Bidirectional power converter

Abstract

The present invention provides a bidirectional power converter, which includes a circuit board, a first rectifier-inverter circuit, a transformer assembly, a second rectifier-inverter circuit, a first bus and a second bus arranged on the circuit board. In the bidirectional power converter, the first bus and the second bus are formed by copper bars to achieve the converging transmission of large current, and at the same time serve as heat dissipation elements to dissipate heat for the second rectifier-inverter switch group, improving the heat dissipation capacity of the bidirectional power converter. Moreover, the internal rectifier-inverter switch groups, transformer windings and filter capacitor assemblies of the first rectifier-inverter circuit and the second rectifier-inverter circuit are arranged adjacently, making the AC path the shortest and reducing the AC loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic circuits, and particularly relates to a bidirectional power converter. Background Art

[0002] One of the core components of electric energy storage is a bidirectional power supply, including a bidirectional DC-DC converter and a bidirectional AC-DC converter, which realizes the charging and discharging functions of a battery.

[0003] In order to realize the miniaturization and light weight of an energy storage system, the improvement of battery technology is an inevitable way. At the same time, the volume and weight of the converter should be reduced, the conversion efficiency should be improved, and the loss should be reduced, so as to ultimately improve the conversion efficiency of the entire energy storage system.

[0004] Taking the bidirectional DC-DC converter as an example, its conversion efficiency, power density and power level are continuously increasing. The improvement of power density must improve the conversion efficiency. The increase of power level means that the output current is getting larger and larger. The connection of ordinary multi-layer thick copper PCBs is not sufficient to support large currents of hundreds of amperes, resulting in limited power level improvement. At the same time, in the traditional bidirectional DC-DC converter, in order to reduce heat generation, the distances between the electrical components are relatively far, resulting in large AC losses.

[0005] Therefore, in the traditional bidirectional DC-DC converter, there are problems of limited power level and large AC losses due to the use of multi-layer thick copper PCBs. Summary of the Invention

[0006] The purpose of the present invention is to provide a bidirectional power converter, aiming to solve the problems of limited power level and large AC losses in the traditional bidirectional DC-DC converter due to the use of multi-layer thick copper PCBs.

[0007] The first solution of the embodiment of the present invention provides a bidirectional power converter, which operates in a boost mode and a buck mode. The bidirectional power converter includes a circuit board and a first rectifier-inverter circuit disposed on the circuit board for switching to an inverter operating state in the buck mode and switching to a rectifier operating state in the boost mode, a transformer assembly for voltage conversion, a second rectifier-inverter circuit for switching to a rectifier operating state in the buck mode and switching to an inverter operating state in the boost mode, and a first bus and a second bus for transmitting a low-voltage DC power supply;

[0008] The transformer assembly includes a transformer composed of a magnetic core, a first side winding and a second side winding coupled to the magnetic core, and pins associated with the first side winding and the second side winding, and an exciting inductor, a resonant capacitor and a resonant inductor connected corresponding to the first side winding. The exciting inductor, the resonant capacitor and the resonant inductor are arranged side by side in sequence in a direction perpendicular to the heat dissipation direction;

[0009] The first rectifier-inverter circuit includes a first rectifier-inverter switch group and at least one first filter capacitor component coupled across the first rectifier-inverter switch group. Each switching device in the first rectifier-inverter switch group is correspondingly connected to the exciting inductor, the resonant capacitor, and the resonant inductor, and is arranged adjacent and side by side along the arrangement direction of the exciting inductor, the resonant capacitor, and the resonant inductor. The first filter capacitor component is arranged adjacent to the resonant capacitor on both sides of the first rectifier-inverter switch group;

[0010] The second rectifier-inverter circuit includes a second rectifier-inverter switch group coupled between the first bus and the second bus and at least one second filter capacitor component coupled across the second rectifier-inverter switch group;

[0011] The first bus and the second bus are arranged to extend around at least three sides of the magnetic core along the heat dissipation direction or the opposite direction of the heat dissipation direction. The first bus and the second bus are composed of copper bars and are subjected to busbar connection. Each switch surface of the second rectifier-inverter switch group is mounted on the circuit board and is located in the space between the magnetic core and the surface of the circuit board.

[0012] In one embodiment, the first rectifier-inverter switch group includes a first switching device, a second switching device, a third switching device, and a fourth switching device that form a symmetrical bridge arm. The second switching device, the first switching device, the third switching device, and the fourth switching device are arranged side by side in sequence along a direction perpendicular to the heat dissipation direction.

[0013] In one embodiment, the connection node between the first switching device and the second switching device is connected to the first end of the resonant inductor. The connection node between the third switching device and the fourth switching device is connected to the first end of the resonant capacitor. The second end of the resonant inductor and the second end of the resonant capacitor are connected to both ends of the first side winding. The exciting inductor is correspondingly coupled between the resonant inductor and the resonant capacitor;

[0014] The first filter capacitor component is arranged adjacent to the resonant capacitor on both sides of the first rectifier-inverter switch group.

[0015] In one embodiment, the second rectifier-inverter switch group includes a fifth switching device, a sixth switching device, a seventh switching device, and an eighth switching device that form a symmetrical bridge arm. The fifth switching device, the sixth switching device, the seventh switching device, and the eighth switching device each include a plurality of electronically switched tubes connected in parallel. The plurality of electronically switched tubes of each switching device are symmetrically mounted on the circuit board on both sides of the magnetic core along the heat dissipation direction or the opposite direction of the heat dissipation direction and are located in the space between the magnetic core and the surface of the circuit board.

[0016] In one embodiment, the fifth switching device includes a first electronic switching tube and a second electronic switching tube connected in parallel, the sixth switching device includes a third electronic switching tube and a fourth electronic switching tube connected in parallel, the seventh switching device includes a fifth electronic switching tube and a sixth electronic switching tube connected in parallel, and the eighth switching device includes a seventh electronic switching tube and an eighth electronic switching tube connected in parallel;

[0017] The first electronic switching tube, the third electronic switching tube, the seventh electronic switching tube, and the fifth electronic switching tube are arranged side by side on a circuit board on one side of the magnetic core of the transformer along the heat dissipation direction or the opposite direction of the heat dissipation direction, and the second electronic switching tube, the fourth electronic switching tube, the eighth electronic switching tube, and the sixth electronic switching tube are arranged side by side on the circuit board on the opposite side of the magnetic core of the transformer along the heat dissipation direction or the opposite direction of the heat dissipation direction.

[0018] In one embodiment, the first bus and the second bus extend around the first side, the second side, and the third side of the magnetic core. The first end and the second end of the first bus and the first end and the second end of the second bus jointly define an open fourth side, and the partial buses of the first bus and the second bus relative to the second side of the magnetic core are laterally positioned with respect to the heat dissipation direction.

[0019] In one embodiment, the partial buses of the first bus and the second bus are wound correspondingly to form an air-core inductor.

[0020] In one embodiment, the second filter capacitor assembly includes a plurality of first filter capacitors connected in parallel and a plurality of second filter capacitors connected in parallel. The plurality of first filter capacitors are symmetrically arranged between the first side of the first bus and the first side of the second bus and between the third side of the first bus and the third side of the second bus. The plurality of second filter capacitors are arranged between the second side of the first bus and the second side of the second bus. The plurality of first filter capacitors are respectively connected to the first switching device, the second switching device, the third switching device, and the fourth switching device for switching filtering, and the plurality of second filter capacitors are correspondingly connected to the first bus and the second bus for input-output filtering.

[0021] In one embodiment, the first filter capacitor assembly includes a third capacitor and a fourth capacitor, and the third capacitor, the fourth capacitor, and the first rectifier-inverter switch group are arranged adjacent to each other side by side in sequence along the heat dissipation direction or the opposite direction of the heat dissipation direction;

[0022] The fourth capacitor is respectively connected to the first switching device, the second switching device, the third switching device, and the fourth switching device and is used for switching filtering. The third capacitor is respectively connected to the first switching device, the second switching device, the third switching device, and the fourth switching device and is used for input / output filtering.

[0023] In one embodiment, the exciting inductor includes a first inductor and a second inductor. The first end of the first inductor is connected to the first end of the resonant inductor. The second end of the first inductor is connected to the first end of the resonant capacitor. The first end of the second inductor is connected to the second end of the resonant inductor. The second end of the second inductor is connected to the second end of the resonant capacitor. The coils of the first inductor and the second inductor are wound around the same magnetic core.

[0024] In the bidirectional power converter according to the embodiment of the present invention, the first bus and the second bus are formed by copper bars to achieve the converging transmission of large currents. At the same time, as heat dissipation elements, they dissipate heat for the second rectifier-inverter switch group, improving the heat dissipation capacity of the bidirectional power converter. Moreover, the internal rectifier-inverter switch groups, transformer windings, and filter capacitor assemblies of the first rectifier-inverter circuit and the second rectifier-inverter circuit are arranged adjacently, making the AC path the shortest and reducing the AC loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the module structure of the bidirectional power converter provided by the embodiment of the present invention;

[0026] Figure 2 It is a schematic circuit diagram of the bidirectional power converter provided by the embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure of the bidirectional power converter provided by the embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram of the first current flow direction in the buck mode of the bidirectional power converter provided by the embodiment of the present invention;

[0029] Figure 5 It is a schematic diagram of the second current flow direction in the buck mode of the bidirectional power converter provided by the embodiment of the present invention;

[0030] Figure 6 It is a schematic diagram of the first current flow direction in the boost mode of the bidirectional power converter provided by the embodiment of the present invention;

[0031] Figure 7 It is a schematic diagram of the second current flow direction in the boost mode of the bidirectional power converter provided by the embodiment of the present invention;

[0032] Figure 8 ForFigure 3 Schematic diagram of the left view of the bidirectional power converter provided by the embodiment. Detailed implementation

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0035] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0036] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0037] In the first aspect of the embodiment of the present invention, a bidirectional power converter is provided.

[0038] As Figure 1 shown, the bidirectional power converter includes a circuit board and a first rectifier-inverter circuit 10, a transformer assembly 20, a second rectifier-inverter circuit 30 that are sequentially connected and disposed on the circuit board, and a first bus bar L1 and a second bus bar L2 that are electrically connected to the second rectifier-inverter circuit 30. The first bus bar L1 and the second bus bar L2 are used to transfer low-voltage DC power.

[0039] Among them, in the step-down mode, the first rectifier-inverter circuit 10 switches to the inverter operating state, and the second rectifier-inverter circuit 30 operates in the rectifier operating state. That is, the input high-voltage DC power supply is inverted by the first rectifier-inverter circuit 10 to output a high-voltage AC power supply. The high-voltage AC power supply is stepped down by the transformer assembly 20 and rectified by the second rectifier-inverter circuit 30 to output a low-voltage DC power supply. The low-voltage DC power supply is output by converging from the first bus bar L1 and the second bus bar L2.

[0040] In the step-up mode, the second rectifier-inverter circuit 30 switches to the inverter operating state, and the first rectifier-inverter circuit 10 operates in the rectifier operating state. The low-voltage DC power supply is input to the first bus bar L1 and the second bus bar L2 and transmitted to the second rectifier-inverter circuit 30. The second rectifier-inverter circuit 30 inversely outputs a low-voltage AC power supply. The low-voltage AC power supply is stepped up by the transformer T1 and rectified by the first rectifier-inverter circuit 10 for output.

[0041] Among them, as Figure 2 and Figure 3 shown, the transformer assembly 20 includes a transformer T1 composed of a magnetic core 21, a first side winding 23 and a second side winding 22 coupled to the magnetic core 21, and pins associated with the first side winding 23 and the second side winding 22, and an exciting inductor, a resonant capacitor Cr and a resonant inductor Lr connected corresponding to the first side winding 23 of the transformer T1. The exciting inductor, the resonant capacitor Cr and the resonant inductor Lr are arranged side by side in sequence in a direction perpendicular to the heat dissipation direction.

[0042] The first rectifier-inverter circuit 10 includes a first rectifier-inverter switch group and at least one first filter capacitor assembly coupled across the first rectifier-inverter switch group. Each switching device in the first rectifier-inverter switch group is correspondingly connected to the exciting inductor, the resonant capacitor Cr and the resonant inductor Lr and is arranged adjacent and side by side along the arrangement direction of the exciting inductor, the resonant capacitor Cr and the resonant inductor Lr. The first filter capacitor assembly and the resonant capacitor are both arranged adjacent to both sides of the first rectifier-inverter switch group.

[0043] The second rectifier-inverter circuit 30 includes a second rectifier-inverter switch group coupled between the first bus bar L1 and the second bus bar L2 and at least one second filter capacitor assembly coupled across the second rectifier-inverter switch group.

[0044] The first bus bar L1 and the second bus bar L2 are arranged to extend around at least three sides of the magnetic core 21 along the heat dissipation direction or the opposite direction of the heat dissipation direction. The first bus bar L1 and the second bus bar L2 are formed by copper bars to constitute a bus bar for converging. Each switch surface of the second rectifier-inverter switch group is mounted on the circuit board and is located in the space between the magnetic core 21 and the surface of the circuit board.

[0045] In this embodiment, both ends of the first rectifier-inverter switch group form the power supply terminals of the first rectifier-inverter circuit 10, and are connected to the first side winding 23 of the transformer T1 through the excitation inductor, the resonant capacitor Cr, and the resonant inductor Lr. The first power supply terminal of the second rectifier-inverter switch group is connected to the second side winding 22 of the transformer T1, and the second power supply terminal of the second rectifier-inverter switch group is respectively connected to the first bus bar L1 and the second bus bar L2. The first bus bar L1 and the second bus bar L2 form the bus bars of the second rectifier-inverter circuit 30. The bus bars are exposed to the cooling air flow for heat dissipation by means of heat exchange. The heat dissipation direction of forced air cooling can be arbitrarily selected. For Figure 3 example, the wind direction can be from right to left or from left to right. Moreover, the first bus bar L1 and the second bus bar L2 adopt a copper bar structure. The copper bar undertakes the functions of large current output and heat dissipation. There is no need to additionally set heat dissipation components in the bidirectional power converter, which saves the board space and cost. And the first bus bar L1 and the second bus bar L2 are arranged to extend around at least three sides of the magnetic core 21, further improving the heat dissipation effect.

[0046] The switching devices in the rectifier-inverter switch group can adopt MOSFETs or IGBTs integrated with fast recovery diodes, or can also adopt third-generation power devices, such as wide bandgap power devices like SiC MOSFETs and GaN. The third-generation power devices can further reduce the drive loss, switching loss, and junction capacitance loss, and have higher efficiency.

[0047] The excitation inductor, the resonant inductor Lr, and the electronic devices can adopt a chip structure or discrete packaging devices. At the same time, multi-layer PCB winding can be used to replace the traditional winding or copper strip, further improving the power density and realizing the module design of miniaturization and light weight. The number of each component can be increased or decreased correspondingly according to the current magnitude and power level.

[0048] In this embodiment, the bidirectional power converter is based on the LLC topology structure to realize bidirectional power conversion.

[0049] Among them, when the bidirectional power converter operates in the buck mode, as Figure 4 shown, when a set of diagonal switching devices Q1 and Q4 in the first rectifier-inverter switch group are simultaneously turned on, the transformer T1 is magnetized forward and operates. In order to ensure that the output waveform of the transformer T1 is close to a sine wave, the switching frequency is close to the resonant frequency of the resonant capacitor Cr and the resonant inductor Lr. Both diagonal switching devices Q1 and Q4 achieve zero-current turn-on. At the same time, a set of diagonal switching devices Q5 and Q8 in the second rectifier-inverter switch group are simultaneously turned on for synchronous rectification. The sine wave current is smoothed by flowing through the second filter capacitor assembly, and then is output by large current converging through the first bus bar L1 and the second bus bar L2.

[0050] Similarly, as Figure 5As shown, when the switching devices Q2 and Q3 at the other pair of diagonals in the first rectifier-inverter switch group are conducting simultaneously, the transformer T1 operates in reverse excitation. The switching frequency is close to the resonance frequency of the resonance capacitor Cr and the resonance inductor Lr. The current in the transformer T1 approaches a sinusoidal waveform, and the switching devices at the diagonals achieve zero-current turn-on. The switching devices Q6 and Q7 at the other pair of diagonals in the second rectifier-inverter switch group conduct simultaneously for synchronous rectification. The sinusoidal current flows through the second filter capacitor assembly and is smoothed, and then large-current convergence output is performed through the first bus bar L1 and the second bus bar L2.

[0051] Because it operates near the resonance frequency and the currents are all sinusoidal, the switching devices can achieve zero-voltage turn-off from turn-on to turn-off. In addition, there is a dead zone between the turn-on and turn-off of the upper and lower switching devices in the same bridge arm to ensure that the upper and lower switching devices in the bridge arm do not conduct simultaneously, avoiding faults caused by short circuits.

[0052] When operating in the boost mode, as Figure 6 shown, when the switching devices Q5 and Q8 at one pair of diagonals in the second rectifier-inverter switch group are conducting simultaneously, the transformer T1 operates in forward excitation. To ensure that the output waveform of the transformer T1 is close to a sinusoidal waveform, the switching frequency is close to the resonance frequency of the resonance capacitor Cr and the resonance inductor Lr. The switching devices at the diagonals achieve zero-current turn-on. At the same time, the switching devices Q1 and Q4 at one pair of diagonals in the first rectifier-inverter switch group conduct simultaneously for synchronous rectification. The sinusoidal current flows through the first filter capacitor assembly and is smoothed, and the ripple current is greatly reduced, achieving a stable DC output.

[0053] Similarly, as Figure 7 shown, when the switching devices Q6 and Q7 at the other pair of diagonals in the second rectifier-inverter switch group are conducting simultaneously, the transformer T1 operates in reverse excitation. The switching frequency is close to the resonance frequency of the resonance capacitor Cr and the resonance inductor Lr. The current in the transformer T1 approaches a sinusoidal waveform, and the switching devices at the diagonals achieve zero-current turn-on. The switching devices Q2 and Q3 at the other pair of diagonals in the first rectifier-inverter switch group conduct for synchronous rectification. The sinusoidal current first flows through the first filter capacitor assembly and is smoothed, and the ripple current is greatly reduced, achieving a stable DC output.

[0054] Because it operates near the resonance frequency and the currents are all sinusoidal, the switching devices can achieve zero-voltage turn-off from turn-on to turn-off. In addition, there is a dead zone between the turn-on and turn-off of the upper and lower switching devices in the same bridge arm to ensure that the upper and lower switching devices in the bridge arm do not conduct simultaneously, avoiding faults caused by short circuits.

[0055] Among them, to reduce the AC connection loop in the boost mode and the buck mode and reduce the AC loss, as Figure 3As shown, the exciting inductor, the resonant capacitor Cr, and the resonant inductor Lr are arranged side by side in sequence in a direction perpendicular to the heat dissipation direction. Each switching device in the first rectifier-inverter switch group is arranged side by side in a direction perpendicular to the heat dissipation direction and symmetrically arranged on the circuit board. The first filter capacitor assembly and the resonant capacitor Cr are both arranged adjacent to both sides of the first rectifier-inverter switch group. Each switch surface of the second rectifier-inverter switch group is mounted on the circuit board and is located in the space between the magnetic core 21 and the surface of the circuit board.

[0056] When operating in the buck mode, the alternating current flows back to the second-side winding 22 of the transformer T1 from the second-side winding 22 of the transformer T1, the diagonal switching devices in the second rectifier-inverter switch group, and the filter capacitor assembly. The alternating current connection loop is the shortest, effectively smoothing the current waveform. At the same time, the AC loss is reduced. Finally, the rectified DC current is output to the load. The first bus bar L1 and the second bus bar L2 adopt a copper bar structure, which not only connects the large current on the low-voltage side, reducing the conduction loss, but also serves as the heat sink for each switching device in the second rectifier-inverter switch group, reducing the temperature rise of the switching device and saving the overall occupied space and cost of the bidirectional power converter.

[0057] When operating in the boost mode, the AC power supply flows back to the first-side winding 23 of the transformer T1 through the first-side winding 23 of the transformer T1, the resonant capacitor Cr, the diagonal switching devices in the first rectifier-inverter switch group, the first filter capacitor assembly C1, and the resonant inductor Lr. The alternating current connection loop is the shortest, effectively smoothing the current waveform and reducing the AC loss. Finally, the DC current is output to the load.

[0058] By setting the positions and structures of the components of the first rectifier-inverter circuit 10 and the second rectifier-inverter circuit 30, the AC path is made the shortest, reducing the AC loss.

[0059] The first rectifier-inverter switch group and the second rectifier-inverter switch group can adopt a half-bridge topology structure or a full-bridge topology structure. In one embodiment, both the first rectifier-inverter switch group and the second rectifier-inverter switch group are full-bridge topology structures.

[0060] One or more switching tubes can be connected in parallel inside the first rectifier-inverter switch group and the second rectifier-inverter switch group according to the power conversion requirements. For example Figure 2 and Figure 3As shown, in one embodiment, the first rectifier-inverter switch group includes a first switching device Q1, a second switching device Q2, a third switching device Q3, and a fourth switching device Q4 that form a symmetrical bridge arm. The second switching device Q2, the first switching device Q1, the third switching device Q3, and the fourth switching device Q4 are arranged side by side in sequence in a direction perpendicular to the heat dissipation direction. One or more switching tubes can be correspondingly arranged in parallel connection for the first switching device Q1, the second switching device Q2, the third switching device Q3, and the fourth switching device Q4 according to the power conversion requirements.

[0061] Meanwhile, the connection node between the first switching device Q1 and the second switching device Q2 is connected to the first end of the resonant inductor Lr. The connection node between the third switching device Q3 and the fourth switching device Q4 is connected to the first end of the resonant capacitor Cr. The second end of the resonant inductor Lr and the second end of the resonant capacitor Cr are connected to both ends of the first side winding. The exciting inductor is correspondingly coupled between the resonant inductor Lr and the resonant capacitor Cr.

[0062] In one embodiment, the second rectifier-inverter switch group includes a fifth switching device Q5, a sixth switching device Q6, a seventh switching device Q7, and an eighth switching device Q8 that form a symmetrical bridge arm. The fifth switching device Q5, the sixth switching device Q6, the seventh switching device Q7, and the eighth switching device Q8 each include a plurality of electronically switched tubes connected in parallel. The multiple electronically switched tubes of each switching device are symmetrically mounted on the circuit boards on both sides of the magnetic core 21 along the heat dissipation direction or the opposite direction of the heat dissipation direction, and are located in the space between the magnetic core 21 and the surface of the circuit board.

[0063] Further, in order to achieve the shortest AC connection loop, in one embodiment, as Figure 3 shown, the fifth switching device Q5 includes a first electronically switched tube Q51 and a second electronically switched tube Q52 connected in parallel. The sixth switching device Q6 includes a third electronically switched tube Q61 and a fourth electronically switched tube Q62 connected in parallel. The seventh switching device Q7 includes a fifth electronically switched tube Q71 and a sixth electronically switched tube Q72 connected in parallel. The eighth switching device Q8 includes a seventh electronically switched tube Q81 and an eighth electronically switched tube Q82 connected in parallel.

[0064] The first electronically switched tube Q51, the third electronically switched tube Q61, the seventh electronically switched tube Q81, and the fifth electronically switched tube Q71 are arranged side by side on the circuit board on one side of the magnetic core 21 of the transformer along the heat dissipation direction or the opposite direction of the heat dissipation direction. The second electronically switched tube Q52, the fourth electronically switched tube Q62, the eighth electronically switched tube Q82, and the sixth electronically switched tube Q72 are arranged side by side on the circuit board on the opposite side of the magnetic core 21 of the transformer along the heat dissipation direction or the opposite direction of the heat dissipation direction.

[0065] Meanwhile, in order to correspond to the connection structure of each electronic switch tube and to improve the heat dissipation capacity, in one embodiment, the first bus bar L1 and the second bus bar L2 extend around the first side, the second side, and the third side of the magnetic core 21. The first end and the second end of the first bus bar L1 and the first end and the second end of the second bus bar L2 jointly define an open fourth side, and the partial bus bars of the first bus bar L1 and the second bus bar L2 relative to the second side of the magnetic core 21 are positioned transversely with respect to the heat dissipation direction.

[0066] Wherein, the first bus bar L1 includes a first metal segment L11 corresponding to the first side, the second side, and the third side of the magnetic core 21, a second metal segment L12, and a third metal segment L13 connecting the first metal segment L11 and the second metal segment L12. The second bus bar L2 includes a fourth metal segment L21 arranged in parallel and spaced apart from the first metal segment L11 corresponding to the first side, the second side, and the third side of the magnetic core 21, a fifth metal segment L22 arranged in parallel and spaced apart from the second metal segment L12, and a sixth metal segment L23 arranged in parallel and spaced apart from the third metal segment L13. The sixth metal segment L23 connects the fourth metal segment L21 and the fifth metal segment L22. The first metal segment L11 is arranged adjacent to the magnetic core 21 of the transformer T1 along the heat dissipation direction or the opposite direction of the heat dissipation direction and is connected to the first electronic switch tube Q51 and the fifth electronic switch tube Q71. The second metal segment L12 is arranged adjacent to the magnetic core 21 of the transformer T1 along the heat dissipation direction or the opposite direction of the heat dissipation direction and is connected to the second electronic switch tube Q52 and the sixth electronic switch tube Q72. The fourth metal segment L21 is correspondingly connected to the third electronic switch tube Q61 and the seventh electronic switch tube Q81. The fifth metal segment L22 is correspondingly connected to the fourth electronic switch tube Q62 and the eighth electronic switch tube Q82. The first filter capacitor is correspondingly arranged and connected between the first metal segment L11 and the fourth metal segment L21, and / or arranged and connected between the first bus bar L1 and the second bus bar L2.

[0067] Furthermore, in order to improve the filtering effect, in one embodiment, partial bus bars of the first bus bar L1 and the second bus bar L2 are correspondingly wound to form an air-core inductor. When the first bus bar L1 and the second bus bar L2 are input and output, inductive filtering is achieved to further smooth the input and output current waveforms.

[0068] One or more first filter capacitor assemblies and second filter capacitor assemblies can be provided, which can be used for switching conversion filtering or input and output filtering. In one embodiment, such as Figure 3As shown, the second filter capacitor assembly includes a plurality of first filter capacitors C1 connected in parallel and a plurality of second filter capacitors C2 connected in parallel. Moreover, the plurality of first filter capacitors C1 are symmetrically arranged between the first side of the first bus bar L1 and the first side of the second bus bar L2, and between the third side of the first bus bar L1 and the third side of the second bus bar L2. The plurality of second filter capacitors C2 are arranged between the second side of the first bus bar L1 and the second side of the second bus bar L2. The plurality of first filter capacitors C1 are respectively connected to the fifth switching device Q5, the sixth switching device Q6, the seventh switching device Q7, and the eighth switching device Q8 for switching filtering, and the plurality of second filter capacitors C2 are correspondingly connected to the first bus bar L1 and the second bus bar L2 for input and output filtering.

[0069] In one embodiment, the number of the first filter capacitors C1 is an even number, and they are symmetrically arranged between the first metal segment L11 and the fourth metal segment L21, and between the second metal segment L12 and the fifth metal segment L22. Specifically, as Figure 3 shown, there are eight first filter capacitors C1. And to save the board space, four of them are arranged side by side between the first metal segment L11 and the fourth metal segment L21, and the other four are arranged side by side between the second metal segment L12 and the fifth metal segment L22.

[0070] In one embodiment, as Figure 3 shown, there are three second filter capacitors C2. The three second filter capacitors C2 are arranged side by side at intervals between the third metal segment L13 and the sixth metal segment L23.

[0071] In one embodiment, the first filter capacitor assembly includes a third capacitor C3 and a fourth capacitor C4. As Figure 3 shown, the third capacitor C3, the fourth capacitor C4, and the first rectifier-inverter switch group are arranged adjacent to each other side by side in the heat dissipation direction or the reverse direction of the heat dissipation direction. The center points of the third capacitor C3, the fourth capacitor C4, the distribution center points of the switches of the first rectifier-inverter switch group, and the center point of the resonant capacitor Cr are on a straight line.

[0072] As Figure 2 shown, the fourth capacitor C4 is respectively connected to the first switching device Q1, the second switching device Q2, the third switching device Q3, and the fourth switching device Q4 for switching filtering, and the third capacitor C3 is respectively connected to the first switching device Q1, the second switching device Q2, the third switching device Q3, and the fourth switching device Q4 and is used for input and output filtering.

[0073] In this embodiment, in the buck mode, when the first switching device Q1 and the fourth switching device Q4 are turned on simultaneously, the transformer T1 is magnetized in the forward direction. On the one hand, the alternating current component flows from the source of the first electronic switching tube Q51 through the drain, through the positive electrode to the negative electrode of the first filter capacitor C1, then through the source of the seventh electronic switching tube Q81 to the drain, and finally returns to the second side winding 22 of the transformer T1. On the other hand, the alternating current component flows from the source of the second electronic switching tube Q52 through the drain, through the positive electrode to the negative electrode of the first filter capacitor C1, then through the source of the eighth electronic switching tube Q82 to the drain, and finally returns to the second side winding 22 of the transformer T1. The alternating current connection loop is the shortest, which not only effectively smooths the current waveform but also reduces the AC loss.

[0074] In the buck mode, when the second switching device Q2 and the third switching device Q3 are turned on simultaneously, the transformer T1 is magnetized in the reverse direction. On the one hand, the alternating current flows from the source of the fifth electronic switching tube Q71 through the drain, through the positive electrode to the negative electrode of the first filter capacitor C1, then through the source of the third electronic switching tube Q61 to the drain, and finally returns to the second side winding 22 of the transformer T1.

[0075] On the other hand, the alternating current component flows from the source of the sixth electronic switching tube Q72 through the drain, through the positive electrode to the negative electrode of the first filter capacitor C1, then through the source of the fourth electronic switching tube Q62 to the drain, and finally returns to the second side winding 22 of the transformer T1. The alternating current connection loop is the shortest, which not only effectively smooths the current waveform but also reduces the AC loss.

[0076] After the alternating current is smoothed by the first filter capacitor C1, the AC component is greatly reduced, and finally it is further smoothed into a direct current through the second filter capacitor to provide stable DC power supply to the load.

[0077] In addition to connecting the large current on the low-voltage side to reduce the conduction loss, the first bus bar L1 and the second bus bar L2 can also be used as heat sinks for the switching tubes to reduce the temperature rise of the switching tubes. Moreover, the placed first bus bar L1 and second bus bar L2 construct a hollow inductor, which acts as a filter inductor to achieve the filtering function, eliminating the need for additional filter inductors, saving the board space and reducing the cost.

[0078] In the boost mode, when the transformer T1 is magnetized in the forward direction, the alternating current passes through the resonant inductor Lr, flows from the source of the first switching device Q1 through the drain, through the positive electrode to the negative electrode of the fourth filter capacitor C4, then through the source of the fourth switching device Q4 to the drain, and finally returns to the first side winding 23 of the transformer T1 through the resonant capacitor Cr.

[0079] When the transformer T1 is reversely excited, the alternating current passes through the resonant capacitor Cr, flows from the source to the drain of the third switching device Q3, passes from the positive electrode to the negative electrode of the fourth filter capacitor C4, and then flows from the source to the drain of the second switching device Q2, and finally returns to the first side winding 23 of the transformer T1 through the resonant inductor Lr.

[0080] Regardless of whether the transformer T1 is forwardly excited or reversely excited, the connection loop of the alternating current is the shortest, which not only effectively smooths the current waveform, but also reduces the AC loss. At the same time, after the alternating current is smoothed by the first filter capacitor C1, the AC component is greatly reduced, and finally, it is further smoothed into a direct current by the second filter capacitor C2 to provide stable DC power supply to the load.

[0081] Further, in order to improve the output efficiency, in one embodiment, the exciting inductor includes a first inductor Lm1 and a second inductor Lm2. The first end of the first inductor Lm1 is connected to the first end of the resonant inductor Lr, the second end of the first inductor Lm1 is connected to the first end of the resonant capacitor Cr, the first end of the second inductor Lm2 is connected to the second end of the resonant inductor Lr, and the second end of the second inductor Lm2 is connected to the second end of the resonant capacitor Cr. And through the magnetic integration technology, the coils of the first inductor Lm1 and the second inductor Lm2 are wound around the same magnetic core 21, saving the board space and cost.

[0082] In order to meet the safety regulations requirements and increase the output current, in one embodiment, as Figure 8 shown, the first side winding 23 of the transformer T1 is an insulated wire structure and is a multi-layer insulated wire structure, the second side winding 22 of the transformer T1 is a copper strip structure, and low-voltage switching tubes are arranged on both sides of the magnetic core 21 of the transformer T1.

[0083] In order to further save the board space, as Figure 3 shown, in one embodiment, the resonant capacitor Cr is a chip capacitor.

[0084] At the same time, the bidirectional power converter can be arranged on the upper surface and / or the lower surface of the circuit board. The circuit board is a multi-layer circuit board, and the components arranged on the circuit board are correspondingly connected through the corresponding copper foils or leads of the multi-layer circuit board.

[0085] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A bidirectional power converter that operates in boost mode and buck mode, characterized in that, It includes a circuit board, a first rectifier-inverter circuit disposed on the circuit board and used to switch to an inverter operating state in a buck mode and to a rectifier operating state in a boost mode, a transformer assembly used for voltage conversion, a second rectifier-inverter circuit used to switch to a rectifier operating state in a buck mode and to an inverter operating state in a boost mode, and a first bus and a second bus used to transfer a low-voltage DC power supply; The transformer assembly includes a transformer composed of a magnetic core, a first side winding and a second side winding coupled to the magnetic core, and pins associated with the first side winding and the second side winding, and an exciting inductor, a resonant capacitor and a resonant inductor connected correspondingly to the first side winding. The exciting inductor, the resonant capacitor and the resonant inductor are arranged side by side in sequence along a direction perpendicular to the heat dissipation direction; The first rectifier-inverter circuit includes a first rectifier-inverter switch group and at least one first filter capacitor assembly coupled across the first rectifier-inverter switch group. Each switching device in the first rectifier-inverter switch group is correspondingly connected to the exciting inductor, the resonant capacitor and the resonant inductor and is arranged adjacent to and side by side along the arrangement direction of the exciting inductor, the resonant capacitor and the resonant inductor. The first filter capacitor assembly is arranged adjacent to the resonant capacitor on both sides of the first rectifier-inverter switch group; The second rectifier-inverter circuit includes a second rectifier-inverter switch group coupled between the first bus and the second bus and at least one second filter capacitor assembly coupled across the second rectifier-inverter switch group; The first bus and the second bus are arranged to extend around at least three sides of the magnetic core along the heat dissipation direction or the opposite direction of the heat dissipation direction. The first bus and the second bus are composed of copper bars and are subjected to busbar connection. Each switch surface of the second rectifier-inverter switch group is mounted on the circuit board and is located in the space between the magnetic core and the surface of the circuit board.

2. The bidirectional power converter according to claim 1, wherein The first rectifier-inverter switch group includes a first switching device, a second switching device, a third switching device and a fourth switching device that form a symmetric bridge arm. The second switching device, the first switching device, the third switching device and the fourth switching device are arranged side by side in sequence along a direction perpendicular to the heat dissipation direction.

3. The bidirectional power converter according to claim 2, wherein The connection node between the first switching device and the second switching device is connected to the first end of the resonant inductor. The connection node between the third switching device and the fourth switching device is connected to the first end of the resonant capacitor. The second end of the resonant inductor, the second end of the resonant capacitor and the two ends of the first side winding are connected. The exciting inductor is correspondingly coupled between the resonant inductor and the resonant capacitor.

4. The bidirectional power converter according to claim 2, characterized in that, The second rectifying and inverting switch group includes a fifth switch device, a sixth switch device, a seventh switch device, and an eighth switch device that form a symmetric bridge arm. The fifth switch device, the sixth switch device, the seventh switch device, and the eighth switch device each include a plurality of electronically switched tubes connected in parallel. The plurality of electronically switched tubes of each switch device are symmetrically mounted on the circuit board on both sides of the magnetic core along the heat dissipation direction or the opposite direction of the heat dissipation direction, and are located in the space between the magnetic core and the surface of the circuit board.

5. The bidirectional power converter according to claim 4, wherein The fifth switch device includes a first electronically switched tube and a second electronically switched tube connected in parallel. The sixth switch device includes a third electronically switched tube and a fourth electronically switched tube connected in parallel. The seventh switch device includes a fifth electronically switched tube and a sixth electronically switched tube connected in parallel. The eighth switch device includes a seventh electronically switched tube and an eighth electronically switched tube connected in parallel. The first electronically switched tube, the third electronically switched tube, the seventh electronically switched tube, and the fifth electronically switched tube are arranged side by side on the circuit board on one side of the magnetic core of the transformer along the heat dissipation direction or the opposite direction of the heat dissipation direction. The second electronically switched tube, the fourth electronically switched tube, the eighth electronically switched tube, and the sixth electronically switched tube are arranged side by side on the circuit board on the opposite side of the magnetic core of the transformer along the heat dissipation direction or the opposite direction of the heat dissipation direction.

6. The bidirectional power converter according to claim 5, wherein The first bus bar and the second bus bar extend around the first side, the second side, and the third side of the magnetic core. The first end and the second end of the first bus bar and the first end and the second end of the second bus bar together define an open fourth side, and the partial bus bars of the first bus bar and the second bus bar relative to the second side of the magnetic core are laterally positioned relative to the heat dissipation direction.

7. The bidirectional power converter according to claim 6, wherein The partial bus bars of the first bus bar and the second bus bar are wound correspondingly to form an air-core inductor.

8. The bidirectional power converter according to claim 7, wherein The second filter capacitor assembly includes a plurality of first filter capacitors connected in parallel and a plurality of second filter capacitors connected in parallel. The plurality of first filter capacitors are symmetrically arranged between the first side of the first bus bar and the first side of the second bus bar and between the third side of the first bus bar and the third side of the second bus bar. The plurality of second filter capacitors are arranged between the second side of the first bus bar and the second side of the second bus bar. The plurality of first filter capacitors are respectively connected to the first switch device, the second switch device, the third switch device, and the fourth switch device for switch filtering. The plurality of second filter capacitors are correspondingly connected to the first bus bar and the second bus bar for input and output filtering.

9. The bidirectional power converter according to claim 8, wherein The first filter capacitor assembly includes a third capacitor and a fourth capacitor. The third capacitor, the fourth capacitor, and the first rectifying and inverting switch group are arranged adjacent to each other side by side in sequence along the heat dissipation direction or the opposite direction of the heat dissipation direction. The fourth capacitor is respectively connected to the first switch device, the second switch device, the third switch device, and the fourth switch device for switch filtering. The third capacitor is respectively connected to the first switch device, the second switch device, the third switch device, and the fourth switch device for input and output filtering.

10. The bidirectional power converter according to any one of claims 1 to 9, characterized in that, The exciting inductance includes a first inductance and a second inductance. A first end of the first inductance is connected to a first end of the resonant inductance, a second end of the first inductance is connected to a first end of the resonant capacitor, a first end of the second inductance is connected to a second end of the resonant inductance, a second end of the second inductance is connected to a second end of the resonant capacitor, and coils of the first inductance and the second inductance are wound around the same magnetic core.

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