DC-DC conversion circuit and power conversion circuit including same

Abstract

The invention provides a DC-DC conversion circuit and a power conversion circuit comprising the same. The DC-DC conversion circuit comprises a positive DC bus, a negative DC bus, a DC power supply and a DC conversion unit. Wherein a neutral line is arranged between the positive direct-current bus and the negative direct-current bus, and the negative electrode of the direct-current power supply is connected with the neutral line. The DC conversion unit comprises a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and a first inductor, two ends of the first switch tube are respectively connected with a positive DC bus and a first end of the first inductor, and two ends of the fourth switch tube are respectively connected with a second end of the first inductor and a positive electrode of a DC power supply; two ends of the second switch tube are respectively connected with the first end of the first inductor and the neutral line. Two ends of the third switch tube are respectively connected with the second end of the first inductor and the negative DC bus. The DC-DC conversion circuit is high in working efficiency and good in EMC (Electro Magnetic Compatibility) characteristic, can be used for a common battery parallel operation system of a single-battery UPS (Uninterrupted Power Supply), and only has one inductor, so that the cost and the space can be saved.

Description

Technical Field

[0001] This invention belongs to the field of power electronics, specifically relating to a DC-DC converter circuit and a power conversion circuit including the same. Background Technology

[0002] The statements in this section are merely to provide background information in relation to the present invention to aid in understanding the invention, and such background information does not necessarily constitute prior art.

[0003] An uninterruptible power supply (UPS) is used to instantly switch to a DC power source to provide continuous power to the load in the event of an abnormal mains power supply, protecting the load from damage caused by the mains power interruption. Therefore, it is widely used in industrial, commercial, and consumer applications. A DC-DC converter (i.e., a DC-DC conversion circuit) is an electrical device widely used in UPS systems. The input of the DC-DC converter is connected to a rechargeable battery, and its output is connected to the positive and negative DC buses of the UPS. When a mains power failure occurs, the DC-DC converter boosts the DC power from the rechargeable battery and outputs it to the positive and negative DC buses. Due to their circuit structure and control methods, existing DC-DC converters are prone to problems such as poor electromagnetic compatibility (EMC) and low charging or power supply efficiency. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a DC-DC converter circuit and a power conversion circuit including the same, which can effectively solve the problems of poor EMC and low charging or power supply efficiency.

[0005] According to a first aspect of the present invention, a DC-DC converter circuit is provided, comprising: a positive DC bus and a negative DC bus, wherein a positive DC bus capacitor and a negative DC bus capacitor are electrically connected in series between the positive DC bus and the negative DC bus, and the node between the positive DC bus capacitor and the negative DC bus capacitor is connected to a neutral line; a rechargeable DC power supply, wherein the negative terminal of the DC power supply is connected to the neutral line; and a DC-DC conversion unit, comprising a first switch, a second switch, a third switch, a fourth switch, and a first inductor, wherein the two ends of the first switch are respectively connected to the positive DC bus capacitor and the negative DC bus capacitor. The positive DC bus is connected to the first end of the first inductor. The two ends of the fourth switch are respectively connected to the second end of the first inductor and the positive terminal of the DC power supply. The two ends of the second switch are respectively connected to the first end of the first inductor and the neutral line. The two ends of the third switch are respectively connected to the second end of the first inductor and the negative DC bus. The positive DC bus and the negative DC bus charge the DC power supply through the DC-DC converter unit, and / or the DC power supply supplies power to the positive DC bus and the negative DC bus through the DC-DC converter unit.

[0006] Preferably, the first and third switching transistors are controllable switching transistors with anti-parallel diodes, and the second and fourth switching transistors are diodes; the first switching transistor is configured to alternately conduct, the third switching transistor is configured to turn off, and the positive DC bus charges the DC power supply; or, the first switching transistor is configured to turn off, the third switching transistor is configured to alternately conduct, and the negative DC bus charges the DC power supply.

[0007] Preferably, the first and third switching transistors are diodes, and the second and fourth switching transistors are controllable switching transistors with anti-parallel diodes; the second switching transistor is configured to conduct alternately, the fourth switching transistor is configured to conduct, and the DC power supply supplies power to the positive DC bus; or, the second switching transistor is configured to conduct, the fourth switching transistor is configured to conduct alternately, and the DC power supply supplies power to the negative DC bus.

[0008] Preferably, the first, second, third, and fourth switching transistors are all controllable switching transistors with anti-parallel diodes; the first switching transistor is configured to alternately conduct, and the second, third, and fourth switching transistors are configured to be off, with the positive DC bus charging the DC power supply; or, the third switching transistor is configured to alternately conduct, and the first, second, and fourth switching transistors are configured to be off, with the negative DC bus charging the DC power supply; or, the fourth switching transistor is configured to conduct, the second switching transistor is configured to alternately conduct, and the first and third switching transistors are configured to be off, with the DC power supply supplying power to the positive DC bus; or, the fourth switching transistor is configured to alternately conduct, the second switching transistor is configured to conduct, and the first and third switching transistors are configured to be off, with the DC power supply supplying power to the negative DC bus.

[0009] According to a second aspect, a DC-DC converter circuit is provided, comprising: a positive DC bus and a negative DC bus, wherein a positive DC bus capacitor and a negative DC bus capacitor are electrically connected in series between the positive DC bus and the negative DC bus, and the node between the positive DC bus capacitor and the negative DC bus capacitor is connected to a neutral line; a rechargeable DC power supply, the positive terminal of which is connected to the neutral line; and a DC-DC converter unit, comprising a first switch, a second switch, a third switch, a fourth switch, and a first inductor, wherein the two ends of the first switch are respectively connected to the negative DC bus and the first end of the first inductor, the two ends of the fourth switch are respectively connected to the second end of the first inductor and the negative terminal of the DC power supply, the two ends of the second switch are respectively connected to the first end of the first inductor and the neutral line, and the two ends of the third switch are respectively connected to the second end of the first inductor and the positive DC bus; the positive DC bus and the negative DC bus charge the DC power supply through the DC-DC converter unit, and / or the DC power supply supplies power to the positive DC bus and the negative DC bus through the DC-DC converter unit.

[0010] Preferably, the first and third switching transistors are controllable switching transistors with anti-parallel diodes, and the second and fourth switching transistors are diodes; the first switching transistor is configured to alternately conduct, the third switching transistor is configured to turn off, and the negative DC bus charges the DC power supply; or, the first switching transistor is configured to turn off, the third switching transistor is configured to alternately conduct, and the positive DC bus charges the DC power supply.

[0011] Preferably, the first and third switching transistors are diodes, and the second and fourth switching transistors are controllable switching transistors with anti-parallel diodes; the second switching transistor is configured to conduct alternately, the fourth switching transistor is configured to conduct, and the DC power supply supplies power to the negative DC bus; or, the second switching transistor is configured to conduct, the fourth switching transistor is configured to conduct alternately, and the DC power supply supplies power to the positive DC bus.

[0012] Preferably, the first, second, third, and fourth switching transistors are all controllable switching transistors with anti-parallel diodes; the first switching transistor is configured to alternately conduct, and the second, third, and fourth switching transistors are configured to be off, with the negative DC bus charging the DC power supply; or, the third switching transistor is configured to alternately conduct, and the first, second, and fourth switching transistors are configured to be off, with the positive DC bus charging the DC power supply; or, the fourth switching transistor is configured to conduct, the second switching transistor is configured to alternately conduct, and the first and third switching transistors are configured to be off, with the DC power supply supplying power to the negative DC bus; or, the fourth switching transistor is configured to alternately conduct, the second switching transistor is configured to conduct, and the first and third switching transistors are configured to be off, with the DC power supply supplying power to the positive DC bus.

[0013] According to a third aspect, a power conversion circuit is provided, comprising a first switch, a rectifier unit, and a DC-DC conversion circuit as described in either the first or second aspect; a first terminal of the first switch is connected to mains power, a second terminal of the first switch is connected to the input terminal of the rectifier unit, and the output terminal of the rectifier unit is connected to the positive DC bus, the negative DC bus, and the neutral line.

[0014] Preferably, the power conversion circuit further includes a second switch, the first end of which is connected to the second end of the first switch, and the second end of which is connected to the second end of the first inductor.

[0015] Preferably, the power conversion circuit further includes a third switch, the first end of which is connected to the second end of the first inductor, and the second end of which is connected to the common connection point of the third switch and the fourth switch; or, the first end of the third switch is connected to the first end of the first inductor, and the second end of which is connected to the common connection point of the first switch and the second switch.

[0016] According to a fourth aspect, an uninterruptible power supply is provided, the uninterruptible power supply including a DC-DC conversion circuit as described in either the first or second aspect, or a power conversion circuit as described in either the third aspect.

[0017] In this embodiment of the DC-DC converter circuit, only one side of the dual DC bus participates in operation, making it more suitable for single-phase AC mains input UPS systems. Furthermore, the voltage difference between the DC-DC terminals is small, resulting in higher efficiency. The direct connection between the battery negative terminal and the neutral line improves the circuit's EMC characteristics and operational reliability. It can also be used in parallel systems with shared batteries in single-cell UPS systems. In addition, this circuit uses only one inductor, saving cost and space. Attached Figure Description

[0018] Figure 1 A schematic diagram of a first-order DC-DC converter circuit connected between a DC bus and a rechargeable battery is shown.

[0019] Figure 2 A schematic diagram of a second prior art DC-DC converter circuit connected between a DC bus and a rechargeable battery is shown.

[0020] Figure 3 It shows Figure 2 The diagram shows the waveforms of the relevant components when the circuit is in operation.

[0021] Figure 4 This diagram illustrates a third type of prior art DC-DC converter circuit connected between a DC bus and a battery.

[0022] Figure 5 A schematic diagram of a fourth type of prior art DC-DC converter circuit connected between a DC bus and a battery is shown.

[0023] Figure 6 A schematic topology of a DC-DC converter circuit according to an embodiment of the present invention is shown;

[0024] Figure 7a and Figure 7b They are shown respectively Figure 6 In the circuit topology of the illustrated embodiment, when the positive DC bus BUS+ is used as an input, the DC bus stores energy in the inductor and charges the battery. Figure 7a ) and the charging of the battery by the inductor ( Figure 7b The corresponding equivalent circuit diagram;

[0025] Figure 7c and Figure 7d They are shown respectively Figure 6 When the negative DC bus BUS- of the circuit topology of the illustrated embodiment is used as an input, the DC bus stores energy in the inductor. Figure 7c ) and the charging of the battery by the inductor ( Figure 7d The corresponding equivalent circuit diagram;

[0026] Figure 8 A schematic topology of a DC-DC converter circuit according to an embodiment of the present invention is shown;

[0027] Figure 9 A schematic topology of a DC-DC converter circuit according to an embodiment of the present invention is shown;

[0028] Figure 10a and Figure 10b They are shown respectively Figure 9 In the circuit topology of the illustrated embodiment, when the DC bus charges the battery, the positive DC bus BUS+ stores energy through the inductor and charges the battery. Figure 10a ) and the charging of the battery by the inductor ( Figure 10b The corresponding equivalent circuit diagram;

[0029] Figure 10c and Figure 10d They are shown respectively Figure 9 In the circuit topology of the illustrated embodiment, when the DC bus is charging the battery, the negative DC bus BUS- is connected to the inductor for energy storage. Figure 10c ) and the charging of the battery by the inductor ( Figure 10d The corresponding equivalent circuit diagram;

[0030] Figure 10e and Figure 10f They are shown respectively Figure 9 In the circuit topology of the illustrated embodiment, when the battery supplies power to the DC bus, the battery stores energy through the inductor. Figure 10c ) and inductor-to-positive DC bus BUS+ power supply ( Figure 10d The corresponding equivalent circuit diagram;

[0031] Figure 10g and Figure 10h They are shown respectively Figure 9 In the circuit topology of the illustrated embodiment, when the battery supplies power to the DC bus, the battery stores energy through the inductor. Figure 10g ) and the inductor supplying power to the negative DC bus (BUS-) Figure 10d The corresponding equivalent circuit diagram;

[0032] Figure 11 An embodiment of the invention is shown. Figure 6 A schematic topology of a mirrored DC-DC converter circuit;

[0033] Figure 12 An embodiment of the invention is shown. Figure 8 A schematic topology of a mirrored DC-DC converter circuit;

[0034] Figure 13 An embodiment of the invention is shown. Figure 9 A schematic topology of a mirrored DC-DC converter circuit;

[0035] Figure 14 A schematic topology of a power conversion circuit according to an embodiment of the present invention is shown;

[0036] Figure 15a It shows Figure 14 The circuit diagram shown in the embodiment is an equivalent circuit diagram corresponding to the mains power supply to the positive DC bus and the positive DC bus charging the battery during the positive half-cycle of the mains mode.

[0037] Figure 15b It shows Figure 14 The circuit diagram shown in the embodiment is an equivalent circuit diagram corresponding to the mains power supply to the negative DC bus and the negative DC bus charging the battery during the negative half-cycle of the mains mode.

[0038] Figure 16a It shows Figure 14 The circuit topology of the embodiment shown is an equivalent circuit diagram of the battery-mode UPS operating in the positive half-cycle of the power frequency when the battery supplies power to the positive DC bus.

[0039] Figure 16b It shows Figure 14 The circuit topology of the embodiment shown is an equivalent circuit diagram of the battery-mode UPS operating in the negative half-cycle of the power frequency when the battery supplies power to the negative DC bus.

[0040] Figure 17a A schematic topology of a power conversion circuit according to an embodiment of the present invention is shown;

[0041] Figure 17b A schematic topology of a power conversion circuit according to an embodiment of the present invention is shown;

[0042] Figure 18a It shows Figure 17a The circuit topology of the embodiment shown is an equivalent circuit diagram of the battery-mode UPS operating in the positive half-cycle of the power frequency when the battery supplies power to the positive DC bus.

[0043] Figure 18b It shows Figure 17a The circuit topology of the embodiment shown is an equivalent circuit diagram of the battery-mode UPS operating in the negative half-cycle of the power frequency when the battery supplies power to the negative DC bus.

[0044] Figure 19A schematic topology of a power conversion circuit including a first alternative rectifier unit is shown according to an embodiment of the present invention;

[0045] Figure 20 A schematic topology of a power conversion circuit including a second replacement rectifier unit is shown according to an embodiment of the present invention; and

[0046] Figure 21 A schematic topology of a power conversion circuit including a third alternative rectifier unit is shown according to an embodiment of the present invention. Detailed Implementation

[0047] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that these embodiments are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, well-known procedures, materials, or methods have not been specifically described to avoid obscuring the invention. The terms "first," "second," etc., appearing in the embodiments do not represent the order of appearance but are used only to distinguish different branch or device names.

[0048] Figure 1 A schematic diagram of a first-generation DC-DC converter circuit connected between a DC bus and a rechargeable battery is shown. Figure 1 As shown, a positive DC bus capacitor C1 and a negative DC bus capacitor C2 are electrically connected in series between the positive DC bus BUS+ and the negative DC bus BUS-. A neutral line N0 is provided between the positive DC bus capacitor C1 and the negative DC bus capacitor C2. This DC-DC converter circuit includes a switch Q1, a diode D1, and an inductor L1. The first terminal of the switch Q1 is connected to the first terminal of the inductor L1 and the cathode of the diode D1. The second terminal of the switch Q1 and the anode of the diode D1 are connected to the positive DC bus BUS+ and the negative DC bus BUS-, respectively. The anode of the diode D1 and the second terminal of the inductor L1 are connected to the negative terminal DC- and the positive terminal DC+ of the battery, respectively. Control device ( Figure 1 (Not shown) A pulse width modulation signal is provided to the control terminal of the switch Q1 (i.e., modulation control is performed) to charge the battery using the electrical energy on the positive DC bus BUS+ and the negative DC bus BUS-.

[0049] when Figure 1 When the circuit shown is applied to a charger for a single-cell UPS, the PFC circuit (or rectifier unit) connected to the DC bus is in operation. Figure 1 (Not shown) Power is supplied to the positive DC bus BUS+ during the positive half-cycle and to the negative DC bus BUS- during the negative half-cycle, but... Figure 1 The circuit shown draws power from both the positive DC bus BUS+ and the negative DC bus BUS- simultaneously during both the positive and negative half-cycles, resulting in a large voltage ripple on the DC bus capacitors. For example, during the positive half-cycle, the positive DC bus BUS+ can draw power from the PFC circuit to supply power to... Figure 1 The circuit shown is in a configuration where the PFC circuit is not supplying power to the negative DC bus BUS-, so it needs to draw power from the negative DC bus capacitor C2 to supply the power conversion circuit. This not only requires a larger DC bus capacitor but also increases the difficulty of controlling the DC bus capacitor voltage. Furthermore, Figure 1 The circuit shown is for a UPS with a power range of 5-11kVA. The DC bus voltage is generally around 700V, while the battery voltage, i.e. the output voltage of the power conversion circuit, is around 200V. The large voltage difference between the input and output terminals results in low charging efficiency of the circuit.

[0050] Figure 2 A schematic diagram of a second prior art DC-DC converter circuit connected between a DC bus and a battery is shown. Figure 2 As shown, a positive DC bus capacitor C1 and a negative DC bus capacitor C2 are electrically connected in series between the positive DC bus BUS+ and the negative DC bus BUS-. The node between the positive DC bus capacitor C1 and the negative DC bus capacitor C2 is connected to the neutral line N0. The battery circuit includes a switch Q1, a diode D1, an inductor L1, a switch Q2, a diode D2, and an inductor L2. Specifically, the switch Q1 and the inductor L1 are connected in series between the positive DC bus BUS+ and the positive terminal DC+ of the battery. The second terminal of the switch Q1 is connected to the positive DC bus BUS+, the first terminal of the switch Q1 is connected to the first terminal of the inductor L1, and the second terminal of the inductor L1 is connected to the positive terminal DC+ of the battery. A switching transistor Q2 and an inductor L2 are connected in series between the negative DC bus BUS- and the negative terminal DC- of the battery. The first terminal of the switching transistor Q2 is connected to the negative DC bus BUS-, and the second terminal of the switching transistor Q2 is connected to the first terminal of the inductor L2. The second terminal of the inductor L2 is connected to the negative terminal DC- of the battery. Diodes D1 and D2 are connected in series between the first node N1 and the second node N2. The cathode of diode D1 is connected to the first node N1, the anode of diode D1 is connected to the cathode of diode D2, and the anode of diode D2 is connected to the second node N2. The first node N1 is located between the switching transistor Q1 and the inductor L1, and the second node N2 is located between the switching transistor Q2 and the inductor L2. The anode of diode D1 and the cathode of diode D2 are connected to the neutral line N0.

[0051] Figure 3 It shows Figure 2The diagram shows the waveforms of the relevant components during circuit operation. When the positive DC bus BUS+ is used as input, switch Q2 is normally off, and switch Q1 performs modulation control. When switch Q1 is on, the positive DC bus BUS+ supplies energy to inductors L1 and L2 and the battery; when switch Q1 is off, inductors L1 and L2 charge the battery through diodes D1 and D2. When the negative DC bus BUS- is used as input, switch Q1 is normally off, and switch Q2 performs modulation control. When switch Q2 is on, the negative DC bus BUS- supplies DC energy to inductors L1 and L2 and the battery; when switch Q2 is off, inductors L1 and L2 charge the battery through diodes D1 and D2. (Reference) Figure 3 Analysis reveals that regardless of whether the positive DC bus BUS+ or the negative DC bus BUS- is used as the input, inductors L1 and L2 typically employ the same design. The voltages of inductors L1 and L2 remain consistent during energy storage and discharge. This results in the battery's negative terminal DC- relative to the neutral line N0 experiencing high-voltage, high-frequency changes during the modulation and control process of switch Q1 or Q2. Figure 2 The circuit shown has very poor EMC characteristics.

[0052] Figure 4 A schematic diagram of a third type of prior art DC-DC converter circuit connected between a DC bus and a battery is shown, which can realize bidirectional DC-DC conversion between two DC buses and a battery. Figure 4 As shown, a battery with a positive DC bus capacitor C1 and a negative DC bus capacitor C2 connected in series is electrically connected between the positive DC bus BUS+ and the negative DC bus BUS-. The circuit includes switching transistors Q1 and Q2 and an inductor L1. The first terminal of switching transistor Q1 is connected to the first terminal of inductor L1 and the second terminal of switching transistor Q2. The second terminal of switching transistor Q1 and the first terminal of switching transistor Q2 are respectively connected to the positive DC bus BUS+ and the negative DC bus BUS-. The first terminal of switching transistor Q2 and the second terminal of inductor L1 are respectively connected to the negative terminal DC- and the positive terminal DC+ of the battery. When both DC buses supply power to the battery, it is a BUCK circuit; when the battery supplies power to both DC buses, it is a BOOST circuit. Figure 1Similar to the circuit described above, when this circuit uses dual DC buses to power the battery, for a single-phase AC input UPS, the DC bus (BUS) capacitor ripple is large, requiring a larger BUS capacitor and increasing the difficulty of BUS control. For small to medium power UPSs, the dual DC bus voltage is generally around 700V, while the battery voltage (i.e., the single DC voltage) is around 200V, resulting in a large voltage drop and low charging efficiency. Furthermore, because the battery negative terminal (DC-) is connected to the negative DC bus (BUS-) in this circuit, for UPS parallel systems, the voltage fluctuations of the negative DC bus relative to the neutral line across different machines make it unsuitable for parallel battery systems.

[0053] Figure 5 A schematic diagram of a fourth type of prior art DC-DC converter circuit connected between a DC bus and a battery is shown, which can realize bidirectional DC-DC conversion between two DC buses and a battery. Figure 5 As shown, a positive DC bus capacitor C1 and a negative DC bus capacitor C2 are electrically connected in series between the positive DC bus BUS+ and the negative DC bus BUS-. The node between the positive DC bus capacitor C1 and the negative DC bus capacitor C2 is connected to the neutral line N0. The battery circuit includes switching transistors Q1, Q2, L1, Q3, Q4, and L2. Specifically, switching transistor Q1 and inductor L1 are connected in series between the positive DC bus BUS+ and the positive terminal DC+ of the battery. The second terminal of switching transistor Q1 is connected to the positive DC bus BUS+, the first terminal of switching transistor Q1 is connected to the first terminal of inductor L1, and the second terminal of inductor L1 is connected to the positive terminal DC+ of the battery. A switching transistor Q4 and an inductor L2 are connected in series between the negative DC bus BUS- and the negative terminal DC- of the battery. The first terminal of the switching transistor Q4 is connected to the negative DC bus BUS-, and the second terminal of the switching transistor Q4 is connected to the first terminal of the inductor L2. The second terminal of the inductor L2 is connected to the negative terminal DC- of the battery. Switches Q2 and Q3 are connected in series between the first node N1 and the second node N2. The second terminal of the switching transistor Q2 is connected to the first node N1, and the first terminal of the switching transistor Q2 is connected to the second terminal of the switching transistor Q3. The first terminal of the switching transistor Q3 is connected to the second node N2. The first node N1 is located between the switching transistor Q1 and the inductor L1, and the second node N2 is located between the switching transistor Q4 and the inductor L2. The first terminals of the switching transistors Q2 and Q3 are connected to the neutral line N0.

[0054] Figure 5 The circuit shown works as follows:

[0055] When the positive DC bus BUS+ is used as input to charge the battery, switch Q4 is normally open and switch Q3 is normally closed. Switches Q1, Q2, inductors L1 and L2 form a BUCK circuit. When the negative DC bus BUS- is used as input to charge the battery, switch Q1 is normally open and switch Q2 is normally closed. Switches Q3, Q4, inductors L1 and L2 form a BUCK circuit.

[0056] When the battery powers the positive DC bus BUS+ as input, switch Q4 is normally open and switch Q3 is normally closed. Switches Q1, Q2, inductors L1 and L2 form the BOOST circuit. When the battery powers the positive DC bus BUS- as input, switch Q1 is normally open and switch Q2 is normally closed. Switches Q3, Q4, inductors L1 and L2 form the BOOST circuit.

[0057] Based on the above working process, it can be concluded that the voltage of the positive and negative terminals of the battery relative to the neutral line N0 changes at a high frequency, which results in poor EMC characteristics of the circuit. Therefore, this control method of the circuit cannot be used in parallel battery systems.

[0058] To address the problems existing in the circuits of the prior art, a DC-DC converter circuit is provided according to an embodiment of the present invention. The DC-DC converter circuit includes: a positive DC bus, a negative DC bus, a rechargeable DC power supply (i.e., a battery), and a DC-DC conversion unit. A positive DC bus capacitor and a negative DC bus capacitor connected in series are electrically connected between the positive and negative DC bus, and the node between the positive and negative DC bus capacitors is connected to the neutral line. The negative terminal of the battery is connected to the neutral line. The DC-DC conversion unit includes a first switch, a second switch, a third switch, a fourth switch, and a first inductor. The two ends of the first switch are respectively connected to the positive DC bus and the first end of the first inductor; the two ends of the fourth switch are respectively connected to the second end of the first inductor and the positive terminal of the battery; the two ends of the second switch are respectively connected to the first end of the first inductor and the neutral line; and the two ends of the third switch are respectively connected to the second end of the first inductor and the negative DC bus. The positive and negative DC buses charge the battery through the DC-DC converter unit, and / or the battery supplies power to the positive and negative DC buses through the DC-DC converter unit.

[0059] like Figure 6As shown, in one embodiment, the DC-DC converter circuit includes: a positive DC bus capacitor C1 and a negative DC bus capacitor C2 connected in series between the positive DC bus BUS+ and the negative DC bus BUS-; the node between the positive DC bus capacitor C1 and the negative DC bus capacitor C2 is connected to the neutral line N0. The neutral line N0 is connected to the negative terminal DC- of the battery. The first and third switching transistors of the DC-DC converter unit are controllable switching transistors with anti-parallel diodes (in this embodiment, the first and third switching transistors are...). Figure 6 (shown as Q1 and Q3 respectively), the second and fourth switching transistors are diodes (in this embodiment, the second and fourth switching transistors are...) Figure 6 (D2 and D4 are shown separately). The first terminal of the controllable switch Q1 is connected to the first terminal of the first inductor L1, the second terminal of the first inductor L1 is connected to the anode of diode D4, the second terminal of the controllable switch Q1 is connected to the positive DC bus BUS+, and the cathode of diode D4 is connected to the positive terminal DC+ of the battery. The first terminal of the controllable switch Q3 is connected to the negative DC bus BUS-, and the second terminal of the controllable switch Q3 is connected to the second terminal of the first inductor L1. The anode of diode D2 is connected to the neutral line N0, and the cathode of diode D2 is connected to the first terminal of the first inductor L1.

[0060] Figure 7a and Figure 7b They are shown respectively Figure 6 In the circuit topology of the illustrated embodiment, when the positive DC bus BUS+ is used as an input, the DC bus stores energy in the inductor and charges the battery. Figure 7a ) and the charging of the battery by the inductor ( Figure 7b The corresponding equivalent circuit diagram is shown below. When the positive DC bus BUS+ is used as the input, the controllable switch Q3 is normally open, and the controllable switch Q1 performs modulation control. For example... Figure 7a As shown, when the controllable switch Q1 is turned on, the current path is: positive DC bus BUS+ → controllable switch Q1 → inductor L1 → diode D4 → battery positive terminal DC+ → battery negative terminal DC- → neutral line N0. The positive DC bus BUS+ stores energy for inductor L1 and the battery. Figure 7b As shown, when the controllable switch Q1 is turned off, the circuit flows from inductor L1 to diode D4, then from the positive terminal of the battery (DC+) to the negative terminal of the battery (DC-), and finally to diode D2. Inductor L1 charges the battery through diodes D2 and D4.

[0061] Figure 7c and Figure 7d They are shown respectively Figure 6 When the negative DC bus BUS- of the circuit topology of the illustrated embodiment is used as an input, the DC bus stores energy in the inductor. Figure 7c ) and the charging of the battery by the inductor ( Figure 7dThe corresponding equivalent circuit diagram is shown below. When the negative DC bus BUS- is used as input, the controllable switch Q1 is normally open, and the controllable switch Q3 performs modulation control. For example... Figure 7c As shown, when the controllable switch Q3 is turned on, the current path is neutral line N0 → diode D2 → inductor L1 → controllable switch Q3 → negative DC bus BUS-, and the negative DC bus BUS- stores energy for inductor L1. Figure 7d As shown, when the controllable switch Q3 is turned off, the circuit flows from inductor L1 to diode D4, then from the positive terminal of the battery (DC+) to the negative terminal of the battery (DC-), and finally to diode D2. Inductor L1 charges the battery through diodes D2 and D4.

[0062] and Figure 1 Compared to the circuit topology, Figure 6 The circuit topology uses a single-sided DC bus as input, making it more suitable for single-phase AC mains input UPS applications. Furthermore, the voltage difference across the step-down circuit is small, resulting in higher efficiency. Figure 2 Compared to the circuit topology, Figure 6 When the circuit topology uses a single-sided DC bus as input, the direct connection between the battery negative terminal DC- and the neutral line N0 results in good EMC characteristics and allows it to be used in parallel systems with shared batteries in single-cell UPS systems. Furthermore, this circuit uses only one inductor, saving cost and space.

[0063] In one embodiment, the first and third switching transistors of the DC-DC converter unit of the DC-DC converter circuit are diodes (in this embodiment, the first and third switching transistors are...). Figure 8 (shown as D1 and D3 respectively), the second and fourth switching transistors are controllable switching transistors with anti-parallel diodes (in this embodiment, the second and fourth switching transistors are in...) Figure 8 (These are shown as Q2 and Q4 respectively). Figure 8 As shown, the anode of diode D1 is connected to the first terminal of the first inductor L1, the second terminal of inductor L1 is connected to the first terminal of the controllable switch Q4, the cathode of diode D1 is connected to the positive DC bus BUS+, and the second terminal of the controllable switch Q4 is connected to the positive terminal DC+ of the battery. The anode of diode D3 is connected to the negative DC bus BUS-, and the cathode of diode D3 is connected to the second terminal of the first inductor L1. The first terminal of the controllable switch Q2 is connected to the neutral line N0, and the second terminal of the controllable switch Q2 is connected to the first terminal of the first inductor L1. The operation of this DC-DC converter circuit is as follows:

[0064] Battery power supply to the positive DC bus: Controlled switch Q4 is normally on, and controlled switch Q2 performs modulation control. When controlled switch Q2 is on, the battery, controlled switch Q4, inductor L1, and controlled switch Q2 directly form a current path, and the battery stores energy for inductor L1. When controlled switch Q2 is off, a current path is formed between the battery, controlled switch Q4, inductor L1, diode D1, positive DC bus BUS+, and neutral line N0, and inductor L1 supplies power to positive DC bus BUS+ through diode D1.

[0065] Battery supplies power to the negative DC bus: Controlled switch Q2 is normally on, and controlled switch Q4 performs modulation control. When controlled switch Q4 is on, a current path is formed between the battery, controlled switch Q4, inductor L1, and controlled switch Q2, and the battery stores energy for inductor L1; when controlled switch Q4 is off, a current path is formed between inductor L1, controlled switch Q2, neutral line N0, negative DC bus BUS-, and diode D3, and inductor L1 supplies power to negative DC bus BUS- through diode D3.

[0066] In one embodiment, the first, second, third, and fourth switching transistors of the DC-DC converter unit of the DC-DC converter circuit are all controllable switching transistors with anti-parallel diodes (in this embodiment, the first, second, third, and fourth switching transistors are in...). Figure 9 (These are represented by Q1, Q2, Q3, and Q4 respectively). Figure 9 As shown, the first terminal of controllable switch Q1 is connected to the first terminal of the first inductor L1, the second terminal of the first inductor L1 is connected to the first terminal of controllable switch Q4, the second terminal of controllable switch Q1 is connected to the positive DC bus BUS+, and the second terminal of controllable switch Q4 is connected to the positive terminal DC+ of the battery. The first terminal of controllable switch Q3 is connected to the negative DC bus BUS-, and the second terminal of controllable switch Q3 is connected to the second terminal of the first inductor L1. The first terminal of controllable switch Q2 is connected to the neutral line N0, and the second terminal of controllable switch Q2 is connected to the first terminal of the first inductor L1.

[0067] Figure 10a and Figure 10b They are shown respectively Figure 9 In the circuit topology of the illustrated embodiment, when the DC bus charges the battery, the positive DC bus BUS+ stores energy through the inductor and charges the battery. Figure 10a ) and the charging of the battery by the inductor ( Figure 10b The corresponding equivalent circuit diagram is shown below. When the positive DC bus BUS+ is used as the input, in mode 1: controllable switch Q3 is normally off, controllable switch Q4 is normally on, and controllable switches Q1 and Q2 perform complementary modulation control. For example... Figure 10aAs shown, when the controllable switch Q1 is on and the controllable switch Q2 is off, the current path is: positive DC bus BUS+ → controllable switch Q1 → inductor L1 → controllable switch Q4 → battery positive terminal DC+ → battery negative terminal DC- → neutral line N0. The positive DC bus BUS+ stores energy for inductor L1 and the battery. Figure 10b As shown, when controllable switch Q1 is off and controllable switch Q2 is on, the current path is: inductor L1 → controllable switch Q4 → battery positive terminal DC+ → battery negative terminal DC- → controllable switch Q2. Inductor L1 can charge the battery. Method 2: Controllable switches Q2, Q3, and Q4 are normally off, and controllable switch Q1 performs modulation control. When controllable switch Q1 is on, please refer to [link to relevant documentation]. Figure 10a The current path is: positive DC bus BUS+ → controllable switch Q1 → inductor L1 → controllable switch Q4 → battery positive terminal DC+ → battery negative terminal DC- → neutral line N0. The positive DC bus BUS+ stores energy for inductor L1 and the battery. When controllable switch Q1 is turned off, please refer to [the documentation / reference needed]. Figure 10b The current path is: inductor L1 → controllable switch Q4 → battery positive terminal DC+ → battery negative terminal DC- → controllable switch Q2. Inductor L1 can charge the battery through the freewheeling diodes in controllable switches Q2 and Q4.

[0068] Figure 10c and Figure 10d They are shown respectively Figure 9 In the circuit topology of the illustrated embodiment, when the DC bus is charging the battery, the negative DC bus BUS- is connected to the inductor for energy storage. Figure 10c ) and the charging of the battery by the inductor ( Figure 10d The corresponding equivalent circuit diagram is shown below. When the negative DC bus BUS- is used as the input, in mode 1: controllable switch Q1 is normally open, controllable switch Q2 is normally on, and controllable switches Q3 and Q4 perform complementary modulation control. For example... Figure 10c As shown, when the controllable switch Q3 is on and the controllable switch Q4 is off, the current path is: neutral line N0 → controllable switch Q2 → inductor L1 → controllable switch Q3 → negative DC bus BUS-, and the negative DC bus BUS- stores energy for inductor L1. Figure 10d As shown, when controllable switch Q3 is off and controllable switch Q4 is on, the circuit flows from inductor L1 → controllable switch Q4 → battery positive terminal DC+ → battery negative terminal DC- → controllable switch Q2, allowing inductor L1 to charge the battery. Method Two: Controllable switches Q1, Q2, and Q4 are normally off, with controllable switch Q3 performing modulation control. When controllable switch Q3 is on, please refer to [link to relevant documentation]. Figure 10cThe current path is: neutral line N0 → controllable switch Q2 → inductor L1 → controllable switch Q3 → negative DC bus BUS-, where the negative DC bus BUS- stores energy for inductor L1. When controllable switch Q3 is turned off, please refer to [the relevant documentation / reference]. Figure 10d Inductor L1 → Controlled switch Q4 → Battery positive terminal DC+ → Battery negative terminal DC- → Controlled switch Q2. Inductor L1 can charge the battery through the freewheeling diodes in controlled switches Q2 and Q4.

[0069] Figure 10e and Figure 10f They are shown respectively Figure 9 In the circuit topology of the illustrated embodiment, when the battery supplies power to the DC bus, the battery stores energy through the inductor. Figure 10c ) and inductor-to-positive DC bus BUS+ power supply ( Figure 10d The corresponding equivalent circuit diagram is shown below. When the battery supplies power to the positive DC bus BUS+, in mode 1: controllable switch Q3 is normally off, controllable switch Q4 is normally on, and controllable switches Q1 and Q2 perform complementary modulation control. For example... Figure 10e As shown, when the controllable switch Q1 is off and the controllable switch Q2 is on, the current path is: battery positive terminal DC+ → controllable switch Q4 → inductor L1 → controllable switch Q2 → battery negative terminal DC-, and the battery stores energy in inductor L1. Figure 10f As shown, when controllable switch Q1 is on and controllable switch Q2 is off, the current path is: inductor L1 → controllable switch Q1 → positive DC bus BUS+ → neutral line N0 → battery negative terminal DC- → battery positive terminal DC+ → controllable switch Q4 → inductor L1. Inductor L1 can supply power to the positive DC bus BUS+. Mode 2: Controllable switch Q4 is normally on, controllable switches Q1 and Q3 are normally off, and controllable switch Q2 performs modulation control. When controllable switch Q2 is on, please refer to... Figure 10e The current path is: battery positive terminal DC+ → controllable switch Q4 → inductor L1 → controllable switch Q2 → battery negative terminal DC-, with the battery storing energy in inductor L1. When controllable switch Q2 is off, please refer to [the documentation / reference needed]. Figure 10f The current path is: inductor L1 → controllable switch Q1 → positive DC bus BUS+ → neutral line N0 → battery negative terminal DC- → battery positive terminal DC+ → controllable switch Q4 → inductor L1. Inductor L1 can supply power to the positive DC bus BUS+ through the freewheeling diode in controllable switch Q1.

[0070] Figure 10g and Figure 10h They are shown respectively Figure 9 In the circuit topology of the illustrated embodiment, when the battery supplies power to the DC bus, the battery stores energy through the inductor. Figure 10g ) and the inductor supplying power to the negative DC bus (BUS-) Figure 10d The corresponding equivalent circuit diagram is shown below. When the battery supplies power to the negative DC bus BUS-, in mode one: controllable switch Q1 is normally open, controllable switch Q2 is normally on, and controllable switches Q3 and Q4 perform complementary modulation control. For example... Figure 10g As shown, when the controllable switch Q3 is off and the controllable switch Q4 is on, the current path is: battery positive terminal DC+ → controllable switch Q4 → inductor L1 → controllable switch Q2 → battery negative terminal DC-, and the battery stores energy in inductor L1. Figure 10h As shown, when controllable switch Q3 is on and controllable switch Q4 is off, the path is: inductor L1 → controllable switch Q2 → neutral line N0 → negative DC bus BUS- → controllable switch Q3 → inductor L1. Inductor L1 can supply power to the negative DC bus BUS-. Method 2: Controllable switch Q2 is normally on, controllable switches Q1 and Q3 are normally off, and controllable switch Q4 performs modulation control. When controllable switch Q4 is on, please refer to [link to relevant documentation]. Figure 10g The current path is: battery positive terminal DC+ → controllable switch Q4 → inductor L1 → controllable switch Q2 → battery negative terminal DC-, with the battery storing energy in inductor L1. When controllable switch Q4 is off, please refer to [link to relevant documentation]. Figure 10h Inductor L1 → Controlled switch Q2 → Neutral line N0 → Negative DC bus BUS- → Controlled switch Q3 → Inductor L1. Inductor L1 can supply power to the negative DC bus BUS- through the freewheeling diode in the controlled switch Q3.

[0071] and Figure 4 Compared to the circuit topology, Figure 9 The circuit topology with dual DC buses only involves one side of the bus, making it more suitable for single-phase AC mains input UPS applications. Furthermore, the voltage difference between the two sides is smaller, resulting in higher efficiency. Figure 5 Compared to the circuit topology, Figure 9 The circuit topology features a direct connection between the battery's negative terminal (DC-) and the neutral line (N0), resulting in good EMC characteristics and allowing it to be used in parallel systems with shared batteries in single-cell UPS systems. Furthermore, the circuit uses only one inductor, saving cost and space.

[0072] According to one embodiment of the present invention, a DC-DC converter circuit is also provided, comprising: a positive DC bus, a negative DC bus, a battery, and a DC-DC converter unit. A positive DC bus capacitor C1 and a negative DC bus capacitor C2, connected in series, are electrically connected between the positive DC bus BUS+ and the negative DC bus BUS-. The node between the positive DC bus capacitor C1 and the negative DC bus capacitor C2 is connected to the neutral line N0. The positive terminal DC+ of the battery is connected to the neutral line N0. The DC-DC converter unit includes a first switch, a second switch, a third switch, a fourth switch, and a first inductor. The two ends of the first switch are respectively connected to the negative DC bus BUS- and the first end of the first inductor L1. The two ends of the fourth switch are respectively connected to the second end of the first inductor L1 and the negative terminal DC- of the battery. The two ends of the second switch are respectively connected to the first end of the first inductor L1 and the neutral line N0. The two ends of the third switch are respectively connected to the second end of the first inductor L1 and the positive DC bus BUS+. The positive DC bus BUS+ and the negative DC bus BUS- charge the battery through the DC-DC converter unit, and / or the battery supplies power to the positive DC bus BUS+ and the negative DC bus BUS- through the DC-DC converter unit.

[0073] In one embodiment, the first and third switching transistors of the DC-DC converter unit of the DC-DC converter circuit are controllable switching transistors with anti-parallel diodes (in this embodiment, the first and third switching transistors are in...). Figure 11 (shown as Q1 and Q3 respectively), the second and fourth switching transistors are diodes (in this embodiment, the second and fourth switching transistors are...) Figure 11 (These are shown as D2 and D4 respectively). Figure 11 As shown, the second terminal of controllable switch Q1 is connected to the first terminal of first inductor L1, the second terminal of first inductor L1 is connected to the cathode of diode D4, the first terminal of controllable switch Q1 is connected to the negative DC bus BUS-, and the anode of diode D4 is connected to the negative terminal DC- of the battery. The second terminal of controllable switch Q3 is connected to the positive DC bus BUS+, and the first terminal of controllable switch Q3 is connected to the second terminal of first inductor L1. The cathode of diode D2 is connected to the neutral line N0, and the anode of diode D2 is connected to the first terminal of first inductor L1. Controllable switch Q1 is configured to conduct alternately, and controllable switch Q3 is configured to be off, with the negative DC bus BUS- charging the battery. (The last sentence is a repetition of the previous one and can be omitted.) Figure 11 DC-DC converter circuit and Figure 6 The DC-DC converter circuits shown are mirror images of each other, and their operating control principle is the same as... Figure 6 The DC-DC converter circuit shown is similar and will not be described in detail here.

[0074] In some embodiments, the first and third switching transistors of the DC-DC converter are diodes (in this embodiment, the first and third switching transistors are diodes). Figure 12 (shown as D1 and D3 respectively), the second and fourth switching transistors are controllable switching transistors with anti-parallel diodes (in this embodiment, the second and fourth switching transistors are in...) Figure 12 (These are shown as Q2 and Q4 respectively). Figure 12 As shown, the cathode of diode D1 is connected to the first terminal of the first inductor L1, the second terminal of the first inductor L1 is connected to the second terminal of the controllable switch Q4, the anode of diode D1 is connected to the negative DC bus BUS-, and the first terminal of the controllable switch Q4 is connected to the negative DC terminal of the battery DC-. The cathode of diode D3 is connected to the positive DC bus BUS+, and the anode of diode D3 is connected to the second terminal of the first inductor L1. The first terminal of the controllable switch Q2 is connected to the neutral line N0, and the second terminal of the controllable switch Q2 is connected to the first terminal of the first inductor L1. Controllable switch Q2 is configured to conduct alternately, controllable switch Q4 is configured to conduct, and the battery supplies power to the negative DC bus BUS-. Controllable switch Q2 is configured to conduct, controllable switch Q4 is configured to conduct alternately, and the battery supplies power to the positive DC bus BUS+. Figure 12 The DC-DC converter circuit shown is Figure 8 The DC-DC converter circuits shown are mirror images of each other, and their operating control principle is the same as... Figure 8 The DC-DC converter circuit shown is similar and will not be described in detail here.

[0075] In some embodiments, the first, second, third, and fourth switching transistors of the DC-DC converter unit are all controllable switching transistors with anti-parallel diodes (in this embodiment, the first, second, third, and fourth switching transistors are...). Figure 13 (These are represented by Q1, Q2, Q3, and Q4 respectively). Figure 13As shown, the second terminal of controllable switch Q1 is connected to the first terminal of first inductor L1, the second terminal of first inductor L1 is connected to the second terminal of controllable switch Q4, the first terminal of controllable switch Q1 is connected to the negative DC bus BUS-, and the first terminal of controllable switch Q4 is connected to the negative terminal DC- of the battery. The second terminal of controllable switch Q3 is connected to the positive DC bus BUS+, and the first terminal of controllable switch Q3 is connected to the second terminal of first inductor L1. The second terminal of controllable switch Q2 is connected to the neutral line N0, and the first terminal of controllable switch Q2 is connected to the first terminal of first inductor L1. Controllable switch Q1 is configured to conduct alternately, while controllable switches Q2, Q3, and Q4 are configured to be off, and the negative DC bus BUS- charges the battery. Controllable switch Q3 is configured to conduct alternately, while controllable switches Q1, Q2, and Q4 are configured to be off, and the positive DC bus BUS+ charges the battery. Controllable switch Q4 is configured to conduct, controllable switch Q2 is configured to conduct alternately, and controllable switches Q1 and Q3 are configured to be off, with the battery supplying power to the negative DC bus BUS-. Controllable switch Q4 is configured to conduct alternately, controllable switch Q2 is configured to conduct, and controllable switches Q1 and Q3 are configured to be off, with the battery supplying power to the positive DC bus BUS+. Figure 13 DC-DC converter circuit and Figure 9 The DC-DC converter circuits shown are mirror images of each other, and their operating control principle is the same as... Figure 9 The DC-DC converter circuit shown is similar and will not be described in detail here.

[0076] UPS systems typically have both AC / DC and battery modes and include dual DC buses. In AC / DC mode, AC power supplies the dual DC buses, and a charging circuit is required to charge the battery. For higher-power battery chargers, the UPS's dual DC buses are generally used as the charger input. In battery mode, the battery supplies power to the dual DC buses. For small to medium-power UPS systems, the battery is typically a single cell with a rated voltage of around 200V. UPS systems generally have parallel operation capabilities, and to save costs, customers often share batteries when operating in parallel. However, for single-battery UPS systems, existing common switching circuits between AC / DC power, battery, and dual DC buses cause voltage fluctuations at the battery terminals relative to the system's neutral (N) potential during both charging and discharging, resulting in poor EMC characteristics. Furthermore, for parallel UPS systems, since the neutral lines of each UPS are short-circuited together, and existing circuits cause voltage fluctuations between the battery's positive and negative terminals relative to the neutral line, it is impossible to share batteries when multiple UPS systems are operating in parallel.

[0077] To address the aforementioned problems, an embodiment of the present invention provides a power conversion circuit, including a first switch S1, a rectifier unit, and a DC-DC conversion circuit as described in any of the preceding embodiments of the present invention. The first terminal of the first switch S1 is connected to the mains power supply, the second terminal of the first switch is connected to the input terminal of the rectifier unit, and the output terminal of the rectifier unit is connected to the positive DC bus BUS+, the negative DC bus BUS-, and the neutral line N0. The following describes... Figure 9 The power conversion circuit shown is used as an example to provide a detailed introduction to this power conversion circuit.

[0078] like Figure 14 As shown, in one embodiment, the power conversion circuit includes: a first switch S1, a rectifier unit (or PFC unit), and a DC-DC converter circuit. The components in the DC-DC converter circuit and their interconnections are as follows: Figure 9 The DC-DC converter circuit shown is the same and will not be described again here. The rectifier unit includes a second inductor L2, a third node N3, a first branch, a second branch, and a third branch. The first end of the second inductor L2 is connected to the mains power L through a first switch S1, and the second end of the second inductor L2 is connected to the third node N3. The first branch includes a diode D1 for controlling the conduction between the third node N3 and the positive DC bus BUS+. The anode of diode D1 is connected to the third node N3, and the cathode of diode D1 is connected to the positive DC bus BUS+. The second branch includes a controllable switch Q5 and a controllable switch Q6 connected in reverse series with the controllable switch Q5. In the embodiments of the present invention, as shown... Figure 14 As shown, the two controllable switches Q5 and Q6 are each equipped with a freewheeling diode. The reverse series connection refers to two controllable switches of the same type connected in reverse order; for example, the second terminal of controllable switch Q5 is connected to the second terminal of controllable switch Q6. The purpose of the reverse series connection is to prevent conduction through the two freewheeling diodes. Controllable switches Q5 and Q6 are used to control the unidirectional conduction between the third node N3 and the neutral line N0. The second terminal of controllable switch Q5 is connected to the second terminal of controllable switch Q6, the first terminal of controllable switch Q5 is connected to the third node N3, and the first terminal of controllable switch Q6 is connected to the neutral line N0. The third branch includes a diode D2 used to control the conduction between the third node N3 and the negative DC bus -BUS. The cathode of diode D2 is connected to the third node N3, and the anode of diode D2 is connected to the negative DC bus -BUS.

[0079] Figure 14 When the circuit shown is in AC power mode, the first switch S1 is turned on.

[0080] During the positive half-cycle of the mains power, in the rectifier unit: controllable switch Q5 is normally on, and controllable switch Q6 is used for modulation control. When controllable switch Q6 is on, the current flow is as follows: Figure 15a Route 1 is shown in the diagram: Mains power → Inductor L2 → Controlled switch Q5 → Controlled switch Q6 → Neutral line N0. The mains power stores energy in inductor L2. When controlled switch Q6 is turned off, the current flow is as follows: Figure 15a Route 2 is shown in the diagram: Mains power → Inductor L2 → Diode D1 → Positive DC bus BUS+ → Neutral line N0. Inductor L1 freewheels to power the positive DC bus BUS+. This achieves mains power supply to the positive DC bus BUS+. Simultaneously, in the DC-DC converter circuit: Controllable switch Q3 is normally off, controllable switch Q4 is normally on, and controllable switches Q1 and Q2 perform complementary modulation control. Please refer to... Figure 15a Route 3 and Figure 10a When the controllable switch Q1 is turned on and the controllable switch Q2 is turned off, the positive DC bus BUS+ supplies energy to inductor L1 and the battery. Please refer to... Figure 15a Route 4 and Figure 10b When the controllable switch Q1 is off and the controllable switch Q2 is on, the inductor L1 charges the battery through the freewheeling diodes in the controllable switches Q2 and Q4. This enables the positive DC bus BUS+ to charge the battery.

[0081] During the negative half-cycle of the mains power, in the rectifier unit: controllable switch Q6 is normally on, and controllable switch Q5 is used for modulation control. When controllable switch Q5 is on, the current flow is as follows: Figure 15b Route 5 is shown in the diagram: Neutral line N0 → Controlled switch Q6 → Controlled switch Q5 → Inductor L2 → Mains power, where the mains power stores energy in inductor L2. When controlled switch Q5 is turned off, the current flow is as follows: Figure 15b Route 6 is shown in the diagram: Neutral line N0 → Negative DC bus BUS- → Diode D4 → Inductor L2 → AC mains power. Inductor L2 freewheels to power the negative DC bus BUS-. Thus, AC mains power is supplied to the negative bus BUS-. Simultaneously, in the DC-DC converter circuit: Controllable switch Q1 is normally off, controllable switch Q2 is normally on, and controllable switches Q3 and Q4 perform complementary modulation control. Please refer to... Figure 15b Route 7 and Figure 10c When the controllable switch Q3 is turned on and the controllable switch Q4 is turned off, the negative DC bus BUS- stores energy in inductor L1. Please refer to... Figure 15b Route 8 and Figure 10d When the controllable switch Q3 is off and the controllable switch Q4 is on, the inductor L1 charges the battery through the freewheeling diodes in the controllable switches Q2 and Q4. This enables the negative DC bus BUS- to charge the battery.

[0082] Figure 14 When the circuit shown is in battery mode, the first switch S1 is turned off.

[0083] When the UPS operates in the positive half-cycle of the power frequency, controllable switch Q3 is normally off, and controllable switch Q4 is normally on. Controllable switches Q1 and Q2 perform complementary modulation control. Please refer to... Figure 16a Route 11 and Figure 10e When the controllable switch Q1 is off and the controllable switch Q2 is on, the battery stores energy in the inductor L1. Please refer to... Figure 16a Route 12 and Figure 10f When the controllable switch Q1 is turned on and the controllable switch Q2 is turned off, the inductor L1 and the battery supply power to the positive DC bus BUS+. This enables the battery to power the positive DC bus BUS+.

[0084] When the UPS operates in the negative half-cycle of the power frequency, controllable switch Q1 is normally off, controllable switch Q2 is normally on, and controllable switches Q3 and Q4 perform complementary modulation control. Please refer to... Figure 16b Route 15 and Figure 10g When the controllable switch Q3 is off and the controllable switch Q4 is on, the battery stores energy in the inductor L1. Please refer to... Figure 16b Route 16 and Figure 10h When the controllable switch Q3 is turned on and the controllable switch Q4 is turned off, the inductor L1 supplies power to the negative DC bus BUS-. This enables the battery to power the negative DC bus BUS-.

[0085] Figure 14 The power conversion circuit uses only one inductor in AC mode, improving inductor utilization and saving space. In battery mode, the charging circuit (i.e., DC-DC converter circuit) can be reused, improving component utilization and supporting higher battery discharge power. The direct connection between the battery negative terminal and the neutral line N0 ensures no voltage fluctuation in the battery line relative to system N, resulting in good EMC characteristics. Furthermore, it can be used in parallel systems with shared batteries in single-cell UPS systems.

[0086] like Figure 17a In one embodiment, the power conversion circuit further includes a second switch S2. The first terminal of the second switch S2 is connected to the second terminal of the first switch S1, and the second terminal of the second switch S2 is connected to the second terminal of the first inductor L1.

[0087] Figure 17a When the power conversion circuit shown is in AC power mode, the first switch S1 is turned on and the second switch S2 is turned off. The control process of this power conversion circuit at this time is the same as... Figure 14 The control process of the circuit shown is the same in AC power mode, and will not be described in detail here.

[0088] Figure 17a When the power conversion circuit shown is in battery mode, the first switch S1 is turned off and the second switch S2 is turned on.

[0089] When the UPS operates in the positive half-cycle of the power frequency, controllable switches Q4 and Q5 are normally on, controllable switch Q3 is normally off, and controllable switch Q6 performs modulation control. When controllable switch Q6 is on, the current flow is as follows: Figure 18a Route 9 is shown in the diagram: Battery positive terminal DC+ → Controllable switch Q4 → Inductor L2 → Controllable switch Q5 → Controllable switch Q6 → Neutral line N0 → Battery negative terminal DC-, the battery stores energy through inductor L2. When controllable switch Q6 is turned off, the current flow is as follows... Figure 18a As shown in route 10: Battery positive terminal DC+ → Controllable switch Q4 → Inductor L2 → Diode D1 → Positive DC bus BUS+, with inductor L2 providing freewheeling current to power the positive DC bus BUS+. Thus, the battery powers the positive DC bus BUS+.

[0090] In one embodiment, while controllable switches Q4 and Q5 are normally on, controllable switch Q3 is normally off, and controllable switch Q6 is subjected to modulation control, complementary modulation control can also be performed on controllable switches Q1 and Q2. When controllable switch Q1 is off and controllable switch Q2 is on, please refer to... Figure 16a Route 11 (or Figure 18a Route 11) and Figure 10e The battery stores energy in the first inductor L1. When the controllable switch Q1 is on and the controllable switch Q2 is off, please refer to... Figure 16a Route 12 (or Figure 18a Route 12) and Figure 10f The inductor L1 provides freewheeling current, and the battery supplies power to the positive DC bus BUS+. The battery supplies power to the positive DC bus via a DC-DC converter unit, and also via a second switch and rectifier unit, thereby improving the power supply efficiency to the positive DC bus. This embodiment of the invention can be compared with... Figure 18a Route 9 or Route 10 can be carried out simultaneously, as an auxiliary method. Figure 18a Route 9 or Route 10 in the diagram improves the efficiency of battery power supply to the positive DC bus BUS+.

[0091] When the UPS operates in the negative half-cycle of the power frequency, controllable switches Q5 and Q6 are normally turned on, and controllable switches Q3 and Q4 perform complementary modulation control. When controllable switch Q4 is turned on and controllable switch Q3 is turned off, the current flow is as follows: Figure 18b Route 13 is shown in the diagram: Battery positive terminal DC+ → Controllable switch Q4 → Inductor L2 → Controllable switch Q5 → Controllable switch Q6 → Neutral line N0 → Battery negative terminal DC-, the battery stores energy through inductor L2. When controllable switch Q4 is off and controllable switch Q3 is on, the current flow is as follows: Figure 18bRoute 14 is shown in the diagram: Negative DC bus BUS- → Controllable switch Q3 → Inductor L2 → Controllable switch Q5 → Controllable switch Q6 → Neutral line N0. Inductor L2 provides freewheeling power to the negative DC bus BUS-. Thus, the battery powers the negative DC bus BUS-.

[0092] In one embodiment, while controllable switches Q5 and Q6 are normally on, and controllable switches Q3 and Q4 are subjected to complementary modulation control, controllable switches Q1 and Q2 can also be subjected to complementary modulation control. Controllable switch Q1 is normally off, controllable switch Q2 is normally on, and controllable switches Q3 and Q4 are subjected to complementary modulation control. When controllable switch Q3 is off and controllable switch Q4 is on, please refer to... Figure 16b Route 15 (or Figure 18b Route 15) and Figure 10g The battery stores energy in the first inductor L1. When the controllable switch Q3 is on and the controllable switch Q4 is off, please refer to... Figure 16b Route 16 ( Figure 18b Route 15) and Figure 10h The first inductor L1 supplies power to the negative DC bus BUS-. Thus, the battery powers the negative DC bus BUS-. The battery supplies power to the negative DC bus via a DC-DC converter unit, and also via a second switch and rectifier unit, thereby improving the power supply efficiency to the negative DC bus. This embodiment of the invention can be compared with... Figure 18b Route 13 or Route 14 can be carried out simultaneously, as an auxiliary method. Figure 18b Route 13 or Route 14 in the diagram improves the efficiency of battery power supply to the negative DC bus BUS-.

[0093] The power conversion circuit of this invention uses only one inductor in AC power mode, improving inductor utilization and saving space costs. In battery mode, the charging circuit and the rectifier circuit from AC power mode can be reused, improving component utilization and supporting higher battery discharge power. The direct connection between the battery negative terminal and the neutral line N0 ensures no voltage fluctuation in the battery line relative to system N, resulting in good EMC characteristics and allowing it to be used in parallel systems with shared batteries in single-cell UPS systems.

[0094] like Figure 17b In one embodiment, the power conversion circuit further includes a third switch S3. The first terminal of the third switch S3 is connected to the second terminal of the first inductor L1, and the second terminal of the third switch S3 is connected to the common connection point of the third and fourth switching transistors. Alternatively, the first terminal of the third switch S3 is connected to the first terminal of the first inductor L1, and the second terminal of the third switch S3 is connected to the common connection point of the first and second switching transistors (this connection method is not specified in the original text). Figure 17b(As shown in the diagram). When the power conversion circuit is in mains power mode, the first switch S1 and the third switch S3 are turned on, and the second switch S2 is turned off. The control process of the power conversion circuit at this time is the same as... Figure 14 The control process of the circuit shown is the same in mains power mode, and will not be described in detail here. When the power conversion circuit is in battery mode, the first switch S1 and the third switch S3 are turned off, and the second switch S2 is turned on. When the UPS is operating in the positive half-cycle of the mains frequency, controllable switches Q4 and Q5 are normally turned on, controllable switch Q3 is normally turned off, and controllable switch Q6 performs modulation control. When controllable switch Q6 is turned on, the current flow is as follows: Figure 18a Route 9 is shown in the diagram: Battery positive terminal DC+ → Controllable switch Q4 → Inductor L2 → Controllable switch Q5 → Controllable switch Q6 → Neutral line N0 → Battery negative terminal DC-, the battery stores energy through inductor L2. When controllable switch Q6 is turned off, the current flow is as follows... Figure 18a Route 10 is shown in the diagram: Battery positive terminal DC+ → Controllable switch Q4 → Inductor L2 → Diode D1 → Positive DC bus BUS+, with inductor L2 providing freewheeling power to the positive DC bus BUS+. This achieves battery power to the positive DC bus BUS+. When the UPS operates in the negative half-cycle of the power frequency, controllable switches Q5 and Q6 are normally on, Q3 is normally off, and Q4 performs modulation control. When controllable switch Q4 is on, the current flow is as follows... Figure 18b Route 13 is shown in the diagram: Battery positive terminal DC+ → Controllable switch Q4 → Inductor L2 → Controllable switch Q5 → Controllable switch Q6 → Neutral line N0 → Battery negative terminal DC-, the battery stores energy through inductor L2. When controllable switch Q4 is turned off, the current flow is as follows: Figure 18b Route 14 is shown in the diagram: Negative DC bus BUS- → Controllable switch Q3 → Inductor L2 → Controllable switch Q5 → Controllable switch Q6 → Neutral line N0. Inductor L2 provides freewheeling power to the negative DC bus BUS-. Thus, the battery powers the negative DC bus BUS-. When the third switch is open, the battery supplies power to both the positive and negative DC buses through the second switch and the rectifier unit. The rectifier unit circuit has fewer components than the DC-DC converter unit, reducing the number of components in the power supply circuit and lowering energy consumption. This embodiment of the invention uses fewer components in the power supply line while meeting the DC bus requirements, reducing line energy consumption and saving battery power.

[0095] Figure 14 , Figure 17a as well as Figure 17b The rectifier unit in the power conversion circuit shown can be replaced with other circuit topologies.

[0096] like Figure 19As shown, in one embodiment, the rectifier unit of the power conversion circuit may include a second inductor L2, a third node N3, a first branch, a second branch, and a third branch. The first end of the second inductor L2 is connected to the mains power L via a first switch S1, and the second end of the second inductor L2 is connected to the third node N3. The first branch includes diodes D1 and D5 for controlling the conduction between the third node N3 and the positive DC bus BUS+. The anode of diode D1 is connected to the third node N3, the cathode of diode D1 is connected to the anode of diode D5, and the cathode of diode D5 is connected to the positive DC bus BUS+. The second branch includes diodes D2 and D6 for controlling the conduction between the third node N3 and the negative DC bus -BUS. The cathode of diode D2 is connected to the third node N3, the anode of diode D2 is connected to the cathode of diode D6, and the anode of diode D6 is connected to the negative DC bus -BUS. The third branch includes controllable switches Q5 and Q6 for controlling the conduction between the fifth node N5 and the sixth node N6. The fifth node N5 is located between diodes D1 and D5, and the sixth node N6 is located between diodes D2 and D6. The first terminal of the controllable switch Q5 and the second terminal of the controllable switch Q6 are respectively connected to the neutral line N0. The second terminal of the controllable switch Q5 is connected to the fifth node N5, and the first terminal of the controllable switch Q6 is connected to the sixth node N6.

[0097] like Figure 20As shown, in one embodiment, the rectifier unit of the power conversion circuit may include a second inductor L2, a third node N3, a first branch, a second branch, a third branch, and a fourth branch. The first terminal of the second inductor L2 is connected to the mains power L via a first switch S1, and the second terminal of the second inductor L2 is connected to the third node N3. The first branch includes diodes D1 and D5 for controlling the conduction between the third node N3 and the positive DC bus BUS+. The anode of diode D1 is connected to the third node N3, the cathode of diode D1 is connected to the anode of diode D5, and the cathode of diode D5 is connected to the positive DC bus BUS+. The second branch includes diodes D2 and D6 for controlling the conduction between the third node N3 and the negative DC bus -BUS. The cathode of diode D2 is connected to the third node N3, the anode of diode D2 is connected to the cathode of diode D6, and the anode of diode D6 is connected to the negative DC bus -BUS. The third branch includes diodes D7 and D8 for controlling the conduction between the fifth node N5 and the sixth node N6. The fifth node N5 is located between diodes D1 and D5, and the sixth node N6 is located between diodes D2 and D6. The anode of diode D7 and the cathode of diode D8 are connected to the neutral line N0, respectively. The cathode of diode D7 is connected to the fifth node N5, and the anode of diode D8 is connected to the sixth node N6. The fourth branch includes a controllable switch Q5 for controlling the conduction between the fifth node N5 and the sixth node N6. The second terminal of the controllable switch Q5 is connected to the fifth node N5, and the first terminal of the controllable switch Q5 is connected to the sixth node N6.

[0098] like Figure 21As shown, in one embodiment, the rectifier unit of the power conversion circuit may include a second inductor L2, a third node N3, a first branch, a second branch, a third branch, and diodes D2 and D7. The first terminal of the second inductor L2 is connected to the mains power L via a first switch S1, and the second terminal of the second inductor L2 is connected to the third node N3. The first branch includes a diode D5 for controlling the conduction between the third node N3 and the positive DC bus BUS+. The anode of diode D5 is connected to the third node N3, and the cathode of diode D5 is connected to the positive DC bus BUS+. The second branch includes a diode D6 for controlling the conduction between the third node N3 and the negative DC bus -BUS. The cathode of diode D6 is connected to the third node N3, and the anode of diode D6 is connected to the negative DC bus -BUS. The third branch includes a diode D1, a controllable switch Q5, and a diode D8 connected in sequence for controlling the conduction between the third node N3 and the neutral line N0. The anode of diode D1 is connected to the third node N3, and the cathode of diode D1 is connected to the second terminal of the controllable switch Q5. The first terminal of the controllable switch Q5 is connected to the anode of diode D8, and diode D8 is connected to the neutral line N0. The anode of diode D2 is connected to the first terminal of the controllable switch Q5, and the cathode of diode D7 is connected to the third node N3. The cathode of diode D7 is connected to the second terminal of the controllable switch Q5, and the anode of diode D7 is connected to the neutral line N0.

[0099] Embodiments of the present invention also provide a UPS, which includes the aforementioned DC-DC conversion circuit or power conversion circuit. Compared with conventional UPS, the UPS of the present invention has higher operational reliability.

[0100] Although the controllable switch is shown as an insulated-gate bipolar transistor (IGBT) with a diode connected in antiparallel between the second and first terminals in various embodiments of the invention, it can be replaced as needed with a metal-oxide-semiconductor field-effect transistor (MOSFET), a silicon controlled rectifier (SCR), or other suitable transistors or other controllable electronic switches with diodes connected in antiparallel. If the controllable switch is an IGBT, its first terminal is the emitter and its second terminal is the collector. If the controllable switch is a MOSFET, its first terminal is the source and its second terminal is the drain.

[0101] The control unit in this embodiment of the invention is used to control the on and off states of a controllable switching transistor (e.g., a control tube). For example, the control unit is configured to include a processing circuit that performs on / off drive control on each transistor. This processing circuit can be composed of digital electronic circuits such as arithmetic processing devices and storage devices, analog electronic circuits such as comparators, operational amplifiers, and differential amplifiers, or a combination of digital and analog electronic circuits.

[0102] According to other embodiments of the present invention, AC switches and DC switches can be replaced by switching elements known in the art.

[0103] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A DC-DC converter circuit, comprising: A positive DC bus and a negative DC bus are provided, and a positive DC bus capacitor and a negative DC bus capacitor are electrically connected in series between the positive DC bus and the negative DC bus. The node between the positive DC bus capacitor and the negative DC bus capacitor is connected to the neutral line. A rechargeable DC power supply, wherein the negative terminal of the DC power supply is connected to the neutral line; and A DC-DC converter unit includes a first switch, a second switch, a third switch, a fourth switch, and a first inductor. The two ends of the first switch are connected to the positive DC bus and the first end of the first inductor, respectively. The two ends of the fourth switch are connected to the second end of the first inductor and the positive terminal of the DC power supply, respectively. The two ends of the second switch are connected to the first end of the first inductor and the neutral line, respectively. The two ends of the third switch are connected to the second end of the first inductor and the negative DC bus, respectively. The positive DC bus and the negative DC bus charge the DC power supply through the DC conversion unit, and / or the DC power supply supplies power to the positive DC bus and the negative DC bus through the DC conversion unit.

2. The DC-DC converter circuit according to claim 1, wherein, The first and third switching transistors are controllable switching transistors with anti-parallel diodes, and the second and fourth switching transistors are diodes; The first switch is configured to be alternately turned on, the third switch is configured to be turned off, and the positive DC bus charges the DC power supply; or, the first switch is configured to be turned off, the third switch is configured to be alternately turned on, and the negative DC bus charges the DC power supply.

3. The DC-DC converter circuit according to claim 1, wherein, The first and third switching transistors are diodes, and the second and fourth switching transistors are controllable switching transistors with anti-parallel diodes. The second switch is configured to conduct alternately, the fourth switch is configured to conduct, and the DC power supply supplies power to the positive DC bus; or, the second switch is configured to conduct, the fourth switch is configured to conduct alternately, and the DC power supply supplies power to the negative DC bus.

4. The DC-DC converter circuit according to claim 1, wherein, The first switch, the second switch, the third switch, and the fourth switch are all controllable switches with anti-parallel diodes; The first switch is configured to be alternately turned on, and the second, third, and fourth switches are configured to be turned off, with the positive DC bus charging the DC power supply; or, the third switch is configured to be alternately turned on, and the first, second, and fourth switches are configured to be turned off, with the negative DC bus charging the DC power supply; or, the fourth switch is configured to be turned on, the second switch is configured to be alternately turned on, and the first and third switches are configured to be turned off, with the DC power supply supplying power to the positive DC bus; or, the fourth switch is configured to be alternately turned on, the second switch is configured to be turned on, and the first and third switches are configured to be turned off, with the DC power supply supplying power to the negative DC bus.

5. A DC-DC converter circuit, comprising: A positive DC bus and a negative DC bus are provided, and a positive DC bus capacitor and a negative DC bus capacitor are electrically connected in series between the positive DC bus and the negative DC bus. The node between the positive DC bus capacitor and the negative DC bus capacitor is connected to the neutral line. A rechargeable DC power supply, wherein the positive terminal of the DC power supply is connected to the neutral line; and A DC-DC converter unit includes a first switch, a second switch, a third switch, a fourth switch, and a first inductor. The two ends of the first switch are connected to the negative DC bus and the first end of the first inductor, respectively. The two ends of the fourth switch are connected to the second end of the first inductor and the negative terminal of the DC power supply, respectively. The two ends of the second switch are connected to the first end of the first inductor and the neutral line, respectively. The two ends of the third switch are connected to the second end of the first inductor and the positive DC bus, respectively. The positive DC bus and the negative DC bus charge the DC power supply through the DC conversion unit, and / or the DC power supply supplies power to the positive DC bus and the negative DC bus through the DC conversion unit.

6. The DC-DC converter circuit according to claim 5, wherein, The first and third switching transistors are controllable switching transistors with anti-parallel diodes, and the second and fourth switching transistors are diodes; The first switch is configured to be alternately turned on, the third switch is configured to be turned off, and the negative DC bus charges the DC power supply; or, the first switch is configured to be turned off, the third switch is configured to be alternately turned on, and the positive DC bus charges the DC power supply.

7. The DC-DC converter circuit according to claim 5, wherein, The first and third switching transistors are diodes, and the second and fourth switching transistors are controllable switching transistors with anti-parallel diodes. The second switch is configured to conduct alternately, the fourth switch is configured to conduct, and the DC power supply supplies power to the negative DC bus; or, the second switch is configured to conduct, the fourth switch is configured to conduct alternately, and the DC power supply supplies power to the positive DC bus.

8. The DC-DC converter circuit according to claim 5, wherein, The first switch, the second switch, the third switch, and the fourth switch are all controllable switches with anti-parallel diodes; The first switch is configured to be alternately turned on, and the second, third, and fourth switches are configured to be turned off, with the negative DC bus charging the DC power supply; or, the third switch is configured to be alternately turned on, and the first, second, and fourth switches are configured to be turned off, with the positive DC bus charging the DC power supply; or, the fourth switch is configured to be turned on, the second switch is configured to be alternately turned on, and the first and third switches are configured to be turned off, with the DC power supply supplying power to the negative DC bus; or, the fourth switch is configured to be alternately turned on, the second switch is configured to be turned on, and the first and third switches are configured to be turned off, with the DC power supply supplying power to the positive DC bus.

9. A power conversion circuit, comprising a first switch, a rectifier unit, and a DC-DC conversion circuit according to any one of claims 1-4 or any one of claims 5-8; The first terminal of the first switch is connected to the mains power, the second terminal of the first switch is connected to the input terminal of the rectifier unit, and the output terminal of the rectifier unit is connected to the positive DC bus, the negative DC bus, and the neutral line.

10. The power conversion circuit according to claim 9, wherein, The power conversion circuit further includes a second switch, the first end of which is connected to the second end of the first switch, and the second end of which is connected to the second end of the first inductor.

11. The power conversion circuit according to claim 9 or 10, wherein the power conversion circuit further comprises a third switch, a first end of the third switch being connected to a second end of the first inductor, and the second end of the third switch being connected to a common connection point of the third switch transistor and the fourth switch transistor; or, the first end of the third switch being connected to a first end of the first inductor, and the second end of the third switch being connected to a common connection point of the first switch transistor and the second switch transistor.

12. An uninterruptible power supply, the uninterruptible power supply comprising the DC-DC conversion circuit according to any one of claims 1-4, or the DC-DC conversion circuit according to any one of claims 5-8, or the power conversion circuit according to any one of claims 9-11.

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