Power conversion system and power system

Abstract

The embodiment of the invention provides a power conversion system and a power system. The power conversion system comprises a power switch circuit and a topology switching unit. The topology switching unit is used for controlling the power switch circuit to be in a first topology form or a second topology form; in the first topological form, the power switch circuit is divided into a first power switch circuit and a second power switch circuit, and a first power conversion path for converting the voltage of the first direct current bus to the alternating current phase line and a second power conversion path for converting the voltage of the second direct current bus to the alternating current phase line are formed respectively; in the second topological form, the first power switch circuit and the second power switch circuit are integrated into a third power switch circuit, and the negative electrode of the first direct current bus is communicated with the positive electrode of the second direct current bus; the third power switch circuit forms a third power conversion path which superposes the voltage of the first direct current bus and the voltage of the second direct current bus and then converts the superposed voltage to the alternating current phase line. Therefore, the cost of the power conversion system can be reduced.

Description

Power conversion systems and power systems Technical Field

[0001] The embodiments in this application relate to the field of circuit technology, specifically to a power conversion system and a power system. Background Technology

[0002] With the continuous development of new energy technologies, power conversion systems are widely used in photovoltaic power generation, grid-connected energy storage, and new energy vehicles. Power conversion systems are typically connected between a DC bus and an AC phase line. The DC bus is used to connect DC sources such as energy storage batteries, while the AC phase line is used to connect AC loads. The power conversion system is used to convert electrical energy between the DC bus and the AC phase line.

[0003] However, different types of AC loads operate at different voltages. For example, some AC loads require an AC voltage of around 800Vac, while others require around 400Vac. Due to the modulation ratio limitations of the power conversion system, a single power conversion system can hardly meet the output requirements of multiple AC voltage levels.

[0004] Currently, to adapt to the operating voltage requirements of different types of AC loads, it is usually necessary to configure multiple DC sources with different DC voltages. This increases the cost of the entire power system to some extent.

[0005] Therefore, how to provide a low-cost power conversion system that can adapt to different AC voltage levels has become an urgent technical problem to be solved. Summary of the Invention

[0006] In view of this, several embodiments of this application aim to provide a power conversion system and power system that can reduce the cost of power conversion systems that can adapt to different AC voltage levels.

[0007] This application provides a power conversion system for connecting a first DC bus, a second DC bus, and an AC phase line. The power conversion system includes: a power switching circuit; and a topology switching unit for controlling the power switching circuit to be in a first topology configuration or a second topology configuration. In the first topology configuration, the topology switching unit divides the power switching circuit into a first power switching circuit and a second power switching circuit. The first power switching circuit is connected between the first DC bus and the AC phase line to form a first power conversion path that converts the voltage of the first DC bus to the AC phase line. The second power switching circuit is connected between the second DC bus and the AC phase line. Between the AC phase lines, a second power conversion path is formed to transform the voltage of the second DC bus to the AC phase line; in the second topology configuration, the topology switching unit integrates the first power switching circuit and the second power switching circuit into a third power switching circuit and connects the negative terminal of the first DC bus and the positive terminal of the second DC bus; one end of the third power switching circuit is connected to the positive terminal of the first DC bus and the negative terminal of the second DC bus, and the other end of the third power conversion circuit is connected to the AC phase line, for forming a third power conversion path that transforms the voltages of the first DC bus and the second DC bus to the AC phase line after superposition.

[0008] This application provides a power system including the power conversion system described in any of the above embodiments.

[0009] In several embodiments provided in this application, a power conversion system is connected to a first DC bus, a second DC bus, and an AC phase line. The power conversion system includes a power switching circuit and a topology switching unit. The topology switching unit can control the power switching circuit to be in a first topology configuration or a second topology configuration. In the first topology configuration, the topology switching unit can divide the power switching circuit into a first power switching circuit and a second power switching circuit. The first power switching circuit is connected between the first DC bus and the AC phase line, and controlled by a control unit, can form a first power conversion path that converts the voltage of the first DC bus to the AC phase line. The second power switching circuit is connected between the second DC bus and the AC phase line, and controlled by a control unit, can form a second power conversion path that converts the voltage of the second DC bus to the AC phase line. Thus, the power conversion system can convert the voltage of its respective DC bus to AC voltage through the independent first and second power conversion paths, and then supply power to the AC load in the AC phase line. In the second topology configuration, the topology switching unit can integrate the first and second power switching circuits into a third power switching circuit and connect the negative terminal of the first DC bus and the positive terminal of the second DC bus. In this system, one end of the third power switching circuit is connected to the positive terminal of the first DC bus and the negative terminal of the second DC bus, while the other end is connected to the AC phase line. Thus, the third power conversion circuit, controlled by the control unit, can form a third power conversion path that superimposes the voltages of the first and second DC buses and converts them to the AC phase line. Since the DC voltage on the DC side of the third power conversion path is the sum of the voltages of the first and second DC buses, the AC voltage output by the third power conversion path can be approximately twice that of the first and second power conversion paths. Therefore, by adjusting the topology of the power switching circuit in the power conversion system through the topology switching unit, the power switching circuit can be reused to output AC power at different AC voltage levels, thereby reducing the cost of the power conversion system. Attached Figure Description

[0010] Figure 1 is a schematic diagram of a power conversion system provided in an embodiment of this application.

[0011] Figure 2 is a schematic diagram of a power switching circuit and topology switching unit provided in an embodiment of this application.

[0012] Figure 3 is a schematic diagram of a power switching circuit and topology switching unit provided in another embodiment of this application.

[0013] Figure 4 is a schematic diagram of a conductive connection portion provided in an embodiment of this application.

[0014] Figure 5 is a schematic diagram of a power switching circuit and topology switching unit provided in another embodiment of this application.

[0015] Figure 6 is a schematic diagram of a conductive connection portion provided in another embodiment of this application.

[0016] Figure 7 is a schematic diagram of a conductive connection portion provided in another embodiment of this application.

[0017] Figure 8 is a schematic diagram of a power conversion system connecting multiple AC phase lines provided in an embodiment of this application.

[0018] Reference numerals: 100, power conversion system; 110, first DC bus; 112, first positive DC bus; 114, first negative DC bus; 120, second DC bus; 122, second positive DC bus; 124, second negative DC bus; 130, power switching circuit; 140, topology switching unit; 142, conductive connection part. Detailed Implementation

[0019] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0020] In the description of the embodiments of this application, it should be understood that 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 indicated technical features. Therefore, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0021] In related technologies, the output voltage range of a power conversion circuit is limited by the input voltage. Specifically, for a power conversion circuit that converts direct current (DC) to alternating current (AC), the output voltage range on the AC side is limited by the input voltage on the DC side. Without changing the input voltage on the DC side, it is difficult for a single power conversion circuit to achieve voltage outputs at various AC voltage levels.

[0022] In new energy application scenarios, the AC side of the power conversion circuit has various AC voltage level output requirements. For example, in some application scenarios, the AC side of the power conversion circuit has medium voltage output requirements such as 800Vac or 690Vac, as well as low voltage output requirements such as 480Vac or 400Vac.

[0023] To accommodate output requirements at different AC voltage levels, related technologies require multiple DC buses with varying DC voltage levels to supply the corresponding input voltage to the power conversion circuit. For example, to meet medium-voltage output requirements such as 800Vac or 690Vac, related technologies require a DC bus of approximately 1500V. To meet low-voltage output requirements such as 480Vac or 400Vac, related technologies require a DC bus of approximately 1000V.

[0024] In related technologies, DC buses with different DC voltage levels can be obtained by configuring energy storage batteries with different voltage levels. Alternatively, DC buses with different DC voltage levels can also be obtained by adding a DC-DC converter circuit for adjusting the DC voltage on the DC side of the power conversion circuit. However, these solutions increase the design complexity and hardware cost of the power conversion system and reduce system efficiency to some extent.

[0025] Therefore, this application provides a power conversion system and a power system. The power conversion system includes a topology switching unit connected to multiple DC buses. The topology switching unit adjusts the topology of the power switching circuit in the power conversion system, enabling the power switching circuit to form power conversion paths with different output voltage levels under different topology configurations. Thus, by reusing the structure of the power switching circuit, it can accommodate outputs of different AC voltage levels, thereby reducing the cost of the power conversion system.

[0026] Referring to Figure 1, this application embodiment provides a power conversion system 100. The power conversion system 100 is used to connect a first DC bus 110, a second DC bus 120, and an AC phase line. The power conversion system 100 includes a power switching circuit 130 and a topology switching unit 140. The topology switching unit 140 is used to control the power switching circuit 130 to be in a first topology configuration or a second topology configuration. In the first topology configuration, the topology switching unit 140 divides the power switching circuit 130 into a first power switching circuit 130 and a second power switching circuit 130; the first power switching circuit 130 is connected between the first DC bus 110 and the AC phase line, forming a first power conversion path that converts the voltage of the first DC bus 110 to the AC phase line; the second power switching circuit 130 is connected between the second DC bus 120 and the AC phase line, forming a second power conversion path that converts the voltage of the second DC bus 120 to the AC phase line; in the second topology configuration... In the pan mode, the topology switching unit 140 integrates the first power switching circuit 130 and the second power switching circuit 130 into a third power switching circuit 130 and connects the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120. One end of the third power switching circuit 130 is connected to the positive terminal of the first DC bus 110 and the negative terminal of the second DC bus 120, and the other end of the third power conversion circuit is connected to the AC phase line, which is used to form a third power conversion path that superimposes the voltages of the first DC bus 110 and the second DC bus 120 and converts them to the AC phase line.

[0027] The power conversion system 100 can refer to a device used to convert direct current (DC) to alternating current (AC) or a system composed of multiple devices. For example, the power conversion system 100 can be a centralized inverter or a distributed inverter. The embodiments in this application are not specifically limited herein.

[0028] The power conversion system 100 is connected to a first DC bus 110, a second DC bus 120, and an AC phase line.

[0029] The first DC bus 110 is a DC-side transmission line used to provide a first DC voltage. The first DC bus 110 may include a first positive DC bus 112 and a first negative DC bus 114. In some embodiments, the first DC bus 110 may be connected to a corresponding DC source to provide the DC power from the corresponding DC source to the power conversion system 100 through the first DC bus 110.

[0030] The second DC bus 120 is a DC-side transmission line used to provide a second DC voltage. The second DC bus 120 may include a second positive DC bus 122 and a second negative DC bus 124. In some embodiments, the second DC bus 120 may be connected to a corresponding DC source to provide the DC power from the corresponding DC source to the power conversion system 100 through the second DC bus 120.

[0031] In some embodiments, the DC sources connected to the first DC bus 110 and the second DC bus 120 may have the same or similar specifications. Correspondingly, the first DC voltage of the first DC bus 110 and the second DC voltage of the second DC bus 120 may be the same or similar. For example, the DC sources connected to the first DC bus 110 and the second DC bus 120 may be battery packs or supercapacitors of the same specifications. This reduces the design cost and complexity of the first DC bus 110 and the second DC bus 120.

[0032] The AC phase line is used to connect to the AC load so that the power conversion system 100 converts the AC power to supply the AC load. The AC phase line can be a phase line in a single-phase system or any phase line in a three-phase system. This application does not specifically limit the embodiments described herein.

[0033] The power switching circuit 130 is a circuit composed of one or more components such as multiple power switching elements, freewheeling diodes, capacitors, and inductors.

[0034] The topology switching unit 140 is a control component used to dynamically reconfigure the electrical connections between at least some components in the power switching circuit 130. Specifically, the topology switching unit 140 may include one or more controllable conducting components connected between different circuit nodes of the power switching circuit 130. By controlling the on / off state of the controllable conducting components, the electrical connections between corresponding circuit nodes in the power switching circuit 130 can be changed, allowing the power switching circuit 130 to be in different topologies.

[0035] When the power switching circuit 130 is in different topologies, under the control commands of the control unit, the power switching elements in the power switching circuit 130 can be combined with other components to form a power conversion path that converts DC power to AC power. Because the electrical connections of the power switching circuit 130 differ under different topologies, the power conversion paths under different topologies can output AC power at different AC voltage levels. This allows for the reuse of most of the components in the power switching circuit 130, thereby reducing the cost of the power conversion system 100.

[0036] Specifically, the topology switching unit 140 can control the power switching circuit 130 to be in the first topology configuration or in the second topology configuration.

[0037] In the first topology configuration, the topology switching unit 140 divides the power switching circuit 130 into a first power switching circuit 130 and a second power switching circuit 130. The control unit can control the power switching elements in the first power switching circuit 130 and the second power switching circuit 130 respectively, forming a first power conversion path and a second power conversion path that operate independently of each other.

[0038] The first power switching circuit 130 is connected between the first DC bus 110 and the AC phase line. Under the control command of the control unit, the power switching element in the first power switching circuit 130 can be combined with other components to form a first power conversion path. The first power conversion path is an energy transmission channel that converts the electrical energy of the first DC bus 110 to the AC phase line. Accordingly, the output voltage level of the first power conversion path is limited by the first DC voltage of the first DC bus 110.

[0039] The second power switching circuit 130 is connected between the second DC bus 120 and the AC phase line. Under the control of the control unit, the power switching elements in the second power switching circuit 130 can be combined with other components to form a second power conversion path. This second power conversion path is the energy transmission channel that converts the electrical energy of the second DC bus 120 to the AC phase line. Correspondingly, the output voltage level of the second power conversion path is limited by the second DC voltage of the second DC bus 120.

[0040] In the first topology, the control unit of the power conversion system 100 can selectively control the power switching elements in the first power switching circuit 130 to form a first power conversion path or control the power switching elements in the second power switching circuit 130 to form a second power conversion path, thereby flexibly utilizing the electrical energy provided by the first DC bus 110 or the second DC bus 120. Alternatively, the control unit of the power conversion system 100 can also selectively control the first power switching circuit 130 and the second power switching circuit 130 to form the first power conversion path and the second power conversion path respectively, and jointly output electrical energy to the AC phase line, thereby increasing the output power of the power conversion system 100.

[0041] In the first topology, the first power conversion path or the second power conversion path can operate independently. Therefore, the control unit can flexibly select the appropriate power conversion path based on the state of different DC buses. Alternatively, the first and second power conversion paths can be connected in parallel and output to the same AC phase line under the coordination of the control unit. In this case, the output currents of the first and second power conversion paths will be superimposed and output to the AC phase line, thereby increasing the output power of the power conversion system 100.

[0042] In the second topology configuration, the topology switching unit 140 integrates the first power switching circuit 130 and the second power switching circuit 130 into a third power switching circuit 130. By connecting the negative terminal of the first DC bus 110 with the positive terminal of the second DC bus 120, the first DC voltage and the second DC voltage are superimposed. Therefore, the control unit can control the power switching elements in the third power switching circuit 130 to form a third power conversion path, converting the superimposed DC voltage to the AC phase line, thereby improving the AC voltage level output by the power conversion system 100.

[0043] The positive line of the DC side of the third power switching circuit 130 is connected to the positive terminal of the first DC bus 110, and the negative line of the DC side of the third power switching circuit 130 is connected to the negative terminal of the second DC bus 120. At this time, the first DC bus 110 and the second DC bus 120 are connected in series. Under the control command of the control unit, the power switching element in the third power switching circuit 130 can be combined with other components to form a third power conversion path. The third power conversion path is an energy transmission channel that superimposes the voltages of the first DC bus 110 and the second DC bus 120 and converts them to the AC phase line. Correspondingly, the output voltage level of the third power conversion path is limited by the sum of the first DC voltage and the second DC voltage. Therefore, compared to the first and second power conversion paths, the third power conversion path can output a higher AC voltage. When the first and second DC voltages are equal, the AC voltage output by the third power conversion path can be approximately doubled compared to the first and second power conversion paths.

[0044] In summary, the power conversion system 100 can dynamically switch the topology of the power switching circuit 130 through the topology switching unit 140, and can reuse the same hardware platform to achieve AC power output of different voltage levels, thereby simplifying the circuit structure and reducing the cost of the power conversion system 100.

[0045] In some embodiments, the first power conversion path may employ a half-bridge inverter topology. Specifically, the first power switching circuit 130 includes a first capacitor bridge arm and a first switch bridge arm connected to the first DC bus 110; in the first topology configuration, the midpoint of the first switch bridge arm is connected to the AC phase line, forming a first power conversion path based on the half-bridge inverter topology.

[0046] The first capacitor bridge arm is a branch used to divide or regulate the first DC voltage of the first DC bus 110. The first capacitor bridge arm can consist of multiple capacitor elements. These multiple capacitor elements can be divided into two groups, with each group having equal or similar equivalent capacitance values. The connection point between the two groups of capacitor elements serves as the midpoint of the first capacitor bridge arm.

[0047] The first switching arm is a circuit structure used to control the current path, thereby converting direct current (DC) to alternating current (AC). The first switching arm includes a power switching element located in the upper arm and a power switching element located in the lower arm. The power switching element can be an insulated-gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET), etc. The embodiments in this application are not specifically limited herein.

[0048] In some embodiments, the power switching element of the upper arm of the first switching bridge arm can serve as the first switching element. The power switching element of the lower arm of the first switching bridge arm can serve as the second switching element.

[0049] A half-bridge inverter topology is a circuit structure that converts DC to AC using a single switching arm. Specifically, an AC load can be connected between the midpoint of the capacitor arm and the midpoint of the switching arm in the half-bridge inverter topology.

[0050] In the first topology, the first switching arm and the first capacitor arm are connected in parallel to the first DC bus 110, and the midpoint of the first switching arm is connected to the AC phase line, forming a half-bridge inverter topology. Accordingly, the control unit of the power conversion system 100 can change the current path by controlling the power switching elements in the upper and lower arms of the first switching arm to alternately conduct, thereby converting DC power into AC power.

[0051] Please refer to Figure 2. Capacitor element C dc11 and capacitor element C dc12 These can serve as two sets of equivalent capacitors in the first capacitor bridge arm. Capacitor element C dc11 and capacitor element C dc12 The connection point can be used as the midpoint of the first capacitor bridge arm.

[0052] Power switching element S1 and power switching element S2 can be used as switching elements in the upper and lower arms of the first switching bridge arm, respectively. Specifically, power switching element S1 can be used as the first switching element. Specifically, power switching element S2 can be used as the second switching element. The midpoint between power switching elements S1 and S2 can be used as the midpoint of the first switching bridge arm.

[0053] R represents the connection port of the AC phase line, which is connected to the midpoint of the first switch bridge arm through the inductor L1.

[0054] Power switching elements X, Y, M, and N can form a topology switching unit 140. When the power switching circuit 130 is in the first topology configuration, power switching elements X, Y, M, and N are all in the off state. At this time, the first capacitor bridge arm and the first switch bridge arm are connected in parallel to the first DC bus 110. Therefore, capacitor element C... dc11 Capacitor element C dc12 Power switching element S1 and power switching element S2 can together form the first power conversion path based on the half-bridge inverter topology. The first power conversion path can convert the DC current of the first DC bus 110 to the AC phase line through the first switching bridge arm.

[0055] In some embodiments, the second power conversion path can also be a half-bridge inverter topology. Specifically, the second power switching circuit 130 includes a second capacitor bridge arm and a second switch bridge arm connected to the second DC bus 120; in the first topology configuration, the midpoint of the second switch bridge arm is connected to the AC phase line, forming a second power conversion path based on the half-bridge inverter topology.

[0056] The second capacitor bridge arm is a branch used to divide or regulate the second DC voltage of the second DC bus 120. The second capacitor bridge arm can consist of multiple capacitor elements. These elements can be divided into two groups, with each group having equal or similar equivalent capacitance values. The connection point between the two groups serves as the midpoint of the second capacitor bridge arm.

[0057] The second switching arm is a circuit structure used to control the current path, realizing the conversion of direct current to alternating current. The second switching arm includes a power switching element located in the upper arm and a power switching element located in the lower arm. The power switching element can be an insulated-gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET), etc. The embodiments in this application are not specifically limited herein.

[0058] In some embodiments, the power switching element of the upper arm of the second switching bridge arm can serve as a third switching element. The power switching element of the lower arm of the second switching bridge arm can serve as a fourth switching element.

[0059] In the first topology, the second switching arm and the second capacitor arm are connected in parallel to the second DC bus 120, and the midpoint of the second switching arm is connected to the AC phase line, forming a half-bridge inverter topology. Accordingly, the control unit of the power conversion system 100 can change the current path by controlling the power switching elements in the upper and lower arms of the second switching arm to alternately conduct, thereby converting DC power into AC power.

[0060] Please refer to Figure 2. Capacitor element C dc21 and capacitor element C dc22 These can serve as two sets of equivalent capacitors in the second capacitor bridge arm. Capacitor element C dc21 and capacitor element C dc22 The connection point can be used as the midpoint of the second capacitor bridge arm.

[0061] Power switching elements S3 and S4 can be used as switching elements in the upper and lower arms of the second switching bridge arm, respectively. Specifically, power switching element S3 can be used as the third switching element. Specifically, power switching element S4 can be used as the fourth switching element. The midpoint between power switching elements S3 and S4 can be used as the midpoint of the second switching bridge arm.

[0062] R represents the connection port of the AC phase line, which is connected to the midpoint of the second switch bridge arm through the inductor L2.

[0063] When the power switching circuit 130 is in the first topology configuration, power switching elements X, Y, M, and N are all in the off state. At this time, the second capacitor bridge arm and the second switch bridge arm are connected in parallel to the second DC bus 120. Therefore, capacitor element C... dc21 Capacitor element C dc22 Power switching element S3 and power switching element S4 can together form a second power conversion path based on a half-bridge inverter topology. The second power conversion path can convert the DC current of the second DC bus 120 to the AC phase line via the second switching bridge arm.

[0064] A half-bridge inverter topology can achieve efficient DC-to-AC conversion with a smaller number of components. In this embodiment, the first and second power conversion paths adopt a half-bridge inverter topology, which simplifies the power switching circuit 130 and reduces costs, while also reducing the difficulty of integrating the first and second power switching circuits 130 into a third power switching circuit 130.

[0065] In some embodiments, the midpoints of the first and second switching bridge arms can be connected to the AC phase lines via their respective inductor elements. Correspondingly, the AC power converted by the first and second power conversion paths can be transmitted to the AC phase lines via their respective inductor elements, thereby allowing for flexible adjustment of the inductor parameters according to application requirements. For example, referring to Figure 2, the midpoint of the first switching bridge is connected to the AC phase line via inductor element L1. The midpoint of the second switching bridge is connected to the AC phase line via inductor element L2.

[0066] In some embodiments, the midpoints of the first and second switch bridge arms are connected to the AC phase line through the same inductor. For example, referring to Figure 3, the midpoints of the first and second switch bridges can be connected through the same inductor L. share Connect the AC phase line. Accordingly, the first power conversion path and the second power conversion path can reuse the same inductor element, thereby further reducing the cost of the power conversion system 100 and simplifying the circuit structure.

[0067] In some embodiments, the topology switching unit 140 can control the topology of the power switching circuit 130 by adjusting the connection state between the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120, as well as the connection state between the midpoint of the first switch bridge arm and the midpoint of the second switch bridge arm.

[0068] Specifically, the topology switching unit 140 includes a first controllable conduction component disposed between the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120, and a second controllable conduction component disposed between the midpoint of the first switch bridge arm and the midpoint of the second switch bridge arm; the topology switching unit 140 configures both the first and second controllable conduction components to the off state to enable the power switching circuit 130 to be in a first topology configuration; the topology switching unit 140 configures both the first and second controllable conduction components to the on state to enable the power switching circuit 130 to be in a second topology configuration.

[0069] The first controllable conduction component can be disposed between the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120, and is used to control whether an electrical path is formed between the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120.

[0070] The second controllable conduction component can be disposed between the midpoint of the first switch bridge arm and the midpoint of the second switch bridge arm, and is used to control whether an electrical path is formed between the midpoint of the first switch bridge arm and the midpoint of the second switch bridge arm.

[0071] When both the first controllable conduction component and the second controllable conduction component are in the off state, the first DC bus 110 and the second DC bus 120 are not directly connected, and the bridge arms of the first power switch circuit 130 and the second power switch circuit 130 are not directly connected, thereby forming an independent first power conversion path and a second power conversion path.

[0072] When both the first controllable conducting component and the second controllable conducting component are in the conducting state, the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120 are electrically connected, and the midpoint of the first switch bridge arm and the midpoint of the second switch bridge arm are electrically connected. Therefore, the first power switch circuit 130 and the second power switch circuit 130 can be integrated into a third power switch circuit 130, forming a third power conversion path that superimposes the voltages of the first DC bus 110 and the second DC bus 120 and converts them to the AC phase line.

[0073] In this embodiment, the topology switching unit 140 can flexibly switch the topology of the power switching circuit 130 by controlling the connection state of the first controllable conduction component and the second controllable conduction component, thereby providing different levels of output voltage according to the needs of different AC loads.

[0074] In some embodiments, the first controllable conduction component includes a controllable switching unit or a detachable conductive connection portion 142. The second controllable conduction component includes a controllable switching unit or a detachable conductive connection portion 142.

[0075] A controllable switching unit is a switching element that changes the electrical connection state based on a control signal. For example, a controllable switching unit can be a relay, an IGBT, or a MOSFET, etc., which are semiconductor switches. The embodiments in this application are not specifically limited herein.

[0076] In some embodiments, the controllable switching unit includes a seventh switching element and an eighth switching element connected in series, wherein the body diodes of the first switching element and the eighth switching element have opposite conduction directions.

[0077] The seventh and eighth switching elements are semiconductor switches that switch between on and off states based on control commands from the control unit. Specifically, the seventh and eighth switching elements can be power switching elements such as IGBTs or MOSFETs. This application does not impose specific limitations on the embodiments described herein.

[0078] The body diode is a parasitic diode in a semiconductor switch. To reduce the risk of abnormal circuit paths forming between the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120, or between the midpoints of the first and second switch arms, due to the presence of the body diode, the body diodes of the seventh and eighth switching elements in the controllable switching unit have opposite conduction directions. This ensures that when both the seventh and eighth switching elements are in the off state, there are no abnormal current paths between the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120, or between the midpoints of the first and second switch arms.

[0079] Referring to Figures 2 and 3, power switch elements X and Y can serve as the seventh and eighth switch elements, respectively, forming a controllable switching unit. The body diodes of power switch elements X and Y have opposite conduction directions. Similarly, power switch elements M and N can also serve as the seventh and eighth switch elements, respectively, forming a controllable switching unit. The body diodes of power switch elements M and N have opposite conduction directions. When all power switch elements X, Y, M, and N are in the off state, the power switch circuit 130 is in the first topology. When all power switch elements X, Y, M, and N are in the on state, the power switch circuit 130 is in the second topology.

[0080] The detachable conductive connection 142 can represent an electrical connection structure that can be physically installed or removed. For example, the detachable conductive connection 142 can be a detachable copper busbar or a pluggable connector. The embodiments in this application are not specifically limited herein.

[0081] Referring to Figure 4, a conductive connection 142 is provided between the midpoint of the first switch arm and the midpoint of the second switch arm, and a conductive connection 142 is also provided between the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120. The conductive connection 142 connecting the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120 can be provided between the drain of the power switching element S2 and the source of the power switching element S3. In this case, the power switching circuit 130 is in a second topology. When the conductive connection 142 between the midpoints of the first and second switch arms and the conductive connection 142 between the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120 are removed, the power switching circuit 130 is in a first topology.

[0082] Depending on the requirements of different application scenarios, the power conversion system 100 can employ different types of first and second controllable conduction components. For example, for applications requiring multiple AC voltage levels, the power conversion system 100 can use a controllable switching unit as both the first and second controllable conduction components, thereby flexibly switching the topology of the power switching circuit 130 to meet the output requirements of various AC voltage levels. Alternatively, for applications with relatively fixed AC voltage requirements, the power conversion system 100 can use a detachable conductive connection 142 as both the first and second controllable conduction components, thereby reducing the cost and improving the reliability of the power conversion system 100. Furthermore, by simply adjusting the types of the first and second controllable conduction components, power conversion systems 100 with different AC output voltage levels can be constructed, which also facilitates the modular production of the power conversion system 100.

[0083] When the topology switching unit 140 controls the power switching circuit 130 to be in the second topology configuration, the first power switching circuit 130 and the second power switching circuit 130 can be integrated into the third power switching circuit 130.

[0084] In some embodiments, the third power switching circuit 130 can form a third power conversion path based on a half-bridge inverter topology. Specifically, the first switching arm includes a first switching element located in the upper arm and a second switching element located in the lower arm; the second switching arm includes a third switching element located in the upper arm and a fourth switching element located in the lower arm; in the second topology configuration, both the second and third switching elements are configured to be in an off state, and the topology switching unit 140 connects the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120, and connects the midpoint of the first switching arm and the midpoint of the second switching arm; correspondingly, the first capacitor arm, the second capacitor arm, the first switching element, and the fourth switching element form a third power conversion path based on a half-bridge inverter topology.

[0085] The first switching element is a power switching element located on the upper arm of the first switching bridge arm. The second switching element is a power switching element located on the lower arm of the first switching bridge arm. The third switching element is a power switching element located on the upper arm of the second switching bridge arm. The fourth switching element is a power switching element located on the lower arm of the second switching bridge arm. The first, second, third, and fourth switching elements can be controlled by control commands from a control unit. The first, second, third, and fourth switching elements can be power switching elements such as IGBTs or MOSFETs. The embodiments in this application are not specifically limited herein.

[0086] Please refer to Figures 2 and 3. Power switching elements S1, S2, S3, and S4 serve as the first, second, third, and fourth switching elements, respectively. Capacitor element C... dc11 and capacitor element C dc12 This forms the first capacitor bridge arm. Capacitor element C dc21 and capacitor element C dc22 This forms the second capacitor bridge arm.

[0087] In the second topology, power switching circuit 130 has power switching elements S1 and S4 directly connected, forming a switching arm of the third power conversion path. For ease of explanation, this switching arm of the third power conversion path is referred to as the third switching arm. Furthermore, capacitor element C... dc12 and capacitor element C dc21 Directly connected, the corresponding first and second capacitor bridge arms can form the capacitor bridge arm of the third power conversion path. For ease of explanation, the capacitor bridge arm of the third power conversion path is referred to as the third capacitor bridge arm. Capacitor element C dc12 and capacitor element C dc21 The connection point is taken as the midpoint of the third capacitor bridge arm.

[0088] Capacitor element C dc12 and capacitor element C dc21 The direct connection connects the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120, and the voltage across the third capacitor bridge arm is the sum of the voltages of the first DC bus 110 and the second DC bus 120.

[0089] Meanwhile, to ensure that the midpoint of the switching arm of the third power conversion path and the midpoint of the capacitor arm of the third power conversion path are not directly connected, power switching elements S2 and S3 need to be kept in the off state. That is, both the second and third switching elements are configured to be in the off state.

[0090] Therefore, the third capacitor bridge arm and the third switch bridge arm are connected in parallel between the positive terminal of the first DC bus 110 and the negative terminal of the second DC bus 120. Thus, the capacitor element C... dc11 Capacitor element C dc12 Capacitor element C dc21 Capacitor element C dc22 Power switching element S1 and power switching element S4 can together form a third power conversion path based on a half-bridge inverter topology. The third power conversion path can convert the voltage superimposed by the first DC bus 110 and the second DC bus 120 to the AC phase line through the third switching bridge arm.

[0091] By integrating the first power switch circuit 130 and the second power switch circuit 130 into a third power switch circuit 130 and forming a third power conversion path based on a half-bridge inverter topology, the cost of the power conversion system 100 can be reduced and the structure of the power conversion system 100 can be simplified without adding too many power switch components.

[0092] In some embodiments, when the first power switch circuit 130 and the second power switch circuit 130 are integrated into the third power switch circuit 130, in order to make more comprehensive use of the power switching elements in the first power switch circuit 130 and the second power switch circuit 130 and improve the performance of the third power conversion path, power switching elements can be added to the power switch circuit 130 to form a third power conversion path based on a three-level inverter topology.

[0093] Specifically, the first switching bridge arm includes a first switching element located on the upper bridge arm and a second switching element located on the lower bridge arm. The midpoint of the first switching bridge arm is connected to the AC phase line through a fifth switching element and a first inductor element, and the connection point between the fifth switching element and the first inductor element serves as the first connection point. The second switching bridge arm includes a third switching element located on the upper bridge arm and a fourth switching element located on the lower bridge arm. The midpoint of the second switching bridge arm is connected to the AC phase line through a sixth switching element and a second inductor element, and the connection point between the sixth switching element and the second inductor element serves as the second connection point. In the second topology configuration, the topology switching unit 140 connects the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120, and connects the first connection point and the second connection point. Correspondingly, the first capacitor bridge arm, the second capacitor bridge arm, the first switching element, the second switching element, the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element form a third power conversion path based on a three-level inverter topology.

[0094] The first inductor is an inductor in the first power switching circuit 130. The second inductor is an inductor in the second power switching circuit 130. In some embodiments, the first inductor and the second inductor may use the same inductor.

[0095] The fifth switching element is a power switching element disposed between the midpoint of the first switching bridge arm and the first inductor element. The sixth switching element is a power switching element disposed between the midpoint of the second switching bridge arm and the second inductor element. The fifth and sixth switching elements can be power switching elements such as IGBTs or MOSFETs. This application does not specifically limit the embodiments described herein. Referring to Figure 5, power switching elements S1, S2, S3, S4, S5, and S6 respectively serve as the first, second, third, fourth, fifth, and sixth switching elements. Capacitor element C dc11 and capacitor element C dc12 This forms the first capacitor bridge arm. Capacitor element C dc21 and capacitor element C dc22 This forms the second capacitor bridge arm.

[0096] In the first topology, the power switching circuit 130 requires the fifth and sixth switching elements to remain in a conducting state so that the connection points of the first and second switching elements are connected to the AC phase line, and the connection points of the third and fourth switching elements are connected to the AC phase line.

[0097] In the second topology, power switching circuit 130 has power switching elements S5 and S6 directly connected, forming the switching arm of the third power conversion path, referred to as the third switching arm. That is, the fifth and sixth switching elements are directly connected. Furthermore, capacitor element C... dc12 and capacitor element C dc21 Directly connected, the corresponding first and second capacitor bridge arms form the capacitor bridge arm of the third power conversion path, which is called the third capacitor bridge arm. Capacitor element C dc12 and capacitor element C dc21 The connection point is taken as the midpoint of the third capacitor bridge arm.

[0098] Capacitor element C dc12 and capacitor element C dc21 The direct connection connects the negative terminal of the first DC bus 110 and the positive terminal of the second DC bus 120, and the voltage across the third capacitor bridge arm is the sum of the voltages of the first DC bus 110 and the second DC bus 120.

[0099] Therefore, capacitor element C dc11 Capacitor element C dc12 Capacitor element C dc21 Capacitor element C dc22Power switching elements S1, S2, S3, S4, S5, and S6 together form the third power conversion path based on a three-level inverter topology.

[0100] In this circuit, power switching elements S1, S5, S6, and S4 serve as the main switching elements of the three-level inverter topology. Specifically, the first, fifth, sixth, and fourth switching elements act as the main switching elements of the three-level inverter topology in the third power conversion path.

[0101] Power switching elements S2 and S3 serve as clamping switching elements in the three-level inverter topology. That is, the second and third switching elements act as clamping switching elements in the third power conversion path of the three-level inverter topology.

[0102] Since the second and third switching elements are controllable power switching elements, this three-level inverter topology is specifically a three-level active neutral point clamped (ANPC) topology.

[0103] In this embodiment, by introducing a fifth and a sixth switching element, a third power conversion path based on a three-level inverter topology is constructed. While reusing the power switching elements of the power switching circuit 130, the output power quality can also be improved.

[0104] To construct a third power conversion path based on a three-level inverter topology, a fifth switching element and a sixth switching element are introduced in the power switching circuit 130. Therefore, in some embodiments, in the first topology configuration, both the fifth and sixth switching elements are configured to be in the ON state, so that the midpoint of the first switching arm is connected to the AC phase line, and the midpoint of the second switching arm is connected to the AC phase line.

[0105] In some cases, if the power switching circuit 130 is in the first topology configuration for most operating scenarios, the fifth and sixth switching elements need to remain in a conducting state for extended periods, which can reduce their lifespan to some extent. Therefore, by short-circuiting the fifth and sixth switching elements via the detachable conductive connection 142, the lifespan of the fifth and sixth switching elements can be improved while simultaneously connecting the midpoint of the first switching arm to the AC phase line and the midpoint of the second switching arm to the AC phase line.

[0106] In some embodiments, referring to FIG6, the fifth and sixth switching elements are provided with detachable conductive connection portions 142 in parallel. In the first topology, the fifth and sixth switching elements are respectively short-circuited by their corresponding conductive connection portions 142. At this time, the fifth and sixth switching elements do not need to operate, and the power switching circuit 130 can form a first power conversion path and a second power conversion path.

[0107] In some embodiments, referring to FIG7, when the first power conversion path and the second power conversion path share the same inductor, the detachable conductive connection portion 142 can be connected between the drain of the first switching element and the source of the fourth switching element.

[0108] In some embodiments, the power conversion system 100 is connected to multiple AC phase lines. Each AC phase line has a corresponding power switching circuit 130 and a topology switching unit 140. The topology switching unit 140 is used to switch the topology of its respective power switching circuit 130.

[0109] Please refer to Figure 8. The power conversion system 100 is connected to three AC phase lines. R, S, and T represent the connection ports of different AC phase lines. Each AC phase line has a corresponding power switching circuit 130 and topology switching unit 140.

[0110] The topology switching unit 140 in the power conversion system 100 shown in Figure 8 is an example of a controllable switching unit. However, it should be noted that in a power conversion system 100 connecting multiple AC phase lines, the topology switching unit 140 can also be composed of other components such as conductive connection part 142. The embodiments of this application are not specifically limited here.

[0111] This application provides a power system including the power conversion system 100 described in any of the above embodiments.

[0112] In some embodiments, the power system may further include a first DC bus 110, a second DC bus 120, and an AC phase line connecting the power conversion system 100.

[0113] For a description of the power system, please refer to other embodiments of this application. This embodiment will not be described in detail here.

[0114] It is understood that the specific examples in this document are only intended to help those skilled in the art better understand the embodiments of this application, and are not intended to limit the scope of the invention.

[0115] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0116] It is understood that the various embodiments described in this application can be implemented individually or in combination, and the embodiments of this application are not limited in this respect.

[0117] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0118] It is understood that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method embodiments can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied as execution by a hardware decoding processor, or as a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0119] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0120] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0121] In the embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0122] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0123] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0124] The above description is merely a specific embodiment of this application, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A power conversion system, characterized in that, The power conversion system, used to connect a first DC bus, a second DC bus, and an AC phase line, includes: a power switching circuit; and a topology switching unit for controlling the power switching circuit to be in a first topology configuration or a second topology configuration. In the first topology configuration, the topology switching unit divides the power switching circuit into a first power switching circuit and a second power switching circuit. The first power switching circuit is connected between the first DC bus and the AC phase line to form a first power conversion path that converts the voltage of the first DC bus to the AC phase line. The second power switching circuit is connected between the second DC bus and the AC phase line to form a second power conversion path that converts the voltage of the second DC bus to the AC phase line. In the second topology configuration, the topology switching unit integrates the first power switching circuit and the second power switching circuit into a third power switching circuit and connects the negative terminal of the first DC bus and the positive terminal of the second DC bus. One end of the third power switching circuit is connected to the positive terminal of the first DC bus and the negative terminal of the second DC bus, and the other end of the third power conversion circuit is connected to the AC phase line to form a third power conversion path that superimposes the voltages of the first DC bus and the second DC bus and converts them to the AC phase line.

2. The power conversion system according to claim 1, characterized in that, The first power switching circuit includes a first capacitor bridge arm and a first switch bridge arm connected to the first DC bus; in the first topology, the midpoint of the first switch bridge arm is connected to the AC phase line, forming a first power conversion path based on a half-bridge inverter topology; the second power switching circuit includes a second capacitor bridge arm and a second switch bridge arm connected to the second DC bus; in the first topology, the midpoint of the second switch bridge arm is connected to the AC phase line, forming a second power conversion path based on a half-bridge inverter topology.

3. The power conversion system according to claim 2, characterized in that, The midpoints of the first and second switch arms are connected to the AC phase line through the same inductor.

4. The power conversion system according to claim 2, characterized in that, The first switching bridge arm includes a first switching element located in the upper bridge arm and a second switching element located in the lower bridge arm; the second switching bridge arm includes a third switching element located in the upper bridge arm and a fourth switching element located in the lower bridge arm; in the second topology configuration, both the second and third switching elements are configured to be in the off state, and the topology switching unit connects the negative terminal of the first DC bus and the positive terminal of the second DC bus, and connects the midpoint of the first switching bridge arm and the midpoint of the second switching bridge arm; correspondingly, the first capacitor bridge arm, the second capacitor bridge arm, the first switching element, and the fourth switching element form a third power conversion path based on a half-bridge inverter topology.

5. The power conversion system according to claim 2, characterized in that, The first switching bridge arm includes a first switching element located on the upper bridge arm and a second switching element located on the lower bridge arm. The midpoint of the first switching bridge arm is connected to the AC phase line through a fifth switching element and a first inductor element, and the connection point between the fifth switching element and the first inductor element serves as a first connection point. The second switching bridge arm includes a third switching element located on the upper bridge arm and a fourth switching element located on the lower bridge arm. The midpoint of the second switching bridge arm is connected to the AC phase line through a sixth switching element and a second inductor element, and the connection point between the sixth switching element and the second inductor element serves as a second connection point. In the second topology configuration, the topology switching unit connects the negative terminal of the first DC bus and the positive terminal of the second DC bus, and connects the first connection point and the second connection point. Correspondingly, the first capacitor bridge arm, the second capacitor bridge arm, the first switching element, the second switching element, the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element form a third power conversion path based on a three-level inverter topology.

6. The power conversion system according to claim 5, characterized in that, In the first topology, both the fifth and sixth switching elements are configured to be in a conducting state; or, the fifth and sixth switching elements are provided with detachable conductive connections in parallel, and in the first topology, the fifth and sixth switching elements are respectively short-circuited by their corresponding conductive connections.

7. The power conversion system according to claim 2, characterized in that, The topology switching unit includes a first controllable conduction component disposed between the negative terminal of the first DC bus and the positive terminal of the second DC bus, and a second controllable conduction component disposed between the midpoint of the first switch bridge arm and the midpoint of the second switch bridge arm; the topology switching unit configures both the first and second controllable conduction components to a turned-off state to enable the power switching circuit to be in the first topology configuration; the topology switching unit configures both the first and second controllable conduction components to a conducted state to enable the power switching circuit to be in the second topology configuration.

8. The power conversion system according to claim 7, characterized in that, The first controllable conduction component includes a controllable switch unit or a detachable conductive connection part, and the second controllable conduction component includes a controllable switch unit or a detachable conductive connection part.

9. The power conversion system according to claim 8, characterized in that, The controllable switching unit includes a seventh switching element and an eighth switching element connected in series, wherein the conduction directions of the body diodes of the first switching element and the eighth switching element are opposite.

10. An electric power system, characterized in that, Includes the power conversion system according to any one of claims 1 to 9.

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