Power conversion device and vehicle-mounted charger

Abstract

The invention provides a power supply conversion device and a vehicle-mounted charger, and relates to the technical field of AC-DC conversion design, the power supply conversion device comprises a matrix switch circuit comprising at least one bridge arm circuit, and the first ends of the at least one bridge arm circuit are connected in parallel to form the first end of the matrix switch circuit; the second ends of the at least one bridge arm circuit are connected in parallel to form the second end of the matrix switch circuit, each bridge arm circuit comprises an upper bridge arm unit and a lower bridge arm unit, and the input end of the matrix switch circuit is connected with the alternating current side port; the primary side first end of the isolation circuit is connected with the first output end of the matrix switch circuit, and the primary side second end of the isolation circuit is connected with the second output end of the matrix switch circuit; the first midpoint end of the voltage conversion circuit is connected with the secondary side first end of the isolation circuit, and the second midpoint end of the voltage conversion circuit is connected with the secondary side second end of the isolation circuit. The efficiency and the power density of the single-stage AC-DC conversion circuit can be improved, and the system structure is simplified.

Description

Technical Field

[0001] The present application relates to the technical field of AC / DC conversion design, and in particular to a power conversion device and an on-board charger. Background Art

[0002] Currently, widely used isolated AC / DC converters typically consist of a two-stage cascade: an AC / DC converter at the front and an isolated DC / DC converter at the back, with busbar capacitance between them. This solution requires a two-stage energy conversion process and numerous passive and switching devices, significantly limiting overall system efficiency and power density. Summary of the Invention

[0003] The main purpose of the present invention is to provide a power conversion device, aiming to improve the efficiency and power density of a single-stage AC / DC conversion circuit and simplify the system structure.

[0004] To achieve the above object, the present invention provides a power conversion device, comprising:

[0005] An AC side port, the AC side port comprising at least one AC connection terminal and an AC neutral terminal;

[0006] A matrix switch circuit, the matrix switch circuit comprising at least one bridge arm circuit, wherein the first end of at least one bridge arm circuit is connected in parallel to form the first end of the matrix switch circuit, and the second end of at least one bridge arm circuit is connected in parallel to form the second end of the matrix switch circuit, each bridge arm circuit comprising an upper bridge arm unit and a lower bridge arm unit, each upper bridge arm unit and the lower bridge arm unit comprising at least two switching transistors, an input end of the matrix switch circuit being connected to the AC side port, and the matrix switch circuit being configured to implement frequency conversion;

[0007] an isolation circuit, wherein a primary first end of the isolation circuit is connected to the first output end of the matrix switch circuit, and a primary second end of the isolation circuit is connected to the second output end of the matrix switch circuit;

[0008] A voltage conversion circuit, wherein the first midpoint terminal of the voltage conversion circuit is connected to the first end of the secondary side of the isolation circuit, the second midpoint terminal of the voltage conversion circuit is connected to the second end of the secondary side of the isolation circuit, the first bridge arm terminal of the voltage conversion circuit is used to connect to the DC positive terminal, and the second bridge arm terminal of the voltage conversion circuit is used to connect to the DC negative terminal. The voltage conversion circuit is used to achieve rectification and / or inversion.

[0009] Optionally, the matrix switch circuit includes 1-4 groups of bridge arm circuits connected in parallel, the midpoint of each bridge arm circuit is connected to a different phase line of the AC power supply, and each bridge arm circuit has two groups of bidirectional switch units connected in series.

[0010] Optionally, the bidirectional switch unit includes any one of two MOS tubes arranged with a common source or a common drain, a GaN bidirectional switch tube, and two IGBT switch tubes arranged with a common emitter or a common collector.

[0011] Optionally, when the bridge arm circuit is a group, the matrix switch circuit further includes:

[0012] A capacitor group, wherein a first end of the capacitor group is connected to the first end of the bridge arm circuit, a second end of the capacitor group is connected to the second end of the bridge arm circuit, and a neutral point of the capacitor group is connected to the AC zero line terminal.

[0013] Optionally, the isolation circuit has a primary side and a secondary side;

[0014] The power conversion device further includes:

[0015] an impedance circuit, wherein an output end of the impedance circuit is connected to a primary side of the isolation circuit;

[0016] or

[0017] The input end of the impedance circuit is connected to the secondary side of the isolation circuit.

[0018] Optionally, the power conversion device is a resonant DAB converter or a non-resonant DAB converter.

[0019] Optionally, when the power conversion device is a non-resonant DAB converter, the impedance circuit includes:

[0020] A first inductor, wherein a first end of the first inductor is connected to a first output end of the matrix switch circuit, and a second end of the first inductor is connected to a primary first end of the isolation circuit.

[0021] Optionally, the impedance circuit further includes a first capacitor, and the first capacitor is electrically connected to any one end of the first inductor.

[0022] Optionally, the impedance circuit further includes:

[0023] a second capacitor, wherein a first end of the second capacitor is connected to the first end of the secondary side of the isolation circuit;

[0024] A third capacitor, wherein a first end of the third capacitor is connected to the second output end of the matrix switch circuit, and a second end of the third capacitor is connected to the second end of the primary side of the isolation circuit.

[0025] Optionally, when the power conversion device is a resonant DAB converter, the impedance circuit includes:

[0026] a fourth capacitor, wherein a first end of the fourth capacitor is connected to the first output end of the matrix switch circuit;

[0027] a third inductor, wherein a first end of the third inductor is connected to the second end of the fourth capacitor, and a second end of the third inductor is connected to the first end of the primary side of the isolation circuit;

[0028] or,

[0029] A first end of the third inductor is connected to a first end of a secondary side of the isolation circuit, and a second end of the third inductor is connected to a first end of the fourth capacitor.

[0030] Optionally, the impedance circuit further includes:

[0031] A fourth inductor, wherein a first end of the fourth inductor is connected to a common node of the third inductor and the first end of the primary side of the isolation circuit, and a second end of the fourth inductor is connected to the second end of the primary side of the isolation circuit.

[0032] Optionally, the impedance circuit further includes:

[0033] A fifth capacitor, wherein a first end of the fifth capacitor is connected to the second output end of the matrix switch circuit, and a second end of the fifth capacitor is connected to the second end of the primary side of the isolation circuit.

[0034] Optionally, the isolation circuit includes:

[0035] an isolation transformer, wherein a primary first end of the isolation transformer is connected to the first output end of the matrix switch circuit, a primary second end of the isolation transformer is connected to the second output end of the matrix switch circuit, a secondary first end of the isolation transformer is connected to the first midpoint end of the voltage conversion circuit, and a secondary second end of the isolation transformer is connected to the second midpoint end of the voltage conversion circuit.

[0036] Optionally, the power conversion device further includes:

[0037] a first filter, wherein an input end of the first filter is used to connect to an AC power supply, and an output end of the first filter is connected to an input end of the matrix switch circuit;

[0038] A second filter, wherein the first input end of the second filter is connected to the first DC end of the voltage conversion circuit, the second input end of the second filter is connected to the second DC end of the voltage conversion circuit, and the output end of the second filter is used to output the filtered DC power supply.

[0039] In addition, to achieve the above-mentioned purpose, the present invention also provides a vehicle-mounted charger, comprising the power conversion device as described above.

[0040] A power conversion device according to an embodiment of the present invention includes an AC side port, a matrix switching circuit, an isolation circuit, and a voltage conversion circuit. The AC side port includes at least one AC connection terminal and an AC neutral terminal. The matrix switching circuit includes at least one bridge arm circuit, wherein the first end of the at least one bridge arm circuit is connected in parallel to form the first end of the matrix switching circuit, and the second end of the at least one bridge arm circuit is connected in parallel to form the second end of the matrix switching circuit. Each bridge arm circuit includes an upper bridge arm unit and a lower bridge arm unit, each of which includes at least two switching transistors. The input end of the matrix switching circuit is connected to the AC side port, and the matrix switching circuit is used to achieve frequency conversion. The primary first end of the isolation circuit is connected to the first output end of the matrix switching circuit, and the primary second end of the isolation circuit is connected to the second output end of the matrix switching circuit. The first midpoint of the voltage conversion circuit is connected to the secondary first end of the isolation circuit, and the second midpoint of the voltage conversion circuit is connected to the secondary second end of the isolation circuit. The first bridge arm end of the voltage conversion circuit is used to connect to the DC positive terminal, and the second bridge arm end of the voltage conversion circuit is used to connect to the DC negative terminal. The voltage conversion circuit is used to achieve rectification and / or inversion. The power conversion device of the embodiment of the present invention reduces the bus capacitance between the front and rear stages, so that the entire power conversion device does not need to go through the charging and discharging process of the bus capacitance, and the energy conversion process is more efficient. Moreover, since the circuit of the power conversion device does not need to be equipped with too many passive devices and switching devices to achieve energy conversion, the loss of the switching device during operation can be greatly reduced. After the power conversion device reduces the intermediate bus capacitance of the two-stage structure, the efficiency and power density of the power conversion device are effectively improved, and the service life of the power conversion device is extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0043] Figure 1 A circuit block diagram of a power conversion device according to an embodiment of the present invention;

[0044] Figure 2 for Figure 1 Circuit block diagram of the matrix switching circuit in;

[0045] Figure 3 for Figure 2A circuit block diagram of multiple bridge arm circuits;

[0046] Figure 4 for Figure 2 Circuit block diagram of the bridge arm circuit in;

[0047] Figure 5 for Figure 1 Circuit diagram of the power conversion device;

[0048] Figure 6 A circuit diagram of a power conversion device according to another embodiment of the present invention;

[0049] Figure 7 for Figure 6 A circuit diagram of another embodiment of the matrix switch circuit;

[0050] Figure 8 for Figure 6 A circuit diagram of another embodiment of the matrix switch circuit;

[0051] Figure 9 A circuit block diagram of a power conversion device according to another embodiment of the present invention;

[0052] Figure 10 A circuit block diagram of a power conversion device according to another embodiment of the present invention;

[0053] Figure 11 for Figure 10 A circuit block diagram of another embodiment of an impedance circuit;

[0054] Figure 12 A circuit block diagram of a power conversion device according to another embodiment of the present invention;

[0055] Figure 13 is a circuit block diagram of a power conversion device according to another embodiment of the present invention;

[0056] Figure 14 A circuit block diagram of a power conversion device according to another embodiment of the present invention;

[0057] Figure 15 A circuit block diagram of a power conversion device according to another embodiment of the present invention;

[0058] Figure 16 for Figure 15 A circuit diagram of another embodiment of an impedance circuit;

[0059] Figure 17 A circuit block diagram of a power conversion device according to another embodiment of the present invention;

[0060] Figure 18 is a circuit block diagram of a power conversion device according to another embodiment of the present invention;

[0061] Figure 19 A circuit block diagram of a power conversion device according to another embodiment of the present invention;

[0062] Figure 20 is a circuit diagram of the power conversion device of the present invention;

[0063] Figure 21 It is a waveform simulation diagram of the power conversion device of the present invention after operation.

[0064] Description of Figure Numbers:

[0065] Label name Label name 10 AC side port 30 Isolation circuit 20 Matrix switching circuit 40 Voltage conversion circuit 21 Bridge arm circuit 50 Impedance circuit 211 Upper arm unit 60 First filter 212 Lower arm unit 70 Second filter 22 capacitor bank - -

[0066] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0067] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments, and well-known modules, units and their connections, links, communications or operations are not shown or described in detail. In addition, the described features, architectures or functions can be combined in any way in one or more embodiments. It should be understood by those skilled in the art that the various embodiments described below are only for illustration and are not intended to limit the scope of protection of the present invention.

[0068] In existing technologies, isolated AC / DC converters typically employ a cascaded structure consisting of a front-stage AC / DC converter and a rear-stage isolated DC / DC converter, connected by a bus capacitor. This structure requires two energy conversion processes, resulting in reduced system efficiency. It also requires a large number of passive and switching devices, limiting power density. For example, in energy storage systems or electric vehicle charging scenarios requiring high power density and efficiency, existing solutions struggle to meet the demands for compactness and high efficiency.

[0069] The existing two-stage conversion structure suffers from the inherent drawback of multiple energy conversions, necessitating topological reconstruction to achieve single-stage energy conversion. To address this issue, the conversion functions for the AC and DC sides are first integrated into the same circuit architecture, reducing the number of components by reusing switching devices. In this process, a matrix switching circuit is combined with an isolation circuit to achieve coordinated control of AC frequency conversion and DC conversion, forming an integrated energy transmission path.

[0070] Based on the above, refer to Figures 1 to 5 、 Figure 19 as well as Figure 20In one embodiment of the present invention, the power conversion device includes an AC side port 10, a matrix switch circuit 20, an isolation circuit 30, and a voltage conversion circuit 40, wherein:

[0071] The AC side port 10 includes at least one AC connection terminal and an AC neutral terminal, the AC connection terminal is used to connect the live wire, and the AC neutral terminal is used to connect the neutral wire; the matrix switch circuit 20 includes at least one bridge arm circuit 21, the first end of at least one bridge arm circuit 21 is connected in parallel to form the first end of the matrix switch circuit 20, and the second end of at least one bridge arm circuit 21 is connected in parallel to form the second end of the matrix switch circuit 20, each bridge arm circuit 21 includes an upper bridge arm unit 211 and a lower bridge arm unit 212, the upper bridge arm unit 211 and the lower bridge arm unit 212 include at least two switch tubes, and the input end of the matrix switch circuit 20 is connected to the AC side port 1 0 is connected, the matrix switch circuit 20 is used to achieve frequency conversion; the first end of the primary side of the isolation circuit 30 is connected to the first output end of the matrix switch circuit 20, and the second end of the primary side of the isolation circuit 30 is connected to the second output end of the matrix switch circuit 20; the first midpoint end of the voltage conversion circuit 40 is connected to the first end of the secondary side of the isolation circuit 30, and the second midpoint end of the voltage conversion circuit 40 is connected to the second end of the secondary side of the isolation circuit 30. The first bridge arm end of the voltage conversion circuit 40 is used to connect to the DC positive terminal, and the second bridge arm end of the voltage conversion circuit 40 is used to connect to the DC negative terminal. The voltage conversion circuit is used to achieve rectification and / or inversion.

[0072] In this embodiment, the AC side port 10 is used to receive an AC voltage, such as a mains voltage, an AC voltage output by a charging station, an AC voltage output by a mobile AC power supply, etc. The received AC voltage may be a three-phase AC voltage, a single-phase AC voltage, etc.

[0073] The AC-side port 10 is an interface capable of connecting to a single-phase or multi-phase AC power source. It can be implemented using a three-phase, four-wire terminal block or a single-phase terminal block. Its terminal design allows for connection to power inputs with different numbers of phases. The bridge arm circuit 21 in the matrix switch circuit 20 is a power module composed of bidirectional switch units. It can be implemented using two sets of MOSFETs connected in reverse series to form a half-bridge structure, which can be connected in parallel to form a scalable switch array. The matrix switch circuit 20 utilizes a parallel bridge arm topology design, allowing the input terminals of multiple bridge arms to be connected in parallel to form a unified port. The independent switch transistors in each bridge arm can be combined to implement conduction paths for different phases. For example, when three-phase operation is required, the three bridge arms can correspond to the three-phase input respectively. When single-phase operation is required, connecting multiple bridge arms in parallel can increase current carrying capacity, thereby adapting to various grid operating conditions, including single-phase, three-phase, phase loss, dual live wires, and unbalanced power. Isolation circuit 30 refers to an energy transmission unit that achieves electrical isolation. This can be implemented using the primary and secondary winding structures of a high-frequency transformer. Impedance matching ensures energy transmission efficiency, and its symmetrical connection ensures magnetic flux balance in different operating modes. The midpoint connection structure of voltage conversion circuit 40 refers to a topology that forms a symmetrical loop on the DC side. This can be implemented using the midpoint extraction method of a dual half-bridge inverter, with midpoint potential control achieving stable DC output. The symmetrical structure of voltage conversion circuit 40 using the midpoint connection method is beneficial for balancing DC side voltage fluctuations, such as when using a half-bridge or full-bridge circuit to convert AC to DC.

[0074] After AC power is connected to the AC-side port 10, the matrix switch generates a variable-frequency AC output by controlling the conduction timing of the switches in each bridge arm. This output is coupled to the secondary side via the isolation circuit 30, where it is rectified by the voltage conversion circuit 40 to output DC. When switching operating modes, the circuit topology can be reconfigured by adjusting the switch combinations of the bridge arm units. For example, in three-phase mode, three independent bridge arms process the three-phase currents separately. In single-phase mode, multiple bridge arms are connected in parallel to process the single-phase current, thus achieving multi-mode compatibility within a single device. This power conversion device achieves operating mode switching through a modular bridge arm design. When connected to a three-phase power source, the three bridge arm circuits 21 are connected to each phase line, and the matrix switch achieves three-phase rectification through time-sharing control. When connected to a single-phase power source, multiple bridge arms operate in parallel to increase current carrying capacity. The primary winding of the isolation transformer T1 receives the high-frequency AC signal, and the secondary side forms a full-wave rectification circuit through the dual-midpoint structure of the voltage conversion circuit 40. The bidirectional switch units in the bridge arms alternately conduct under variable frequency control, converting the industrial frequency AC into a high-frequency AC signal. After isolated transmission, the signal is rectified into a smooth DC by the voltage conversion circuit 40. This topology can adapt to different phase inputs by simply changing the number of bridge arms connected, without changing the main circuit architecture.

[0075] Traditional single-stage converters use fixed phase line connections. For example, a three-phase, three-leg configuration is incompatible with single-phase input. However, this embodiment dynamically configures parallel legs, enabling the same topology to operate in both three-phase, three-leg mode and single-phase, multi-leg parallel mode. This embodiment achieves mode switching directly through topological reconfiguration of the matrix switch, eliminating the need for additional power devices.

[0076] This embodiment can integrate the conversion process from AC to DC into a single-stage energy conversion, avoiding the efficiency loss of the traditional two-stage architecture. The high-frequency switching capability of the matrix switching circuit improves the power density, and the midpoint connection structure of the voltage conversion device realizes bidirectional energy flow, which is suitable for application scenarios that require high efficiency and compact design, such as renewable energy grid connection or electric vehicle fast charging system. The modular bridge arm design enables the system to automatically adjust the working mode according to the input power supply, and improve the power capacity by paralleling the bridge arm when working in single phase. The symmetrical isolation structure and dual midpoint conversion design ensure the energy transmission efficiency in different modes and avoid the energy loss during mode switching of the traditional scheme. This structure also simplifies the circuit complexity, removes the intermediate energy storage capacitor, and extends the service life of the equipment. And based on Figure 19 A specific topology of a typical application is simulated and verified, and the following is obtained: Figure 20 The experimental waveforms shown verify the high efficiency and stability of the power conversion device in different working modes.

[0077] The power conversion device of this embodiment includes an AC side port 10, a matrix switch circuit 20, an isolation circuit 30, and a voltage conversion circuit 40. The AC side port 10 includes at least one AC connection terminal and an AC neutral terminal; the matrix switch circuit 20 includes at least one bridge arm circuit 21, the first end of at least one bridge arm circuit 21 is connected in parallel to form the first end of the matrix switch circuit 20, and the second end of at least one bridge arm circuit 21 is connected in parallel to form the second end of the matrix switch circuit 20. Each bridge arm circuit 21 includes an upper bridge arm unit 211 and a lower bridge arm unit 212. The upper bridge arm unit 211 and the lower bridge arm unit 212 include at least two switching transistors. The input end of the matrix switch circuit 20 is connected to the AC side port 10. The matrix switch circuit 20 is connected to achieve frequency conversion; the primary first end of the isolation circuit 30 is connected to the first output end of the matrix switch circuit 20, and the primary second end of the isolation circuit 30 is connected to the second output end of the matrix switch circuit 20; the first midpoint end of the voltage conversion circuit 40 is connected to the secondary first end of the isolation circuit 30, and the second midpoint end of the voltage conversion circuit 40 is connected to the secondary second end of the isolation circuit 30. The first bridge arm end of the voltage conversion circuit 40 is connected to the DC positive terminal, and the second bridge arm end of the voltage conversion circuit 40 is connected to the DC negative terminal. The voltage conversion circuit 40 is used to achieve rectification and / or inversion. The power conversion device of the embodiment of the present invention reduces the bus capacitance between the front and rear stages, so that the entire power conversion device does not need to go through the charging and discharging process of the bus capacitance, and the energy conversion process is more efficient. Moreover, since the circuit of the power conversion device does not need to be equipped with too many passive devices and switching devices to achieve energy conversion, the loss of the switching device during operation can be greatly reduced. After the power conversion device reduces the intermediate bus capacitance of the two-stage structure, the efficiency and power density of the power conversion device are effectively improved, and the service life of the power conversion device is extended. It has the advantages of improving efficiency, reducing costs, increasing power density and realizing multi-functional integration.

[0078] Optionally, refer to Figures 6 to 8 Another embodiment of the present invention provides a power conversion device, based on the above Figures 1 to 5 In the embodiment shown, the matrix switch circuit 20 includes 1-4 groups of bridge arm circuits 21 connected in parallel with each other, the midpoint of each bridge arm circuit 21 is respectively connected to a different phase line of the AC power supply, and each bridge arm circuit 21 has two groups of bidirectional switch units connected in series with each other.

[0079] The matrix switch circuit forms a multi-channel topology by connecting one to four bridge arm circuits in parallel. The midpoint of each bridge arm circuit is connected to a phase line of the AC power supply. For example, in a three-phase AC system, three bridge arm circuits can be used to correspond to the three phases of the input. The two sets of bidirectional switch units in each bridge arm circuit are connected in series to form the upper and lower bridge arms. Frequency conversion between the AC side and the isolation circuit is achieved by controlling the conduction timing of the bidirectional switch units.

[0080] Among them, the bridge arm circuit refers to a circuit module formed by two bidirectional switch units in series. It can be implemented by forming an upper and lower bridge arm structure by connecting bidirectional switch units in series. By connecting multiple groups of bridge arm circuits in parallel, the system redundancy and current carrying capacity can be improved. 1 to 4 groups of bridge arm circuits 21 connected in parallel refer to selecting the number of parallel bridge arms according to actual application requirements. For example, when a single group of bridge arms is used, it can be adapted to a single-phase input mode, and when three groups of bridge arms are used, it can be adapted to a three-phase input mode without a neutral line. The phase compatibility of the topological structure is achieved by adjusting the number of bridge arms. When the number of bridge arm circuits is 1, the structure is suitable for a single-phase system; when the number of bridge arm circuits is 3 or 4, it can be adapted to a three-phase or four-phase system, thereby expanding the application scenarios. The midpoint of each bridge arm circuit 21 is connected to a different phase line, which means that the midpoint of each bridge arm is independently connected to the corresponding phase line of the AC power supply. For example, in a three-phase mode, each group of bridge arms is connected to phase A, phase B, and phase C respectively to ensure independent control of each phase line. Two sets of bidirectional switch units connected in series mean that each bridge arm is composed of two bidirectionally conducting devices connected in series, such as a common-source MOS transistor or a common-emitter IGBT combination. The on-off switching of the switches enables bidirectional energy flow and voltage conversion. A bidirectional switch unit refers to a combination of semiconductor devices capable of bidirectional conduction and shutoff. These can be implemented using MOS transistors with a common source or drain configuration, GaN bidirectional switches, or IGBT switches with a common emitter / common collector. The series connection of bidirectional switch units allows for flexible control of the energy transmission path between the AC side and the isolation circuit. Connecting different phase lines to the bridge arm midpoint refers to connecting each phase line of the AC power supply to the midpoint of a different bridge arm circuit. This can be achieved by connecting the bridge arm midpoint to the phase line of the AC side port in a one-to-one correspondence. Independently connecting multiple phase lines can balance the loads of each phase and reduce harmonic interference.

[0081] The configurable number of bridge arms allows the topology to be adjusted based on the number of phases of the input power. When the input is single-phase, only one set of bridge arms needs to be enabled, while when the input is three-phase, all three sets of bridge arms are enabled, thus achieving compatibility between single-phase and three-phase modes. The midpoint of each set of bridge arms is independently connected to the corresponding phase line, ensuring that the energy transmission paths between the phase lines do not interfere with each other. A controllable variable-frequency switching network is formed through the series structure of bidirectional switch units. The two sets of series-connected devices in the bidirectional switch unit achieve bidirectional conduction through complementary drive signals. For example, the first set of switches turns on during forward conduction, and the second set turns on during reverse conduction, thereby completing AC-to-DC frequency conversion in a single-stage structure.

[0082] Traditional two-stage AC / DC converters require a cascaded structure of front-stage AC / DC and back-stage DC / DC to achieve energy conversion. However, this embodiment uses a single-stage matrix switching circuit to directly complete frequency conversion and energy transmission from the AC side to the isolated DC side, reducing the use of intermediate bus capacitors and redundant switching devices. Furthermore, the parallel bridge arm structure, with independent access via multiple phase lines, avoids the interphase interference caused by shared bridge arms in traditional topologies.

[0083] Through the above technical solutions, this embodiment simplifies the system architecture and reduces the number of components, while also improving current distribution uniformity and system reliability through a multi-bridge parallel design. The series connection of bidirectional switch units flexibly controls the direction of energy transmission, adapting to rectification or inversion requirements under different operating conditions. The independent multi-phase line connection further optimizes harmonic suppression and load balancing capabilities. The series connection of bidirectional switch units simplifies the frequency conversion control logic and enhances topological flexibility.

[0084] Optionally, the bidirectional switch unit includes any one of two MOS tubes arranged with a common source or a common drain, a GaN bidirectional switch tube, and two IGBT switch tubes arranged with a common emitter or a common collector.

[0085] Among them, two MOS tubes with a common source or common drain arrangement refer to physically connecting the source or drain terminals of two metal oxide semiconductor field effect transistors to form a bidirectional current path. This can be achieved by using discrete components in parallel or an integrated packaging process, with the bidirectional conduction state controlled by a gate drive signal. Among them, a GaN bidirectional switch tube refers to a monolithic integrated bidirectional electronic device based on gallium nitride material, which can achieve bidirectional blocking and conduction functions using a lateral device structure. Among them, two IGBT switch tubes with a common emitter or common collector refer to connecting the emitter or collector terminals of two insulated gate bipolar transistors in series. A bidirectional switch structure can be constructed using a back-to-back connection.

[0086] When a common-source connected MOS transistor combination is used, the body diodes of the two devices form a complementary anti-parallel structure, enabling bidirectional conduction during the AC cycle. When operating in high-frequency conversion scenarios, the low parasitic capacitance of the GaN bidirectional switch reduces switching losses. When used in high-current applications, a common-emitter connected IGBT combination enhances conduction capability through carrier injection. These three structures leverage differences in semiconductor physical properties and circuit topology to meet the operating requirements of different voltage levels and power densities.

[0087] Conventional bidirectional switches employ only a single type of power device or a fixed connection method, such as using only an anti-parallel thyristor structure or a single MOS device combination. Such solutions are unable to adapt to the differentiated requirements of high-frequency conversion and high-current application scenarios, resulting in limited topological adaptability. Existing isolated AC / DC converters typically employ unidirectional switching devices in conjunction with diodes to achieve bidirectional energy flow, resulting in a complex circuit structure and high losses. However, this embodiment employs an integrated bidirectional switch unit, directly utilizing the inherent bidirectional conduction characteristics of MOS tubes, GaN, or IGBTs, eliminating external diodes and redundant switching devices, simplifying the circuit layout, and reducing the conduction voltage drop. Through the selective configuration of multiple power device combinations, this embodiment enables the matrix switch circuit 20 to adapt to single-phase or three-phase AC input modes, while meeting the operational requirements of high frequency, low loss, and high current, high reliability. This significantly reduces the number of switching devices and conduction losses in the bridge arm circuit, thereby improving the overall efficiency and power density of the power conversion device.

[0088] Optionally, refer to Figure 9 Another embodiment of the present invention provides a power conversion device based on the above Figures 6 to 8 In the embodiment shown, when the bridge arm circuit 21 is a group, the matrix switch circuit 20 further includes a capacitor group 22, wherein:

[0089] The first end of the capacitor group 22 is connected to the first end of the bridge arm circuit 21 , the second end of the capacitor group 22 is connected to the second end of the bridge arm circuit 21 , and the neutral point of the capacitor group 22 is connected to the AC neutral line terminal.

[0090] Among them, the capacitor group 22 refers to a filter element composed of two or more capacitor units connected in series, which can be implemented by using electrolytic capacitors or film capacitors with equal equivalent capacitance values. The two capacitor units are connected in series to form a series voltage divider structure. The neutral point refers to the connection node of the two capacitor units in the capacitor group 22. The node is configured to be directly connected to the AC neutral line terminal through a wire, and a potential balance reference is established through the neutral line loop. The first end and the second end of the bridge arm circuit 21 refer to the output endpoints on both sides of the upper bridge arm unit 211 and the lower bridge arm unit 212 in the bridge arm circuit 21, respectively. Copper busbars or wires can be used to achieve electrical connection for transmitting electrical energy and forming a voltage difference.

[0091] Among them, by setting a capacitor group 22 connected across the two ends of the bridge arm circuit 21, the capacitor units are connected in series to divide the voltage and form a neutral point. The neutral point is forcibly connected to the AC neutral line end. In the single-phase working mode, the neutral point potential and the neutral line end form an equipotential relationship, and the midpoint potential of the bridge arm circuit 21 is constrained to a symmetrical voltage reference. When the matrix switch circuit 20 performs high-frequency switching, the capacitor group 22 absorbs the switching transient energy through charging and discharging, thereby suppressing voltage fluctuations. Under single-phase input conditions, the neutral point of the capacitor group 22 and the neutral line end form a closed loop, and the common-mode current is discharged through the neutral line to avoid high-frequency harmonic interference. In addition, the energy storage characteristics of the capacitor group 22 compensate for the voltage drop when the bridge arm circuit 21 is configured as a single group, thereby maintaining the stability of the DC bus voltage.

[0092] The existing solution uses multiple groups of bridge arms in parallel to form a virtual neutral point, which increases the number of components and losses. This embodiment uses the capacitor group 22 to construct a voltage-dividing neutral point. Without increasing the number of bridge arms, it can achieve voltage symmetry equivalent to that of a three-phase system under single-phase conditions. At the same time, it uses the energy storage characteristics of the capacitor to suppress harmonics, reducing system complexity. This embodiment realizes automatic balancing of the AC side voltage in a single-bridge arm circuit scenario, reduces the voltage withstand requirements of the switching tube, and can effectively solve the voltage imbalance problem in the single-phase working mode when a single bridge arm is configured. By connecting the neutral point to the neutral line end, a symmetrical voltage reference is forced to be established, eliminating the common-mode interference caused by the insufficient number of bridge arms, greatly simplifying the capacitor configuration, reducing the circuit volume and cost, and thus improving the power density and reliability of the converter. The energy storage function of the capacitor group 22 smoothes the voltage fluctuations caused by the switching action, reduces the harmonic content, and enables the single-phase topology to have electrical characteristics compatible with the three-phase system, realizing seamless switching between single-phase and three-phase working modes.

[0093] It should be noted that the isolation circuit 30 has a primary side and a secondary side.

[0094] Based on the above circuit structure, refer to Figure 10 and Figure 11 Another embodiment of the present invention provides a power conversion device, based on the above Figures 1 to 5 In the embodiment shown, the power conversion device further includes an impedance circuit 50, wherein:

[0095] The output end of the impedance circuit 50 is connected to the primary side of the isolation circuit 30 ; or, the input end of the impedance circuit 50 is connected to the secondary side of the isolation circuit 30 .

[0096] Isolation circuit 30 is a circuit that electrically isolates the primary and secondary sides through electromagnetic coupling. This circuit can be implemented using an isolation transformer T1 combined with a rectifier circuit, and is used to achieve electrical isolation and energy transfer between the AC and DC sides. Impedance circuit 50 is a circuit module that can adjust the current or voltage amplitude and phase relationship, and is used to achieve power regulation or harmonic suppression during energy transfer.

[0097] Among them, the impedance circuit 50 is configured on the primary side or the secondary side of the isolation circuit 30. Primary side connection refers to setting the impedance circuit 50 on the high voltage side of the isolation transformer T1, and secondary side connection refers to setting the impedance circuit 50 on the low voltage side of the isolation transformer T1. When the impedance circuit 50 is connected to the primary side, its output end is connected to the primary side port, and by adjusting the equivalent impedance parameters of the primary side, the energy transmission efficiency is optimized, such as changing the resonant frequency or matching the input voltage of different phases, so that stable energy transmission can be achieved when the AC side port 10 is connected to a single-phase or three-phase AC power supply; when the impedance circuit 50 is connected to the secondary side, its input end is connected to the secondary side port, and by adjusting the impedance parameters of the secondary side, the influence of high-frequency harmonics on the DC output is suppressed, such as adjusting the voltage ripple of the DC output end or suppressing high-frequency harmonics, thereby adapting to different DC load requirements. By placing the impedance circuit 50 on either the primary or secondary side, the two connection modes can be flexibly switched based on actual operating conditions. Impedance matching can be performed for AC input or DC output characteristics, optimizing the energy transmission path. For example, with single-phase input, the primary-side impedance circuit 50 is used to reduce switching losses, while with three-phase input, the secondary-side impedance circuit 50 is used to improve output stability. This bidirectional configuration allows the device to flexibly select the location of the impedance circuit 50 based on actual operating conditions, adapting to different operating modes.

[0098] The impedance circuit 50 of existing isolated single-stage converters is typically fixedly connected to a single side, such as the primary or secondary side. This prevents dynamic impedance adjustment based on the number of input phases or load requirements, limiting the compatibility of the topology. However, this embodiment allows the impedance circuit 50 to be flexibly configured on either the primary or secondary side. For example, a resonant DAB converter can be used on the primary side to adapt to the resonant characteristics of a three-phase input, or a non-resonant DAB converter can be used on the secondary side to optimize the DC output quality of a single-phase input. This switchable configuration overcomes the limitations of conventional topologies on operating modes.

[0099] This embodiment integrates the impedance circuit directly on the primary or secondary side of the isolation circuit, achieving resonant characteristic adjustment and harmonic suppression during single-stage energy conversion without the need for additional support capacitors or filtering devices. This reduces the number of energy conversions and the number of passive components. This reduces the impact of high-frequency switching noise on energy transmission and improves the adaptability of the isolation circuit in different operating modes.

[0100] Optionally, the power conversion device is a resonant DAB converter or a non-resonant DAB converter.

[0101] Among them, a resonant DAB converter refers to a circuit topology that achieves bidirectional energy transmission through the resonant characteristics of inductors and capacitors. It can be implemented using a series resonant or parallel resonant structure. It matches the switching frequency with the natural frequency of the resonant cavity, allowing the switch to turn on or off under zero voltage or zero current conditions. Its function is to use the resonant characteristics to reduce switching losses and improve energy transmission efficiency. A non-resonant DAB converter refers to a circuit topology that achieves energy transmission based on phase shift control. It can be implemented using a full-bridge or half-bridge structure. Its function is to control the power flow by adjusting the phase shift angle, simplifying the circuit parameter design. Alternatively, a non-resonant DAB converter refers to a circuit that achieves energy transmission through conventional inductors. It can be implemented using a single inductor or a coupled inductor structure. Its power transmission relies on the linear change of the inductor current and does not require frequency matching of the resonant cavity.

[0102] Among them, the resonant DAB converter achieves soft switching through resonant elements. For example, at a specific frequency, the inductive reactance of the inductor and the capacitive reactance of the capacitor cancel each other out, allowing the switch tube to switch under zero voltage or zero current conditions, reducing switching losses during high-frequency operation, and is suitable for scenarios with high efficiency requirements. The non-resonant DAB converter changes the conduction time of the power transmission path by adjusting the phase shift angle between the primary and secondary bridge arms, thereby controlling the direction of energy transfer. Or the non-resonant DAB converter simplifies the resonant elements and achieves power transmission with conventional inductors, reducing circuit complexity and manufacturing costs. By choosing a resonant or non-resonant structure, the same topology can adapt to AC inputs with different numbers of phases: in single-phase operation mode, the resonant structure improves efficiency through soft switching characteristics; in three-phase operation mode, the non-resonant structure meets the balancing requirements of multi-phase inputs by simplifying the circuit design.

[0103] This embodiment combines two-stage energy conversion into a single-stage structure through direct coupling of the matrix switching circuit and the isolation circuit in combination with a resonant or non-resonant DAB topology, significantly reducing the number of passive components and energy conversion links.

[0104] Through the above technical solution, this embodiment solves the problems of low efficiency and limited power density of traditional two-stage converters, reduces system complexity through single-stage integrated design, and optimizes switching losses by using resonant or non-resonant control strategies, thereby improving overall energy efficiency and power density.

[0105] Optionally, refer to Figure 12 Another embodiment of the present invention provides a power conversion device based on the above Figure 10 and Figure 11In the embodiment shown, when the power conversion device is a non-resonant DAB converter, the impedance circuit 50 includes a first inductor L1, wherein:

[0106] A first end of the first inductor L1 is connected to a first output end of the matrix switch circuit 20 , and a second end of the first inductor L1 is connected to a primary first end of the isolation circuit 30 .

[0107] A non-resonant DAB converter is a dual-active bridge converter that achieves energy transfer through non-resonant elements such as inductors or capacitors. This can be achieved using either a series inductor or a parallel capacitor, and its operating frequency is not limited by the resonant point. The first inductor L1 is an inductive element that serves as the primary energy transmission channel and can be implemented using a ferrite core wound inductor or a planar inductor. Power regulation is achieved through the inductor's current continuity characteristics.

[0108] The alternating voltage signal output by the matrix switching circuit 20 is transmitted to the primary winding of the isolation circuit 30 via the first inductor L1. In non-resonant mode, the inductor controls the current waveform by adjusting the switching frequency or duty cycle, allowing energy to be transferred between the primary and secondary sides of the isolation transformer T1 in a non-resonant manner. Because no resonant components are used, the tolerance range of the inductor parameters is large, allowing the circuit to maintain stable transmission in operating modes with different phase numbers. For example, with single-phase input, the inductor only needs to handle unidirectional current; with three-phase input, the inductor achieves current diversion by connecting multiple bridge arms in parallel without changing the inductor structure.

[0109] This embodiment directly connects a single inductor in series with the main energy transmission loop, simplifying the impedance matching structure while also being compatible with both single-phase and three-phase input modes through the scalability of the inductor parameters. This embodiment optimizes the structure of the non-resonant DAB converter, reducing the number of components and circuit complexity. While maintaining the basic functionality of the non-resonant DAB converter, it simplifies the circuit topology, improving system integration and reliability, and enabling the system to maintain efficient energy transmission over a wide range of input conditions.

[0110] Optionally, refer to Figure 13 Another embodiment of the present invention provides a power conversion device, based on the above Figure 12 In the embodiment shown, the impedance circuit 50 further includes a first capacitor C1, wherein:

[0111] The first capacitor C1 is electrically connected to any one end of the first inductor L1.

[0112] Among them, the first inductor L1 refers to an energy storage element connected in series between the output end of the matrix switch circuit 20 and the primary side of the isolation circuit 30. It can be implemented by winding a ferrite core or a planar inductor structure. Its inductance can be, for example, in the range of 10μH to 200μH, and is used to limit the current change rate and transfer energy. The first capacitor C1 refers to a high-frequency filtering element connected in series or in parallel with the inductor. It can be implemented by using a ceramic capacitor, a thin film capacitor or a multi-layer stacked capacitor. Its capacitance can be, for example, in the range of 10nF to 1μF, and is used to form a resonant path with the inductor to suppress electromagnetic interference in a specific frequency band. The connection position selection of the capacitor and the inductor means that the capacitor can be configured on the side of the inductor close to the matrix switch circuit 20 or close to the isolation circuit 30. This can be achieved by adjusting the PCB layout. This flexibility allows the resonant frequency characteristics to be optimized according to actual working conditions.

[0113] Among them, when high-frequency current flows through the inductor, the capacitor forms a high-frequency current loop through charging and discharging, and generates a reverse voltage at both ends of the inductor to offset the high-frequency ripple. For example, at the moment the switch tube is turned off, the voltage spike generated by the inductor is absorbed by the capacitor, effectively reducing the voltage stress borne by the switching device. When the capacitor is connected to the input end of the inductor, it can preferentially filter out high-frequency noise from the matrix switching circuit 20; when connected to the output end, it focuses on suppressing electromagnetic interference transmitted to the isolation circuit 30. By adjusting the capacitor access position, the resonant frequency can be controlled within the range of 50kHz to 500kHz, for example, to match the operating requirements of different power levels. At the same time, the second-order filtering characteristics formed by the LC network have an attenuation slope of about 40dB / dec for high-frequency harmonics compared to a single inductor structure, significantly improving electromagnetic compatibility performance.

[0114] This embodiment introduces a reconfigurable LC network, maintaining the simplicity of a non-resonant topology while enhancing high-frequency noise suppression and enabling resonant parameter adjustment through optional capacitor placement. For example, in an electric vehicle charging scenario, when the grid is exposed to high-frequency harmonic pollution, the capacitor can be placed before the inductor to prioritize filtering out grid-side interference. To reduce transformer losses, the capacitor can be moved after the inductor to optimize system efficiency.

[0115] This embodiment effectively addresses the issues of insufficient high-frequency filtering and limited parameter adjustment in non-resonant converters. Without requiring the addition of complex control circuitry, it improves electromagnetic interference suppression capabilities by optimizing the passive component layout. This design enables the converter to adapt to operating requirements in diverse electromagnetic environments while reducing the voltage stress of switching devices by approximately 20% to 30%, improving system reliability and compatibility with complex operating conditions. It achieves superior electromagnetic compatibility performance within a comparable footprint, thereby enhancing the converter's overall reliability.

[0116] Optionally, refer to Figure 14Another embodiment of the present invention provides a power conversion device based on the above Figure 13 In the embodiment shown, the impedance circuit 50 further includes a second capacitor C2 and a third capacitor C3, wherein:

[0117] The first end of the second capacitor C2 is connected to the first end of the secondary side of the isolation circuit 30; the first end of the third capacitor C3 is connected to the second output end of the matrix switch circuit 20, and the second end of the third capacitor C3 is connected to the second end of the primary side of the isolation circuit 30.

[0118] The second capacitor C2 is a capacitor directly connected to the secondary side of the isolation circuit 30 and can be implemented as a film capacitor or a ceramic capacitor. This capacitor is used to absorb high-frequency ripple current on the secondary side and adjust the resonant frequency. The third capacitor C3 is a capacitor connected between the output terminal of the matrix switch circuit 20 and the second terminal of the primary side of the isolation circuit 30 and can be implemented as an electrolytic capacitor or a metallized polypropylene capacitor. This capacitor forms a high-frequency current path by coupling with the primary circuit, suppressing switching transient voltage spikes.

[0119] Among them, when the converter is in single-phase operating mode, the second capacitor C2 reduces the impact of voltage fluctuations on the back-end circuit by filtering out the high-order harmonic components generated by the secondary voltage conversion circuit 40. At the same time, its capacitance and the leakage inductance of the isolation transformer T1 together constitute the resonant parameters to ensure the achievement of soft switching conditions. After switching to three-phase operating mode, the third capacitor C3 and the equivalent inductance at the output end of the matrix switch circuit 20 form an LC filter network, which performs multi-stage attenuation on high-frequency switching noise and maintains the continuity of energy transmission through coupling with the primary winding. The synergistic effect of the second capacitor C2 and the third capacitor C3 enables the primary resonant circuit and the secondary filter network to form a distributed impedance matching structure, automatically adjusting the system resonance characteristics under different input phase numbers, thereby achieving smooth switching between single-phase and three-phase operating modes.

[0120] This embodiment adds a second capacitor, C2, to the secondary side and simultaneously optimizes the layout of the third capacitor, C3, on the primary side, creating a composite filtering network covering both the primary and secondary sides. This creates independent filtering paths on both the primary and secondary sides, reducing the number of passive components and improving energy conversion efficiency. This embodiment effectively suppresses switching noise and voltage spikes generated during the frequency conversion process, reducing system losses and increasing power density. It also reduces reliance on additional filtering components and simplifies the circuit structure.

[0121] Optionally, refer to Figure 15 and Figure 16 Another embodiment of the present invention provides a power conversion device, based on the above Figure 10 and Figure 11In the embodiment shown, when the power conversion device is a resonant DAB converter, the impedance circuit 50 includes a fourth capacitor C4 and a third inductor L3, wherein:

[0122] The first end of the fourth capacitor C4 is connected to the first output end of the matrix switch circuit 20; the first end of the third inductor L3 is connected to the second end of the fourth capacitor C4, and the second end of the third inductor L3 is connected to the first end of the primary side of the isolation circuit 30;

[0123] Alternatively, the first end of the third inductor L3 is connected to the first end of the secondary side of the isolation circuit 30 , and the second end of the third inductor L3 is connected to the first end of the fourth capacitor C4 .

[0124] The fourth capacitor C4 is a resonant capacitor with a specific capacitance value, which can be implemented using a film capacitor or a ceramic capacitor. This capacitor and the inductor in the circuit together form a resonant network, which is used to adjust the absorption capacity of high-frequency harmonics and control the resonant frequency. The third inductor L3 is a wound inductor with a specific inductance value, which can be implemented using a ferrite core or a nanocrystalline core. This inductor and capacitor form a series resonant structure to generate zero-voltage switching conditions in different connection positions.

[0125] When the third inductor L3 is connected to the primary side, it forms a resonant circuit in series with the fourth capacitor C4, resulting in a sinusoidal current waveform. This reduces conduction losses in the switching devices and enables soft switching characteristics of the primary-side power devices during high-frequency switching cycles through the resonant current. When the third inductor L3 is reversibly connected to the secondary side, it interacts with the capacitors in the voltage conversion circuit 40 to form a secondary-side resonant path. The resonant circuit on the secondary side directly participates in the voltage conversion process, achieving zero-voltage or zero-current switching and reducing energy loss during the switching process.

[0126] This embodiment achieves universal operation of the isolated converter under both single-phase and three-phase input conditions, while ensuring that the resonant network achieves zero-voltage switching in all operating modes, effectively reducing switching losses. The reconfigurable connection between the fourth capacitor C4 and the third inductor L3 allows the same circuit topology to adapt to different input voltage conditions, enabling mode switching without the need for additional power devices.

[0127] Optionally, refer to Figure 17 Another embodiment of the present invention provides a power conversion device based on the above Figure 15 and Figure 16 In the illustrated embodiment, the impedance circuit 50 further includes a fourth inductor L4, wherein:

[0128] A first end of the fourth inductor L4 is connected to a common node of the third inductor L3 and the primary first end of the isolation circuit 30 , and a second end of the fourth inductor L4 is connected to the primary second end of the isolation circuit 30 .

[0129] The fourth inductor L4 is an inductive element connected in series with the primary side of the isolation circuit 30. It can be made of a wound coil or magnetic material. It forms a resonant circuit with the third inductor L3 and the fourth capacitor C4, improving energy transmission efficiency and reducing switching losses. The common node is the connection point between the third inductor L3 and the first end of the primary side of the isolation circuit 30. It can be implemented with a wire or circuit board copper foil. It is used to provide a current diversion path and optimize the resonance parameters.

[0130] The fourth inductor L4 is configured on the primary side of the isolation circuit 30. One end of the fourth inductor L4 is connected to the connection point between the third inductor L3 and the first terminal of the primary side of the isolation circuit 30, and the other end is connected to the second terminal of the primary side of the isolation circuit 30. The introduction of the fourth inductor L4 adjusts the equivalent inductance of the primary side, thereby expanding the matching range between the resonant frequency and the switching frequency, thereby maintaining the resonant state during the frequency conversion process. The fourth inductor L4, the third inductor L3, and the fourth capacitor C4 together form a composite resonant network, which achieves high-frequency energy transfer through magnetic energy storage and release.

[0131] In a resonant DAB converter, the third inductor L3 and the fourth inductor L4 are connected in series to form a primary-side resonant inductor. The primary current flows through the third and fourth inductors L3 and L4 before entering the isolation transformer. By adjusting the inductance parameters of the fourth inductor L4, the resonant network can achieve zero-voltage switching conditions at specific frequencies. For example, when the matrix switching circuit outputs high-frequency AC, the third and fourth inductors L3 and L4 jointly store and release magnetic energy, forming an LC resonance with the fourth capacitor C4. This allows the switch to complete state switching when the current crosses zero, thereby reducing switching losses.

[0132] Traditional single-stage converters typically use a single inductor to achieve resonance, which limits their resonant frequency range and makes them difficult to adapt to wide input voltage or load variations. However, this embodiment adds a fourth inductor, L4, to form a multi-stage resonant network, expanding the frequency adjustment freedom and enabling high-efficiency energy transmission in different operating modes.

[0133] Through the above technical solution, this embodiment effectively enhances the flexibility of resonant network parameter design, enabling the converter to maintain high-efficiency operation under various load conditions. Furthermore, the dual-inductor structure disperses current stress, reducing the required size of a single inductor, facilitating converter miniaturization, reducing switching losses, and improving energy transmission stability.

[0134] Optionally, refer to Figure 18Another embodiment of the present invention provides a power conversion device, based on the above Figure 15 and Figure 16 or Figure 17 In any of the illustrated embodiments, the impedance circuit 50 further includes a fifth capacitor C5, wherein:

[0135] A first end of the fifth capacitor C5 is connected to the second output end of the matrix switch circuit 20 , and a second end of the fifth capacitor C5 is connected to the second primary end of the isolation circuit 30 .

[0136] The fifth capacitor C5 is a capacitive element connected in parallel between the output terminal of the matrix switch circuit 20 and the primary side of the isolation circuit 30. It can be implemented as an electrolytic capacitor or a thin film capacitor. It forms a resonant network with the third inductor L3 and the fourth inductor L4 to adjust the resonant frequency. Connected between the second output terminal of the matrix switch circuit 20 and the second terminal of the primary side of the isolation circuit 30, the fifth capacitor C5 balances voltage fluctuations on the primary side and reduces harmonic interference generated during the switching process.

[0137] The second output terminal of the matrix switch circuit 20 is directly connected to the second terminal of the primary side of the isolation circuit 30 via the fifth capacitor C5, forming a resonant circuit on the primary side comprising the third inductor L3, the fourth inductor L4, and the fifth capacitor C5. When the matrix switch circuit 20 switches at different frequencies, the fifth capacitor C5 and the inductor elements interact to produce specific resonant characteristics, thereby supporting switching between single-phase and three-phase operating modes. For example, in single-phase mode, the fifth capacitor C5 is connected in series with the third inductor L3 to form a resonant path; in three-phase mode, the fifth capacitor C5 is connected in parallel with the fourth inductor L4 to expand the resonant bandwidth, enabling compatible operation in different modes.

[0138] This embodiment connects the fifth capacitor directly in parallel between the output of the matrix switching circuit and the primary side of the isolation circuit. This not only reduces the number of discrete components but also reduces the size of the magnetic components by optimizing the resonant parameters. This also preserves the soft switching characteristics of the resonant converter, achieving efficient energy transmission without increasing circuit complexity, effectively suppressing voltage spikes caused by high-frequency switching, and improving the converter's operating stability under various load conditions. This embodiment, through the synergistic effect of the fifth capacitor C5 and the primary-side inductor, enables flexible adjustment of the resonant parameters, supporting smooth switching between different modes, while also improving conversion efficiency and extending device life.

[0139] Optionally, refer to Figures 12 to 18 Another embodiment of the present invention provides a power conversion device based on the above Figures 1 to 5 In the embodiment shown, the isolation circuit 30 includes an isolation transformer T1, wherein:

[0140] The first primary end of the isolation transformer T1 is connected to the first output end of the matrix switch circuit 20, the second primary end of the isolation transformer T1 is connected to the second output end of the matrix switch circuit 20, the first secondary end of the isolation transformer T1 is connected to the first midpoint end of the voltage conversion circuit 40, and the second secondary end of the isolation transformer T1 is connected to the second midpoint end of the voltage conversion circuit 40.

[0141] Among them, the isolation transformer T1 refers to an electromagnetic energy conversion device that can achieve electrical isolation between the primary side and the secondary side. It can be implemented by using a double-winding transformer, which realizes energy transfer through magnetic coupling while blocking the direct electrical connection between the primary side and the secondary side.

[0142] The AC power output by the matrix switch circuit 20 undergoes voltage conversion and electrical isolation via an isolation transformer T1. The secondary output of the isolation transformer T1 is connected to the AC side of the voltage conversion circuit 40. This structure integrates isolation and current conversion functions, achieving AC / DC conversion without the need for intermediate bus capacitors, allowing both single-phase and three-phase input modes to fit within the same circuit framework.

[0143] Traditional isolated converters typically require independent intermediate DC bus capacitors for voltage stabilization. However, this embodiment achieves AC / DC conversion and electrical isolation in a single-stage structure through the coordinated operation of the matrix switch circuit 20, the isolation transformer T1, and the voltage conversion circuit 40, eliminating the size and cost constraints of the intermediate energy storage link. While the prior art layout of the voltage conversion circuit 40 and the isolation transformer T1 increases system complexity, this embodiment integrates the voltage conversion circuit 40 directly on the secondary side of the isolation transformer T1, reducing parasitic parameters in the power transmission path.

[0144] This embodiment directly couples the matrix switching circuit and the voltage conversion circuit through an isolation transformer, omitting the intermediate DC link and associated passive components, reducing the number of energy conversions and the number of components. This simplifies the circuit topology, reduces energy loss during transmission, and reduces the number of passive components used, thereby improving the overall efficiency and power density of the system. In addition, the direct coupling design of the isolation transformer avoids the voltage fluctuation problem of the intermediate DC bus and enhances system stability. By eliminating the intermediate bus capacitor in this embodiment, the overall system volume can be compressed, the power density is improved, and the impact of the life of the electrolytic capacitor on system reliability is avoided.

[0145] Optionally, refer to Figure 19 Another embodiment of the present invention provides a power conversion device, based on the above Figures 1 to 5 In the embodiment shown, the power conversion device further includes a first filter 60 and a second filter 70, wherein:

[0146] The input end of the first filter 60 is used to connect to the AC power supply, and the output end of the first filter 60 is connected to the input end of the matrix switch circuit 20; the first input end of the second filter 70 is connected to the DC first end of the voltage conversion circuit 40, the second input end of the second filter 70 is connected to the DC second end of the voltage conversion circuit 40, and the output end of the second filter 70 is used to output the filtered DC power supply.

[0147] The first filter 60 is a filter structure disposed between the AC power input and the matrix switch circuit 20. It can be implemented using an LC filter or an EMI filter to filter out high-frequency harmonics and electromagnetic interference on the AC power input side. The second filter 70 is a filter structure disposed between the DC output of the voltage conversion circuit 40 and the load. It can be implemented using an electrolytic capacitor or a thin film capacitor bank 22 to eliminate voltage ripple and transient fluctuations on the DC output side. The first filter 60 and the second filter 70 form a two-stage filtering architecture, with the former suppressing conducted interference on the AC side and the latter improving power quality on the DC side.

[0148] When AC power is connected through the first filter 60, the conducted interference generated by the high-frequency switching operation is confined to the front end of the matrix switch circuit 20. After the power energy is frequency-modulated by the matrix switch circuit 20 and transmitted to the voltage conversion circuit 40 via the isolation circuit 30, the pulsating DC power output is filtered twice by the second filter 70, ultimately outputting smooth DC power. The two-stage filter forms a dual suppression barrier at the input and output ends of the AC / DC conversion link. The first filter 60 reduces the contamination of the high-frequency switching noise on the power grid, while the second filter 70 improves the stability of the DC output.

[0149] Traditional single-stage converters only have a single filter capacitor on the DC side, which cannot effectively suppress AC-side conducted interference and DC-side voltage fluctuations. This embodiment uses a two-stage structure with input-side AC filtering and output-side DC filtering to form a bidirectional input and output filtering protection mechanism, which can simultaneously optimize input and output power quality. This two-stage filtering design not only reduces the voltage stress on switching devices, but also reduces the number of passive components required, thereby improving overall system efficiency.

[0150] This embodiment adopts a dual-stage input and output filtering design. While maintaining the advantages of a single-stage conversion structure, it suppresses the impact of high-frequency interference on the AC side on the power grid and improves the stability of the DC side output voltage. It effectively solves the problems of power quality degradation and device loss caused by insufficient filtering in the prior art. Through the synergistic effect of the dual-stage input and output filtering, the conversion efficiency and output stability of the power conversion device are significantly improved, while simplifying the circuit structure.

[0151] The present invention further provides an on-board charger, which includes the power conversion device as described in the above embodiment.

[0152] It is worth noting that since the on-board charger of the present invention is based on the above-mentioned power conversion device, the embodiments of the on-board charger of the present invention include all technical solutions of all embodiments of the above-mentioned power conversion device, and the technical effects achieved are also exactly the same, which will not be repeated here.

[0153] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A power conversion device, characterized in that: The power conversion device includes: An AC side port, the AC side port comprising at least one AC connection terminal and an AC neutral terminal; A matrix switch circuit, the matrix switch circuit comprising at least one bridge arm circuit, wherein the first end of at least one bridge arm circuit is connected in parallel to form the first end of the matrix switch circuit, and the second end of at least one bridge arm circuit is connected in parallel to form the second end of the matrix switch circuit, each bridge arm circuit comprising an upper bridge arm unit and a lower bridge arm unit, each upper bridge arm unit and the lower bridge arm unit comprising at least two switching transistors, an input end of the matrix switch circuit being connected to the AC side port, and the matrix switch circuit being configured to implement frequency conversion; an isolation circuit, wherein a primary first end of the isolation circuit is connected to the first output end of the matrix switch circuit, and a primary second end of the isolation circuit is connected to the second output end of the matrix switch circuit; A voltage conversion circuit, wherein the first midpoint terminal of the voltage conversion circuit is connected to the first end of the secondary side of the isolation circuit, the second midpoint terminal of the voltage conversion circuit is connected to the second end of the secondary side of the isolation circuit, the first bridge arm terminal of the voltage conversion circuit is used to connect to the DC positive terminal, and the second bridge arm terminal of the voltage conversion circuit is used to connect to the DC negative terminal. The voltage conversion circuit is used to achieve rectification and / or inversion.

2. The power conversion device according to claim 1, wherein: The matrix switch circuit includes 1-4 groups of bridge arm circuits connected in parallel, the midpoint of each bridge arm circuit is connected to different phase lines of the AC power supply, and each bridge arm circuit has two groups of bidirectional switch units connected in series.

3. The power conversion device according to claim 2, wherein: The bidirectional switch unit includes any one of two MOS tubes with a common source or a common drain, a GaN bidirectional switch tube, and two IGBT switch tubes with a common emitter or a common collector.

4. The power conversion device according to claim 2, wherein: When the bridge arm circuit is a group, the matrix switch circuit further includes: A capacitor group, wherein a first end of the capacitor group is connected to the first end of the bridge arm circuit, a second end of the capacitor group is connected to the second end of the bridge arm circuit, and a neutral point of the capacitor group is connected to the AC zero line terminal.

5. The power conversion device according to claim 1, wherein: The isolation circuit has a primary side and a secondary side; The power conversion device further includes: an impedance circuit, wherein an output end of the impedance circuit is connected to a primary side of the isolation circuit; or The input end of the impedance circuit is connected to the secondary side of the isolation circuit.

6. The power conversion device according to claim 5, wherein: The power conversion device is a resonant DAB converter or a non-resonant DAB converter.

7. The power conversion device according to claim 6, wherein: In the case where the power conversion device is a non-resonant DAB converter, the impedance circuit includes: A first inductor, wherein a first end of the first inductor is connected to a first output end of the matrix switch circuit, and a second end of the first inductor is connected to a primary first end of the isolation circuit.

8. The power conversion device according to claim 7, wherein: The impedance circuit further includes a first capacitor electrically connected to any one end of the first inductor.

9. The power conversion device according to claim 8, wherein: The impedance circuit further includes: a second capacitor, wherein a first end of the second capacitor is connected to the first end of the secondary side of the isolation circuit; A third capacitor, wherein a first end of the third capacitor is connected to the second output end of the matrix switch circuit, and a second end of the third capacitor is connected to the second end of the primary side of the isolation circuit.

10. The power conversion device according to claim 6, wherein: In the case where the power conversion device is a resonant DAB converter, the impedance circuit includes: a fourth capacitor, wherein a first end of the fourth capacitor is connected to the first output end of the matrix switch circuit; a third inductor, wherein a first end of the third inductor is connected to the second end of the fourth capacitor, and a second end of the third inductor is connected to the first end of the primary side of the isolation circuit; or, A first end of the third inductor is connected to a first end of a secondary side of the isolation circuit, and a second end of the third inductor is connected to a first end of the fourth capacitor.

11. The power conversion device according to claim 10, wherein: The impedance circuit further includes: A fourth inductor, wherein a first end of the fourth inductor is connected to a common node of the third inductor and the first end of the primary side of the isolation circuit, and a second end of the fourth inductor is connected to the second end of the primary side of the isolation circuit.

12. The power conversion device according to claim 10 or 11, wherein: The impedance circuit further includes: A fifth capacitor, wherein a first end of the fifth capacitor is connected to the second output end of the matrix switch circuit, and a second end of the fifth capacitor is connected to the second end of the primary side of the isolation circuit.

13. The power conversion device according to claim 1, wherein: The isolation circuit comprises: an isolation transformer, wherein a primary first end of the isolation transformer is connected to the first output end of the matrix switch circuit, a primary second end of the isolation transformer is connected to the second output end of the matrix switch circuit, a secondary first end of the isolation transformer is connected to the first midpoint end of the voltage conversion circuit, and a secondary second end of the isolation transformer is connected to the second midpoint end of the voltage conversion circuit.

14. The power conversion device according to claim 1, wherein: The power conversion device further includes: a first filter, wherein an input end of the first filter is used to connect to an AC power supply, and an output end of the first filter is connected to an input end of the matrix switch circuit; A second filter, wherein the first input end of the second filter is connected to the first DC end of the voltage conversion circuit, the second input end of the second filter is connected to the second DC end of the voltage conversion circuit, and the output end of the second filter is used to output the filtered DC power supply.

15. A vehicle-mounted charger, characterized in that: It comprises the power conversion device as described in any one of claims 1-14.

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