint of the fourth bridge arm is connected to the opposite-name terminal on the low-voltage side of transformer TX1, and the midpoint of the fifth bridge arm is connected to the same-name terminal on the low-voltage side of transformer TX1. The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor Lik, the second terminal of the fifth inductor Lik is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor Cr, and the second terminal of the third capacitor Cr is connected to the midpoint of the second bridge arm. That is, the second terminal of the third capacitor Cr is the fifth terminal of the voltage conversion circuit.

[0392] When this voltage conversion circuit is used to charge the battery pack, the "bidirectional DC-DC topology composed of the second bridge arm and bus capacitor E1" operates in half-bridge LLC resonant converter mode. That is, the LC resonant cavity and the inductor in transformer TX1 (not shown in the figure) form an LLC resonant network, enabling the bidirectional DC-DC topology to form a half-bridge LLC resonant converter, achieving a wider range of voltage regulation and zero-voltage turn-on. For the specific working principle, please refer to the introduction of half-bridge LLC resonant converters in the prior art, which will not be repeated here.

[0393] When the voltage conversion circuit is used to discharge the battery pack, the "bidirectional DC-DC topology composed of the second bridge arm and bus capacitor E1" of the voltage conversion circuit operates in the full-bridge secondary LC resonant voltage doubler converter mode. That is, the secondary side of transformer TX1 and the LC resonant cavity form a voltage doubler rectifier circuit, so that the bidirectional DC-DC topology forms a full-bridge secondary LC resonant voltage doubler converter. The output voltage of the bidirectional DC-DC topology is twice that of the secondary voltage of transformer TX1, achieving the purpose of doubling the voltage and improving the boost ratio of the bidirectional DC-DC topology.

[0394] Specifically, during the positive half-cycle of the output voltage V2 on the secondary side of transformer TX1, the third capacitor Cr in the resonant cavity stores energy. At this time, the voltage across the third capacitor Cr reaches √2 times the peak value of V2 and remains constant. During the negative half-cycle of the output voltage V2 on the secondary side of transformer TX1, the secondary side of transformer TX1 and the third capacitor Cr in the resonant cavity simultaneously provide the output voltage, causing the output voltage of the bidirectional DC-DC topology to reach √2 times the peak value of V2 and remain constant. At this time, the output voltage of the bidirectional DC-DC topology is twice the voltage on the secondary side of transformer TX1.

[0395] For example, taking a bidirectional DC-DC topology with an output voltage of 200V as an example, under the above full-bridge secondary LC resonant voltage multiplier converter mode, transformer TX1 only needs to boost the voltage output of the battery pack to 100V to make the output voltage of the bidirectional DC-DC topology reach 200V.

[0396] It should be understood that when discharging the battery pack, the secondary side of the transformer TX1 connected to the LC resonant cavity is the high-voltage side of the voltage conversion circuit, and when charging the battery pack, the secondary side of the transformer TX1 connected to the first voltage conversion unit is the low-voltage side of the voltage conversion circuit.

[0397] Optionally, the high-voltage side of the transformer, the LC resonant cavity, the second voltage conversion unit, and the second bridge arm can also be configured as follows: Figures 25 to 31 The connection method shown. The only difference is that, when... Figures 25 to 31 When the connection method shown is applied in this embodiment, the second bridge arm is used instead. Figures 25 to 31 The seventh bridge arm. In these implementations, the end of the voltage conversion circuit connected to the midpoint of the second bridge arm is the fifth terminal of the voltage conversion circuit, which will not be elaborated further.

[0398] Figure 36A Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 8 , Figure 36B Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 9 See also Figure 36A and Figure 36BWhen the high-voltage side of the aforementioned transformer is connected to the LC resonant cavity, the second voltage conversion unit, and the second bridge arm, Figure 30 or Figure 31 In the connection configuration shown, the first terminal of the high-voltage side of transformer TX1 is the third terminal of the voltage conversion circuit, and the second terminal of the high-voltage side of transformer TX1 is the fourth terminal of the voltage conversion circuit; further details are omitted. In this case, the connection configuration between the high-voltage side of the transformer and the LC resonant cavity, the second voltage conversion unit, and the second bridge arm can be, for example, as shown below. Figure 36A or Figure 36B As shown.

[0399] Accordingly, the first voltage conversion unit involved in this embodiment can also be adopted as follows: Figures 32 to 35 The structural replacements shown will not be elaborated further.

[0400] It should be understood that when implementing the voltage conversion circuit using any of the above variations, the operating modes of the "bidirectional DC-DC topology composed of the second bridge arm and bus capacitor E1" during battery charging and during battery discharging are different from those of the voltage conversion circuit. Figure 36 The voltage conversion circuit shown is the same, so it will not be described in detail again.

[0401] The following is based on Figure 36 Taking the structure of the three-arm topology shown as an example, the states of each switch, each switching transistor, and the current flow of the three-arm topology under different power supply modes are illustrated:

[0402] Figure 37 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 1 .like Figure 37 As shown, in the first stage of the external power supply mode, that is, in the first stage of the positive half-cycle of the input AC power (i.e., the AC power input through the positive and negative voltage input terminals of the three-arm topology), the second switch Q2, the fourth switch Q4, the fifth switch Q5, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0403] 1. The live wire of the AC mains power supply → the first inductor L1 → the second switch Q2 → the fourth switch Q4 → the neutral wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0404] 2. BUS+ → Fifth switch Q5 → Second inductor L2 → First capacitor Co → Fourth switch Q4 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0405] 3. BUS+ → Eleventh switch Q11 → Fifth inductor Lik → Same-name terminal on the high-voltage side of TX1 → Different-name terminal on the high-voltage side of TX1 → Third capacitor Cr → Fourth switch Q4 → BUS-, so that the bus capacitor E1 can transfer energy to the transformer TX1 and form the energy storage circuit of the third capacitor Cr. TX1 low-voltage side same-name terminal → Ninth switch Q9 → Battery pack positive terminal → Battery pack negative terminal → Eighth switch Q8 → Different-name terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the ninth switch Q9 and the eighth switch Q8 are used to implement the rectification function.

[0406] Figure 38 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 2 .like Figure 38 As shown, in the second stage of the external power supply mode, that is, in the second stage of the positive half-cycle of the input AC power, the second switch Q2, the fourth switch Q4, the fifth switch Q5, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0407] 1. The live wire of the AC mains power supply → the first inductor L1 → the second switch Q2 → the fourth switch Q4 → the neutral wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0408] 2. BUS+ → Fifth switch Q5 → Second inductor L2 → First capacitor Co → Fourth switch Q4 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0409] 3. Cr positive terminal → opposite terminal on the high-voltage side of TX1 → same terminal on the high-voltage side of TX1 → fifth inductor Lik → twelfth switch Q12 → fourth switch Q4 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side opposite terminal → seventh switch Q7 → battery pack positive terminal → battery pack negative terminal → tenth switch Q10 → same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0410] Figure 39 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 3 .like Figure 39 As shown, in the third stage of the external power supply mode, that is, in the third stage of the positive half-cycle of the input AC power, the fourth switch Q4, the fifth switch Q5, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0411] 1. The live wire of the AC mains power supply → first inductor L1 → first switching transistor Q1 → bus capacitor E1 → fourth switching transistor Q4 → neutral wire of the AC mains power supply forms the energy storage circuit of bus capacitor E1. At this time, the AC mains power and the first inductor L1 simultaneously provide energy to bus capacitor E1.

[0412] 2. BUS+ → Fifth switch Q5 → Second inductor L2 → First capacitor Co → Fourth switch Q4 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0413] 3. BUS+ → Eleventh switch Q11 → Fifth inductor Lik → Same-name terminal on the high-voltage side of TX1 → Different-name terminal on the high-voltage side of TX1 → Third capacitor Cr → Fourth switch Q4 → BUS-, so that the bus capacitor E1 can transfer energy to the transformer TX1 and form the energy storage circuit of the third capacitor Cr. TX1 low-voltage side same-name terminal → Ninth switch Q9 → Battery pack positive terminal → Battery pack negative terminal → Eighth switch Q8 → Different-name terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the ninth switch Q9 and the eighth switch Q8 are used to implement the rectification function.

[0414] Figure 40 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 4 .like Figure 40 As shown, in the fourth stage of the external power supply mode, that is, in the fourth stage of the positive half-cycle of the input AC power, the fourth switch Q4, the fifth switch Q5, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0415] 1. The live wire of the AC mains power supply → first inductor L1 → first switching transistor Q1 → bus capacitor E1 → fourth switching transistor Q4 → neutral wire of the AC mains power supply forms the energy storage circuit of bus capacitor E1. At this time, the AC mains power and the first inductor L1 simultaneously provide energy to bus capacitor E1.

[0416] 2. BUS+ → Fifth switch Q5 → Second inductor L2 → First capacitor Co → Fourth switch Q4 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0417] 3. Cr positive terminal → opposite terminal on the high-voltage side of TX1 → same terminal on the high-voltage side of TX1 → fifth inductor Lik → twelfth switch Q12 → fourth switch Q4 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side opposite terminal → seventh switch Q7 → battery pack positive terminal → battery pack negative terminal → tenth switch Q10 → same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0418] Figure 41 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 5 .like Figure 41 As shown, in the fifth stage of the external power supply mode, that is, in the fifth stage of the positive half-cycle of the input AC power, the second switch Q2, the fourth switch Q4, the sixth switch Q6, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0419] 1. The live wire of the AC mains power supply → the first inductor L1 → the second switch Q2 → the fourth switch Q4 → the neutral wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0420] 2. The second inductor L2 → the first capacitor Co → the fourth switch Q4 → the sixth switch Q6 → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0421] 3. BUS+ → Eleventh switch Q11 → Fifth inductor Lik → Same-name terminal on the high-voltage side of TX1 → Different-name terminal on the high-voltage side of TX1 → Third capacitor Cr → Fourth switch Q4 → BUS-, so that the bus capacitor E1 can transfer energy to the transformer TX1 and form the energy storage circuit of the third capacitor Cr. TX1 low-voltage side same-name terminal → Ninth switch Q9 → Battery pack positive terminal → Battery pack negative terminal → Eighth switch Q8 → Different-name terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the ninth switch Q9 and the eighth switch Q8 are used to implement the rectification function.

[0422] Figure 42 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 6 .like Figure 42 As shown, in the sixth stage of the external power supply mode, that is, in the sixth stage of the positive half-cycle of the input AC power, the second switch Q2, the fourth switch Q4, the sixth switch Q6, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0423] 1. The live wire of the AC mains power supply → the first inductor L1 → the second switch Q2 → the fourth switch Q4 → the neutral wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0424] 2. The second inductor L2 → the first capacitor Co → the fourth switch Q4 → the sixth switch Q6 → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0425] 3. Cr positive terminal → opposite terminal on the high-voltage side of TX1 → same terminal on the high-voltage side of TX1 → fifth inductor Lik → twelfth switch Q12 → fourth switch Q4 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side opposite terminal → seventh switch Q7 → battery pack positive terminal → battery pack negative terminal → tenth switch Q10 → same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0426] Figure 43 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 7 .like Figure 43 As shown, in the seventh stage of the external power supply mode, that is, in the seventh stage of the positive half-cycle of the input AC power, the fourth switch Q4, the sixth switch Q6, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0427] 1. The live wire of the AC mains power supply → first inductor L1 → first switching transistor Q1 → bus capacitor E1 → fourth switching transistor Q4 → neutral wire of the AC mains power supply forms the energy storage circuit of bus capacitor E1. At this time, the AC mains power and the first inductor L1 simultaneously provide energy to bus capacitor E1.

[0428] 2. The second inductor L2 → the first capacitor Co → the fourth switch Q4 → the sixth switch Q6 → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0429] 3. BUS+ → Eleventh switch Q11 → Fifth inductor Lik → Same-name terminal on the high-voltage side of TX1 → Different-name terminal on the high-voltage side of TX1 → Third capacitor Cr → Fourth switch Q4 → BUS-, so that the bus capacitor E1 can transfer energy to the transformer TX1 and form the energy storage circuit of the third capacitor Cr. TX1 low-voltage side same-name terminal → Ninth switch Q9 → Battery pack positive terminal → Battery pack negative terminal → Eighth switch Q8 → Different-name terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the ninth switch Q9 and the eighth switch Q8 are used to implement the rectification function.

[0430] Figure 44 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 8 .like Figure 44 As shown, in the eighth stage of the external power supply mode, that is, in the eighth stage of the positive half-cycle of the input AC power, the fourth switch Q4, the sixth switch Q6, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0431] 1. The live wire of the AC mains power supply → first inductor L1 → first switching transistor Q1 → bus capacitor E1 → fourth switching transistor Q4 → neutral wire of the AC mains power supply forms the energy storage circuit of bus capacitor E1. At this time, the AC mains power and the first inductor L1 simultaneously provide energy to bus capacitor E1.

[0432] 2. The second inductor L2 → the first capacitor Co → the fourth switch Q4 → the sixth switch Q6 → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0433] 3. Cr positive terminal → opposite terminal on the high-voltage side of TX1 → same terminal on the high-voltage side of TX1 → fifth inductor Lik → twelfth switch Q12 → fourth switch Q4 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side opposite terminal → seventh switch Q7 → battery pack positive terminal → battery pack negative terminal → tenth switch Q10 → same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0434] Figure 45 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 9 .like Figure 45 As shown, in the ninth stage of the external power supply mode, that is, in the first stage of the negative half-cycle of the input AC power, the first switch Q1, the third switch Q3, the sixth switch Q6, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0435] 1. The neutral wire of the AC mains power supply → the third switch Q3 → the first switch Q1 → the first inductor L1 → the live wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0436] 2. BUS+ → Third switch Q3 → First capacitor Co → Second inductor L2 → Sixth switch Q6 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0437] 3. BUS+ → Third switch Q3 → Third capacitor Cr → Opposite terminal on the high-voltage side of TX1 → Same terminal on the high-voltage side of TX1 → Fifth inductor Lik → Twelfth switch Q12 → BUS-, so that the bus capacitor E1 transfers energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr. TX1 low-voltage side opposite terminal → Seventh switch Q7 → Battery pack positive terminal → Battery pack negative terminal → Tenth switch Q10 → Same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0438] Figure 46 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 .like Figure 46 As shown, in the tenth stage of the external power supply mode, that is, in the second stage of the negative half-cycle of the input AC power, the first switch Q1, the third switch Q3, the sixth switch Q6, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0439] 1. The neutral wire of the AC mains power supply → the third switch Q3 → the first switch Q1 → the first inductor L1 → the live wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0440] 2. BUS+ → Third switch Q3 → First capacitor Co → Second inductor L2 → Sixth switch Q6 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0441] 3. Cr positive terminal → third switch Q3 → eleventh switch Q11 → fifth inductor Lik → same-name terminal on the high-voltage side of TX1 → opposite-name terminal on the high-voltage side of TX1 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side same-name terminal → ninth switch Q9 → battery pack positive terminal → battery pack negative terminal → eighth switch Q8 → opposite-name terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the ninth switch Q9 and the eighth switch Q8 are used to implement the rectification function.

[0442] Figure 47 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 1. For example Figure 47 As shown, in the eleventh stage of the external power supply mode, that is, in the third stage of the negative half-cycle of the input AC power, the third switch Q3, the sixth switch Q6, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0443] 1. The neutral wire of the AC mains power supply → third switch Q3 → bus capacitor E1 → second switch Q2 → first inductor L1 → live wire of the AC mains power supply forms the energy storage circuit of bus capacitor E1. At this time, the AC mains power and the first inductor L1 simultaneously provide energy to bus capacitor E1.

[0444] 2. BUS+ → Third switch Q3 → First capacitor Co → Second inductor L2 → Sixth switch Q6 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0445] 3. BUS+ → Third switch Q3 → Third capacitor Cr → Opposite terminal on the high-voltage side of TX1 → Same terminal on the high-voltage side of TX1 → Fifth inductor Lik → Twelfth switch Q12 → BUS-, so that the bus capacitor E1 transfers energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr. TX1 low-voltage side opposite terminal → Seventh switch Q7 → Battery pack positive terminal → Battery pack negative terminal → Tenth switch Q10 → Same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0446] Figure 48 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 2. For example Figure 48 As shown, in the twelfth stage of the external power supply mode, that is, in the fourth stage of the negative half-cycle of the input AC power, the third switch Q3, the sixth switch Q6, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0447] 1. The neutral wire of the AC mains power supply → third switch Q3 → bus capacitor E1 → second switch Q2 → first inductor L1 → live wire of the AC mains power supply forms the energy storage circuit of bus capacitor E1. At this time, the AC mains power and the first inductor L1 simultaneously provide energy to bus capacitor E1.

[0448] 2. BUS+ → Third switch Q3 → First capacitor Co → Second inductor L2 → Sixth switch Q6 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0449] 3. Cr positive terminal → third switch Q3 → eleventh switch Q11 → fifth inductor Lik → same-name terminal on the high-voltage side of TX1 → opposite-name terminal on the high-voltage side of TX1 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side same-name terminal → ninth switch Q9 → battery pack positive terminal → battery pack negative terminal → eighth switch Q8 → opposite-name terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the ninth switch Q9 and the eighth switch Q8 are used to implement the rectification function.

[0450] Figure 49 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 Three. For example... Figure 49 As shown, in the thirteenth stage of the external power supply mode, that is, in the fifth stage of the negative half-cycle of the input AC power, the first switch Q1, the third switch Q3, the fifth switch Q5, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0451] 1. The neutral wire of the AC mains power supply → the third switch Q3 → the first switch Q1 → the first inductor L1 → the live wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0452] 2. The second inductor L2 → the fifth switch Q5 → the third switch Q3 → the first capacitor Co → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0453] 3. BUS+ → Third switch Q3 → Third capacitor Cr → Opposite terminal on the high-voltage side of TX1 → Same terminal on the high-voltage side of TX1 → Fifth inductor Lik → Twelfth switch Q12 → BUS-, so that the bus capacitor E1 transfers energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr. TX1 low-voltage side opposite terminal → Seventh switch Q7 → Battery pack positive terminal → Battery pack negative terminal → Tenth switch Q10 → Same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0454] Figure 50 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 IV. For example Figure 50 As shown, in the fourteenth stage of the external power supply mode, that is, in the sixth stage of the negative half-cycle of the input AC power, the first switch Q1, the third switch Q3, the fifth switch Q5, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0455] 1. The neutral wire of the AC mains power supply → the third switch Q3 → the first switch Q1 → the first inductor L1 → the live wire of the AC mains power supply constitutes the energy storage circuit of the first inductor L1.

[0456] 2. The second inductor L2 → the fifth switch Q5 → the third switch Q3 → the first capacitor Co → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0457] 3. Cr positive terminal → third switch Q3 → eleventh switch Q11 → fifth inductor Lik → same-name terminal on the high-voltage side of TX1 → opposite-name terminal on the high-voltage side of TX1 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side same-name terminal → ninth switch Q9 → battery pack positive terminal → battery pack negative terminal → eighth switch Q8 → opposite-name terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the ninth switch Q9 and the eighth switch Q8 are used to implement the rectification function.

[0458] Figure 51 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 5. For example Figure 51 As shown, in the fifteenth stage of the external power supply mode, that is, in the seventh stage of the negative half-cycle of the input AC power, the third switch Q3, the fifth switch Q5, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0459] 1. The neutral wire of the AC mains power supply → third switch Q3 → bus capacitor E1 → second switch Q2 → first inductor L1 → live wire of the AC mains power supply forms the energy storage circuit of bus capacitor E1. At this time, the AC mains power and the first inductor L1 simultaneously provide energy to bus capacitor E1.

[0460] 2. The second inductor L2 → the fifth switch Q5 → the third switch Q3 → the first capacitor Co → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0461] 3. BUS+ → Third switch Q3 → Third capacitor Cr → Opposite terminal on the high-voltage side of TX1 → Same terminal on the high-voltage side of TX1 → Fifth inductor Lik → Twelfth switch Q12 → BUS-, so that the bus capacitor E1 transfers energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr. TX1 low-voltage side opposite terminal → Seventh switch Q7 → Battery pack positive terminal → Battery pack negative terminal → Tenth switch Q10 → Same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0462] Figure 52 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in external power supply mode. Figure 10 6. For example Figure 52 As shown, in the sixteenth stage of the external power supply mode, that is, in the eighth stage of the negative half-cycle of the input AC power, the third switch Q3, the fifth switch Q5, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0463] 1. The neutral wire of the AC mains power supply → third switch Q3 → bus capacitor E1 → second switch Q2 → first inductor L1 → live wire of the AC mains power supply forms the energy storage circuit of bus capacitor E1. At this time, the AC mains power and the first inductor L1 simultaneously provide energy to bus capacitor E1.

[0464] 2. The second inductor L2 → the fifth switch Q5 → the third switch Q3 → the first capacitor Co → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0465] 3. Cr positive terminal → third switch Q3 → eleventh switch Q11 → fifth inductor Lik → same-name terminal on the high-voltage side of TX1 → opposite-name terminal on the high-voltage side of TX1 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side same-name terminal → ninth switch Q9 → battery pack positive terminal → battery pack negative terminal → eighth switch Q8 → opposite-name terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the ninth switch Q9 and the eighth switch Q8 are used to implement the rectification function.

[0466] Figure 53 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 1 .like Figure 53 As shown, in the first stage of the battery-powered mode, that is, in the first stage of the positive half-cycle of the output AC power (i.e., the AC power output through the first and second output terminals of the three-arm topology), the fourth switch Q4, the fifth switch Q5, the seventh switch Q7, the tenth switch Q10, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0467] 1. Battery pack positive terminal → seventh switch Q7 → opposite terminal on the low-voltage side of TX1 → same terminal on the low-voltage side of TX1 → tenth switch Q10 → battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. TX1 high-voltage side opposite terminal → third capacitor Cr → fourth switch Q4 → twelfth switch Q12 → fifth inductor Lik → same terminal on the high-voltage side of TX1, forming the energy storage circuit of the third capacitor Cr.

[0468] 2. BUS+ → Fifth switch Q5 → Second inductor L2 → First capacitor Co → Fourth switch Q4 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0469] Figure 54 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 2 .like Figure 54 As shown, in the second stage of the battery-powered mode, that is, in the second stage of the positive half-cycle of the output AC power, the fourth switch Q4, the fifth switch Q5, the eighth switch Q8, the ninth switch Q9, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge arm topology is as follows:

[0470] 1. Battery pack positive terminal → Ninth switch Q9 → Same-name terminal on the low-voltage side of TX1 → Different-name terminal on the low-voltage side of TX1 → Eighth switch Q8 → Battery pack negative terminal, so that the battery pack transfers energy to transformer TX1. TX1 high-voltage side same-name terminal → Fifth inductor Lik → Eleventh switch Q11 → BUS+ → BUS- → Fourth switch Q4 → Third capacitor Cr → Different-name terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0471] 2. BUS+ → Fifth switch Q5 → Second inductor L2 → First capacitor Co → Fourth switch Q4 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0472] Figure 55 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 3 .like Figure 55 As shown, in the third stage of the battery-powered mode, that is, in the third stage of the positive half-cycle of the output AC power, the fourth switch Q4, the sixth switch Q6, the seventh switch Q7, the tenth switch Q10, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0473] 1. Battery pack positive terminal → seventh switch Q7 → opposite terminal on the low-voltage side of TX1 → same terminal on the low-voltage side of TX1 → tenth switch Q10 → battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. TX1 high-voltage side opposite terminal → third capacitor Cr → fourth switch Q4 → twelfth switch Q12 → fifth inductor Lik → same terminal on the high-voltage side of TX1, forming the energy storage circuit of the third capacitor Cr.

[0474] 2. The second inductor L2 → the first capacitor Co → the fourth switch Q4 → the sixth switch Q6 → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0475] Figure 56 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 4 .like Figure 56 As shown, in the fourth stage of the battery-powered mode, that is, in the fourth stage of the positive half-cycle of the output AC power, the fourth switch Q4, the sixth switch Q6, the eighth switch Q8, the ninth switch Q9, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0476] 1. Battery pack positive terminal → Ninth switch Q9 → Same-name terminal on the low-voltage side of TX1 → Different-name terminal on the low-voltage side of TX1 → Eighth switch Q8 → Battery pack negative terminal, so that the battery pack transfers energy to transformer TX1. TX1 high-voltage side same-name terminal → Fifth inductor Lik → Eleventh switch Q11 → BUS+ → BUS- → Fourth switch Q4 → Third capacitor Cr → Different-name terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0477] 2. The second inductor L2 → the first capacitor Co → the fourth switch Q4 → the sixth switch Q6 → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0478] Figure 57 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 5 .like Figure 57 As shown, in the fifth stage of the battery-powered mode, that is, in the first stage of the negative half-cycle of the output AC power, the third switch Q3, the sixth switch Q6, the seventh switch Q7, the tenth switch Q10, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0479] 1. Battery pack positive terminal → seventh switch Q7 → opposite terminal on the low-voltage side of TX1 → same terminal on the low-voltage side of TX1 → tenth switch Q10 → battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. TX1 high-voltage side opposite terminal → third capacitor Cr → third switch Q3 → BUS+ → BUS- → twelfth switch Q12 → fifth inductor Lik → same terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0480] 2. BUS+ → Third switch Q3 → First capacitor Co → Second inductor L2 → Sixth switch Q6 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0481] Figure 58 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 6 .like Figure 58 As shown, in the sixth stage of the battery-powered mode, that is, in the second stage of the negative half-cycle of the output AC power, the third switch Q3, the sixth switch Q6, the eighth switch Q8, the ninth switch Q9, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0482] 1. Battery pack positive terminal → Ninth switch Q9 → Same-name terminal on the low-voltage side of TX1 → Different-name terminal on the low-voltage side of TX1 → Eighth switch Q8 → Battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. Same-name terminal on the high-voltage side of TX1 → Fifth inductor Lik → Eleventh switch Q11 → Third switch Q3 → Third capacitor Cr → Different-name terminal on the high-voltage side of TX1, forming the energy storage circuit of the third capacitor Cr.

[0483] 2. BUS+ → Third switch Q3 → First capacitor Co → Second inductor L2 → Sixth switch Q6 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0484] Figure 59 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 7 .like Figure 59 As shown, in the seventh stage of the battery-powered mode, that is, in the third stage of the negative half-cycle of the output AC power, the third switch Q3, the fifth switch Q5, the seventh switch Q7, the tenth switch Q10, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0485] 1. Battery pack positive terminal → seventh switch Q7 → opposite terminal on the low-voltage side of TX1 → same terminal on the low-voltage side of TX1 → tenth switch Q10 → battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. TX1 high-voltage side opposite terminal → third capacitor Cr → third switch Q3 → BUS+ → BUS- → twelfth switch Q12 → fifth inductor Lik → same terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0486] 2. The second inductor L2 → the fifth switch Q5 → the third switch Q3 → the first capacitor Co → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0487] Figure 60 Current diagram of the seventeenth three-arm topology device provided in the embodiments of this application in battery-powered mode. Figure 8 .like Figure 60 As shown, in the eighth stage of the battery-powered mode, that is, in the fourth stage of the negative half-cycle of the output AC power, the third switch Q3, the fifth switch Q5, the eighth switch Q8, the ninth switch Q9, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0488] 1. Battery pack positive terminal → Ninth switch Q9 → Same-name terminal on the low-voltage side of TX1 → Different-name terminal on the low-voltage side of TX1 → Eighth switch Q8 → Battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. Same-name terminal on the high-voltage side of TX1 → Fifth inductor Lik → Eleventh switch Q11 → Third switch Q3 → Third capacitor Cr → Different-name terminal on the high-voltage side of TX1, forming the energy storage circuit of the third capacitor Cr.

[0489] 2. The second inductor L2 → the fifth switch Q5 → the third switch Q3 → the first capacitor Co → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0490] Although the above example illustrates the three-arm topology device provided in this embodiment using a battery-powered low-voltage, high-current UPS system powered by AC mains electricity as the external power source, those skilled in the art will understand that this three-arm topology device can also be applied to UPS systems using other external power sources.

[0491] Figure 61 This is a schematic diagram of the eighteenth three-arm topology device provided in the embodiments of this application. For example, it can be... Figure 36The AC mains power supply in the middle is replaced with a DC photovoltaic power supply, resulting in the following: Figure 61 The three-bridge-arm topology shown. At this time... Figure 61 The B21 structure shown in the diagram is a three-bridge topology that can be applied to battery-powered low-voltage, high-current UPS systems that use photovoltaic DC power as an external power source.

[0492] In this application scenario, the second terminal of the first inductor L1 serves as the positive voltage input terminal PV+ of the three-arm bridge topology. BUS- serves as the negative voltage input terminal PV- of the three-arm bridge topology. The positive terminal of the photovoltaic DC power supply is connected to the positive voltage input terminal PV+, and the negative terminal of the photovoltaic DC power supply is connected to the negative voltage input terminal PV-.

[0493] Optionally, in some embodiments, the positive terminal of the photovoltaic (PV) DC power supply is connected to the positive voltage input terminal PV+ via switch K6 to meet the safety requirements of the three-arm topology. It should be understood that the switch K6 can be, for example, a unidirectional electronic switch, a bidirectional thyristor, etc.

[0494] It should be understood that Figure 61 The working principle and technical effects of the three-bridge-arm topology device shown can be found in [reference needed]. Figure 36 The description of the three-bridge-arm topology device in the text will not be repeated here.

[0495] Figure 62 This is a schematic diagram of the nineteenth three-arm topology device provided in the embodiments of this application. Exemplarily, it can be... Figure 36 Based on this, a photovoltaic (PV) DC power supply, an eighth bridge arm, and a sixth inductor L6 are added to the three-arm bridge topology. At this point, Figure 62 The B21 structure shown in the diagram can be applied to a battery-powered low-voltage, high-current UPS system that uses both photovoltaic DC power and AC mains power as external power sources.

[0496] The eighth bridge arm includes a seventeenth switch Q17 and an eighteenth switch Q18, which are connected in series between BUS+ and BUS-. For example, the first terminal of the seventeenth switch Q17 is connected to BUS+, the second terminal of the seventeenth switch Q17 is connected to the first terminal of the eighteenth switch Q18, and the second terminal of the eighteenth switch Q18 is connected to BUS-. The common terminal of the seventeenth switch Q17 and the eighteenth switch Q18 is called the midpoint of the eighth bridge arm. That is, the eighth bridge arm is connected in parallel with the bus capacitor E1 between the positive output terminal and the negative output terminal of the bus. Through the above-mentioned eighth bridge arm, the output voltage or current of the photovoltaic DC power supply can be changed, so that the photovoltaic DC power supply operates at the maximum power point, realizing the maximum power point tracking (MPPT) of the photovoltaic DC power supply.

[0497] The second terminal of the first inductor L1 serves as the first positive voltage input terminal AC_L of the three-bridge topology. The midpoint of the second bridge arm serves as the first negative voltage input terminal AC_N of the three-bridge topology. The live wire of the AC mains power supply AC is connected to the first positive voltage input terminal AC_L, and the neutral wire of the AC mains power supply AC is connected to the first negative voltage input terminal AC_N.

[0498] The midpoint of the eighth bridge arm is connected to the first terminal of the sixth inductor L6, and the second terminal of the sixth inductor L6 serves as the second positive voltage input terminal PV+ of the three-bridge-arm topology. The negative output terminal of the bus serves as the second negative voltage input terminal PV- of the three-bridge-arm topology. The positive terminal of the photovoltaic DC power supply is connected to the second positive voltage input terminal PV+, and the negative terminal of the photovoltaic DC power supply is connected to the second negative voltage input terminal PV-.

[0499] Optionally, in some embodiments, the positive terminal of the photovoltaic (PV) DC power supply is connected to the second positive voltage input terminal PV+ via switch K6 to meet the safety requirements of the three-arm topology. It should be understood that the switch K6 can be, for example, a unidirectional electronic switch, a bidirectional thyristor, etc.

[0500] Optionally, the photovoltaic (PV) DC power supply and the mains AC power supply can serve as backup power supplies for each other. In practice, the photovoltaic (PV) DC power supply and / or the mains AC power supply can be selected as the external power supply for the three-arm topology device according to actual needs, and there are no restrictions on this.

[0501] In the application scenario provided in this embodiment, Figure 62 The working principle and technical effects of the three-bridge-arm topology device shown can be found in [reference needed]. Figure 36 The description of the three-bridge-arm topology device in the text will not be repeated here.

[0502] In addition, although the above Figures 37 to 60 The current flow of the three-arm topology shown is all in the direction of Figure 36 The seventeenth type of three-bridge topology is illustrated as an example. However, those skilled in the art will understand that the current flow, as well as the states of each switch and each switching transistor, also apply to this. Figure 61 and Figure 62 The three-bridge topology shown is implemented on a similar principle, and will not be described in detail here.

[0503] Structure B22: Applied to low-voltage, high-current inverter systems for batteries.

[0504] Figure 63 This is a schematic diagram of the twentieth three-arm topology device provided in the embodiments of this application. Figure 63 As shown, in this embodiment, the first end of the first capacitor Co is the first external connection end of the three-arm topology device, and the second end of the first capacitor Co is the second external connection end of the three-arm topology device.

[0505] When discharging the battery pack, the first external connection terminal can be referred to as the first output terminal of the three-arm topology, and the second external connection terminal can be referred to as the second output terminal of the three-arm topology, both of which are connected to the load. When charging the battery pack, the first external connection terminal can be referred to as the positive voltage input terminal of the three-arm topology, and is connected to the first terminal of the external power supply, and the second external connection terminal can be referred to as the negative voltage input terminal of the three-arm topology, and is connected to the second terminal of the external power supply.

[0506] For example, if the external power supply is a photovoltaic DC power supply, then the first terminal of the external power supply is the positive terminal of the photovoltaic DC power supply, and the second terminal of the external power supply is the negative terminal of the photovoltaic DC power supply. If the external power supply is an AC mains power supply, then the first terminal of the external power supply is the live wire of the AC mains power supply, and the second terminal of the external power supply is the neutral wire of the AC mains power supply.

[0507] Taking AC mains power as an example, the AC mains power and the load are connected to the first terminal and the second terminal of the first capacitor Co, respectively, via a relay. When discharging the battery pack, the relay connects the load to the first capacitor Co. When charging the battery pack, the relay connects the AC mains power to the first capacitor Co.

[0508] For ease of description, AC is used in the diagram. It should be understood that when discharging the battery pack, AC here represents the alternating current output by the three-arm topology. When charging the battery pack, AC here represents the AC mains power supply supplying power to the three-arm topology.

[0509] The positive terminal of the battery pack is connected to the first terminal of the voltage conversion circuit, and the negative terminal of the battery pack is connected to the second terminal of the voltage conversion circuit. The third terminal of the voltage conversion circuit is connected to BUS+, the fourth terminal of the voltage conversion circuit is connected to BUS-, and the fifth terminal of the voltage conversion circuit is connected to the midpoint of the first bridge arm.

[0510] In this embodiment, the voltage conversion circuit, the first arm of the three-arm circuit, and the bus capacitor E1 constitute a bidirectional DC-DC topology (also known as a bidirectional DC-DC converter) to achieve bidirectional voltage conversion. The bus capacitor E1, the second arm, the third arm, and the LC filter of the three-arm circuit constitute a bidirectional DCAC topology (also known as a bidirectional DCAC converter) to achieve inversion or rectification. That is, the bidirectional DC-DC topology and the bidirectional DCAC topology reuse the bus capacitor E1 of the three-arm circuit.

[0511] In this embodiment, the three-arm topology device has two modes: battery charging mode and battery power supply mode.

[0512] In battery charging mode, the AC mains power supply powers the three-bridge-arm circuit, and the bidirectional DC-DC topology charges the battery pack. At this time, the bidirectional DC-AC topology operates in AC-DC mode (i.e., full-bridge rectifier PFC converter mode), and the bidirectional DC-DC topology operates in BUCK mode (i.e., buck mode). The BUS voltage output from the DC bus capacitor E1 is stepped down to obtain the charging voltage for the battery pack, which is then used to charge the battery pack. In this mode, the battery pack serves as the output source for the bidirectional DC-DC topology. In this way, in battery charging mode, both the voltage conversion circuit and the three-bridge-arm circuit participate in the operation; that is, all components of the three-bridge-arm topology device are involved in the operation.

[0513] In battery-powered mode, the battery pack serves as the input source for the bidirectional DC-DC topology, while the output of the bidirectional DC-DC topology powers the bidirectional DC-AC topology. That is, the bidirectional DC-DC topology discharges the battery pack. At this time, the bidirectional DC-DC topology operates in Boost mode, boosting the output voltage of the battery pack. The boosted voltage is then input to the DC bus capacitor E1 to maintain bus voltage balance. The bidirectional DC-AC topology operates in DC-AC mode (full-bridge inverter mode), where the DC bus capacitor E1 filters the boosted DC power to obtain stable DC power. The second and third arms of the three-bridge circuit operate in inverter mode, converting the stable DC power into AC power and outputting it to the load to power it. Simultaneously, the DC bus capacitor E1 can store energy. In this way, in battery-powered mode, both the voltage conversion circuit and the three-bridge circuit participate in the operation; that is, all components of the three-bridge topology device are involved in the operation.

[0514] It is understood that the voltage conversion circuit involved in the embodiments of this application can be a voltage conversion circuit with electrical isolation or a voltage conversion circuit without electrical isolation.

[0515] Continue to refer to Figure 63 The voltage conversion circuit involved in the embodiments of this application may include, for example, a first voltage conversion unit, a transformer, an LC resonant cavity, and a second voltage conversion unit. The first voltage conversion unit is connected to the low-voltage side of the transformer, and the high-voltage side of the transformer is connected to the LC resonant cavity and the second voltage conversion unit.

[0516] Continue to refer to Figure 63 For example, the first voltage conversion unit includes a fourth bridge arm and a fifth bridge arm. The LC resonant cavity includes a fifth inductor Lik and an inductor Cr. The second voltage conversion unit includes a sixth bridge arm. That is, the second voltage conversion unit involved in this embodiment is a half-bridge topology.

[0517] It should be understood that the structure of the voltage conversion circuit involved in this embodiment is different from that of the voltage conversion circuit in the present embodiment. Figure 36 The voltage conversion circuits used in the three-arm topology shown have the same structure. For descriptions of the fourth arm, fifth arm, and LC resonant cavity, please refer to [link to relevant documentation]. Figure 36 The description of this part will not be repeated here. The difference is that in this embodiment, the fifth terminal of the voltage conversion circuit is connected to the midpoint of the first bridge arm, while... Figure 36 The fifth terminal of the voltage conversion circuit used in the three-arm bridge topology shown is connected to the midpoint of the second arm.

[0518] When using Figure 63 When the voltage conversion circuit shown is charging the battery pack, the bidirectional DC-DC topology operates in full-bridge LLC resonant converter mode. At this time, a full-bridge phase-shift control strategy can be used to control the full-bridge LLC resonant converter, enabling the leading arm of the full-bridge LLC resonant converter to achieve zero-voltage turn-on, and the lagging arm to achieve zero-voltage turn-on and zero-current turn-off. For specific operating principles, please refer to the existing technology descriptions of full-bridge LLC resonant converters; further details will not be elaborated here.

[0519] When using Figure 63 The voltage conversion circuit shown operates in the full-bridge secondary LC resonant converter mode when the battery pack is discharging, achieving zero-voltage turn-on and zero-current turn-off. For details on the working principle, please refer to the existing technology for the introduction of the full-bridge secondary LC resonant converter, which will not be repeated here.

[0520] It should be understood that when the voltage conversion circuit is used to discharge the battery pack, the secondary side of the transformer TX1 connected to the LC resonant cavity is the high-voltage side of the voltage conversion circuit. When the voltage conversion circuit is used to charge the battery pack, the secondary side of the transformer TX1 connected to the first voltage conversion unit is the low-voltage side of the voltage conversion circuit.

[0521] Optionally, the high-voltage side of the transformer, the LC resonant cavity, the second voltage conversion unit, and the second bridge arm can also be configured as follows: Figures 25 to 31 The connection method shown. The only difference is that, when... Figures 25 to 31 When the connection method shown is applied to this embodiment, the first bridge arm is used instead. Figures 25 to 31 The seventh bridge arm. In these implementations, the end of the voltage conversion circuit connected to the midpoint of the first bridge arm is the fifth terminal of the voltage conversion circuit, which will not be elaborated further.

[0522] Figure 63A Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 10 , Figure 63B Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 10 1. See also Figure 63A and Figure 63B When the high-voltage side of the aforementioned transformer is connected to the LC resonant cavity, the second voltage conversion unit, and the second bridge arm, Figure 30 or Figure 31 In the connection method shown, the first terminal of the transformer high-voltage side is the third terminal of the voltage conversion circuit, and the second terminal of the transformer high-voltage side is the fourth terminal of the voltage conversion circuit; the third terminal of the voltage conversion circuit is connected to the positive output terminal of the bus, and the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus; the voltage conversion circuit also includes a fifth terminal, which is connected to the midpoint of the first bridge arm.

[0523] Accordingly, the first voltage conversion unit involved in this embodiment can also be adopted as follows: Figures 32 to 35 The structural replacements shown will not be elaborated further.

[0524] It should be understood that when implementing the voltage conversion circuit using any of the above variations, the operating modes of the "bidirectional DC-DC topology composed of the voltage conversion circuit, the first bridge arm, and the bus capacitor E1" during battery charging and during battery discharging are different from those of the voltage conversion circuit. Figure 63 The voltage conversion circuit shown is the same, so it will not be described in detail again.

[0525] The following is based on Figure 63Taking the structure of the three-arm topology shown as an example, the states of each switch, each switching transistor, and the current flow of the three-arm topology under different power supply modes are illustrated:

[0526] Figure 64 Current diagram of the twentieth three-arm topology device provided in this application embodiment in battery-powered mode Figure 1 .like Figure 64 As shown, in the first stage of the battery-powered mode, i.e., during the positive half-cycle of the output AC power, the second switch Q2, the eighth switch Q8, the ninth switch Q9, and the eleventh switch Q11 are turned on. At this time, the current flow in the three-bridge-arm topology is as follows:

[0527] 1. Battery pack positive terminal → Ninth switch Q9 → Same-name terminal on the low-voltage side of TX1 → Different-name terminal on the low-voltage side of TX1 → Eighth switch Q8 → Battery pack negative terminal, so that the battery pack transfers energy to transformer TX1. TX1 high-voltage side same-name terminal → Fifth inductor Lik → Eleventh switch Q11 → BUS+ → BUS- → Second switch Q2 → Third capacitor Cr → Different-name terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0528] Figure 65 Current diagram of the twentieth three-arm topology device provided in this application embodiment in battery-powered mode Figure 2 .like Figure 65 As shown, in the second stage of the battery-powered mode, i.e., during the negative half-cycle of the output AC power, the first switch Q1, the seventh switch Q7, the tenth switch Q10, and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0529] 1. Battery pack positive terminal → seventh switch Q7 → opposite terminal on the low-voltage side of TX1 → same terminal on the low-voltage side of TX1 → tenth switch Q10 → battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. TX1 high-voltage side opposite terminal → third capacitor Cr → first switch Q1 → BUS+ → BUS- → twelfth switch Q12 → fifth inductor Lik → same terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0530] Figure 66 Current diagram of the twentieth three-arm topology device provided in this application embodiment in battery charging mode. Figure 1 .like Figure 66As shown, in the first stage of the battery charging mode, i.e., during the positive half-cycle of the input AC power, the second switch Q2 and the eleventh switch Q11 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0531] 1. BUS+ → Eleventh switch Q11 → Fifth inductor Lik → Same-name terminal on the high-voltage side of TX1 → Different-name terminal on the high-voltage side of TX1 → Third capacitor Cr → Second switch Q2 → BUS-, so that the bus capacitor E1 transfers energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr. 2. Same-name terminal on the low-voltage side of TX1 → Ninth switch Q9 → Battery pack positive terminal → Battery pack negative terminal → Eighth switch Q8 → Different-name terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the ninth switch Q9 and the eighth switch Q8 are used to implement the rectification function.

[0532] Figure 67 Current diagram of the twentieth three-arm topology device provided in this application embodiment in battery charging mode. Figure 2 .like Figure 67 As shown, in the second stage of the battery charging mode, i.e., during the negative half-cycle of the input AC power, the first switch Q1 and the twelfth switch Q12 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0533] 1. BUS+ → First switch Q1 → Third capacitor Cr → Opposite terminal on the high-voltage side of TX1 → Same terminal on the high-voltage side of TX1 → Fifth inductor Lik → Twelfth switch Q12 → BUS-, so that the bus capacitor E1 transfers energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr. 2. Opposite terminal on the low-voltage side of TX1 → Seventh switch Q7 → Battery pack positive terminal → Battery pack negative terminal → Tenth switch Q10 → Same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0534] Structure B23: The voltage conversion circuit in this three-arm topology achieves voltage conversion by multiplexing the second arm of the three-arm circuit and the bus capacitor E1. This three-arm topology can be applied to battery low-voltage, high-current inverter systems.

[0535] Figure 68 This is a schematic diagram of the twenty-first three-arm topology device provided in this application embodiment. Figure 68 As shown, in this embodiment, the first end of the first capacitor Co is the first external connection end of the three-arm topology device, and the second end of the first capacitor Co is the second external connection end of the three-arm topology device.

[0536] When discharging the battery pack, the first external connection terminal can be referred to as the first output terminal of the three-arm topology, and the second external connection terminal can be referred to as the second output terminal of the three-arm topology, both of which are connected to the load. When charging the battery pack, the first external connection terminal can be referred to as the positive voltage input terminal of the three-arm topology, and is connected to the first terminal of the external power supply, and the second external connection terminal can be referred to as the negative voltage input terminal of the three-arm topology, and is connected to the second terminal of the external power supply.

[0537] For example, if the external power supply is a photovoltaic DC power supply, then the first terminal of the external power supply is the positive terminal of the photovoltaic DC power supply, and the second terminal of the external power supply is the negative terminal of the photovoltaic DC power supply. If the external power supply is an AC mains power supply, then the first terminal of the external power supply is the live wire of the AC mains power supply, and the second terminal of the external power supply is the neutral wire of the AC mains power supply.

[0538] Taking AC mains power as an example, the AC mains power and the load are connected to the first terminal and the second terminal of the first capacitor Co, respectively, via a relay. When discharging the battery pack, the relay connects the load to the first capacitor Co. When charging the battery pack, the relay connects the AC mains power to the first capacitor Co.

[0539] For ease of description, AC is used in the diagram. It should be understood that when discharging the battery pack, AC here represents the alternating current output by the three-arm topology. When charging the battery pack, AC here represents the AC mains power supply supplying power to the three-arm topology.

[0540] The positive terminal of the battery pack is connected to the first terminal of the voltage conversion circuit, and the negative terminal of the battery pack is connected to the second terminal of the voltage conversion circuit. The third terminal of the voltage conversion circuit is connected to the midpoint of the first bridge arm, and the fourth terminal of the voltage conversion circuit is connected to the midpoint of the second bridge arm.

[0541] In this embodiment, the voltage conversion circuit, the first and second arms of the three-arm circuit, and the bus capacitor E1 constitute a bidirectional DC-DC topology (also known as a bidirectional DC-DC converter) to achieve bidirectional voltage conversion. The bus capacitor E1, the second and third arms of the three-arm circuit, and the LC filter constitute a bidirectional DC-AC topology (also known as a bidirectional DC-AC converter). That is, the bidirectional DC-DC topology and the bidirectional DC-AC topology reuse the second arm and the bus capacitor E1.

[0542] In this embodiment, the three-arm topology device has two modes: battery charging mode and battery power supply mode.

[0543] In battery charging mode, the AC mains power supply powers the three-bridge-arm circuit. The bidirectional DC-AC topology operates in AC-DC mode (i.e., full-bridge rectifier PFC converter mode), and the bidirectional DC-CDC topology operates in BUCK mode (i.e., buck mode). The BUS voltage output from the DC bus capacitor E1 is stepped down to obtain the battery pack charging voltage, which is then used to charge the battery pack. In this mode, the battery pack serves as the output source for the bidirectional DC-CDC topology. In this way, both the voltage conversion circuit and the three-bridge-arm circuit participate in the operation during battery charging mode; that is, all components of the three-bridge-arm topology device are involved in the operation.

[0544] In battery-powered mode, the battery pack serves as the input source for the bidirectional DC-DC topology, while the output of the bidirectional DC-DC topology powers the three-arm circuit. That is, the bidirectional DC-DC topology discharges the battery pack. At this time, the bidirectional DC-DC topology operates in Boost mode, boosting the output voltage of the battery pack. The boosted voltage is then input to the DC bus capacitor E1 to maintain bus voltage balance. The bidirectional DC-AC topology operates in DC-AC mode (full-bridge inverter mode). The DC bus capacitor E1 filters the boosted DC power to obtain stable DC power. The second and third arms operate in inverter mode, converting the stable DC power into AC power and outputting it to the load to power it. Simultaneously, the DC bus capacitor E1 can store energy. In this way, in battery-powered mode, both the voltage conversion circuit and the three-arm circuit participate in the operation; that is, all components of the three-arm topology device are involved in the operation.

[0545] Continue to refer to Figure 1A The existing low-voltage, high-current battery inverter system shown has the following problems in addition to low integration and low device reuse rate:

[0546] First, the switching devices of the Buck converter are connected in series in the main power circuit of the battery low-voltage high-current inverter system, which increases the conduction loss and thermal cost of the existing battery low-voltage high-current inverter system and reduces its reliability.

[0547] Secondly, in battery charging mode, multiple voltage regulation (i.e., the AC power supplied by the mains AC power supply is first boosted by a full-bridge rectifier PFC converter, and then stepped down by a Buck converter before being supplied to the bidirectional DC-DC converter) increases the system complexity of the low-voltage, high-current battery inverter system and reduces the system efficiency.

[0548] Compared to Figure 1A The provided battery low-voltage high-current inverter system with a three-stage converter is an embodiment of this application. Figure 63 and Figure 68When the provided three-arm topology device is applied to a battery voltage high-current inverter system, it can modify the battery low-voltage high-current inverter system from a three-stage converter topology to a two-stage converter topology through bidirectional DC-DC topology and bidirectional DC-AC topology.

[0549] Under this two-stage converter topology, all devices in the three-arm topology device participate in the operation, whether in battery power supply mode or battery charging mode. This improves the integration and device reuse rate of the battery low-voltage high-current inverter system, reduces the material cost of the system, reduces the conduction loss and heat cost of the existing battery low-voltage high-current inverter system, and improves reliability.

[0550] In addition, after modifying the battery low-voltage high-current inverter system from a three-stage converter topology to a two-stage converter topology, the power conversion path is shorter, improving system efficiency.

[0551] Figure 69 This is a schematic diagram of the twenty-second three-arm topology device provided in this application embodiment. Figure 69 As shown, when Figure 68 When the three-arm topology shown is applied to a unidirectional low-voltage, high-current battery inverter system (i.e., the system only supports power supply to the load, and charging of the battery pack requires an external charger), the above... Figure 68 The first and second switching transistors in the first arm of the three-arm topology shown can be replaced by two diodes, for example... Figure 69 The structure of the three-arm topology device is shown. Under this structure, the principle of power supply to the load by the three-arm topology device is the same as... Figure 68 The principle of powering the load using the three-arm topology shown is similar, and will not be elaborated further.

[0552] In addition, the voltage conversion circuit involved in the embodiments of this application can be a voltage conversion circuit with electrical isolation or a voltage conversion circuit without electrical isolation.

[0553] Continue to refer to Figure 68 The voltage conversion circuit involved in the embodiments of this application may include, for example, a first voltage conversion unit, a transformer, and an LC resonant cavity. The first voltage conversion unit is connected to the low-voltage side of the transformer, and the high-voltage side of the transformer is connected to the LC resonant cavity.

[0554] Continue to refer to Figure 68 For example, the first voltage conversion unit includes a fourth bridge arm and a fifth bridge arm. The LC resonant cavity includes a fifth inductor Lik and an inductor Cr.

[0555] The fourth bridge arm includes a seventh switch Q7 and an eighth switch Q8 connected in series (i.e., the first end of the seventh switch Q7 is connected to the first end of the eighth switch Q8); the fifth bridge arm includes a ninth switch Q9 and a tenth switch Q10 connected in series (i.e., the first end of the ninth switch Q9 is connected to the first end of the tenth switch Q10). The fourth bridge arm and the fifth bridge arm are connected in parallel (i.e., the second end of the seventh switch Q7 is connected to the second end of the ninth switch Q9, and the second end of the eighth switch Q8 is connected to the second end of the tenth switch Q10).

[0556] For a description of the fourth bridge arm, the fifth bridge arm, and the LC resonant cavity, please refer to the preceding text. Figure 3 The descriptions of the fourth and fifth bridge arms and the LC resonant cavity are omitted here. In some embodiments, the above... Figure 68 The first voltage conversion unit shown can also be called a full-bridge converter circuit.

[0557] The second terminal of the seventh switch Q7 is the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch Q8 is the second terminal of the voltage conversion circuit.

[0558] The midpoint of the fourth bridge arm is connected to the opposite-name terminal on the low-voltage side of transformer TX1, and the midpoint of the fifth bridge arm is connected to the same-name terminal on the low-voltage side of transformer TX1. The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor Lik, the second terminal of the fifth inductor Lik is connected to the midpoint of the first bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor Cr, and the second terminal of the third capacitor Cr is connected to the midpoint of the second bridge arm. That is, the second terminal of the fifth inductor Lik is the third terminal of the voltage conversion circuit, and the second terminal of the third capacitor Cr is the fourth terminal of the voltage conversion circuit.

[0559] When using this voltage conversion circuit to charge the battery pack, the bidirectional DC-DC topology operates in half-bridge LLC resonant converter mode, achieving a wider voltage regulation range and zero-voltage turn-on. When using this voltage conversion circuit to discharge the battery pack, the bidirectional DC-DC topology operates in full-bridge secondary-side LC resonant voltage doubler converter mode, achieving a two-fold voltage boost and improving the boost ratio of the bidirectional DC-DC topology.

[0560] It should be understood that when the voltage conversion circuit is used to discharge the battery pack, the secondary side of the transformer TX1 connected to the LC resonant cavity is the high-voltage side of the voltage conversion circuit. When the voltage conversion circuit is used to charge the battery pack, the secondary side of the transformer TX1 connected to the first voltage conversion unit is the low-voltage side of the voltage conversion circuit.

[0561] Optionally, the high-voltage side of the transformer and the LC resonant cavity, the first bridge arm, and the second bridge arm can also be configured as follows: Figures 25 to 31The connection method shown. The only difference is that, when... Figures 25 to 31 When the connection method shown is applied to this embodiment, the first bridge arm is used instead. Figures 25 to 31 The sixth bridge arm is replaced by the second bridge arm. Figures 25 to 31 The seventh bridge arm. In these implementations, the end of the voltage conversion circuit connected to the midpoint of the first bridge arm is the third terminal of the voltage conversion circuit, and the end connected to the midpoint of the second bridge arm is the fourth terminal of the voltage conversion circuit. This will not be elaborated further.

[0562] Figure 68A Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 10 two, Figure 68B Partial connection diagram of the voltage conversion circuit provided in the embodiments of this application Figure 10 III. See also Figure 68A When the high-voltage side of the above-mentioned transformer is connected to the LC resonant cavity, the first bridge arm, and the second bridge arm, Figure 30 In the connection configuration shown, the second end of the first switching transistor is connected to the first opposite-name terminal of the high-voltage side of the transformer, and the second end of the second switching transistor is connected to the second opposite-name terminal of the high-voltage side of the transformer; the first same-name terminal of the high-voltage side of the transformer is connected to the positive output terminal of the bus, and the second same-name terminal of the high-voltage side of the transformer is connected to the negative output terminal of the bus; the first end of the fifth inductor is the third end of the voltage conversion circuit, the second end of the fifth inductor is connected to the first end of the third capacitor, and the second end of the third capacitor is the fourth end of the voltage conversion circuit.

[0563] See Figure 68B When the high-voltage side of the above-mentioned transformer is connected to the LC resonant cavity, the first bridge arm, and the second bridge arm, Figure 31 In the connection configuration shown, the second end of the first switching transistor is connected to the first opposite-name terminal of the high-voltage side of the transformer, and the second end of the second switching transistor is connected to the second opposite-name terminal of the high-voltage side of the transformer; the first same-name terminal of the high-voltage side of the transformer is connected to the positive output terminal of the bus, and the second same-name terminal of the high-voltage side of the transformer is connected to the negative output terminal of the bus; the first end of the third capacitor is the third terminal of the voltage conversion circuit, the second end of the third capacitor is connected to the first end of the fifth inductor, and the second end of the fifth inductor is the fourth terminal of the voltage conversion circuit.

[0564] Accordingly, the first voltage conversion unit involved in this embodiment can also be adopted as follows: Figures 32 to 35 The structural replacements shown will not be elaborated further.

[0565] It should be understood that when implementing the voltage conversion circuit using any of the above variations, the operating modes of the "bidirectional DC-DC topology composed of the voltage conversion circuit, the first bridge arm, the second bridge arm, and the bus capacitor E1" during battery charging and during battery discharging are different from those of the voltage conversion circuit. Figure 68 The voltage conversion circuit shown is the same, so it will not be described in detail again.

[0566] The following is based on Figure 68 Taking the structure of the three-arm topology shown as an example, the states of each switch, each switching transistor, and the current flow of the three-arm topology under different power supply modes are illustrated:

[0567] Figure 70 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 1 .like Figure 70 As shown, in the first stage of the battery-powered mode, that is, in the first stage of the positive half-cycle of the output AC power, the second switch Q2, the fourth switch Q4, the fifth switch Q5, the seventh switch Q7, and the tenth switch Q10 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0568] 1. Battery pack positive terminal → seventh switch Q7 → opposite terminal on the low-voltage side of TX1 → same terminal on the low-voltage side of TX1 → tenth switch Q10 → battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. TX1 high-voltage side opposite terminal → third capacitor Cr → fourth switch Q4 → second switch Q2 → fifth inductor Lik → TX1 high-voltage side same terminal, forming the energy storage circuit of the third capacitor Cr.

[0569] 2. BUS+ → Fifth switch Q5 → Second inductor L2 → First capacitor Co → Fourth switch Q4 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0570] Figure 71 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 2 .like Figure 71 As shown, in the second stage of the battery-powered mode, that is, in the second stage of the positive half-cycle of the output AC power, the first switch Q1, the fourth switch Q4, the fifth switch Q5, the eighth switch Q8, and the ninth switch Q9 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0571] 1. Battery pack positive terminal → Ninth switch Q9 → Same-name terminal on the low-voltage side of TX1 → Different-name terminal on the low-voltage side of TX1 → Eighth switch Q8 → Battery pack negative terminal, so that the battery pack transfers energy to transformer TX1. TX1 high-voltage side same-name terminal → Fifth inductor Lik → First switch Q1 → BUS+ → BUS- → Fourth switch Q4 → Third capacitor Cr → Different-name terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0572] 2. BUS+ → Fifth switch Q5 → Second inductor L2 → First capacitor Co → Fourth switch Q4 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0573] Figure 72 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 3 .like Figure 72 As shown, in the third stage of the battery-powered mode, that is, in the third stage of the positive half-cycle of the output AC power, the second switch Q2, the fourth switch Q4, the sixth switch Q6, the seventh switch Q7, and the tenth switch Q10 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0574] 1. Battery pack positive terminal → seventh switch Q7 → opposite terminal on the low-voltage side of TX1 → same terminal on the low-voltage side of TX1 → tenth switch Q10 → battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. TX1 high-voltage side opposite terminal → third capacitor Cr → fourth switch Q4 → second switch Q2 → fifth inductor Lik → TX1 high-voltage side same terminal, forming the energy storage circuit of the third capacitor Cr.

[0575] 2. The second inductor L2 → the first capacitor Co → the fourth switch Q4 → the sixth switch Q6 → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0576] Figure 73 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 4 .like Figure 73 As shown, in the fourth stage of the battery-powered mode, that is, in the fourth stage of the positive half-cycle of the output AC power, the first switch Q1, the fourth switch Q4, the sixth switch Q6, the eighth switch Q8, and the ninth switch Q9 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0577] 1. Battery pack positive terminal → Ninth switch Q9 → Same-name terminal on the low-voltage side of TX1 → Different-name terminal on the low-voltage side of TX1 → Eighth switch Q8 → Battery pack negative terminal, so that the battery pack transfers energy to transformer TX1. TX1 high-voltage side same-name terminal → Fifth inductor Lik → First switch Q1 → BUS+ → BUS- → Fourth switch Q4 → Third capacitor Cr → Different-name terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0578] 2. The second inductor L2 → the first capacitor Co → the fourth switch Q4 → the sixth switch Q6 → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0579] Figure 74 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 5 .like Figure 74 As shown, in the fifth stage of the battery-powered mode, that is, in the first stage of the negative half-cycle of the output AC power, the first switch Q1, the third switch Q3, the sixth switch Q6, the eighth switch Q8, and the ninth switch Q9 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0580] 1. Battery pack positive terminal → Ninth switch Q9 → Same-name terminal on the low-voltage side of TX1 → Different-name terminal on the low-voltage side of TX1 → Eighth switch Q8 → Battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. Same-name terminal on the high-voltage side of TX1 → Fifth inductor Lik → First switch Q1 → Third switch Q3 → Third capacitor Cr → Different-name terminal on the high-voltage side of TX1, forming the energy storage circuit of the third capacitor Cr.

[0581] 2. BUS+ → Third switch Q3 → First capacitor Co → Second inductor L2 → Sixth switch Q6 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0582] Figure 75 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 6 .like Figure 75 As shown, in the sixth stage of the battery-powered mode, that is, in the second stage of the negative half-cycle of the output AC power, the first switch Q1, the second switch Q2, the third switch Q3, the sixth switch Q6, the seventh switch Q7, and the tenth switch Q10 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0583] 1. Battery pack positive terminal → seventh switch Q7 → opposite terminal on the low-voltage side of TX1 → same terminal on the low-voltage side of TX1 → tenth switch Q10 → battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. TX1 high-voltage side opposite terminal → third capacitor Cr → first switch Q1 → BUS+ → BUS- → second switch Q2 → fifth inductor Lik → same terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0584] 2. BUS+ → Third switch Q3 → First capacitor Co → Second inductor L2 → Sixth switch Q6 → BUS-, to provide energy to the load through bus capacitor E1. The second inductor L2 and the first capacitor Co are used for filtering.

[0585] Figure 76 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 7 .like Figure 76 As shown, in the seventh stage of the battery-powered mode, that is, in the third stage of the negative half-cycle of the output AC power, the first switch Q1, the third switch Q3, the fifth switch Q5, the eighth switch Q8, and the ninth switch Q9 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0586] 1. Battery pack positive terminal → Ninth switch Q9 → Same-name terminal on the low-voltage side of TX1 → Different-name terminal on the low-voltage side of TX1 → Eighth switch Q8 → Battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. Same-name terminal on the high-voltage side of TX1 → Fifth inductor Lik → First switch Q1 → Third switch Q3 → Third capacitor Cr → Different-name terminal on the high-voltage side of TX1, forming the energy storage circuit of the third capacitor Cr.

[0587] 2. The second inductor L2 → the fifth switch Q5 → the third switch Q3 → the first capacitor Co → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0588] Figure 77 Current diagram of the twenty-first three-arm topology device provided in this application embodiment in battery-powered mode. Figure 8 .like Figure 77 As shown, in the eighth stage of the battery-powered mode, that is, in the fourth stage of the negative half-cycle of the output AC power, the first switch Q1, the second switch Q2, the third switch Q3, the fifth switch Q5, the seventh switch Q7, and the tenth switch Q10 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0589] 1. Battery pack positive terminal → seventh switch Q7 → opposite terminal on the low-voltage side of TX1 → same terminal on the low-voltage side of TX1 → tenth switch Q10 → battery pack negative terminal, so that the battery pack can transfer energy to transformer TX1. 2. TX1 high-voltage side opposite terminal → third capacitor Cr → first switch Q1 → BUS+ → BUS- → second switch Q2 → fifth inductor Lik → same terminal on the high-voltage side of TX1, forming the energy storage circuit for bus capacitor E1. At this time, transformer TX1 and third capacitor Cr simultaneously provide energy to bus capacitor E1.

[0590] 2. The second inductor L2 → the fifth switch Q5 → the third switch Q3 → the first capacitor Co → the second inductor L2, so as to provide energy to the load through the second inductor L2. Among them, the second inductor L2 and the first capacitor Co are used to realize the filtering function.

[0591] Figure 78 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 1 .like Figure 78 As shown, in the first stage of the battery charging mode, that is, in the first stage of the positive half-cycle of the input AC power, the first switch Q1, the fourth switch Q4, and the sixth switch Q6 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0592] 1. The live wire of the AC mains power supply → the second inductor L2 → the sixth switch Q6 → the fourth switch Q4 → the neutral wire of the AC mains power supply constitutes the energy storage circuit of the second inductor L2.

[0593] 2. BUS+ → First switch Q1 → Fifth inductor Lik → Same-name terminal on the high-voltage side of TX1 → Different-name terminal on the high-voltage side of TX1 → Third capacitor Cr → Fourth switch Q4 → BUS-, so that the bus capacitor E1 transmits energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr.

[0594] The energy storage circuit of the battery pack is formed by the same-name terminal on the low-voltage side of TX1 → the ninth switch Q9 → the positive terminal of the battery pack → the negative terminal of the battery pack → the eighth switch Q8 → the opposite-name terminal on the low-voltage side of TX1. Among them, the ninth switch Q9 and the eighth switch Q8 are used to realize the rectification function.

[0595] Figure 79 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 2 .like Figure 79 As shown, in the second stage of the battery charging mode, that is, in the second stage of the positive half-cycle of the input AC power, the second switch Q2, the fourth switch Q4, and the sixth switch Q6 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0596] 1. The live wire of the AC mains power supply → the second inductor L2 → the sixth switch Q6 → the fourth switch Q4 → the neutral wire of the AC mains power supply constitutes the energy storage circuit of the second inductor L2.

[0597] 2. Cr positive terminal → opposite terminal on the high-voltage side of TX1 → same terminal on the high-voltage side of TX1 → fifth inductor Lik → second switch Q2 → fourth switch Q4 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side opposite terminal → seventh switch Q7 → battery pack positive terminal → battery pack negative terminal → tenth switch Q10 → same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0598] Figure 80 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 3 .like Figure 80 As shown, in the third stage of the battery charging mode, that is, in the third stage of the positive half-cycle of the input AC power, the first switch Q1, the fourth switch Q4, and the fifth switch Q5 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0599] 1. The live wire of the AC mains power supply → the second inductor L2 → the fifth switch Q5 → BUS+ → BUS- → the fourth switch Q4 → the neutral wire of the AC mains power supply constitutes an energy storage circuit in which the second inductor L2 and the AC mains power supply simultaneously store energy for the DC bus capacitor E1.

[0600] 2. BUS+ → First switch Q1 → Fifth inductor Lik → Same-name terminal on the high-voltage side of TX1 → Different-name terminal on the high-voltage side of TX1 → Third capacitor Cr → Fourth switch Q4 → BUS-, so that the bus capacitor E1 transmits energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr.

[0601] The energy storage circuit of the battery pack is formed by the same-name terminal on the low-voltage side of TX1 → the ninth switch Q9 → the positive terminal of the battery pack → the negative terminal of the battery pack → the eighth switch Q8 → the opposite-name terminal on the low-voltage side of TX1. Among them, the ninth switch Q9 and the eighth switch Q8 are used to realize the rectification function.

[0602] Figure 81 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 4 .like Figure 81 As shown, in the fourth stage of the battery charging mode, that is, in the fourth stage of the positive half-cycle of the input AC power, the second switch Q2, the fourth switch Q4, and the fifth switch Q5 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0603] 1. The live wire of the AC mains power supply → the second inductor L2 → the fifth switch Q5 → BUS+ → BUS- → the fourth switch Q4 → the neutral wire of the AC mains power supply constitutes an energy storage circuit in which the second inductor L2 and the AC mains power supply simultaneously store energy for the DC bus capacitor E1.

[0604] 2. Cr positive terminal → opposite terminal on the high-voltage side of TX1 → same terminal on the high-voltage side of TX1 → fifth inductor Lik → second switch Q2 → fourth switch Q4 → Cr negative terminal, so that Cr acts as a transformer for TX1 to transfer energy. TX1 low-voltage side opposite terminal → seventh switch Q7 → battery pack positive terminal → battery pack negative terminal → tenth switch Q10 → same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0605] Figure 82 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 5 .like Figure 82 As shown, in the fifth stage of the battery charging mode, that is, in the first stage of the negative half-cycle of the input AC power, the second switch Q2, the third switch Q3, and the fifth switch Q5 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0606] 1. The neutral wire of the AC mains power supply → the third switch Q3 → the fifth switch Q5 → the second inductor L2 → the live wire of the AC mains power supply, forming the energy storage circuit of the second inductor L2.

[0607] 2. BUS+ → Third switch Q3 → Third capacitor Cr → Opposite terminal on the high-voltage side of TX1 → Same terminal on the high-voltage side of TX1 → Fifth inductor Lik → Second switch Q2 → BUS-, so that the bus capacitor E1 transfers energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr. TX1 low-voltage side opposite terminal → Seventh switch Q7 → Battery pack positive terminal → Battery pack negative terminal → Tenth switch Q10 → Same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0608] Figure 83 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 6 .like Figure 83 As shown, in the sixth stage of the battery charging mode, that is, in the second stage of the negative half-cycle of the input AC power, the first switch Q1, the third switch Q3, and the fifth switch Q5 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0609] 1. The neutral wire of the AC mains power supply → the third switch Q3 → the fifth switch Q5 → the second inductor L2 → the live wire of the AC mains power supply, forming the energy storage circuit of the second inductor L2.

[0610] 2. Cr positive terminal → third switch Q3 → first switch Q1 → fifth inductor Lik → same-name terminal on the high-voltage side of TX1 → opposite-name terminal on the high-voltage side of TX1 → Cr negative terminal, so that Cr can act as a transformer for TX1 to transfer energy.

[0611] The energy storage circuit of the battery pack is formed by the same-name terminal on the low-voltage side of TX1 → the ninth switch Q9 → the positive terminal of the battery pack → the negative terminal of the battery pack → the eighth switch Q8 → the opposite-name terminal on the low-voltage side of TX1. Among them, the ninth switch Q9 and the eighth switch Q8 are used to realize the rectification function.

[0612] Figure 84 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 7 .like Figure 84 As shown, in the seventh stage of the battery charging mode, that is, in the third stage of the negative half-cycle of the input AC power, the second switch Q2, the third switch Q3, and the sixth switch Q6 are turned on. At this time, the current flow in the three-bridge topology is as follows:

[0613] 1. The neutral wire of the AC mains power supply → the third switch Q3 → BUS+ → BUS- → the sixth switch Q6 → the second inductor L2 → the live wire of the AC mains power supply constitutes an energy storage circuit in which the second inductor L2 and the AC mains power supply simultaneously store energy for the DC bus capacitor E1.

[0614] 2. BUS+ → Third switch Q3 → Third capacitor Cr → Opposite terminal on the high-voltage side of TX1 → Same terminal on the high-voltage side of TX1 → Fifth inductor Lik → Second switch Q2 → BUS-, so that the bus capacitor E1 transfers energy to the transformer TX1 and forms the energy storage circuit of the third capacitor Cr. TX1 low-voltage side opposite terminal → Seventh switch Q7 → Battery pack positive terminal → Battery pack negative terminal → Tenth switch Q10 → Same terminal on the low-voltage side of TX1, forming the energy storage circuit of the battery pack. Among them, the seventh switch Q7 and the tenth switch Q10 are used to implement the rectification function.

[0615] Figure 85 A schematic diagram of the current in battery charging mode for the twenty-first three-arm topology device provided in this application embodiment. Figure 8 .like Figure 85 As shown, in the eighth stage of the battery charging mode, that is, in the fourth stage of the negative half-cycle of the input AC power, the first switch Q1, the third switch Q3, and the sixth switch Q6 are turned on. At this time, the current flow in the three-arm topology is as follows:

[0616] 1. The neutral wire of the AC mains power supply → the third switch Q3 → BUS+ → BUS- → the sixth switch Q6 → the second inductor L2 → the live wire of the AC mains power supply constitutes an energy storage circuit in which the second inductor L2 and the AC mains power supply simultaneously store energy for the DC bus capacitor E1.

[0617] 2. Cr positive terminal → third switch Q3 → first switch Q1 → fifth inductor Lik → same-name terminal on the high-voltage side of TX1 → opposite-name terminal on the high-voltage side of TX1 → Cr negative terminal, so that Cr can act as a transformer for TX1 to transfer energy.

[0618] The energy storage circuit of the battery pack is formed by the same-name terminal on the low-voltage side of TX1 → the ninth switch Q9 → the positive terminal of the battery pack → the negative terminal of the battery pack → the eighth switch Q8 → the opposite-name terminal on the low-voltage side of TX1. Among them, the ninth switch Q9 and the eighth switch Q8 are used to realize the rectification function.

[0619] It should be noted that the above-mentioned three-arm topology device applied to the battery low-voltage high-current inverter system ( Figures 63 to 85 In the three-arm topology shown, the connection relationship between the LC filter and the second and third arms can also be as follows:

[0620] Figure 86 This is a schematic diagram illustrating the connection relationship between an LC filter and the second and third bridge arms, as provided in an embodiment of this application. Figure 86 As shown, the midpoint of the second bridge arm is connected to the first end of the second inductor L2, the second end of the second inductor L2 is connected to the second end of the first capacitor Co, and the first end of the first capacitor Co is connected to the midpoint of the third bridge arm. The first end of the first capacitor Co is the first external connection terminal of the three-bridge-arm topology, and the second end of the first capacitor Co is the second external connection terminal of the three-bridge-arm topology.

[0621] In some implementations, the above-mentioned three-arm topology device applied to a battery low-voltage high-current inverter system ( Figures 63 to 85 The LC filter in the three-bridge topology shown can also be replaced by an LCL filter (i.e., a filter consisting of two inductors and one capacitor).

[0622] Figure 87 This diagram illustrates the connection relationship between an LCL filter and its second and third bridge arms, as provided in an embodiment of this application. Taking an LCL filter comprising "a second inductor L2, a first capacitor Co, and a fourth inductor L4" as an example, the connection relationship can be as follows:

[0623] The midpoint of the third bridge arm is connected to the first end of the second inductor L2. The second end of the second inductor L2 is connected to the first end of the first capacitor Co. The second end of the first capacitor Co is connected to the first end of the fourth inductor L4. The second end of the fourth inductor L4 is connected to the midpoint of the second bridge arm. The first end of the first capacitor Co is the first external connection terminal of the three-bridge-arm topology, and the second end of the first capacitor Co is the second external connection terminal of the three-bridge-arm topology.

[0624] It should be understood that although the above-described three-arm topology devices are illustrated using examples of battery-powered low-voltage, high-current UPS systems or battery-powered low-voltage, high-current inverter systems, those skilled in the art will understand that the three-arm topology devices used in battery-powered low-voltage, high-current UPS systems can also be applied to other UPS systems (e.g., high-power UPS systems), or other systems that use different power sources (mains power or battery packs) under different conditions (e.g., inverter systems), etc., which will not be elaborated further. Similarly, the three-arm topology devices used in battery-powered low-voltage, high-current inverter systems can also be applied to other inverter systems (e.g., high-power UPS systems), etc., which will not be elaborated further.

[0625] It is understood that the various numbers involved in the embodiments of this application (such as first switch tube, second switch tube, first switch, second switch, etc.) are only for the convenience of description and are not intended to limit the scope of the embodiments of this application.

[0626] It is understood that the switching transistors involved in the embodiments of this application can be any switching transistor capable of being turned on or off based on control, such as an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOS), a transistor, or a thyristor. The switching transistors used in different circuits can be different or the same. For example, a MOS transistor can be used in the voltage conversion circuit, and an IGBT can be used in the three-arm bridge circuit, or both the voltage conversion circuit and the three-arm bridge circuit can use IGBTs. Furthermore, the same switching transistor or different switching transistors can be used in the same circuit; this is not limited.

[0627] Furthermore, although the above embodiments illustrate the states of each switch and the current flow of various three-arm topology devices with different power supply modes provided in the embodiments of this application, those skilled in the art will understand that for switches not mentioned in the above description, in the external power supply mode or battery power supply mode of the three-arm topology device, they may be in an off state, or rectification may be achieved through an external diode of the switch, or rectification may be achieved by the switch itself being turned on, which can be determined according to the control method. That is to say, the control methods of each switch in the three-arm topology device provided in the embodiments of this application include, but are not limited to, the methods listed in the above embodiments, and may also be implemented in other ways, which are not limited in this application.

[0628] On the other hand, embodiments of this application also provide an uninterruptible power supply system, which includes: an external power supply, a load, and the three-arm topology device shown in the foregoing embodiments (e.g., Figure 2 , Figures 4 to 7 ,as well as, Figures 14 to 23 , Figures 24 to 61 (Any of the three-arm bridge topologies shown in the diagram). The first terminal of the external power supply is connected to the positive voltage input terminal AC_L of the three-arm bridge topology, the second terminal of the external power supply is connected to the negative voltage input terminal AC_N of the three-arm bridge topology, and the first and second output terminals of the three-arm bridge topology are connected to the load. The external power supply mentioned here can be, for example, AC mains power or DC photovoltaic power.

[0629] Furthermore, embodiments of this application also provide an uninterruptible power supply system, which includes: a first external power supply, a second external power supply, a load, and the three-arm topology device shown in the foregoing embodiments (e.g., Figure 62 The diagram shows a three-bridge topology. The first terminal of the first external power supply is connected to the first positive voltage input terminal of the three-bridge topology, the second terminal of the first external power supply is connected to the first negative voltage input terminal of the three-bridge topology, the first terminal of the second external power supply is connected to the second positive voltage input terminal of the three-bridge topology, the second terminal of the second external power supply is connected to the second negative voltage input terminal of the three-bridge topology, and both the first and second output terminals of the three-bridge topology are connected to the load.

[0630] The first and second external power supplies mentioned here can be two different sources. For example, the first external power supply could be AC ​​mains power, and the second external power supply could be DC photovoltaic (PV) power. In this example, the live wire of the AC mains power supply is connected to the first positive voltage input terminal AC_L of the three-arm topology, the neutral wire of the AC mains power supply is connected to the first negative voltage input terminal AC_N of the three-arm topology, the positive terminal of the PV DC power supply is connected to the second positive voltage input terminal PV+ of the three-arm topology, and the negative terminal of the PV DC power supply is connected to the second negative voltage input terminal PV- of the three-arm topology.

[0631] Alternatively, the first external power supply may be a photovoltaic (PV) DC power supply, and the second external power supply may be an AC mains power supply. In this example, the live wire of the AC mains power supply is connected to the second positive voltage input terminal AC_L of the three-arm topology, the neutral wire of the AC mains power supply is connected to the second negative voltage input terminal AC_N of the three-arm topology, the positive terminal of the PV DC power supply is connected to the first positive voltage input terminal PV+ of the three-arm topology, and the negative terminal of the PV DC power supply is connected to the first negative voltage input terminal PV- of the three-arm topology.

[0632] The uninterruptible power supply system provided in this application embodiment can be, for example, a battery low-voltage high-current UPS system, or an online small-to-medium power UPS system, etc.

[0633] The UPS system provided in this application embodiment is similar in principle and technical effect to the three-arm topology device applied to the battery low-voltage high-current UPS system mentioned above, and will not be described again here.

[0634] Furthermore, embodiments of this application also provide an inverter system, comprising: a load, and the three-arm topology device shown in the foregoing embodiments (e.g., Figures 63 to 68 , Figures 70 to 85 (Any of the three-bridge topologies shown).

[0635] In battery-powered mode, both the first and second external connection terminals of the three-arm topology are connected to the load.

[0636] Optionally, the inverter system may further include: an external power supply; in battery charging mode, both the first external connection terminal and the second external connection terminal of the three-arm topology device are connected to the external power supply.

[0637] The inverter system provided in this application embodiment can be, for example, a battery low-voltage high-current inverter system or an online small-to-medium power inverter system. The implementation principle and technical effects of the inverter system provided in this application embodiment are similar to the aforementioned three-arm topology device applied to the battery low-voltage high-current inverter system, and will not be repeated here.

[0638] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A three-arm topology device, characterized in that, The three-bridge topology device includes: a battery pack, a voltage conversion circuit, and a three-bridge circuit; The three-bridge circuit includes: a first bridge arm, a second bridge arm, a third bridge arm, a first inductor, a second inductor, a DC bus capacitor, and a first capacitor; The first bridge arm includes a first switch and a second switch connected in series; The second bridge arm includes a third switch and a fourth switch connected in series; The third bridge arm includes a fifth switch and a sixth switch connected in series; The first bridge arm, the second bridge arm, the third bridge arm, and the DC bus capacitor are connected in parallel between the positive output terminal and the negative output terminal of the bus. The midpoint of the first bridge arm is connected to the first end of the first inductor, and the second end of the first inductor serves as the positive voltage input terminal of the three-bridge-arm topology. The midpoint of the second bridge arm or the negative output terminal of the bus serves as the negative voltage input terminal of the three-bridge-arm topology. The midpoint of the third bridge arm is connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the first capacitor, the second end of the first capacitor is connected to the midpoint of the second bridge arm, the first end of the first capacitor is the first output terminal of the three-bridge-arm topology, the second end of the first capacitor is the second output terminal of the three-bridge-arm topology, and both the first and second output terminals are connected to the load. The positive terminal of the battery pack is connected to the first terminal of the voltage conversion circuit, the negative terminal of the battery pack is connected to the second terminal of the voltage conversion circuit, the third terminal of the voltage conversion circuit is connected to the positive output terminal of the bus, the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus, the first terminal of the external power supply is connected to the positive voltage input terminal, and the second terminal of the external power supply is connected to the negative voltage input terminal. The voltage conversion circuit is used to charge the battery pack in external power supply mode and to discharge the battery pack in battery power supply mode. The midpoint of the second bridge arm serves as the negative voltage input terminal of the three-bridge-arm topology. The three-arm topology device also includes: a switching switch; The third terminal of the voltage conversion circuit is connected to the positive output terminal of the bus and the positive voltage input terminal respectively through the switching switch; The switching switch is used to control the voltage conversion circuit to charge the battery pack in external power supply mode; and in battery power supply mode, to connect the voltage conversion circuit in series with the boost circuit formed by the first inductor and the first bridge arm, and to control the voltage conversion circuit to discharge the battery pack.

2. The apparatus according to claim 1, characterized in that, The voltage conversion circuit includes: a first voltage conversion unit, a second voltage conversion unit, a transformer, and an LC resonant cavity; the LC resonant cavity includes: a fifth inductor and a third capacitor; The first voltage conversion unit is connected to the low-voltage side of the transformer, and the high-voltage side of the transformer is connected to the resonant cavity and the second voltage conversion unit.

3. The apparatus according to claim 2, characterized in that, The first voltage conversion unit includes a fourth bridge arm and a fifth bridge arm; the fourth bridge arm includes a seventh switch and an eighth switch; the fifth bridge arm includes a ninth switch and a tenth switch. The first end of the seventh switch is connected to the first end of the eighth switch, the first end of the ninth switch is connected to the first end of the tenth switch, the second end of the seventh switch is connected to the second end of the ninth switch, and the second end of the eighth switch is connected to the second end of the tenth switch. The midpoint of the fourth bridge arm is connected to the opposite-named end of the low-voltage side of the transformer, and the midpoint of the fifth bridge arm is connected to the same-named end of the low-voltage side of the transformer. The second terminal of the seventh switch is the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch is the second terminal of the voltage conversion circuit.

4. The apparatus according to claim 2, characterized in that, The first voltage conversion unit includes: a seventh switch and an eighth switch; The first end of the seventh switch is connected to the first terminal of the same name on the low-voltage side of the transformer, the first end of the eighth switch is connected to the terminal of the opposite name on the low-voltage side of the transformer, and the second end of the seventh switch is connected to the second end of the eighth switch. The second terminal of the seventh switch is the second terminal of the voltage conversion circuit.

5. The apparatus according to claim 4, characterized in that, The second terminal with the same name on the low-voltage side of the transformer is the first terminal of the voltage conversion circuit. Alternatively, the first voltage conversion unit may further include a ninth switch; the first end of the ninth switch is connected to the second terminal of the same name on the low-voltage side of the transformer, and the second end of the ninth switch is the first terminal of the voltage conversion circuit.

6. The apparatus according to claim 2, characterized in that, The first voltage conversion unit includes: a fourth bridge arm, a fifth bridge arm, and a fourth capacitor; The fourth bridge arm includes a seventh switch and an eighth switch; the fifth bridge arm includes a ninth switch and a tenth switch; the first end of the seventh switch is connected to the first end of the eighth switch, and the first end of the ninth switch is connected to the first end of the tenth switch. The second end of the seventh switch is connected to the first opposite-name terminal of the low-voltage side of the transformer; the second end of the eighth switch is connected to the second opposite-name terminal of the low-voltage side of the transformer; the second end of the ninth switch and the first end of the fourth capacitor are both connected to the first same-name terminal of the low-voltage side of the transformer; the second end of the tenth switch and the second end of the fourth capacitor are both connected to the second same-name terminal of the low-voltage side of the transformer; and the midpoint of the fourth bridge arm is connected to the midpoint of the fifth bridge arm. The second terminal of the seventh switch is the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch is the second terminal of the voltage conversion circuit.

7. The apparatus according to claim 2, characterized in that, The battery pack includes a first battery sub-group and a second battery sub-group connected in series. The negative terminal of the first battery sub-group is connected to the positive terminal of the second battery sub-group. The positive terminal of the first battery sub-group is the positive terminal of the battery pack, and the negative terminal of the second battery sub-group is the negative terminal of the battery pack. The first voltage conversion unit includes a fourth bridge arm, which includes a seventh switch and an eighth switch; the first terminal of the seventh switch is connected to the first terminal of the eighth switch. The negative terminal of the first battery sub-group is connected to the opposite terminal on the low-voltage side of the transformer, and the midpoint of the fourth bridge arm is connected to the same terminal on the low-voltage side of the transformer. The second terminal of the seventh switch is the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch is the second terminal of the voltage conversion circuit.

8. The apparatus according to any one of claims 2-7, characterized in that, The second voltage conversion unit includes a sixth bridge arm and a seventh bridge arm; The sixth bridge arm includes an eleventh switch and a twelfth switch; the seventh bridge arm includes a thirteenth switch and a fourteenth switch. The first end of the eleventh switch is connected to the first end of the twelfth switch, the first end of the thirteenth switch is connected to the first end of the fourteenth switch, the second end of the eleventh switch is connected to the second end of the thirteenth switch, and the second end of the twelfth switch is connected to the second end of the fourteenth switch. The second terminal of the thirteenth switch is the third terminal of the voltage conversion circuit, and the second terminal of the fourteenth switch is the fourth terminal of the voltage conversion circuit.

9. The apparatus according to claim 8, characterized in that, The second voltage conversion unit further includes: a second capacitor, the first end of which is connected to the second end of the thirteenth switching transistor, and the second end of which is connected to the second end of the fourteenth switching transistor.

10. The apparatus according to claim 8, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, the second terminal of the fifth inductor is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the midpoint of the seventh bridge arm.

11. The apparatus according to claim 8, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, and the second terminal of the fifth inductor is connected to the midpoint of the seventh bridge arm.

12. The apparatus according to claim 8, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the first terminal of the fifth inductor, the second terminal of the fifth inductor is connected to the midpoint of the sixth bridge arm, and the opposite-name terminal on the high-voltage side of the transformer is connected to the midpoint of the seventh bridge arm.

13. The apparatus according to claim 8, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, the second terminal of the fifth inductor is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the midpoint of the sixth bridge arm, and the opposite-name terminal on the high-voltage side of the transformer is connected to the midpoint of the seventh bridge arm.

14. The apparatus according to claim 8, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the first terminal of the fifth inductor, and the second terminal of the fifth inductor is connected to the midpoint of the seventh bridge arm.

15. The apparatus according to claim 8, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, the second terminal of the fifth inductor is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the midpoint of the seventh bridge arm.

16. The apparatus according to claim 8, characterized in that, The second end of the eleventh switch is connected to the first opposite-name terminal of the high-voltage side of the transformer; the second end of the twelfth switch is connected to the second opposite-name terminal of the high-voltage side of the transformer; the second end of the thirteenth switch is connected to the first same-name terminal of the high-voltage side of the transformer; the second end of the fourteenth switch is connected to the second same-name terminal of the high-voltage side of the transformer; the midpoint of the sixth bridge arm is connected to the first end of the fifth inductor; the second end of the fifth inductor is connected to the first end of the third capacitor; and the second end of the third capacitor is connected to the midpoint of the seventh bridge arm.

17. The apparatus according to claim 8, characterized in that, The second end of the eleventh switch is connected to the first opposite-name terminal of the high-voltage side of the transformer; the second end of the twelfth switch is connected to the second opposite-name terminal of the high-voltage side of the transformer; the second end of the thirteenth switch is connected to the first same-name terminal of the high-voltage side of the transformer; the second end of the fourteenth switch is connected to the second same-name terminal of the high-voltage side of the transformer; the midpoint of the sixth bridge arm is connected to the first end of the third capacitor; the second end of the third capacitor is connected to the first end of the fifth inductor; and the second end of the fifth inductor is connected to the midpoint of the seventh bridge arm.

18. The apparatus according to any one of claims 2-7, characterized in that, The second voltage conversion unit includes: a sixth bridge arm; the sixth bridge arm includes: an eleventh switch and a twelfth switch; The first terminal of the eleventh switch is connected to the first terminal of the twelfth switch, the second terminal of the eleventh switch is the third terminal of the voltage conversion circuit, and the second terminal of the twelfth switch is the fourth terminal of the voltage conversion circuit. The voltage conversion circuit also includes a fifth terminal, which is connected to the midpoint of the second bridge arm.

19. The apparatus according to claim 18, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, the second terminal of the fifth inductor is connected to the midpoint of the sixth bridge arm, and the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor. The second terminal of the third capacitor is the fifth terminal of the voltage conversion circuit.

20. The apparatus according to claim 18, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the midpoint of the sixth bridge arm, and the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor. The second terminal of the fifth inductor is the fifth terminal of the voltage conversion circuit.

21. The apparatus according to claim 18, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the first terminal of the fifth inductor, and the second terminal of the fifth inductor is connected to the midpoint of the sixth bridge arm. The opposite terminal on the high-voltage side of the transformer is the fifth terminal of the voltage conversion circuit.

22. The apparatus according to claim 18, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, the second terminal of the fifth inductor is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the midpoint of the sixth bridge arm. The opposite terminal on the high-voltage side of the transformer is the fifth terminal of the voltage conversion circuit.

23. The apparatus according to claim 18, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the first terminal of the fifth inductor. The second terminal of the fifth inductor is the fifth terminal of the voltage conversion circuit.

24. The apparatus according to claim 18, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, and the second terminal of the fifth inductor is connected to the first terminal of the third capacitor. The second terminal of the third capacitor is the fifth terminal of the voltage conversion circuit.

25. The apparatus according to any one of claims 2-7, characterized in that, The second voltage conversion unit includes: a sixth bridge arm; the sixth bridge arm includes: an eleventh switch and a twelfth switch; The first end of the eleventh switch is connected to the first end of the twelfth switch, the second end of the eleventh switch is connected to the first opposite-name terminal of the high-voltage side of the transformer, and the second end of the twelfth switch is connected to the second opposite-name terminal of the high-voltage side of the transformer. The first terminal on the high-voltage side of the transformer is the third terminal of the voltage conversion circuit, and the second terminal on the high-voltage side of the transformer is the fourth terminal of the voltage conversion circuit. The fifth terminal of the voltage conversion circuit is connected to the midpoint of the second bridge arm.

26. The apparatus according to claim 25, characterized in that, The midpoint of the sixth bridge arm is connected to the first end of the fifth inductor, and the second end of the fifth inductor is connected to the first end of the third capacitor; The second terminal of the third capacitor is the fifth terminal of the voltage conversion circuit.

27. The apparatus according to claim 25, characterized in that, The midpoint of the sixth bridge arm is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the first terminal of the fifth inductor. The second terminal of the fifth inductor is the fifth terminal of the voltage conversion circuit.

28. The apparatus according to claim 1, characterized in that, The switching device includes: a first switch, a second switch, and a balancing component; The third terminal of the voltage conversion circuit is connected to the fixed terminal of the first switch, the first selection terminal of the first switch is connected to the first terminal of the balancing component, the second terminal of the balancing component is connected to the positive output terminal of the bus, the second selection terminal of the first switch is connected to the positive voltage input terminal, the first terminal of the second switch is connected to the first terminal of the external power supply, the second terminal of the second switch is connected to the positive voltage input terminal, and the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus. The balancing component is used to balance the voltage between the bus and the voltage conversion circuit.

29. The apparatus according to claim 28, characterized in that, The balancing component is a resistor, and the switching switch further includes a third switch; The third terminal of the voltage conversion circuit is connected to the first terminal of the third switch, and the second terminal of the third switch is connected to the positive output terminal of the bus; or, the third switch is connected in parallel with the resistor.

30. The apparatus according to claim 1, characterized in that, The switching device includes: a first switch, a second switch, and a balancing component; The third terminal of the voltage conversion circuit is connected to the first terminal of the first switch and the first selection terminal of the second switch, the second terminal of the first switch is connected to the first terminal of the balancing component, the second terminal of the balancing component is connected to the positive output terminal of the bus, the second selection terminal of the second switch is connected to the first terminal of the external power supply, the fixed terminal of the second switch is connected to the positive voltage input terminal, and the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus. The balancing component is used to balance the voltage between the bus and the voltage conversion circuit.

31. The apparatus according to claim 30, characterized in that, The balancing component is a resistor, and the switching switch further includes a third switch; The third terminal of the voltage conversion circuit is connected to the first terminal of the third switch, and the second terminal of the third switch is connected to the positive output terminal of the bus; or, the third switch is connected in parallel with the resistor.

32. The apparatus according to claim 1, characterized in that, The switching device includes: a first switch, a second switch, a third switch, and a balancing component; The third terminal of the voltage conversion circuit is connected to the first terminal of the first switch and the first terminal of the third switch, respectively. The second terminal of the first switch is connected to the positive voltage input terminal. The first terminal of the second switch is connected to the first terminal of the external power supply. The second terminal of the second switch is connected to the positive voltage input terminal. The second terminal of the third switch is connected to the first terminal of the balancing component. The second terminal of the balancing component is connected to the positive output terminal of the bus. The fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus. The balancing component is used to balance the voltage between the bus and the voltage conversion circuit.

33. The apparatus according to claim 32, characterized in that, The balancing component is a resistor, and the switching switch further includes: a fourth switch; The third terminal of the voltage conversion circuit is connected to the first terminal of the fourth switch, and the second terminal of the fourth switch is connected to the positive output terminal of the bus; or, the fourth switch is connected in parallel with the resistor.

34. The apparatus according to any one of claims 28, 30, and 32, characterized in that, The balancing component is any one of the following: a varistor, a thermistor with a negative temperature coefficient, or a third inductor.

35. The apparatus according to any one of claims 28-33, characterized in that, The external power supply is AC mains power; The first end of the external power supply is the live wire of the AC mains power supply, and the second end of the external power supply is the neutral wire of the AC mains power supply.

36. The apparatus according to any one of claims 1-7, 19-24, and 26-27, characterized in that, The midpoint of the second bridge arm serves as the negative voltage input terminal of the three-bridge-arm topology device, and the external power supply is AC mains power; the first terminal of the external power supply is the live wire of the AC mains power, and the second terminal of the external power supply is the neutral wire of the AC mains power. Alternatively, the negative output terminal of the bus can serve as the negative voltage input terminal of the three-arm topology device, the external power supply can be a photovoltaic DC power supply, the first terminal of the external power supply can be the positive terminal of the photovoltaic DC power supply, and the second terminal of the external power supply can be the negative terminal of the photovoltaic DC power supply.

37. The apparatus according to any one of claims 1-7, 19-24, and 26-27, characterized in that, The second end of the first inductor serves as the first positive voltage input terminal of the three-arm bridge topology, the midpoint of the second bridge arm serves as the first negative voltage input terminal of the three-arm bridge topology, the external power supply is AC mains power, the first end of the external power supply is the live wire of the AC mains power, and the second end of the external power supply is the neutral wire of the AC mains power. The device also includes: an eighth bridge arm, and a sixth inductor; The eighth bridge arm includes a seventeenth switch and an eighteenth switch, which are connected in series between the positive output terminal and the negative output terminal of the bus. The midpoint of the eighth bridge arm is connected to the first end of the sixth inductor, the second end of the sixth inductor serves as the second positive voltage input terminal of the three-bridge-arm topology, and the negative output terminal of the bus serves as the second negative voltage input terminal of the three-bridge-arm topology; the positive terminal of the photovoltaic DC power supply is connected to the second positive voltage input terminal, and the negative terminal of the photovoltaic DC power supply is connected to the second negative voltage input terminal.

38. An uninterruptible power supply system, characterized in that, The system includes: an external power supply, a load, and a three-arm topology device as described in any one of claims 1 to 36; The first terminal of the external power supply is connected to the positive voltage input terminal of the three-arm topology, the second terminal of the external power supply is connected to the negative voltage input terminal of the three-arm topology, and the first and second output terminals of the three-arm topology are both connected to the load.

39. An uninterruptible power supply system, characterized in that, The system includes: a first external power supply, a second external power supply, a load, and the three-arm topology device as described in claim 37. Wherein, the first terminal of the first external power supply is connected to the first positive voltage input terminal of the three-arm topology device, the second terminal of the first external power supply is connected to the first negative voltage input terminal of the three-arm topology device, the first terminal of the second external power supply is connected to the second positive voltage input terminal of the three-arm topology device, the second terminal of the second external power supply is connected to the second negative voltage input terminal of the three-arm topology device, and the first output terminal and the second output terminal of the three-arm topology device are both connected to the load.

40. A control method for a three-arm topology device, characterized in that, The method is used to control the three-arm topology device as described in claim 28, the method comprising: In external power supply mode, the fixed terminal of the first switch is connected to the first selection terminal of the first switch, and the second switch is closed; In battery-powered mode, the fixed terminal of the first switch is connected to the second select terminal of the first switch, and the second switch is disconnected.

41. A control method for a three-arm topology device, characterized in that, The method is used to control the three-arm topology device as described in claim 29, the method comprising: In external power supply mode, the fixed terminal of the first switch is connected to the first selection terminal of the first switch, the second switch is closed, and the third switch is closed when the voltage difference between the bus and the voltage conversion circuit of the three-arm topology is less than or equal to a preset threshold. In battery-powered mode, the fixed terminal of the first switch is connected to the second select terminal of the first switch, while the second switch and the third switch are disconnected.

42. A control method for a three-arm topology device, characterized in that, The method is used to control the three-arm topology device as described in claim 30, the method comprising: In external power supply mode, the first switch is closed, and the fixed terminal of the second switch is connected to the second selection terminal of the second switch; In battery-powered mode, the first switch is turned off, and the fixed terminal of the second switch is connected to the first select terminal of the second switch.

43. A control method for a three-arm topology device, characterized in that, The method is used to control the three-arm topology device as described in claim 31, the method comprising: In external power supply mode, the first switch is closed, the fixed terminal of the second switch is connected to the second selection terminal of the second switch, and the third switch is closed when the voltage difference between the bus and the voltage conversion circuit of the three-arm topology is less than or equal to a preset threshold. In battery-powered mode, the third switch and the first switch are disconnected, and the fixed terminal of the second switch is connected to the first selection terminal of the second switch.

44. A control method for a three-arm topology device, characterized in that, The method is used to control the three-arm topology device as described in claim 32, the method comprising: In external power supply mode, the first switch is opened, and the second and third switches are closed; In battery-powered mode, the first switch is closed, and the second and third switches are open.

45. A control method for a three-arm topology device, characterized in that, The method is used to control the three-arm topology device as described in claim 33, the method comprising: In external power supply mode, the first switch is opened, the second and third switches are closed, and the fourth switch is closed when the voltage difference between the bus and the voltage conversion circuit of the three-arm topology is less than or equal to a preset threshold. In battery-powered mode, the first switch is closed, and the second, third, and fourth switches are opened.

46. ​​A control method for a three-arm topology device, characterized in that, The method is used to control the three-arm topology device as described in any one of claims 18-27, the method comprising: In the first stage of the external power supply mode, control the second, fourth, fifth, and eleventh switching transistors to conduct; In the second stage of the external power supply mode, the second switch, the fourth switch, the fifth switch, and the twelfth switch are turned on. In the third stage of the external power supply mode, the fourth switch, the fifth switch, and the eleventh switch are turned on. In the fourth stage of the external power supply mode, the fourth switch, the fifth switch, and the twelfth switch are turned on. In the fifth stage of the external power supply mode, the second switch, the fourth switch, the sixth switch, and the eleventh switch are turned on. In the sixth stage of the external power supply mode, the second switch, the fourth switch, the sixth switch, and the twelfth switch are turned on. In the seventh stage of the external power supply mode, the fourth switch, the sixth switch, and the eleventh switch are turned on. In the eighth stage of the external power supply mode, the fourth switch, the sixth switch, and the twelfth switch are turned on. In the ninth stage of the external power supply mode, the first switch, the third switch, the sixth switch, and the twelfth switch are turned on. In the tenth stage of the external power supply mode, the first switch, the third switch, the sixth switch, and the eleventh switch are controlled to be turned on; In the eleventh stage of the external power supply mode, the third switch, the sixth switch, and the twelfth switch are turned on. In the twelfth stage of the external power supply mode, the third switch, the sixth switch, and the eleventh switch are turned on. In the thirteenth stage of the external power supply mode, the first switch, the third switch, the fifth switch, and the twelfth switch are turned on. In the fourteenth stage of the external power supply mode, the first switch, the third switch, the fifth switch, and the eleventh switch are turned on. In the fifteenth stage of the external power supply mode, the third switch, the fifth switch, and the twelfth switch are turned on. In the sixteenth stage of the external power supply mode, the third switch, the fifth switch, and the eleventh switch are turned on. In the first stage of the battery-powered mode, the fourth, fifth, seventh, tenth, and twelfth switches are turned on. In the second stage of the battery-powered mode, the fourth, fifth, eighth, ninth, and eleventh switches are turned on. In the third stage of the battery-powered mode, the fourth, sixth, seventh, tenth, and twelfth switches are turned on. In the fourth stage of the battery-powered mode, the fourth, sixth, eighth, ninth, and eleventh switches are turned on. In the fifth stage of the battery-powered mode, the third, sixth, seventh, tenth, and twelfth switches are turned on. In the sixth stage of the battery-powered mode, the third switch, the sixth switch, the eighth switch, the ninth switch, and the eleventh switch are turned on. In the seventh stage of the battery-powered mode, the third switch, the fifth switch, the seventh switch, the tenth switch, and the twelfth switch are turned on. In the eighth stage of the battery-powered mode, the third, fifth, eighth, ninth, and eleventh switches are turned on.

47. A three-arm topology device, characterized in that, The three-bridge-arm topology device includes: a battery pack, a voltage conversion circuit, and a three-bridge-arm circuit. The three-arm circuit includes: a first arm, a second arm, a third arm, a DC bus capacitor, and a filter; The first bridge arm includes a first switch and a second switch connected in series; The second bridge arm includes a third switch and a fourth switch connected in series; The third bridge arm includes a fifth switch and a sixth switch connected in series; The first bridge arm, the second bridge arm, the third bridge arm, and the DC bus capacitor are connected in parallel between the positive output terminal and the negative output terminal of the bus; the midpoint of the second bridge arm and the midpoint of the third bridge arm are both connected to the filter; The positive terminal of the battery pack is connected to the first terminal of the voltage conversion circuit, the negative terminal of the battery pack is connected to the second terminal of the voltage conversion circuit, and the third and fourth terminals of the voltage conversion circuit are both connected to the three-arm circuit. The filter is provided with a first external connection terminal and a second external connection terminal of the three-arm topology device, and is connected to the load in battery power supply mode. The voltage conversion circuit discharges the battery pack in the battery-powered mode; wherein, the voltage conversion circuit realizes the voltage conversion function by reusing the DC bus capacitor and / or the second bridge arm of the three-bridge-arm circuit to form a bidirectional DC-DC topology.

48. The apparatus according to claim 47, characterized in that, The voltage conversion circuit includes: a first voltage conversion unit, a transformer, and an LC resonant cavity; the LC resonant cavity includes: a fifth inductor and a third capacitor; The first voltage conversion unit is connected to the low-voltage side of the transformer, and the high-voltage side of the transformer is connected to the resonant cavity.

49. The apparatus according to claim 48, characterized in that, The first voltage conversion unit includes a fourth bridge arm and a fifth bridge arm; the fourth bridge arm includes a seventh switch and an eighth switch; the fifth bridge arm includes a ninth switch and a tenth switch. The first end of the seventh switch is connected to the first end of the eighth switch, the first end of the ninth switch is connected to the first end of the tenth switch, the second end of the seventh switch is connected to the second end of the ninth switch, and the second end of the eighth switch is connected to the second end of the tenth switch. The midpoint of the fourth bridge arm is connected to the opposite-named end of the low-voltage side of the transformer, and the midpoint of the fifth bridge arm is connected to the same-named end of the low-voltage side of the transformer. The second terminal of the seventh switch is the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch is the second terminal of the voltage conversion circuit.

50. The apparatus according to claim 48, characterized in that, The first voltage conversion unit includes: a seventh switch and an eighth switch; The first end of the seventh switch is connected to the first terminal of the same name on the low-voltage side of the transformer, the first end of the eighth switch is connected to the terminal of the opposite name on the low-voltage side of the transformer, and the second end of the seventh switch is connected to the second end of the eighth switch. The second terminal of the seventh switch is the second terminal of the voltage conversion circuit.

51. The apparatus according to claim 50, characterized in that, The second terminal with the same name on the low-voltage side of the transformer is the first terminal of the voltage conversion circuit. Alternatively, the first voltage conversion unit may further include a ninth switch; the first end of the ninth switch is connected to the second terminal of the same name on the low-voltage side of the transformer, and the second end of the ninth switch is the first terminal of the voltage conversion circuit.

52. The apparatus according to claim 48, characterized in that, The first voltage conversion unit includes: a fourth bridge arm, a fifth bridge arm, and a fourth capacitor; The fourth bridge arm includes a seventh switch and an eighth switch; the fifth bridge arm includes a ninth switch and a tenth switch; the first end of the seventh switch is connected to the first end of the eighth switch, and the first end of the ninth switch is connected to the first end of the tenth switch. The second end of the seventh switch is connected to the first opposite-name terminal of the low-voltage side of the transformer; the second end of the eighth switch is connected to the second opposite-name terminal of the low-voltage side of the transformer; the second end of the ninth switch and the first end of the fourth capacitor are both connected to the first same-name terminal of the low-voltage side of the transformer; the second end of the tenth switch and the second end of the fourth capacitor are both connected to the second same-name terminal of the low-voltage side of the transformer; and the midpoint of the fourth bridge arm is connected to the midpoint of the fifth bridge arm. The second terminal of the seventh switch is the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch is the second terminal of the voltage conversion circuit.

53. The apparatus according to claim 48, characterized in that, The battery pack includes a first battery sub-group and a second battery sub-group connected in series. The negative terminal of the first battery sub-group is connected to the positive terminal of the second battery sub-group. The positive terminal of the first battery sub-group is the positive terminal of the battery pack, and the negative terminal of the second battery sub-group is the negative terminal of the battery pack. The first voltage conversion unit includes a fourth bridge arm, which includes a seventh switch and an eighth switch; the first terminal of the seventh switch is connected to the first terminal of the eighth switch. The negative terminal of the first battery sub-group is connected to the opposite terminal on the low-voltage side of the transformer, and the midpoint of the fourth bridge arm is connected to the same terminal on the low-voltage side of the transformer. The second terminal of the seventh switch is the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch is the second terminal of the voltage conversion circuit.

54. The apparatus according to any one of claims 48-53, characterized in that, The voltage conversion circuit includes: a second voltage conversion unit, the second voltage conversion unit including: a sixth bridge arm; the sixth bridge arm including: an eleventh switch and a twelfth switch; The first terminal of the eleventh switch is connected to the first terminal of the twelfth switch, the second terminal of the eleventh switch is the third terminal of the voltage conversion circuit, and the second terminal of the twelfth switch is the fourth terminal of the voltage conversion circuit; the third terminal of the voltage conversion circuit is connected to the positive output terminal of the bus, and the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus. The voltage conversion circuit also includes a fifth terminal, which is connected to the midpoint of the first bridge arm.

55. The apparatus according to claim 54, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, the second terminal of the fifth inductor is connected to the midpoint of the sixth bridge arm, and the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor. The second terminal of the third capacitor is the fifth terminal of the voltage conversion circuit.

56. The apparatus according to claim 54, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the midpoint of the sixth bridge arm, and the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor. The second terminal of the fifth inductor is the fifth terminal of the voltage conversion circuit.

57. The apparatus according to claim 54, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the first terminal of the fifth inductor, and the second terminal of the fifth inductor is connected to the midpoint of the sixth bridge arm. The opposite terminal on the high-voltage side of the transformer is the fifth terminal of the voltage conversion circuit.

58. The apparatus according to claim 54, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, the second terminal of the fifth inductor is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the midpoint of the sixth bridge arm. The opposite terminal on the high-voltage side of the transformer is the fifth terminal of the voltage conversion circuit.

59. The apparatus according to claim 54, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the first terminal of the fifth inductor. The second terminal of the fifth inductor is the fifth terminal of the voltage conversion circuit.

60. The apparatus according to claim 54, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the midpoint of the sixth bridge arm, the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, and the second terminal of the fifth inductor is connected to the first terminal of the third capacitor. The second terminal of the third capacitor is the fifth terminal of the voltage conversion circuit.

61. The apparatus according to any one of claims 48-53, characterized in that, The second voltage conversion unit includes: a sixth bridge arm; the sixth bridge arm includes: an eleventh switch and a twelfth switch; The first end of the eleventh switch is connected to the first end of the twelfth switch, the second end of the eleventh switch is connected to the first opposite-name terminal of the high-voltage side of the transformer, and the second end of the twelfth switch is connected to the second opposite-name terminal of the high-voltage side of the transformer. The first terminal of the high-voltage side of the transformer is the third terminal of the voltage conversion circuit, and the second terminal of the high-voltage side of the transformer is the fourth terminal of the voltage conversion circuit; the third terminal of the voltage conversion circuit is connected to the positive output terminal of the bus, and the fourth terminal of the voltage conversion circuit is connected to the negative output terminal of the bus. The voltage conversion circuit also includes a fifth terminal, which is connected to the midpoint of the first bridge arm.

62. The apparatus according to claim 61, characterized in that, The midpoint of the sixth bridge arm is connected to the first end of the fifth inductor, and the second end of the fifth inductor is connected to the first end of the third capacitor; The second terminal of the third capacitor is the fifth terminal of the voltage conversion circuit.

63. The apparatus according to claim 61, characterized in that, The midpoint of the sixth bridge arm is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the first terminal of the fifth inductor. The second terminal of the fifth inductor is the fifth terminal of the voltage conversion circuit.

64. The apparatus according to any one of claims 48-53, characterized in that, The third terminal of the voltage conversion circuit is connected to the midpoint of the first bridge arm, and the fourth terminal of the voltage conversion circuit is connected to the midpoint of the second bridge arm.

65. The apparatus according to claim 64, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, and the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor. The second terminal of the fifth inductor is the third terminal of the voltage conversion circuit, and the second terminal of the third capacitor is the fourth terminal of the voltage conversion circuit.

66. The apparatus according to claim 64, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, and the opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor. The second terminal of the third capacitor is the third terminal of the voltage conversion circuit, and the second terminal of the fifth inductor is the fourth terminal of the voltage conversion circuit.

67. The apparatus according to claim 64, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the first terminal of the fifth inductor; The second terminal of the fifth inductor is the third terminal of the voltage conversion circuit, and the opposite terminal on the high-voltage side of the transformer is the fourth terminal of the voltage conversion circuit.

68. The apparatus according to claim 64, characterized in that, The same-name terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, and the second terminal of the fifth inductor is connected to the first terminal of the third capacitor; The second terminal of the third capacitor is the third terminal of the voltage conversion circuit, and the opposite terminal on the high-voltage side of the transformer is the fourth terminal of the voltage conversion circuit.

69. The apparatus according to claim 64, characterized in that, The opposite-name terminal on the high-voltage side of the transformer is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is connected to the first terminal of the fifth inductor. The same-named terminal on the high-voltage side of the transformer is the third terminal of the voltage conversion circuit, and the second terminal of the fifth inductor is the fourth terminal of the voltage conversion circuit.

70. The apparatus according to claim 64, characterized in that, The opposite-named terminal on the high-voltage side of the transformer is connected to the first terminal of the fifth inductor, and the second terminal of the fifth inductor is connected to the first terminal of the third capacitor; The same-named terminal on the high-voltage side of the transformer is the third terminal of the voltage conversion circuit, and the second terminal of the third capacitor is the fourth terminal of the voltage conversion circuit.

71. The apparatus according to claim 64, characterized in that, The second end of the first switching transistor is connected to the first opposite-name terminal of the high-voltage side of the transformer, and the second end of the second switching transistor is connected to the second opposite-name terminal of the high-voltage side of the transformer. The first terminal of the transformer high voltage side is connected to the positive output terminal of the bus, and the second terminal of the transformer high voltage side is connected to the negative output terminal of the bus. The first terminal of the fifth inductor is the third terminal of the voltage conversion circuit, the second terminal of the fifth inductor is connected to the first terminal of the third capacitor, and the second terminal of the third capacitor is the fourth terminal of the voltage conversion circuit; or, the first terminal of the third capacitor is the third terminal of the voltage conversion circuit, the second terminal of the third capacitor is connected to the first terminal of the fifth inductor, and the second terminal of the fifth inductor is the fourth terminal of the voltage conversion circuit.

72. The apparatus according to any one of claims 65-71, characterized in that, Both the first and second switching transistors are diodes.

73. The apparatus according to any one of claims 47-53, 55-60, 62-63, and 65-71, characterized in that, The first external connection terminal and the second external connection terminal are connected to an external power supply in battery charging mode; The voltage conversion circuit is also used to charge the battery pack during the battery charging mode.

74. The apparatus according to any one of claims 47-53, 55-60, 62-63, and 65-71, characterized in that, The filter includes: a second inductor and a first capacitor; the first terminal of the first capacitor is the first external connection terminal of the three-arm topology device, and the second terminal of the first capacitor is the second external connection terminal of the three-arm topology device; The midpoint of the third bridge arm is connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the midpoint of the second bridge arm. Alternatively, the midpoint of the second bridge arm is connected to the first end of the second inductor, the second end of the second inductor is connected to the second end of the first capacitor, and the first end of the first capacitor is connected to the midpoint of the third bridge arm.

75. The apparatus according to any one of claims 47-53, 55-60, 62-63, and 65-71, characterized in that, The filter includes: a second inductor, a first capacitor, and a fourth inductor; The midpoint of the third bridge arm is connected to the first end of the second inductor, the second end of the second inductor is connected to the first end of the first capacitor, the second end of the first capacitor is connected to the first end of the fourth inductor, and the second end of the fourth inductor is connected to the midpoint of the second bridge arm. The first end of the first capacitor is the first external connection terminal of the three-arm topology device, and the second end of the first capacitor is the second external connection terminal of the three-arm topology device.

76. An inverter system, characterized in that, The system includes: a load, and a three-arm topology device as described in any one of claims 47 to 75; In battery-powered mode, both the first and second external connection terminals of the three-arm topology are connected to the load.

77. The system according to claim 76, characterized in that, The system further includes an external power supply; in battery charging mode, both the first and second external connection terminals of the three-arm topology device are connected to the external power supply.

78. A control method for a three-arm topology device, characterized in that, The method is used to control the three-arm topology device as described in any one of claims 54-63, the method comprising: In the first stage of the battery-powered mode, the second, eighth, ninth, and eleventh switches are turned on. In the second stage of the battery-powered mode, the first, seventh, tenth, and twelfth switching transistors are turned on. In the first stage of the battery charging mode, the second switch and the eleventh switch are turned on. In the second stage of the battery charging mode, the first switch and the twelfth switch are turned on.

79. A control method for a three-arm topology device, characterized in that, The method is used to control the three-arm topology device as described in any one of claims 64-71, the method comprising: In the first stage of the battery-powered mode, the second, fourth, fifth, seventh, and tenth switching transistors are turned on. In the second stage of the battery-powered mode, the first switch, the fourth switch, the fifth switch, the eighth switch, and the ninth switch are turned on. In the third stage of the battery-powered mode, the second switch, the fourth switch, the sixth switch, the seventh switch, and the tenth switch are turned on. In the fourth stage of the battery-powered mode, the first switch, the fourth switch, the sixth switch, the eighth switch, and the ninth switch are turned on. In the fifth stage of the battery-powered mode, the first switch, the third switch, the sixth switch, the eighth switch, and the ninth switch are turned on. In the sixth stage of the battery-powered mode, the first switch, the second switch, the third switch, the sixth switch, the seventh switch, and the tenth switch are turned on. In the seventh stage of the battery-powered mode, the first switch, the third switch, the fifth switch, the eighth switch, and the ninth switch are turned on. In the eighth stage of the battery-powered mode, the first switch, the second switch, the third switch, the fifth switch, the seventh switch, and the tenth switch are turned on. In the first stage of the battery charging mode, the first switch, the fourth switch, and the sixth switch are turned on. In the second stage of the battery charging mode, the second switch, the fourth switch, and the sixth switch are turned on. In the third stage of the battery charging mode, the first switch, the fourth switch, and the fifth switch are turned on. In the fourth stage of the battery charging mode, the second switch, the fourth switch, and the fifth switch are turned on. In the fifth stage of the battery charging mode, the second switch, the third switch, and the fifth switch are turned on. In the sixth stage of the battery charging mode, the first switch, the third switch, and the fifth switch are turned on. In the seventh stage of the battery charging mode, the second switch, the third switch, and the sixth switch are turned on. In the eighth stage of the battery charging mode, the first switch, the third switch, and the sixth switch are turned on.

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