Redundant power supply circuit for multi-level converter power module

Abstract

The utility model provides a redundant power supply circuit for a multi-level converter power module, and relates to the technical field of power supply of the multi-level converter power module. The multi-level converter power module comprises a power semiconductor unit, a direct-current capacitor and a bypass switch, and the redundant power supply circuit comprises a voltage-sharing resistor which is connected with the direct-current capacitor in parallel and comprises at least three resistors which are connected in series; one end of the voltage conversion unit is connected with the second end of a third resistor of the at least three resistors; one end of the first connecting unit is connected with the first end of a second resistor of the at least three resistors, and the other end of the first connecting unit is connected with the other end of the voltage conversion unit; and one end of the second connecting unit is connected with the second end of the second resistor, and the other end is connected with one end of the energy storage capacitor of the bypass switch. The redundant power supply circuit realizes redundant power supply of the DC capacitor to the energy storage capacitor of the bypass switch and the control board card under the condition that the power board card fails by reasonably utilizing the voltage-sharing resistor.

Description

Technical Field

[0001] The present application relates to the technical field of power supply for a multi-level converter power module, and in particular to a redundant power supply circuit for a multi-level converter power module. Background Art

[0002] Multilevel converter technology is commonly used in flexible AC / DC transmission systems. With its modularity, low losses, and low harmonics, multilevel converter technology is widely used in power equipment such as flexible DC transmission converters, static VAR compensation devices, and unified power flow controllers.

[0003] Multilevel converters typically consist of hundreds or even thousands of power modules connected in series. To prevent a single power module failure from causing an explosion, potentially widening the fault range and leading to system downtime, the power module AC ports are typically equipped with bypass switches. When a power module fails, the bypass switch is immediately triggered, removing the faulty power module from system operation. However, reliable closing of the bypass switch depends on the proper functioning of the control and power boards. If the power board fails, not only will the bypass switch's actuator lose energy storage, but the control board will also be unable to issue commands. This is especially true in the event of a power failure before system startup. Therefore, improving the reliability of the power module power supply is crucial.

[0004] The industry has conducted extensive research and attempts to improve the reliability of power module power supply, such as by duplicating power supply boards and cross-powering adjacent modules. However, due to the complex design, high cost, and large size of high-voltage power supply boards, this solution has a low cost-effectiveness ratio. Research institutions and scholars have also proposed patents for self-triggering bypass solutions for faulty modules. For example, invention patent CN201710228027.X proposes a self-triggering circuit for bypass switches in multilevel converter submodules. However, if the power supply board fails before the system starts, the bypass switch's energy storage capacitor cannot be fully charged, preventing the system from closing. Another example is invention patent CN108111007A, which proposes a redundant power supply circuit and control method for power modules. This invention incorporates multiple high-voltage zener diodes, resulting in low reliability. It also incorporates multiple high-voltage switches, requiring isolation and control, making it complex and impractical to implement. More importantly, if the bypass switch fails to operate, or worse, the higher-level control system will not be aware of the faulty module's status. Continuing operation despite a bypass failure can further escalate the fault and cause further losses. For example, invention patent CN109167507B proposes a redundant power supply circuit and control method for a multi-level converter submodule. This solution utilizes the voltage-sharing resistor design of the power module to achieve redundant power supply for the power module without increasing system power consumption. It can not only store energy in the bypass switch, but also supply power to the control board. The bypass timing is flexible and controllable, and the power module status can be monitored. However, due to the overall power of the voltage-sharing resistor, the operating voltage range of the power module, and the operating voltage range of the bypass switch, the redundant power supply startup operating point is relatively high, and the monitoring blind area is relatively large. Utility Model Content

[0005] In order to solve at least one of the above problems, the present application proposes a redundant power supply circuit for a multi-level converter power module.

[0006] According to the first aspect of the present application, at least one embodiment of the present application provides a redundant power supply circuit for a multi-level converter power module, wherein the multi-level converter power module includes a power semiconductor unit, a DC capacitor and a bypass switch, and the redundant power supply circuit includes: a voltage equalizing resistor, connected in parallel with the DC capacitor, and including at least three resistors connected in series; a voltage conversion unit, one end of which is connected to the second end of the third resistor of the at least three resistors; a first connection unit, one end of which is connected to the first end of the second resistor of the at least three resistors, and the other end is connected to the other end of the voltage conversion unit; a second connection unit, one end of which is connected to the second end of the second resistor, and the other end is connected to one end of the energy storage capacitor of the bypass switch.

[0007] For example, in some embodiments of the present application, the bypass switch includes: a primary contact, connected in parallel with the power semiconductor unit; the energy storage capacitor, the other end of which is connected to the second end of the third resistor; and a control coil, connected to the other end of the second connection unit.

[0008] For example, in some embodiments of the present application, it also includes: a control board connected to the positive pole of the DC capacitor and to the voltage conversion unit; a power board connected to the positive pole of the DC capacitor and to the control board.

[0009] For example, in some embodiments of the present application, the first connection unit and the second connection unit both include: at least one of a diode, a mechanical switch, a relay, an electronic switch and / or a semiconductor controllable device.

[0010] For example, in some embodiments of the present application, when the first connection unit is a diode, the anode of the first connection unit is connected to the first end of the second resistor, and the cathode of the first connection unit is connected to the positive input of the voltage conversion unit.

[0011] For example, in some embodiments of the present application, when the second connecting unit is a diode, the anode of the second connecting unit is connected to the second end of the second resistor, and the cathode of the second connecting unit is connected to the positive electrode of the energy storage capacitor.

[0012] For example, in some embodiments of the present application, the voltage conversion unit includes: an isolated or non-isolated switching power converter, or a linear voltage regulator circuit.

[0013] For example, in some embodiments of the present application, the power semiconductor unit includes: at least two power semiconductor devices using a half-bridge connection method; or at least four power semiconductor devices using a full-bridge connection method.

[0014] For example, in some embodiments of the present application, the ratio of the resistance of the third resistor to the series resistance of the first resistor, the second resistor and the third resistor of the at least three resistors is less than or equal to the ratio of the withstand voltage of the energy storage capacitor of the bypass switch to the maximum operating voltage of the multi-level converter power module.

[0015] For example, in some embodiments of the present application, the ratio of the series resistance of the third resistor and the second resistor to the series resistance of the first resistor, the second resistor and the third resistor of the at least three resistors is less than or equal to the ratio of the maximum operating voltage of the voltage conversion unit to the maximum operating voltage of the multilevel converter power module.

[0016] Through the above-mentioned example embodiments, the present application provides a redundant power supply circuit for a multi-level converter power module. By rationally utilizing the voltage-equalizing resistor, the DC capacitor can be used to provide redundant power to the energy storage capacitor and control board of the bypass switch under the condition of a power board failure. This does not increase the loss of the multi-level converter power module, reduces the input voltage of the voltage conversion unit, increases the input power and operating range of the voltage conversion unit, reduces the working blind spot of the redundant power supply, solves the difficult problem of the withstand voltage of the bypass switch's energy storage capacitor and the input voltage coupling design of the voltage conversion unit, and avoids the voltage conversion unit from powering off and stopping working due to the discharge of the bypass switch. The circuit structure is simple and reliable, does not require additional control, is low-cost, reduces design difficulty, and has high engineering feasibility. The connecting unit is preferably a diode, which is simple and reliable, and reduces the energy consumption of the voltage-equalizing resistor on the voltage conversion unit and the energy storage capacitor of the bypass switch.

[0017] It should be understood that the foregoing general description and the following detailed description are merely illustrative and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By describing in detail exemplary embodiments thereof with reference to the accompanying drawings, the above and other objects, features and advantages of the present application will become more apparent. The drawings described below are only some embodiments of the present application, and are not intended to limit the present application.

[0019] Figure 1 A schematic diagram of a redundant power supply circuit for a multilevel converter power module according to an exemplary embodiment is shown;

[0020] Figure 2 Another embodiment of a schematic diagram of an exemplary redundant power supply circuit for a multilevel converter power module is shown;

[0021] Figure 3A A schematic diagram illustrating a half-bridge connection of a multilevel converter power module according to an exemplary embodiment;

[0022] Figure 3B A schematic diagram illustrating a full-bridge connection of power modules of a multilevel converter according to an exemplary embodiment. DETAILED DESCRIPTION

[0023] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the drawings represent like or similar parts, and thus repetitive description thereof will be omitted.

[0024] The described features, structures or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. may be employed. In these cases, well-known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0025] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0026] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0027] Those skilled in the art will understand that the drawings are merely schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily necessary for implementing the present application, and therefore cannot be used to limit the scope of protection of the present application.

[0028] Figure 1 A schematic diagram of a redundant power supply circuit for a multi-level converter power module according to an exemplary embodiment is shown.

[0029] like Figure 1 As shown, the multi-level converter power module 10 includes a power semiconductor unit 101 , a DC capacitor 102 and a bypass switch 103 .

[0030] The bypass switch 103 includes a primary contact 1031 , an energy storage capacitor 1032 , and a control coil 1033 . The primary contact 1031 is connected in parallel to the power semiconductor unit 101 . The control coil 1033 is connected to one end of the second connection unit 204 .

[0031] The redundant power supply circuit 20 includes a voltage grading resistor 201 , a voltage conversion unit 202 , a first connection unit 203 and a second connection unit 204 .

[0032] The voltage-equalizing resistor 201 is connected in parallel with the DC capacitor 102. The voltage-equalizing resistor 201 includes at least three resistors connected in series: a first resistor R1, a second resistor R2, and a third resistor R3. The first end of the first resistor R1 is connected to the positive electrode of the DC capacitor 102, and the connection point where the second end of the first resistor R1 and the first end of the second resistor R2 are connected is connected to the positive input electrode of the voltage conversion unit 202 via a first connection unit 203. The connection point where the second end of the second resistor R2 and the first end of the third resistor R3 are connected is connected to the positive electrode of the energy storage capacitor 1032 of the bypass switch 103 via a second connection unit 204. The second end of the third resistor R3 is connected to the negative electrode of the DC capacitor 102. The negative input electrode of the voltage conversion unit 202 is connected to the second end of the third resistor R3. The negative electrode of the energy storage capacitor 1032 of the bypass switch 103 is connected to the second end of the third resistor R3.

[0033] The redundant power supply circuit rationally utilizes the voltage-sharing resistor to enable the DC capacitor to redundantly supply power to the bypass switch's energy storage capacitor and the control board. This circuit can supply power to the control board and store energy in the bypass switch even when the power board fails, ensuring reliable bypass and fault state uploading of the multilevel converter power module, thereby improving the operational reliability of the multilevel converter power module. Furthermore, without increasing the loss of the multilevel converter power module, the circuit reduces the input voltage of the voltage conversion unit, increases the input power and operating range of the voltage conversion unit, and reduces the operating blind spot of the redundant power supply. This solves the difficult problem of withstand voltage of the bypass switch's energy storage capacitor and the input voltage coupling design of the voltage conversion unit, thus preventing the voltage conversion unit from powering off and ceasing operation due to discharge caused by closing the bypass switch.

[0034] According to some embodiments, the first connection unit 203 and the second connection unit 204 each include at least one of a diode, a mechanical switch, a relay, an electronic switch, and / or a semiconductor controllable device.

[0035] like Figure 2 As shown, when the first connecting unit 203 is a diode, the anode of the first connecting unit 203 is connected to the first end of the second resistor R2, and the cathode of the first connecting unit 203 is connected to the positive input electrode of the voltage conversion unit 202. When the second connecting unit 204 is a diode, the anode of the second connecting unit 204 is connected to the second end of the second resistor R2, and the cathode of the second connecting unit 204 is connected to the positive electrode of the energy storage capacitor 1032.

[0036] According to some embodiments, the first connecting unit and the second connecting unit are diodes. Diodes have unidirectional conductivity, are simple and reliable, and can reduce the energy consumption of the energy storage capacitor of the bypass switch or the voltage conversion unit by the voltage grading resistor.

[0037] According to some embodiments, the voltage conversion unit 202 includes: an isolated or non-isolated switching power converter, or a linear voltage regulator circuit.

[0038] According to some embodiments, isolated switching power converters include flyback converters, forward converters, etc. Non-isolated switching power converters include Buck converters, etc. Switching power converters have advantages such as high efficiency and small size.

[0039] According to some embodiments, the power semiconductor unit 101 includes at least two power semiconductor devices connected in a half-bridge manner, such as Figure 3A As shown; or at least four power semiconductor devices using a full-bridge connection, such as Figure 3B shown.

[0040] According to an exemplary embodiment, the redundant power supply circuit further includes a control board 205 and a power board 206 .

[0041] The control board 205 is connected to the positive electrode of the DC capacitor 102 and is also connected to the voltage conversion unit 202. The power board 206 is connected to the positive electrode of the DC capacitor 102 and is also connected to the control board 205.

[0042] According to an example embodiment, a ratio of the resistance of the third resistor to the series resistance of the first resistor, the second resistor, and the third resistor of the at least three resistors is less than or equal to a ratio of the withstand voltage of the energy storage capacitor of the bypass switch to the maximum operating voltage of the multilevel converter power module.

[0043]

[0044] Among them, R1, R2, and R3 are the first resistor, the second resistor, and the third resistor respectively, U1 is the maximum operating voltage of the multilevel converter power module, and U3 is the withstand voltage of the energy storage capacitor of the bypass switch.

[0045] According to an example embodiment, a ratio of a series resistance of the third resistor and the second resistor to a series resistance of the first resistor, the second resistor, and the third resistor of the at least three resistors is less than or equal to a ratio of a maximum operating voltage of the voltage conversion unit to a maximum operating voltage of the multilevel converter power module.

[0046]

[0047] Wherein, U2 is the maximum operating voltage of the voltage conversion unit.

[0048] This application utilizes a multi-stage voltage division design to ensure the voltage resistance and safety of the energy storage capacitors in the voltage conversion unit and the bypass switch, while also reducing the design difficulty of the voltage conversion unit. Furthermore, the resistance ratio of the first, second, and third resistors can be varied as needed to flexibly adjust the startup threshold and output power of the redundant power supply to the bypass switch and voltage conversion unit.

[0049] The present application provides a redundant power supply circuit for a multi-level converter power module. By rationally utilizing the equalizing resistor, it is possible to realize redundant power supply of the DC capacitor to the energy storage capacitor of the bypass switch and the control board under the condition of a power board failure, so that the power module has status monitoring and active bypass functions, and reduces the monitoring blind spot of the power module. It does not increase the loss of the multi-level converter power module, reduces the input voltage of the voltage conversion unit, improves the input power and working range of the voltage conversion unit, reduces the working blind spot of the redundant power supply, solves the difficult problem of the withstand voltage of the energy storage capacitor of the bypass switch and the coupling design of the input voltage of the voltage conversion unit, and avoids the voltage conversion unit from powering off and stopping working due to the discharge of the bypass switch. The circuit structure is simple and reliable, does not require additional control, is low in cost, reduces the design difficulty, and has high engineering feasibility.

[0050] It should be clearly understood that this application describes how to form and use specific examples, but this application is not limited to any details of these examples. On the contrary, based on the teaching of the content disclosed in this application, these principles can be applied to many other embodiments.

[0051] Furthermore, it should be noted that the aforementioned figures are merely illustrative of the processes included in the methods according to exemplary embodiments of the present application and are not intended to be limiting. It is readily understood that the processes illustrated in the aforementioned figures do not indicate or limit the temporal order of these processes. Furthermore, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0052] While the exemplary embodiments of the present application have been specifically illustrated and described above, it should be understood that the present application is not limited to the detailed structures, configurations, or implementations described herein; rather, the present application is intended to encompass various modifications and equivalent configurations within the spirit and scope of the appended claims.

Claims

1. A redundant power supply circuit for a multi-level converter power module, characterized in that: The multilevel converter power module includes a power semiconductor unit, a DC capacitor and a bypass switch, and the redundant power supply circuit includes: a voltage-equalizing resistor connected in parallel with the DC capacitor and comprising at least three resistors connected in series; a voltage conversion unit, one end of which is connected to the second end of the third resistor of the at least three resistors; a first connecting unit, one end of which is connected to the first end of the second resistor of the at least three resistors, and the other end of which is connected to the other end of the voltage conversion unit; The second connecting unit has one end connected to the second end of the second resistor and the other end connected to one end of the energy storage capacitor of the bypass switch.

2. The redundant power supply circuit according to claim 1, wherein: The bypass switch comprises: a primary contact connected in parallel with the power semiconductor unit; The energy storage capacitor has its other end connected to the second end of the third resistor; The control coil is connected to the other end of the second connection unit.

3. The redundant power supply circuit according to claim 1, wherein: Also includes: A control board connected to the positive electrode of the DC capacitor and to the voltage conversion unit; The power supply board is connected to the positive electrode of the DC capacitor and the control board.

4. The redundant power supply circuit according to claim 1, wherein: The first connection unit and the second connection unit both include: At least one of a diode, a mechanical switch, a relay, an electronic switch and / or a semiconductor controllable device.

5. The redundant power supply circuit according to claim 4, wherein: In the case that the first connection unit is a diode, an anode of the first connection unit is connected to the first end of the second resistor, and a cathode of the first connection unit is connected to the positive input electrode of the voltage conversion unit.

6. The redundant power supply circuit according to claim 4, wherein: In the case that the second connecting unit is a diode, the anode of the second connecting unit is connected to the second end of the second resistor, and the cathode of the second connecting unit is connected to the positive electrode of the energy storage capacitor.

7. The redundant power supply circuit according to claim 1, wherein: The voltage conversion unit includes: Isolated or non-isolated switching power converter, or linear voltage regulator circuit.

8. The redundant power supply circuit according to claim 1, wherein: The power semiconductor unit comprises: At least two power semiconductor devices using a half-bridge connection; or Use at least four power semiconductor devices in a full-bridge connection.

9. The redundant power supply circuit according to claim 1, wherein: A ratio of the resistance of the third resistor to the series resistance of the first resistor, the second resistor, and the third resistor of the at least three resistors is less than or equal to a ratio of the withstand voltage of the energy storage capacitor of the bypass switch to the maximum operating voltage of the multilevel converter power module.

10. The redundant power supply circuit according to claim 1, wherein: A ratio of a series resistance of the third resistor and the second resistor to a series resistance of the first resistor, the second resistor, and the third resistor of the at least three resistors is less than or equal to a ratio of a maximum operating voltage of the voltage conversion unit to a maximum operating voltage of the multilevel converter power module.

Images