Three-phase uninterruptible power supply system

Abstract

The utility model is suitable for the technical field of power electronics, and provides a three-phase uninterruptible power supply system. The three-phase uninterruptible power supply system comprises a three-phase Vienna PFC (Power Factor Correction) circuit and a battery charging and discharging circuit, the three-phase Vienna PFC circuit comprises a three-phase diode rectifier bridge, three branches and an output capacitor, and each phase of bridge arm corresponds to one branch; a first input end of the battery charging and discharging circuit is connected with a battery positive electrode end, and a second input end of the battery charging and discharging circuit is connected with a battery negative electrode end; a first output end and a second output end of the battery charge-discharge circuit are respectively connected with two ends of the output capacitor, and a third output end of the battery charge-discharge circuit is connected with the neutral point; the three-phase Vienna PFC circuit is used for correcting an input power factor of commercial power, and the battery charging and discharging circuit is used for controlling charging and discharging of a battery. According to the three-phase uninterruptible power supply system provided by the utility model, the system efficiency is effectively improved, the device cost is low, and the problem that the switching of the input relay has a large requirement on the number of bus capacitors can be solved.

Description

Technical Field

[0001] This utility model belongs to the field of power electronics technology, and in particular relates to a three-phase uninterruptible power supply system. Background Technology

[0002] like Figure 1 As shown, the battery discharge circuit and power factor correction (PFC) circuit of a three-phase uninterruptible power supply (UPS) system mainly adopt a dual-boost topology. This scheme uses a silicon controlled rectifier (SCR) to switch the input source so that the battery discharge circuit and the PFC circuit can share the boost circuit. The battery discharge circuit adopts a three-phase interleaved parallel configuration. Because the PFC circuit adopts a dual-boost topology, an external rectifier bridge is required to achieve the PFC function, which makes it difficult to improve efficiency. Related technologies use a bridgeless PFC topology, which switches the input source through relays, thereby enabling the battery and mains discharge circuits to share power devices.

[0003] like Figure 2 As shown, in this topology, the PFC topology of phase B adopts an interleaved parallel configuration. The positive discharge circuit reuses one power device from phases A and B, while the negative discharge circuit reuses one power device from phases C and B. Due to the use of Vienna PFC current, compared to a dual-boost topology, the PFC circuit uses one less rectifier device, thus reducing losses and improving overall efficiency. However, this design requires an additional charger to charge the battery, and the switching between relays necessitates strict control of the switching time to avoid shared risks. During switching, the output energy needs to be provided by the bus capacitor, placing significant demands on the number of bus capacitors. Utility Model Content

[0004] This invention provides a three-phase uninterruptible power supply system, which aims to solve the problem that existing three-phase UPS systems require additional chargers to charge batteries and that the output energy during relay switching places large demands on the number of bus capacitors.

[0005] This utility model provides a three-phase uninterruptible power supply system, including:

[0006] Three-phase Vienna PFC circuit and battery charging and discharging circuit;

[0007] The three-phase Vienna PFC circuit includes: a three-phase diode rectifier bridge, three branches and an output capacitor, with each phase corresponding to one branch, and each branch including an inductor and a bidirectional switch; the bidirectional switch includes two switching transistors connected in reverse series.

[0008] The input terminals of the three branches are used to connect to the mains power, and the output capacitor is used to output DC power.

[0009] The first input terminal of the battery charging and discharging circuit is connected to the positive terminal of the battery, and the second input terminal of the battery charging and discharging circuit is connected to the negative terminal of the battery; the first output terminal and the second output terminal of the battery charging and discharging circuit are respectively connected to the two ends of the output capacitor, and the third output terminal of the battery charging and discharging circuit is connected to the neutral point.

[0010] The three-phase Vienna PFC circuit is used to correct the input power factor of the mains power, and the battery charging and discharging circuit is used to independently control the charging and discharging of the battery.

[0011] In some embodiments, the battery charging and discharging circuit includes: a first battery charging and discharging circuit and a second battery charging and discharging circuit.

[0012] The first battery charging and discharging circuit includes: a first relay, a first inductor, and a first bidirectional switch, wherein the first bidirectional switch includes a first switching transistor and a second switching transistor;

[0013] The first terminal of the first relay is connected to the positive terminal of the battery, the second terminal of the first relay is connected to the first terminal of the first inductor, the second terminal of the first inductor is connected to the current outflow terminal of the first switch and the current inflow terminal of the second switch respectively, the current inflow terminal of the first switch is connected to the positive terminal of the output capacitor, and the current outflow terminal of the second switch is connected to the neutral point.

[0014] The second battery charging and discharging circuit includes: a second relay, a second inductor, and a second bidirectional switch, wherein the second bidirectional switch includes a third switching transistor and a fourth switching transistor;

[0015] The first terminal of the second relay is connected to the negative terminal of the battery, the second terminal of the second relay is connected to the first terminal of the second inductor, the second terminal of the second inductor is connected to the current output terminal of the third switch and the current inflow terminal of the fourth switch, the current inflow terminal of the third switch is connected to the neutral point, and the current output terminal of the fourth switch is connected to the negative terminal of the output capacitor.

[0016] In some embodiments, each branch further includes a relay, the first end of which is connected to the mains power, and the second end of which is connected to an inductor on the corresponding branch.

[0017] In some embodiments, each branch is connected to the neutral point.

[0018] In some embodiments, the positive terminal of the battery is also connected to the neutral point, and the negative terminal of the battery is also connected to the neutral point.

[0019] In some embodiments, the output capacitor includes a first capacitor and a second capacitor; the current inflow terminal of the first switch is connected to the positive terminal of the first capacitor, and the current outflow terminal of the fourth switch is connected to the negative terminal of the second capacitor.

[0020] The negative terminal of the first capacitor and the positive terminal of the second capacitor are both connected to the neutral point.

[0021] The three-phase uninterruptible power supply system provided by this utility model achieves independent control of battery charging and discharging by setting up a separate battery charging and discharging circuit. Therefore, there is no time for switching between mains power and battery. When the mains power is abnormal, the bus voltage drops, and the battery charging and discharging circuit can start discharging to maintain the bus voltage within the working range. This also reduces the number of bus capacitors, thereby reducing the requirements for the number of bus capacitors. Compared with the existing technology, the three-phase uninterruptible power supply system reduces the number of components by eliminating two diodes in the discharge circuit, adds two bidirectional switches, and simplifies the entire battery charging and discharging circuit. Attached Figure Description

[0022] Figure 1 This is one of the circuit structure diagrams of a three-phase uninterruptible power supply system provided by existing technology;

[0023] Figure 2 This is the second schematic diagram of the circuit structure of a three-phase uninterruptible power supply system provided by existing technology;

[0024] Figure 3 This is one of the circuit structure diagrams of the three-phase uninterruptible power supply system provided in this embodiment of the utility model;

[0025] Figure 4 This is the second schematic diagram of the circuit structure of the three-phase uninterruptible power supply system provided in this embodiment of the utility model;

[0026] Figure 5 This is the third schematic diagram of the circuit structure of the three-phase uninterruptible power supply system provided in this embodiment of the utility model. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present utility model, and should not be construed as limiting the present utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining the present utility model and are not intended to limit the present utility model.

[0028] In the description of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0033] The following is combined Figure 3 and Figure 4 The three-phase uninterruptible power supply system provided in the embodiments of this utility model will be described in detail.

[0034] Figure 3 This is one of the circuit structure diagrams of a three-phase uninterruptible power supply system provided in this embodiment of the utility model. Figure 4 This is the second schematic diagram of the circuit structure of the three-phase uninterruptible power supply system provided in this embodiment of the utility model.

[0035] like Figure 3 and Figure 4 As shown, this utility model embodiment provides a three-phase uninterruptible power supply system, including:

[0036] Three-phase Vienna PFC circuit 10 and battery charging and discharging circuit 20;

[0037] The three-phase Vienna PFC circuit 10 includes: a three-phase diode rectifier bridge, three branches and an output capacitor. Each phase corresponds to one branch, and each branch includes an inductor and a bidirectional switch. The bidirectional switch includes two switching transistors connected in reverse series.

[0038] The input terminals of the three branches are used to connect to the mains power, and the output capacitor is used to output DC power.

[0039] The first input terminal of the battery charging and discharging circuit 20 is connected to the positive terminal of the battery, and the second input terminal of the battery charging and discharging circuit 20 is connected to the negative terminal of the battery; the first output terminal and the second output terminal of the battery charging and discharging circuit 20 are respectively connected to the two ends of the output capacitor, and the third output terminal of the battery charging and discharging circuit 20 is connected to the neutral point.

[0040] The three-phase Vienna PFC circuit 10 is used to correct the input power factor of the mains power, and the battery charging and discharging circuit 20 is used to independently control the charging and discharging of the battery. The mains power is three-phase AC, namely phase A, phase B, and phase C. Mains power is commonly used to power various electronic devices and systems.

[0041] like Figure 3 As shown, a three-phase diode rectifier bridge consists of six diodes connected together in a bridge full-wave rectifier circuit configuration: diodes D1, D2, D3, D4, D5, and D6. The three-phase diode rectifier bridge converts the three-phase alternating current (AC) to direct current (DC). In the three-phase diode rectifier bridge, each diode is responsible for allowing current to flow when it is forward-biased. As the phase of the three-phase AC changes, different diodes sequentially turn on and off, ensuring that the current always flows through the load in the same direction, thus achieving the rectification function.

[0042] like Figure 3 As shown, each phase corresponds to one branch, for a total of three branches. The input terminals of the three branches are used to input three-phase AC power. Each branch is connected in series with an inductor and a bidirectional switch.

[0043] A bidirectional switch consists of two switching transistors connected in reverse series, utilizing their inherent anti-parallel diodes to share a drive signal, thus reducing the difficulty of control and drive.

[0044] The switching transistor can be a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated-gate bipolar transistor (IGBT), without any specific limitation here.

[0045] like Figure 3 As shown, the switching transistors in the three-phase diode rectifier bridge 10 are MOSFETs. Figure 4 As shown, the switching transistors in the three-phase diode rectifier bridge 10 and the battery charging and discharging circuit 20 are both IGBTs. Figure 3 and Figure 4 The switching transistors in this example are for illustrative purposes only and are not specifically limited in this embodiment.

[0046] It should be noted that MOSFETs can include P-type MOSFETs and N-type MOSFETs. In an N-type MOSFET, when the source is connected to a low potential and the drain is connected to a high potential, the current flows from the source to the drain; while in a P-type MOSFET, the current flows from the source to the drain when the source is connected to a high potential and the drain is connected to a low potential.

[0047] IGBTs are also divided into N-type IGBTs and P-type IGBTs. For N-type IGBTs, when a positive voltage is applied to the gate, the current flows from the collector to the emitter; for P-type IGBTs, when a negative voltage is applied to the gate, the current flows from the emitter to the collector.

[0048] The three branches can be the first branch corresponding to A, the second branch corresponding to B, and the third branch corresponding to C. The first branch includes inductor L2, switch Q5, and switch Q6; the second branch includes inductor L3, switch Q7, and switch Q8; and the third branch includes inductor L4, switch Q9, and switch Q10.

[0049] In some embodiments, the output capacitor includes a first capacitor C1 and a second capacitor C2. The connection point of the first capacitor C1 and the second capacitor C2 is connected to the neutral point.

[0050] The output capacitor, also known as the bus capacitor, is used to stabilize the output DC voltage and provide energy buffering. The DC power output from the output capacitor includes a positive terminal (BUS+) and a negative terminal (BUS-). The three-phase diode rectifier bridge and the battery charging / discharging circuit 20 are both connected in parallel across the output capacitor.

[0051] It should be noted that in the three-phase Vienna PFC circuit 10, each phase is connected to the neutral point, forming a three-phase four-wire power supply system. The neutral point plays a crucial role in the three-phase circuit; it serves not only as a reference point for voltage and current but also influences the circuit's balance and stability. The number of neutral points is the same as in a standard three-phase circuit, ensuring circuit balance and stable system operation.

[0052] The three-phase Vienna PFC circuit 10 in this embodiment of the present invention includes a battery charging and discharging circuit 20.

[0053] like Figure 4 As shown, the battery charging and discharging circuit 20 is relative to... Figure 2 The topology shown reduces the number of diodes in the discharge circuit, adds two bidirectional switches, and simplifies the entire battery charging and discharging circuit.

[0054] The battery charging and discharging circuit 20 includes a first input terminal and a second input terminal, which are used to connect to the positive terminal (BAT+) and the negative terminal (BAT-) of the battery, respectively. The battery charging and discharging circuit 20 includes a first output terminal, a second output terminal, and a third output terminal. The first output terminal is used to connect to the positive terminal of the first capacitor C1, the second output terminal is used to connect to the neutral point, and the third output terminal is used to connect to the negative terminal of the second capacitor C2.

[0055] The battery charging and discharging circuit 20 can independently control the charging and discharging of the battery, so there is no time for switching between mains power and battery. When the mains power is abnormal, the bus voltage drops, and the battery charging and discharging circuit 20 can start discharging to maintain the bus voltage within the working range. This can also reduce the number of bus capacitors, thereby reducing the requirements for the number of bus capacitors.

[0056] In some embodiments, the three-phase Vienna PFC circuit can be replaced with a single-phase circuit and applied to a single-phase UPS system.

[0057] In some embodiments, the battery charging and discharging circuit 20 includes: a first battery charging and discharging circuit and a second battery charging and discharging circuit.

[0058] The first battery charging and discharging circuit includes: a first relay RLY1, a first inductor L1 and a first bidirectional switch, wherein the first bidirectional switch includes a first switching transistor Q1 and a second switching transistor Q2;

[0059] The first terminal of the first relay RLY1 is connected to the positive terminal (BAT+) of the battery. The second terminal of the first relay RLY1 is connected to the first terminal of the first inductor L1. The second terminal of the first inductor L1 is connected to the current output terminal of the first switch Q1 and the current input terminal of the second switch Q2. The current input terminal of the first switch Q1 is connected to the positive terminal of the output capacitor. The current output terminal of the second switch Q2 is connected to the neutral point.

[0060] The second battery charging and discharging circuit includes: a second relay RLY5, a second inductor L5, and a second bidirectional switch. The second bidirectional switch includes a third switch Q3 and a fourth switch Q4.

[0061] The first terminal of the second relay RLY5 is connected to the negative terminal (BAT-) of the battery. The second terminal of the second relay RLY5 is connected to the first terminal of the second inductor L5. The second terminal of the second inductor L5 is connected to the current output terminal of the third switch Q3 and the current input terminal of the fourth switch Q4. The current input terminal of the third switch Q3 is connected to the neutral point. The current output terminal of the fourth switch Q4 is connected to the negative terminal of the output capacitor.

[0062] In actual implementation, the first battery charging and discharging circuit and the second battery charging and discharging circuit are illustrated using an N-type IGBT as an example of the switching transistor.

[0063] Reference Figure 4 The first terminal of the first relay RLY1 is connected to the positive terminal (BAT+) of the battery, the second terminal of the first relay RLY1 is connected to the first terminal of the first inductor L1, the second terminal of the first inductor L1 is connected to the emitter of the first IGBT (Q1) and the collector of the second IGBT (Q2), the collector of the first IGBT (Q1) is connected to the positive terminal of the output capacitor, and the emitter of the second IGBT (Q2) is connected to the neutral point.

[0064] The first terminal of the second relay RLY5 is connected to the negative terminal (BAT-) of the battery. The second terminal of the second relay RLY5 is connected to the first terminal of the second inductor L5. The second terminal of the second inductor L5 is connected to the emitter of the third IGBT (Q3) and the collector of the fourth IGBT (Q4). The collector of the third IGBT (Q3) is connected to the neutral point. The emitter of the fourth IGBT (Q4) is connected to the negative terminal of the output capacitor.

[0065] In actual implementation, the first battery charging and discharging circuit and the second battery charging and discharging circuit are illustrated using an N-type MOS transistor as an example of the switching transistor.

[0066] The first terminal of the first relay RLY1 is connected to the positive terminal (BAT+) of the battery. The second terminal of the first relay RLY1 is connected to the first terminal of the first inductor L1. The second terminal of the first inductor L1 is connected to the source of the first MOSFET Q1 and the drain of the second MOSFET Q2. The drain of the first MOSFET Q1 is connected to the positive terminal of the output capacitor. The source of the second MOSFET Q2 is connected to the neutral point.

[0067] The first terminal of the second relay RLY5 is connected to the negative terminal (BAT-) of the battery. The second terminal of the second relay RLY5 is connected to the first terminal of the second inductor L5. The second terminal of the second inductor L5 is connected to the source of the third MOSFET Q3 and the drain of the fourth MOSFET Q4. The drain of the third MOSFET Q3 is connected to the neutral point. The source of the fourth MOSFET Q4 is connected to the negative terminal of the output capacitor. The source of the second MOSFET Q2 is connected to the neutral point, or the drain of the fourth MOSFET Q4 is connected to the neutral point.

[0068] In some embodiments, each branch also includes a relay, with a first terminal for connection to mains power and a second terminal for connection to an inductor on the corresponding branch.

[0069] It should be noted that the inductor in each branch is also connected to a relay, so the three branches also include relays RLY2, RLY3 and RLY4.

[0070] The first terminal of relay RLY2 receives the AC power corresponding to phase A of the mains; the first terminal of relay RLY3 receives the AC power corresponding to phase B of the mains; and the first terminal of relay RLY4 receives the AC power corresponding to phase C of the mains.

[0071] The second terminal of relay RLY2 is connected to the first terminal of inductor L2; the second terminal of relay RLY3 is connected to the first terminal of inductor L3; and the second terminal of relay RLY4 is connected to the first terminal of inductor L4.

[0072] Reference Figure 3 Taking an N-type MOSFET as an example, the second end of inductor L2 is connected to the drain of MOSFET Q5, the second end of inductor L3 is connected to the drain of MOSFET Q7, and the second end of inductor L4 is connected to the drain of MOSFET Q9.

[0073] The source of MOSFET Q5 is connected to the source of MOSFET Q6; the source of MOSFET Q7 is connected to the source of MOSFET Q8; and the source of MOSFET Q9 is connected to the source of MOSFET Q10.

[0074] The drain of MOSFET Q6 is connected to the neutral point, the drain of MOSFET Q8 is connected to the neutral point, and the drain of MOSFET Q10 is connected to the neutral point.

[0075] Reference Figure 4 Taking an N-type IGBT as an example, the second end of inductor L2 is connected to the collector of IGBT (Q5), the second end of inductor L3 is connected to the collector of IGBT (Q7), and the second end of inductor L4 is connected to the collector of IGBT (Q9).

[0076] The emitter of IGBT (Q5) is connected to the emitter of IGBT (Q6); the emitter of IGBT (Q7) is connected to the emitter of IGBT (Q8); and the emitter of IGBT (Q9) is connected to the emitter of IGBT (Q10).

[0077] The collector of IGBT (Q6) is connected to the neutral point, the collector of IGBT (Q8) is connected to the neutral point, and the collector of IGBT (Q10) is connected to the neutral point.

[0078] In some embodiments, the current inflow terminal of the first switch Q1 is connected to the positive terminal of the first capacitor C1, and the current outflow terminal of the fourth switch Q4 is connected to the negative terminal of the second capacitor C2.

[0079] The negative terminal of the first capacitor C1 and the positive terminal of the second capacitor C2 are both connected to the neutral point.

[0080] In actual implementation, refer to Figure 4Taking IGBT as an example, the collector of the first IGBT (Q1) is connected to the positive terminal of the first capacitor C1, and the emitter of the first IGBT (Q1) is connected to the collector of the second IGBT (Q2) and the second terminal of the first inductor L1, respectively.

[0081] The emitter of the fourth IGBT (Q4) is connected to the negative terminal of the second capacitor C2, and the collector of the fourth IGBT (Q4) is connected to the emitter of the third IGBT (Q3) and the second terminal of the second inductor L5.

[0082] Taking a MOSFET as an example, the drain of the first MOSFET Q1 is connected to the positive terminal of the first capacitor C1, and the source of the first MOSFET Q1 is connected to the drain of the second MOSFET Q2 and the second terminal of the first inductor L1.

[0083] The source of the fourth MOSFET Q4 is connected to the negative terminal of the second capacitor C2, and the drain of the fourth MOSFET Q4 is connected to the source of the third MOSFET Q3 and the second terminal of the second inductor L5.

[0084] Depend on Figure 3 It can be seen that the drains of MOSFET Q6, MOSFET Q8, and MOSFET Q10, the negative terminal of the first capacitor C1, and the positive terminal of the second capacitor C2 are all connected to the neutral point.

[0085] Depend on Figure 4 It can be seen that the collectors of IGBT (Q6), IGBT (Q8), and IGBT (Q10), the negative terminal of the first capacitor C1, and the positive terminal of the second capacitor C2 are all connected to the neutral point.

[0086] In some embodiments, each branch is connected to the neutral point.

[0087] In practice, the mains power connected to the three-phase Vienna PFC circuit is connected to the same neutral point, meaning that each phase of AC power is connected to the same neutral point.

[0088] In some embodiments, the positive terminal of the battery is also connected to the neutral point, and the negative terminal of the battery is also connected to the neutral point.

[0089] In actual implementation, such as Figure 4 As shown, the positive terminal (BAT+) of the battery is also connected to a neutral point, and the negative terminal (BAT-) of the battery is also connected to a neutral point.

[0090] In some embodiments, the positive terminal (BAT+) and the negative terminal (BAT-) of the battery correspond to a battery pack, and a neutral point may not be required.

[0091] like Figure 5As shown, the three-phase Vienna PFC circuit 10 and battery charging and discharging circuit 20 included in the three-phase uninterruptible power supply system have been described in detail in the above embodiments, and will not be repeated here. Figure 5 The positive terminal (BAT+) of the battery is not connected to the neutral point, and the negative terminal (BAT-) of the battery is also not connected to the neutral point.

[0092] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A three-phase uninterruptible power supply system, characterized in that, include: Three-phase Vienna PFC circuit and battery charging and discharging circuit; The three-phase Vienna PFC circuit includes: a three-phase diode rectifier bridge, three branches and an output capacitor, with each phase corresponding to one branch, and each branch including an inductor and a bidirectional switch; the bidirectional switch includes two switching transistors connected in reverse series. The input terminals of the three branches are used to connect to the mains power, and the output capacitor is used to output DC power. The first input terminal of the battery charging and discharging circuit is connected to the positive terminal of the battery, and the second input terminal of the battery charging and discharging circuit is connected to the negative terminal of the battery; the first output terminal and the second output terminal of the battery charging and discharging circuit are respectively connected to the two ends of the output capacitor, and the third output terminal of the battery charging and discharging circuit is connected to the neutral point. The three-phase Vienna PFC circuit is used to correct the input power factor of the mains power, and the battery charging and discharging circuit is used to independently control the charging and discharging of the battery.

2. The three-phase uninterruptible power supply system according to claim 1, characterized in that, The battery charging and discharging circuit includes: a first battery charging and discharging circuit and a second battery charging and discharging circuit. The first battery charging and discharging circuit includes: a first relay, a first inductor, and a first bidirectional switch, wherein the first bidirectional switch includes a first switching transistor and a second switching transistor; The first terminal of the first relay is connected to the positive terminal of the battery, the second terminal of the first relay is connected to the first terminal of the first inductor, the second terminal of the first inductor is connected to the current outflow terminal of the first switch and the current inflow terminal of the second switch respectively, the current inflow terminal of the first switch is connected to the positive terminal of the output capacitor, and the current outflow terminal of the second switch is connected to the neutral point. The second battery charging and discharging circuit includes: a second relay, a second inductor, and a second bidirectional switch, wherein the second bidirectional switch includes a third switching transistor and a fourth switching transistor; The first terminal of the second relay is connected to the negative terminal of the battery, the second terminal of the second relay is connected to the first terminal of the second inductor, the second terminal of the second inductor is connected to the current output terminal of the third switch and the current inflow terminal of the fourth switch, the current inflow terminal of the third switch is connected to the neutral point, and the current output terminal of the fourth switch is connected to the negative terminal of the output capacitor.

3. The three-phase uninterruptible power supply system according to claim 1, characterized in that, Each branch also includes a relay, the first end of which is connected to the mains power, and the second end of which is connected to the inductor on the corresponding branch.

4. The three-phase uninterruptible power supply system according to claim 3, characterized in that, Each branch is connected to the neutral point.

5. The three-phase uninterruptible power supply system according to claim 2, characterized in that, The positive terminal of the battery is also connected to the neutral point, and the negative terminal of the battery is also connected to the neutral point.

6. The three-phase uninterruptible power supply system according to claim 2, characterized in that, The output capacitor includes a first capacitor and a second capacitor; the current inflow terminal of the first switch is connected to the positive terminal of the first capacitor, and the current outflow terminal of the fourth switch is connected to the negative terminal of the second capacitor. The negative terminal of the first capacitor and the positive terminal of the second capacitor are both connected to the neutral point.

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