Reconfigurable series-parallel network converter with strong overcurrent capability and construction method

Abstract

The present invention provides a reconfigurable series-parallel meshed converter with strong overcurrent capability and a construction method, belonging to the technical field of power electronic directional power converters. The method comprises: connecting two ports corresponding to two asymmetric half-bridge modules, symmetric half-bridge modules or H-bridge modules respectively through two bridge-type bidirectional switches or anti-series bidirectional switches, and connecting two non-corresponding ports of a group of the above modules through a third bridge-type bidirectional switch or anti-series bidirectional switch; the converter example connects two ports corresponding to two H-bridge modules respectively through two bridge-type bidirectional switches, and connects two non-corresponding ports of a group of two H modules through a third bridge-type bidirectional switch; the present invention significantly improves the overcurrent capability of the meshed converter without increasing the number of modules, and avoids the saturation problem of magnetic components such as power semiconductor devices and filter inductors; the system is modular, the structure is simple and scalable, and it is easy to standardize.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronic direction power converters, and in particular relates to a reconfigurable series-parallel network-type converter with strong overcurrent capability and a construction method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Grid-connected converters are required for applications such as photovoltaic power generation, wind power generation, grid-connected energy storage, electric vehicle chargers / charging stations, high-voltage AC / DC transmission, power quality management, and microgrids. They perform AC / DC power conversion. Based on their grid support function, grid-connected converters can be divided into two categories: grid-following converters and grid-forming converters. Grid-following converters are equivalent to controlled current sources, while grid-forming converters are equivalent to controlled voltage sources. The latter offer advantages such as seamless on-grid and off-grid switching, excellent weak grid stability, programmable inertia and damping, and automatic multi-machine synchronization, playing a vital role in modern power grids.

[0004] Severe overcurrent is one of the key challenges facing grid-type converters. According to standards and grid guidelines, grid-type converters must withstand overcurrents of approximately three times their rated capacity for 10 seconds. However, the overcurrent capacity of power semiconductors and magnetic components must not exceed 1.5 times their rated capacity, creating an irreconcilable conflict. To improve overcurrent capacity, existing grid-type converters typically consist of several converters connected in parallel, which presents drawbacks such as high cost, bulk, weight, low efficiency, and complex control.

[0005] In addition, existing methods for improving the overcurrent capacity of grid-type converters are mostly targeted at power semiconductor devices and cannot solve the problem of saturation of magnetic components such as filter inductors. In addition, the control cost of related drive circuits is high and the design is complex, making them difficult to universalize and standardize. Summary of the Invention

[0006] To address these issues, the present invention proposes a reconfigurable series-parallel grid-type converter with strong overcurrent capability and a construction method. This invention utilizes bidirectional switches to connect modules according to a specific rule, enabling real-time reconfiguration of the modules into series or parallel operation based on grid demand. Compared to traditional grid-type converters, this invention significantly improves the overcurrent capability of the grid-type converter without increasing the number of modules, while maintaining a simple and scalable structure.

[0007] According to some embodiments, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for constructing a reconfigurable series-parallel grid-type converter with strong overcurrent capability.

[0009] A method for constructing a reconfigurable series-parallel grid-type converter with strong overcurrent capability includes:

[0010] Connect the corresponding two ends of at least two modules together through a bidirectional switch, and connect the two non-corresponding two ends of the two modules together through another bidirectional switch. Figure 4 .

[0011] In a second aspect, the present invention provides an example of a reconfigurable series-parallel grid-type converter with strong overcurrent capability.

[0012] The reconfigurable series-parallel network-type converter with strong overcurrent capability adopts the reconfigurable series-parallel network-type converter construction method described in the first aspect, through at least three Figure 2a The bidirectional switch shown will have at least two Figure 1c The H-bridge modules shown are connected to form Figure 6 The reconfigurable series-parallel network converter shown includes: at least three bidirectional switches, at least two H-bridge modules, and at least two output terminals;

[0013] The first port of the first H-bridge module is connected to the first port of the second H-bridge module via a first bidirectional switch, the second port of the first H-bridge module is connected to the second port of the second H-bridge module via a second bidirectional switch, and the second port of the first H-bridge module is connected to the first port of the second H-bridge module via a third bidirectional switch.

[0014] The first port of the first H-bridge module is the first output port of the meshed converter, and the second port of the second H-bridge module is the second output port of the meshed converter.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] Compared with traditional meshed converters, the present invention can reconstruct the converter into a module series or parallel operation state in real time as needed; significantly improve the converter's overcurrent capacity without increasing the number of modules; in the series operation state, the voltage can be evenly distributed between modules and more level outputs can be achieved; in the parallel operation state, the current can be evenly distributed between modules, avoiding the saturation of power semiconductor devices and magnetic components (including filter inductors); the converter has a simple structure and is easy to standardize. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0018] Figure 1a This is a traditional asymmetric half-bridge module structure diagram;

[0019] Figure 1b This is a traditional symmetrical half-bridge module structure diagram;

[0020] Figure 1c This is a diagram of the traditional H-bridge module structure;

[0021] Figure 2a This is a traditional bridge-type bidirectional switch structure diagram;

[0022] Figure 2b This is a traditional anti-series bidirectional switch structure diagram;

[0023] Figure 3a This is the structure diagram of the traditional cascade network converter;

[0024] Figure 3b This is the structure diagram of the traditional parallel network converter;

[0025] Figure 4 This is a structural diagram of a reconfigurable series-parallel network-type converter construction method implemented by the present invention;

[0026] Figure 5 This is a structural diagram of a three-phase construction method of a reconfigurable series-parallel network-type converter implemented by the present invention;

[0027] Figure 6 This is a structural diagram of an example of a reconfigurable series-parallel network-type converter implemented in the present invention;

[0028] Figure 7a This is a schematic diagram of a series working state of an example of a reconfigurable series-parallel network-type converter implemented by the present invention;

[0029] Figure 7b 1. It is a schematic diagram of a parallel working state of an example of a reconfigurable series-parallel network-type converter implemented in the present invention;

[0030] Figure 8a The load voltage of the reconfigurable series-parallel network converter implemented by the present invention is v load and load current i load (Upper left), module current i ac1 / i ac2 (Upper right), bidirectional switch voltage v s1 / v s2 / v s3 (lower left), bidirectional switch current i s1 / is2 / i s3 (lower right) Simulation waveform.

[0031] Figure 8b The load voltage of the reconfigurable series-parallel network converter implemented by the present invention is v load and load current i load (Upper left), module current i ac1 / i ac2 (Upper right), bidirectional switch voltage v s1 / v s2 / v s3 (lower left), bidirectional switch current i s1 / i s2 / i s3 (lower right) Simulation waveform.

[0032] Table 1 is a table of simulation system and control parameters of an example of a reconfigurable series-parallel networked converter implemented in the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the term "comprising" is used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] In the present invention, terms such as "connected" and "connection" should be interpreted broadly to mean a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediary. Relevant researchers or technicians in this field may determine the specific meanings of these terms in the present invention based on specific circumstances, and they should not be construed as limitations on the present invention.

[0037] Example 1

[0038] This embodiment provides a method for constructing a reconfigurable series-parallel grid-type converter with strong overcurrent capability.

[0039] A method for constructing a reconfigurable series-parallel grid-type converter with strong overcurrent capability includes:

[0040] The first ports (418 and 417) corresponding to at least two modules 411 (specifically, an asymmetric half-bridge module 101 or a symmetric half-bridge module 102 or an H-bridge module 103) and a module 412 (specifically, an asymmetric half-bridge module 101 or a symmetric half-bridge module 102 or an H-bridge module 103) are connected together through a first bidirectional switch 413 (specifically, a bridge bidirectional switch 201 or an anti-series bidirectional switch 202); the module 411 (specifically, an asymmetric half-bridge module 101 or a symmetric half-bridge module 102 or an H-bridge module 103) and the module 412 (specifically, an asymmetric half-bridge module 101 or a symmetric half-bridge module The second ports (416 and 419) corresponding to the reconfigurable series-parallel grid-type converter (102 or H-bridge module 103) are connected together through a second bidirectional switch 415 (specifically, a bridge bidirectional switch 201 or an anti-series bidirectional switch 202); the second port 416 of module 411 (specifically, an asymmetric half-bridge module 101 or a symmetric half-bridge module 102 or an H-bridge module 103) and the first port 417 of module 412 (specifically, an asymmetric half-bridge module 101 or a symmetric half-bridge module 102 or an H-bridge module 103) are connected together through a third bidirectional switch 414 (specifically, a bridge bidirectional switch 201 or an anti-series bidirectional switch 202). After the connection is completed, port 418 becomes the first output port of the reconfigurable series-parallel grid-type converter, and port 419 becomes the second output port of the reconfigurable series-parallel grid-type converter. Figure 4 shown.

[0041] Optionally, module 411 and module 412 may be ( Figure 1a The asymmetric half-bridge module 101 shown), ( Figure 1b Symmetrical half-bridge module 102 shown) or ( Figure 1c H-bridge module 103 shown).

[0042] Optionally, the first bidirectional switch 413, the third bidirectional switch 414 and the second bidirectional switch 415 may be ( Figure 2a The bridge bidirectional switch 201 shown) or ( Figure 2b The anti-series bidirectional switch 202 is shown.

[0043] Among them, such as Figure 1aAs shown, the asymmetric half-bridge module 101 includes at least two switches (a first switch 111 and a second switch 112), at least one energy storage element 113, and at least one filter inductor 114 or filter inductor 115. The first port of the first switch 111 is connected to one port of the energy storage element 113 (connection point 116), the other port of the energy storage element 113 is connected to the second port of the second switch 112 (connection point 117), the first port of the second switch 112 is connected to the second port of the first switch 111 (connection point 118), the connection point 118 between the two switches is the second port of the filter inductor 114, the first port of the filter inductor 114 is the first output port 119 of the module, the connection point 117 between the second port of the energy storage element and the second switch is the second port of the filter inductor 113, the first port of the filter inductor 113 is the second output port 1110 of the module, and the filter inductor 114 and the filter inductor 113 can operate simultaneously or one of them can be short-circuited.

[0044] Among them, such as Figure 1b As shown, the symmetrical half-bridge module 102 includes at least two switches (a first switch 121 and a second switch 122), at least two energy storage elements (a first energy storage element 123 and a second energy storage element 124), and at least one filter inductor 125 or filter inductor 126. The first port of the first switch 121 is connected to the first port of the first energy storage element 123 (connection point 127), the second port of the second switch 122 is connected to the second port of the second energy storage element 124 (connection point 128), and the second port of the first switch 121 is connected to the second switch 122. The first port of the first energy storage element 123 is connected to the first port of the second energy storage element 124 (connection point 1210), the second port of the first energy storage element 123 is connected to the first port of the second energy storage element 124, the connection point 129 of the two switches is the second port of the filter inductor 125, the first port of the filter inductor 125 is the first output port 1211 of the module, the connection point 1210 of the two energy storage elements is the second port of the filter inductor 126, the first port of the filter inductor 126 is the second output port 1212 of the module, and the filter inductor 125 and the filter inductor 126 can work simultaneously or one of them can be short-circuited.

[0045] Among them, such as Figure 1cAs shown, the H-bridge module 103 includes at least four switches (a first switch 131, a second switch 132, a third switch 133, and a fourth switch 134), at least one energy storage element 135, and at least one filter inductor 136 or filter inductor 137. The first port of the first switch 131 is connected to the first port of the energy storage element 135 and the first port of the third switch 133 (connection point 138), the second port of the second switch 132 is connected to the second port of the energy storage element 135 and the second port of the fourth switch 134 (connection point 139), and the second port of the first switch 131 is connected to the second port of the third switch 133. The first port of the second switch 132 (connection point 1310) and the second port of the third switch 133 are connected to the first port of the fourth switch 134 (connection point 1311). The connection point 1310 between the first and second switches is the second port of the filter inductor 136. The first port of the filter inductor 136 is the first output port 1312 of the module. The connection point 1311 between the third and fourth switches is the second port of the filter inductor 137. The first port of the filter inductor 137 is the second output port 1313 of the module. The two filter inductors 136 and 137 can operate simultaneously or one of them can be short-circuited.

[0046] Among them, such as Figure 2a As shown, the bridge bidirectional switch 201 includes at least one semiconductor power switch 211 and at least four diodes (a first diode 212, a second diode 213, a third diode 214, and a fourth diode 215). The first port of the semiconductor power switch 211 is connected to the first port of the first diode 212 and the first port of the third diode 214 (connection point 216), the second port of the semiconductor power switch 211 is connected to the second port of the second diode 213 and the second port of the fourth diode 215 (connection point 217), the second port of the first diode 212 is connected to the first port of the second diode 213 and serves as a first output port 218 of the bridge bidirectional switch, and the second port of the third diode 214 is connected to the first port of the fourth diode 215 and serves as a second output port 219 of the bridge bidirectional switch.

[0047] Among them, such as Figure 2b As shown, the anti-series bidirectional switch 202 includes at least two switches (a first switch 221 and a second switch 222). The first port of the first switch 221 is connected to the first port of the second switch 222 (connection point 223). The second port of the first switch 221 is the anti-series bidirectional switch first output port 224. The second port of the second switch 222 is the anti-series bidirectional switch second output port 225.

[0048] Optionally, the switch may include an IGBT, MOSFET, SiC or GaN power switching device.

[0049] Optionally, the energy storage element includes: a capacitor, a lithium battery pack, a lead-acid battery pack or a sodium-sulfur battery pack.

[0050] Example 2

[0051] This embodiment provides an example of a reconfigurable series-parallel grid-type converter with strong overcurrent capability.

[0052] A reconfigurable series-parallel grid-type converter with strong overcurrent capability adopts the reconfigurable series-parallel grid-type converter construction method described in Example 1, including: at least two H-bridge modules 103, at least three bidirectional switches 413, 414, 415 as shown in FIG. Figure 6 shown.

[0053] See attached Figure 1a The asymmetric half-bridge module 101 has three operating modes: positive voltage output, zero voltage output, and open circuit mode. When the first switch 111 or the second switch 112 is on, the positive voltage output mode and the zero voltage output mode are respectively active; when all switches are off, the open circuit mode is active. By varying the time proportions of the different operating modes, the voltages at the output ports 119 and 1110 of the asymmetric half-bridge module can be adjusted.

[0054] See attached Figure 1b The symmetrical half-bridge module 102 has three operating modes: positive voltage output, negative voltage output, and open-circuit mode. When the first switch 121 or the second switch 122 is on, it operates in the positive or negative voltage output mode, respectively; when all switches are off, it operates in the open-circuit mode. By controlling the time proportions of the different operating modes, the voltages at the output ports 1211 and 1212 of the symmetrical half-bridge module can be adjusted.

[0055] See attached Figure 1c The H-bridge module 103 has four operating modes: positive voltage output, negative voltage output, zero voltage output, and open circuit mode. When two diagonal switches 131, 134 or 132, 133 are conducting, they operate in positive and negative voltage output modes, respectively. When two upper switches 131, 133 or two lower switches 132, 134 are conducting, they operate in zero voltage output mode. When all switches are off, they operate in open circuit mode. By controlling the time proportions of different operating modes, the voltages at output ports 1312 and 1313 of the H-bridge module can be adjusted.

[0056] See attached Figure 2a The bridge bidirectional switch 201 has two operating modes, including a conducting mode and an open mode. When the switch 211 is conducting, the bridge bidirectional switch 201 is in the conducting mode, and when the switch 211 is off, the bridge bidirectional switch 201 is in the open mode.

[0057] See attached Figure 2bThe anti-series bidirectional switch 202 has two operating modes: a conducting mode and an open mode. The conducting mode of the anti-series bidirectional switch 202 occurs when both the first switch 221 and the second switch 222 are conducting, while the open mode of the anti-series bidirectional switch 202 occurs when both the first switch 221 and the second switch 222 are off.

[0058] See attached Figure 3a , multiple modules 311 (asymmetric half-bridge modules 101 or symmetric half-bridge modules 102 or H-bridge modules 103 ) can be connected in series end to end to form a traditional module series network converter 301 .

[0059] See attached Figure 3a , multiple modules 321 (asymmetric half-bridge modules 101 or symmetric half-bridge modules 102 or H-bridge modules 103 ) can be connected in parallel at both ends to form a traditional module parallel network converter 302 .

[0060] See attached Figure 4 , a single-phase reconfigurable series-parallel grid-type converter can be constructed based on the above modules and bidirectional switches according to the construction method described in Example 1.

[0061] See attached Figure 5 , you can Figure 4 A set of corresponding ends of each of the three reconfigurable series-parallel meshed converters shown are connected, and the unconnected ports are used as output ends, thereby constructing a three-phase reconfigurable series-parallel meshed converter.

[0062] See attached Figure 6 ,Will Figure 4 The two modules 411 and 412 of 401 are replaced by the H-bridge module 103, and the first bidirectional switch 413, the third bidirectional switch 414 and the second bidirectional switch 415 are replaced by the bidirectional switch 201, thereby obtaining a reconfigurable series-parallel network converter example.

[0063] See attached Figure 7a When the first bidirectional switch 413 and the second bidirectional switch 415 are turned off and the bidirectional switch 414 is turned on, the reconfigurable series-parallel grid-type converter can realize the series operation of modules.

[0064] See attached Figure 7b When the first bidirectional switch 413 and the second bidirectional switch 415 are turned on and the bidirectional switch 414 is turned off, the reconfigurable series-parallel grid-type converter can realize parallel operation of modules.

[0065] The simulation system and control parameters of the reconfigurable series-parallel network converter implemented in the present invention are shown in Table 1.

[0066] Table 1 Simulation system and control parameters

[0067]

[0068] See attached Figure 8a , showing the load voltage of the reconfigurable series-parallel grid-type converter in the series working state v load and load current i load (Upper left), module current i ac1 / i ac2 (Upper right), bidirectional switch voltage v s1 / v s2 / v s3 (lower left), bidirectional switch current i s1 / i s2 / i s3 (lower right) simulation waveform; Figure 8a It can be seen that in the series mode, the modules can evenly share the load voltage. At the same time, the turned-off bidirectional switches evenly share the load voltage, and the turned-on bidirectional switches bear the load current.

[0069] See attached Figure 8b , showing the load voltage of the reconfigurable series-parallel grid-type converter in parallel working state v load and load current i load (Upper left), module current i ac1 / i ac2 (Upper right), bidirectional switch voltage v s1 / v s2 / v s3 (lower left), bidirectional switch current i s1 / i s2 / i s3 (lower right) simulation waveform; Figure 8b It can be seen that in parallel mode, the modules can evenly share the load current, improving the overcurrent capacity of the grid-type converter by at least 2 times while ensuring that the current-carrying capacity of the power semiconductor and filter inductor remains unchanged. At the same time, the turned-on bidirectional switches evenly share the load current, and the turned-off bidirectional switches bear the load voltage.

[0070] This invention provides a method for constructing a reconfigurable series-parallel grid-type converter and an example of a reconfigurable series-parallel grid-type converter. The converter can be applied to scenarios such as photovoltaic power generation, wind power generation, grid-connected energy storage, electric vehicle chargers / charging piles, high-voltage AC / DC transmission, power quality management, and microgrids. Compared with traditional grid-type converters, this invention significantly improves the grid-type converter's overcurrent capability without increasing the number of modules. Furthermore, the voltage and current can be evenly distributed between modules as needed, resulting in a simple and scalable structure.

[0071] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for constructing a reconfigurable series-parallel grid-type converter with strong overcurrent capability, characterized in that: include: Connecting the first ports corresponding to at least two modules together through a first bidirectional switch; The two modules are the first module and the second module; Connecting the second ports corresponding to the first module and the second module together through a second bidirectional switch; connecting the second port of the first module and the first port of the second module together through a third bidirectional switch; After the connection is completed, the first port of the first module is the first output port of the reconfigurable series-parallel meshed converter, and the second port of the second module is the second output port of the reconfigurable series-parallel meshed converter.

2. The method for constructing a reconfigurable series-parallel grid-type converter according to claim 1, characterized in that: The first module and the second module may be asymmetric half-bridge modules, symmetric half-bridge modules or symmetric H-bridge modules.

3. The method for constructing a reconfigurable series-parallel grid-type converter according to claim 1, characterized in that: The first bidirectional switch, the second bidirectional switch, and the third bidirectional switch may be bridge-type bidirectional switches or anti-series bidirectional switches.

4. The method for constructing a reconfigurable series-parallel grid-type converter according to claim 2, wherein: The asymmetric half-bridge module includes at least two switches, at least one energy storage element and at least one filter inductor; The two switches are respectively a first switch and a second switch; the filter inductor is the first filter inductor or the second filter inductor; The first port of the first switch is connected to one port of the energy storage element, the other port of the energy storage element is connected to the second port of the second switch, the first port of the second switch is connected to the second port of the first switch, the connection point between the first switch and the second switch is the second port of the first filter inductor, the first port of the first filter inductor is the first output port of the module, the connection point between the second port of the energy storage element and the second switch is the second port of the second filter inductor, the first port of the second filter inductor is the second output port of the module, and the two filter inductors can work simultaneously or one of them can be short-circuited.

5. The method for constructing a reconfigurable series-parallel grid-type converter according to claim 2, wherein: The symmetrical half-bridge module includes at least two switches, at least two energy storage elements and at least one filter inductor; The two switches are respectively a first switch and a second switch; the two energy storage elements are respectively a first energy storage element and a second energy storage element; the filter inductor is respectively a first filter inductor or a second filter inductor; The first port of the first switch is connected to the first port of the first energy storage element, the second port of the second switch is connected to the second port of the second energy storage element, the second port of the first switch is connected to the first port of the second switch, and the second port of the first energy storage element is connected to the first port of the second energy storage element. The connection point of the two switches is the second port of the first filter inductor, the first port of the first filter inductor is the first output port of the module, the connection point of the two energy storage elements is the second port of the second filter inductor, and the first port of the second filter inductor is the second output port of the module. The two filter inductors can work simultaneously or one of them can be short-circuited.

6. The method for constructing a reconfigurable series-parallel grid-type converter according to claim 2, wherein: The H-bridge module includes at least four switches, at least one energy storage element and at least one filter inductor; The four switches are respectively a first switch, a second switch, a third switch, and a fourth switch; the filter inductor is the first filter inductor or the second filter inductor; The first port of the first switch is connected to the first port of the energy storage element and the first port of the third switch, the second port of the second switch is connected to the second port of the energy storage element and the second port of the fourth switch, the second port of the first switch is connected to the first port of the second switch, and the second port of the third switch is connected to the first port of the fourth switch. The connection point between the first switch and the second switch is the second port of the first filter inductor, the first port of the first filter inductor is the first output port of the module, the connection point between the third switch and the fourth switch is the second port of the second filter inductor, the first port of the second filter inductor is the second output port of the module, and the two filter inductors can work simultaneously or one of them can be short-circuited.

7. The method for constructing a reconfigurable series-parallel grid-type converter according to claim 3, characterized in that: The bridge bidirectional switch includes at least one semiconductor power switch and at least four diodes; The four diodes are the first diode, the second diode, the third diode, and the fourth diode; The first port of the semiconductor power switch is connected to the first port of the first diode and the first port of the third diode, the second port of the semiconductor power switch is connected to the second port of the second diode and the second port of the fourth diode, the second port of the first diode is connected to the first port of the second diode and serves as the first output port of the bridge bidirectional switch, and the second port of the third diode is connected to the first port of the fourth diode and serves as the second output port of the bridge bidirectional switch.

8. The method for constructing a reconfigurable series-parallel grid-type converter according to claim 3, wherein: The anti-series bidirectional switch includes at least two switches; The two switches are respectively a first switch and a second switch; The first port of the first switch is connected to the first port of the second switch, the second port of the first switch is the first output port of the anti-series bidirectional switch, and the second port of the second switch is the second output port of the anti-series bidirectional switch.

9. The method for constructing a reconfigurable series-parallel grid-type converter according to any one of claims 1 to 8, wherein: The switches include: IGBT, MOSFET, SiC or GaN power switching devices.

10. The method for constructing a reconfigurable series-parallel grid-type converter according to any one of claims 4 to 6, characterized in that: The energy storage element includes: capacitor, lithium battery pack, lead-acid battery pack or sodium-sulfur battery pack.

11. The method for constructing a reconfigurable series-parallel grid-type converter according to claim 1, characterized in that: The method is suitable for three-phase applications and can be connected in a star structure by three single-phase converters.

12. A reconfigurable series-parallel grid-type converter with strong overcurrent capability, characterized in that: The reconfigurable series-parallel network converter is obtained by adopting the construction method of the reconfigurable series-parallel network converter according to claim 1, comprising: two H-bridge modules and three bidirectional switches.

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