Resistance voltage division control redundancy power supply circuit for multi-level converter power sub-module

Abstract

The invention provides a resistance voltage division control redundancy power supply circuit for a multi-level converter power sub-module, and relates to the technical field of power supply of the multi-level converter power sub-module. The resistor voltage division control redundancy power supply circuit comprises n voltage division resistors which are connected in series and are connected with a high-voltage direct-current capacitor in parallel; one end of the first through-current unit is connected with a connection point of the (k-1) th divider resistor and the kth divider resistor; one end of the second through-flow unit is connected with a connection point of the (j-1) th divider resistor and the jth divider resistor, and the other end of the second through-flow unit is connected with an energy storage capacitor of the bypass switch; one end of the resistance voltage division control branch is connected with one end of the first through-current unit, and the other end is connected with the negative electrode of the high-voltage direct-current capacitor; and two ends of the redundant power supply and energy taking module are respectively connected with the other end of the first through-current unit and the negative electrode of the high-voltage direct-current capacitor. In the low-voltage pre-charging stage of the multi-level converter power sub-module, starting of redundant power supply is achieved, black module faults are avoided, and the system reliability is improved.

Description

Technical Field

[0001] This application relates to the technical field of power supply for power sub - modules of multilevel converters. Specifically, it relates to a resistive voltage - dividing control redundant power supply circuit for power sub - modules of multilevel converters. Background Art

[0002] Modular Multilevel Converter (MMC), with its superior performance, has a modular structure, is easy to expand, has low harmonic content in the AC - side output, low switching losses, and does not require a transformer. It has been widely used in large - capacity high - voltage transmission equipment such as Flexible DC Transmission Converter, Unified Power Flow Controller, and Static Var Generator.

[0003] The multilevel converter can withstand high voltages through the series voltage equalization of multiple power sub - modules. The explosion of a single power sub - module caused by over - voltage or over - current faults will affect the surrounding power sub - modules, expanding the scope of fault damage and leading to the overall shutdown of the system. Therefore, mechanical bypass switches are usually configured at the AC ports of power sub - modules. When a power sub - module fails, the bypass switch immediately operates to remove the faulty power sub - module from the system, controlling the loss within a single power sub - module. The timely and reliable operation of the bypass switch depends on the bypass command issued by the control board. When the high - voltage power supply board has a certain probability of being unable to supply power to the control board due to life limitations, aging, failure, and other external reasons, the control board loses its working ability and cannot issue bypass commands. Therefore, how to improve the power supply reliability of the control board is crucial for the overall operation reliability of the modular multilevel converter. At present, there are many studies on how to improve the power supply reliability of the control board, such as dual high - voltage power supply boards and cross - power supply of adjacent power sub - modules, but inevitably, it will increase the number of hardware boards and the equipment cost.

[0004] Some scholars have proposed a patent solution for self - triggering of bypass switches: Invention Patent CN107147305B proposes a self - triggering circuit for bypass switches of multilevel converter sub - modules, which charges the energy - storage capacitor of the bypass switch through the AC terminal of the power sub - module. However, if the power supply board has failed before the system starts, the closing coil of the bypass switch will short - circuit the energy - storage capacitor of the bypass switch in parallel, so the energy - storage capacitor cannot complete charging and cannot provide the energy required for the bypass switch to close.

[0005] The invention patent CN108111007A proposes a redundant power supply circuit and control method for a power module. This invention realizes the operation of the bypass switch by breaking down the zener diode when the power supply board fails. However, this solution requires a large number of high-voltage switches, has a complex control logic, a high cost, poor feasibility, and if a black module occurs in the power sub-module, the operation of the bypass switch cannot be completed, which will cause the loss to further expand to the surrounding power sub-modules;

[0006] The invention patent CN109274256B proposes a redundant power supply circuit and control method for a power module based on a breakdown diode. When a fault occurs in the power supply board card of the power module, the redundant power supply circuit provides the energy required for closing the bypass switch and powers the control board card of the power module to ensure reliable closing of the bypass switch. However, this solution is limited by the overall power of the voltage-dividing resistors, the operating voltage range of the power module, and the operating voltage range of the bypass switch, and has a relatively high redundant power supply startup working point and a large monitoring blind area. Summary of the Invention

[0007] To solve at least one of the above problems, the present application proposes a resistor voltage division control redundant power supply circuit for a power sub-module of a multilevel converter.

[0008] According to a first aspect of the present application, at least one embodiment of the present application provides a resistor voltage division control redundant power supply circuit for a power sub-module of a multilevel converter. The power sub-module of the multilevel converter includes: a power semiconductor unit, a high-voltage DC capacitor, and a bypass switch. The resistor voltage division control redundant power supply circuit includes: n voltage-dividing resistors, the n voltage-dividing resistors connected in series are connected in parallel with the high-voltage DC capacitor, where n is an integer greater than or equal to 3; a first current-carrying unit, one end of which is connected to the connection point between the (k - 1)-th voltage-dividing resistor and the k-th voltage-dividing resistor; a second current-carrying unit, one end of which is connected to the connection point between the (j - 1)-th voltage-dividing resistor and the j-th voltage-dividing resistor, and the other end of which is connected to the energy storage capacitor of the bypass switch, where 1 < k < j ≤ n, and k and j are both integers; a resistor voltage division control branch, one end of which is connected to the one end of the first current-carrying unit, and the other end of which is connected to the negative electrode of the high-voltage DC capacitor; a redundant power supply energy extraction module, the first end of which is connected to the other end of the first current-carrying unit, and the second end of which is connected to the negative electrode of the high-voltage DC capacitor.

[0009] For example, in some embodiments of the present application, the resistor voltage division control branch includes: a controllable voltage-dividing resistor, one end of which is connected to the one end of the first current-carrying unit; a voltage division control switch, one end of which is connected to the other end of the controllable voltage-dividing resistor, and the other end of which is connected to the negative electrode of the high-voltage DC capacitor.

[0010] For example, in some embodiments of the present application, the resistor voltage division control branch includes: m resistor voltage division control sub-branches connected in parallel, where m is an integer greater than or equal to 2. Each resistor voltage division control sub-branch in the m resistor voltage division control sub-branches includes: a controllable voltage division resistor, one end of which is connected to the one end of the first current-carrying unit; a voltage division control switch, one end of which is connected to the other end of the controllable voltage division resistor, and the other end of which is connected to the negative electrode of the high-voltage DC capacitor.

[0011] For example, in some embodiments of the present application, the voltage division control switch of each resistor voltage division control sub-branch in the m resistor voltage division control sub-branches is used to close in segments according to a control instruction to smoothly change the input voltage of the redundant power supply and energy extraction module.

[0012] For example, in some embodiments of the present application, the control instruction is used to control the voltage division control switch to close when the voltage of the redundant power supply and energy extraction module is a first set threshold, or to control the voltage division control switch to close after a first period of time when the pre-charging of the multi-level converter power sub-module ends.

[0013] For example, in some embodiments of the present application, the resistance value of the input controllable voltage division resistor satisfies the following formula:

[0014]

[0015] where, R i is the resistance value of the i-th voltage division resistor, R x is the total resistance value of the input controllable voltage division resistors, U1 is the maximum operating voltage of the multi-level converter power sub-module, U2 is the maximum operating voltage of the redundant power supply and energy extraction module, where i is an integer greater than or equal to 1 and less than or equal to n.

[0016] For example, in some embodiments of the present application, the ratio of the series resistance value of the k-th voltage division resistor to the n-th voltage division resistor to the sum of the resistance values of the n voltage division resistors is less than or equal to the ratio of the maximum operating voltage of the redundant power supply and energy extraction module to the pre-charging voltage of the multi-level converter power sub-module.

[0017] For example, in some embodiments of the present application, the ratio of the series resistance value of the j-th voltage division resistor to the n-th voltage division resistor to the series resistance value of the k-th voltage division resistor to the n-th voltage division resistor 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 redundant power supply and energy extraction module.

[0018] For example, in some embodiments of the present application, the bypass switch includes: a fast mechanical switch, connected in parallel with the power semiconductor unit; the energy storage capacitor, with the positive electrode connected to the other end of the second current-carrying unit and the negative electrode connected to the negative electrode of the high-voltage DC capacitor; a bypass switch control coil, with one end connected to the other end of the second current-carrying unit and the other end used to control the fast mechanical switch.

[0019] For example, in some embodiments of the present application, the multi-level converter power sub-module further includes: a control board, with the first end connected to the third end of the redundant power supply energy extraction module, and the redundant power supply energy extraction module is used to supply power to the control board. The second end of the control board is connected to the power semiconductor unit of the multi-level converter power sub-module to control the power semiconductor unit; a high-voltage power board, connected to the high-voltage DC capacitor, the control board, and the energy storage capacitor of the bypass switch respectively, to draw power from the high-voltage DC capacitor and supply power to the control board and the energy storage capacitor of the bypass switch.

[0020] Through the above exemplary embodiments, a resistive voltage division control redundant power supply circuit for a multi-level converter power sub-module provided by the present application uses the segmented switching of controllable voltage division resistors to solve the problem of insufficient power of the resistive voltage division redundant energy extraction circuit at a lower DC capacitor voltage, and realizes the balanced control of the input voltage amplitude limit and output power regulation of the power supply module. By adding a resistive voltage division control branch in the redundant power supply branch, the input power and the working voltage range of the redundant power supply energy extraction module are greatly improved, the working blind area of the redundant power supply is reduced, the redundant power supply of the control board under the low-voltage pre-charging condition is realized, and the overall operation reliability is improved.

[0021] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] By referring to the accompanying drawings and describing its exemplary embodiments in detail, the above and other objects, features, and advantages of the present application will become more obvious. The following described drawings are only some embodiments of the present application and do not limit the present application.

[0023] Figure 1 Showing the schematic diagram of the resistive voltage division control redundant power supply circuit of the multi-level converter power sub-module of the present application;

[0024] Figure 2 Showing the schematic diagram of the resistive voltage division control redundant power supply circuit of the multi-level converter power sub-module of the present application;

[0025] Figure 3 Showing the schematic diagram of the resistive voltage division control redundant power supply circuit of the present application;

[0026] Figure 4 It is a schematic diagram of a half - bridge power sub - module composed of two power devices;

[0027] Figure 5 It is a schematic diagram of a full - bridge power sub - module composed of four power devices. Detailed implementation manners

[0028] Now, example embodiments will be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. Identical reference numerals in the figures denote the same or similar parts, and thus their repeated description will be omitted.

[0029] The described features, structures, or characteristics can be combined in one or more embodiments in any suitable manner. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure can be practiced without one or more of these specific details, or other means, components, materials, devices, etc. can be adopted. In these cases, well - known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.

[0030] The flowcharts shown in the accompanying drawings are merely illustrative and not necessarily include all the contents and operations / steps, nor are they necessarily executed in the described order. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined. Therefore, the actual execution order may change according to the actual situation.

[0031] The terms "first", "second", etc. in the specification and claims of this application and the above - mentioned accompanying drawings are used to distinguish different objects rather than to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non - exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0032] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily essential for implementing this application, so they cannot be used to limit the protection scope of this application.

[0033] Figure 1 It shows the schematic diagram of the resistor - voltage - division control redundant power supply circuit of the multilevel converter power sub - module of this application.

[0034] As Figure 1 shown, the power sub-module of the multi-level converter includes: a bypass switch 101, a power semiconductor unit 102, and a high-voltage DC capacitor 103. Among them, the bypass switch 101 includes: a primary fast mechanical switch 1011, an energy storage capacitor 1012, and a bypass switch control coil 1013. The primary fast mechanical switch 1011 is connected in parallel with the power semiconductor unit 102. One end of the energy storage capacitor 1012 is connected to the other end of the second current-carrying unit 2032, and the other end is connected to the negative electrode of the high-voltage DC capacitor 103. One end of the bypass switch control coil 1013 is connected to the other end of the second current-carrying unit 2032, and the other end is used to control the fast mechanical switch 1011.

[0035] According to some embodiments, the power semiconductor unit 102 includes: at least two power semiconductor devices connected in a half-bridge manner, such as Figure 4 shown; or at least four power semiconductor devices connected in a full-bridge manner, such as Figure 5 shown.

[0036] The resistor voltage division control redundant power supply circuit includes: n voltage division resistors 201 (R1...Rn), a resistor voltage division control branch 202, a first current-carrying unit 2031, a second current-carrying unit 2032, and a redundant power supply energy extraction module 204. Among them, n is an integer greater than or equal to 3.

[0037] The n voltage division resistors 201 connected in series are connected in parallel with the high-voltage DC capacitor 103.

[0038] Each voltage division resistor has two ports. The port close to the positive electrode of the high-voltage DC capacitor 103 is the upper port, and the port close to the negative electrode of the high-voltage DC capacitor 103 is the lower port. After being connected in series, the upper port of the first voltage division resistor R1 is connected to the positive electrode of the high-voltage DC capacitor 103, and the lower port of the nth voltage division resistor Rn is connected to the negative electrode of the high-voltage DC capacitor 103.

[0039] One end of the resistor voltage division control branch 202 is connected to one end of the first current-carrying unit 2031, and the other end is connected to the negative electrode of the high-voltage DC capacitor 103.

[0040] The resistor voltage division control branch 202 includes: a controllable voltage division resistor R x1 and a voltage division control switch Q. One end of the controllable voltage division resistor R x1 is connected to the upper port of the kth voltage division resistor R k , the other end is connected to one end of the voltage division control switch Q, and the other end of the voltage division control switch Q1 is connected to the negative electrode of the high-voltage DC capacitor 103.

[0041] According to some embodiments, the resistor voltage division control branch 202 includes: m resistor voltage division control sub-branches 2021 - 202m connected in parallel, where m is an integer greater than or equal to 2, such as Figure 3 shown.

[0042] A single resistor voltage division control sub-branch includes: a controllable voltage division resistor R xm and a voltage division control switch Q m . One end of the controllable voltage division resistor R xm is connected to the upper port of the kth voltage division resistor R k , and the other end is connected to one end of the voltage division control switch Q m . The other end of the voltage division control switch Q m is connected to the negative electrode of the high-voltage DC capacitor 103.

[0043] According to some embodiments, the voltage division control switches of each resistor voltage division control sub-branch in the m resistor voltage division control sub-branches are used to close in segments according to a control instruction to smoothly change the input voltage of the redundant power supply energy extraction module.

[0044] After the pre-charging of the multi-level converter power sub-module is completed and during the process of the multi-level converter power sub-module transitioning to normal operation, control the voltage division control switches of the m resistor voltage division control sub-branches to close in segments. The control instruction is used to control the voltage division control switch to close when the voltage of the redundant power supply energy extraction module is the first set threshold, or to control the voltage division control switch to close at the first moment after the pre-charging of the multi-level converter power sub-module is completed.

[0045] During the process from the uncontrolled charging to the normal operation of the multi-level converter power sub-module, the AC / DC power grid charges the high-voltage DC capacitor. In the initial state, none of the voltage division control switches in the resistor voltage division control redundant power supply circuit is closed, the voltage of the high-voltage DC capacitor rises monotonically, and the redundant power supply energy extraction module draws power from the high-voltage DC capacitor.

[0046] When the voltage of the redundant power supply energy acquisition module rises to the first set threshold, the first voltage-dividing control switch is turned on at this time, and the corresponding resistor voltage-dividing control sub-branch is turned on. The controllable voltage-dividing resistors of this resistor voltage-dividing control sub-branch are connected in parallel, so that the voltage-dividing ratio decreases, resulting in a decrease in the voltage obtained by the redundant power supply energy acquisition module. The redundant power supply energy acquisition module continues to draw power from the high-voltage DC capacitor. As the charging continues, when the voltage of the redundant power supply energy acquisition module reaches the first set threshold for the second time, at this time, the voltage-dividing control switch of another resistor voltage-dividing control sub-branch is turned on again. The controllable voltage-dividing resistors of this resistor voltage-dividing control sub-branch are connected in parallel, so that the voltage-dividing ratio further decreases, and the voltage obtained by the redundant power supply energy acquisition module decreases again. The redundant power supply energy acquisition module continues to draw power from the high-voltage DC capacitor. By turning on the resistor voltage-dividing control sub-branch when the voltage of the redundant power supply energy acquisition module reaches the first set threshold, it is ensured that the voltage obtained by the redundant power supply energy acquisition module is always lower than the first set threshold. The above process of turning on the voltage-dividing control switch continues until the power sub-module of the multi-level converter enters normal operation or until all voltage-dividing control switches are closed.

[0047] According to some embodiments, the first set threshold can be set by itself. For example, it is the maximum operating voltage. When the voltage of the redundant power supply energy acquisition module rises to be close to or equal to the maximum operating voltage, the voltage-dividing control switch is controlled to close.

[0048] Also, for example, the method of turning on the voltage-dividing control switch (that is, the method of controlling the voltage-dividing control switch to close) can be: within a certain time after the pre-charging of the power sub-module of the multi-level converter ends, the voltage-dividing control switch 1 is closed at an interval of the first time, the voltage-dividing control switch 2 is closed at an interval of the second time,..., and the voltage-dividing control switch n is closed at an interval of the nth time. Among them, the first time, the second time 2,..., the nth time can be set by itself. For example, the first time, the second time 2,..., the nth time are all 10 ms. This application only takes this as an example, but is not limited thereto.

[0049] One end of the first current-carrying unit 2031 is connected to the connection point of the (k - 1)th voltage-dividing resistor and the kth voltage-dividing resistor. One end of the second current-carrying unit 2032 is connected to the connection point of the (j - 1)th voltage-dividing resistor and the jth voltage-dividing resistor, and the other end is connected to the energy storage capacitor 1012. Wherein, 1 < k < j ≤ n, and k and j are both integers.

[0050] According to some embodiments, the first current-carrying unit 2031 and the second current-carrying unit 2032 include one or more of a diode, a fast mechanical switch, a relay, a semiconductor controllable device, and / or an electronic switch.

[0051] According to some embodiments, when the first current-carrying unit 2031 is a unidirectional current-carrying device represented by a diode, the current inflow end is connected to the kth voltage-dividing resistor R kis connected to the upper port, and the current output terminal is connected to the positive input of the redundant power supply energy extraction module 204. When the second current-carrying unit 2032 is a unidirectional current-carrying device represented by a diode, the current input terminal is connected to the jth voltage-dividing resistor R j is connected to the upper port, and the current output terminal is connected to one end of the bypass switch control coil 1013.

[0052] According to some embodiments, the first current-carrying unit 2031 and the second current-carrying unit 2032 are preferably diodes, such as Figure 2 shown. As one of the most mature unidirectional current-carrying devices, the diode is simple and reliable, has strong current-carrying capacity, and small conduction voltage drop, which can reduce the energy loss of the energy storage capacitor of the bypass switch and the redundant power supply energy extraction module.

[0053] According to some embodiments, the voltage-dividing control switch includes one or more of: a fast mechanical switch, a relay, a semiconductor controllable device, and / or an electronic switch.

[0054] The first end of the redundant power supply energy extraction module 204 is connected to the other end of the first current-carrying unit 2031, and the second end is connected to the negative pole of the high-voltage DC capacitor 103.

[0055] According to some embodiments, the redundant power supply energy extraction module 204 includes one or more of: an isolated / non-isolated switch-mode power converter and / or a linear voltage regulator circuit.

[0056] According to some embodiments, the switch-mode power converter has advantages such as high energy conversion efficiency and small volume, and the redundant power supply energy extraction module 204 preferably uses a switch-mode power converter. The isolated switch-mode power converter includes a flyback converter, a forward converter, etc.; the non-isolated switch-mode power converter includes a Buck converter, etc.

[0057] According to the exemplary embodiments, the multi-level converter power sub-module further includes: a control board 30 and a high-voltage power supply board 40.

[0058] The first end of the control board 30 is connected to the third end of the redundant power supply energy extraction module 204, and the redundant power supply energy extraction module 204 is used to supply power to the control board. The second end of the control board 30 is connected to the power semiconductor unit 102 of the multi-level converter power sub-module to control the power semiconductor unit.

[0059] The control board 30 includes: a voltage sampling circuit 301, a control core unit 302, and a driving module 303. Among them, one end of the voltage sampling circuit 301 is connected to the positive pole of the high-voltage DC capacitor 103, and the other end is connected to one end of the control core unit 302. The other end of the control core unit 302 is connected to one end of the driving module 303, and the other end of the driving module 303 is connected to the semiconductor power unit 102.

[0060] The high-voltage power supply board 40 is respectively connected to the high-voltage DC capacitor 103, the control board 30, and the energy storage capacitor 1012 of the bypass switch, so as to draw power from the high-voltage DC capacitor 103, supply power to the control board 30 and the energy storage capacitor 1012 of the bypass switch, and convert the energy obtained from the high-voltage DC capacitor into a stable power supply to supply the control board and the energy storage capacitor of the bypass switch.

[0061] The resistor voltage division control redundant power supply circuit realizes the redundant power supply of the energy storage capacitor of the bypass switch and the control board by the high-voltage DC capacitor through the current-carrying unit by reasonably using the voltage division resistors, solves the problems of the voltage withstand of the energy storage capacitor of the bypass switch and the input voltage coupling design of the redundant power supply energy extraction module. By adding a resistor voltage division control branch in the resistor voltage division control redundant power supply circuit, the input power and the working voltage range of the redundant power supply energy extraction module are greatly improved, the working blind area of the redundant power supply is reduced, the redundant power supply of the control board under the condition of resistor voltage division control is realized, and the overall operation reliability is improved.

[0062] According to some embodiments, for the kth voltage division resistor connected to one end of the first current-carrying unit 2031, the series resistance value of the first voltage division resistor to the (k - 1)th voltage division resistor is defined as Ra; the series resistance value of the kth voltage division resistor to the nth voltage division resistor is defined as Rb; the parallel resistance value of Rb and the inserted controllable voltage division resistor Rx is defined as Rc. The ratio of the resistance value of Rc to the resistance value of Rc + Ra needs to be less than or equal to the ratio of the maximum working voltage of the redundant power supply energy extraction module to the maximum working voltage of the power sub-module of the multi-level converter.

[0063]

[0064] where, R i is the resistance value of the ith voltage division resistor, i is an integer greater than or equal to 1 and less than or equal to n, R x is the total resistance value of the inserted controllable voltage division resistors in the system; U1 is the maximum working voltage of the power sub-module of the multi-level converter, and U2 is the maximum working voltage of the redundant power supply energy extraction module.

[0065] According to some embodiments, for the kth voltage division resistor connected to one end of the first current-carrying unit 2031, the ratio of the series resistance value of the kth voltage division resistor to the nth voltage division resistor to the sum of the series resistance values of all voltage division resistors needs to be less than or equal to the ratio of the maximum working voltage of the redundant power supply energy extraction module to the pre-charging voltage of the power sub-module of the multi-level converter.

[0066]

[0067] where, U3 is the pre-charging voltage of the power sub-module.

[0068] According to some embodiments, for the j-th voltage-dividing resistor connected to one end of the second current-carrying unit 2032, the ratio of the series resistance value of the j-th voltage-dividing resistor to the n-th voltage-dividing resistor to the series resistance value of the k-th voltage-dividing resistor to the n-th voltage-dividing resistor 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 redundant power supply energy extraction module.

[0069]

[0070] Among them, U4 is the withstand voltage of the energy storage capacitor of the bypass switch.

[0071] The present application provides a resistor voltage-dividing control redundant power supply circuit for a multi-level converter power sub-module. By reasonably utilizing the voltage-dividing resistors, the high-voltage DC capacitor can supply redundant power to the energy storage capacitor of the bypass switch and the control board through the current-carrying unit. By adding multiple levels of voltage-dividing resistors, the problem of the coupled design of the withstand voltage of the energy storage capacitor of the bypass switch and the input voltage of the redundant power supply energy extraction power supply is solved. By adding a resistor voltage-dividing control branch, the input power and the operating voltage range of the redundant power supply energy extraction module are greatly improved, the working blind area of the redundant power supply is reduced, and the redundant power supply of the control board under low-voltage pre-charging conditions is realized. When the multi-level converter power sub-module is in the normal operation process from the end of the pre-charging stage, by segmentally switching the voltage-dividing control switches Q1 to Qm, the input voltage of the redundant power supply energy extraction module adapts to the operating voltage of the multi-level converter power sub-module, and the redundant power supply for the entire process from low-voltage pre-charging to operation of the multi-level converter power sub-module is completed.

[0072] It should be clearly understood that the present application describes how to form and use specific examples, but the present application is not limited to any details of these examples. Instead, based on the teachings of the content disclosed in the present application, these principles can be applied to many other embodiments.

[0073] In addition, it should be noted that the above-mentioned drawings are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present application, rather than for limiting purposes. It is easy to understand that the processes shown in the above-mentioned drawings do not indicate or limit the time sequence of these processes. Additionally, it is also easy to understand that these processes can be executed, for example, synchronously or asynchronously in multiple modules.

[0074] The above specifically shows and describes the exemplary embodiments of the present application. It should be understood that the present application is not limited to the detailed structures, setting manners, or implementation methods described herein; instead, the present application is intended to cover various modifications and equivalent settings included within the scope and purpose of the appended claims.

Claims

1. A resistor voltage division controlled redundant power supply circuit for a multi-level converter power submodule, characterized in that: The power sub-module of the multi-level converter includes: a power semiconductor unit, a high-voltage DC capacitor, and a bypass switch. The resistor voltage division control redundant power supply circuit includes: n voltage division resistors, and the series-connected n voltage division resistors are connected in parallel with the high-voltage DC capacitor, where n is an integer greater than or equal to 3; A first current-carrying unit, one end of which is connected to the connection point between the (k - 1)-th voltage division resistor and the k-th voltage division resistor; A second current-carrying unit, one end of which is connected to the connection point between the (j - 1)-th voltage division resistor and the j-th voltage division resistor, and the other end of which is connected to the energy storage capacitor of the bypass switch, where 1 < k < j ≤ n, and both k and j are integers; A resistor voltage division control branch, one end of which is connected to the one end of the first current-carrying unit, and the other end of which is connected to the negative electrode of the high-voltage DC capacitor; A redundant power supply energy extraction module, the first end of which is connected to the other end of the first current-carrying unit, and the second end of which is connected to the negative electrode of the high-voltage DC capacitor.

2. The resistor voltage division controlled redundant power supply circuit according to claim 1, characterized in that: The resistor voltage division control branch includes: A controllable voltage division resistor, one end of which is connected to the one end of the first current-carrying unit; A voltage division control switch, one end of which is connected to the other end of the controllable voltage division resistor, and the other end of which is connected to the negative electrode of the high-voltage DC capacitor.

3. The resistor voltage division controlled redundant power supply circuit according to claim 1, characterized in that: The resistor voltage division control branch includes: m resistor voltage division control sub-branches connected in parallel, where m is an integer greater than or equal to 2, and each resistor voltage division control sub-branch in the m resistor voltage division control sub-branches includes: A controllable voltage division resistor, one end of which is connected to the one end of the first current-carrying unit; A voltage division control switch, one end of which is connected to the other end of the controllable voltage division resistor, and the other end of which is connected to the negative electrode of the high-voltage DC capacitor.

4. The resistor voltage division control redundant power supply circuit according to claim 3, wherein The voltage division control switch of each resistor voltage division control sub-branch in the m resistor voltage division control sub-branches is used to close in segments according to a control instruction to smoothly change the input voltage of the redundant power supply energy extraction module.

5. The resistor voltage division controlled redundant power supply circuit according to claim 4, characterized in that: The control instruction is used to control the voltage division control switch to close when the voltage of the redundant power supply energy extraction module is a first set threshold, or is used to control the voltage division control switch to close at the first moment after the pre-charging of the multi-level converter power sub-module ends.

6. The resistor voltage division controlled redundant power supply circuit according to claim 2 or 3, characterized in that: The resistance value of the put-in controllable voltage division resistor satisfies the following formula: Among them, R i is the resistance value of the i-th voltage divider resistor, R x is the total resistance of the controllable voltage-dividing resistors put into use, U1 is the maximum operating voltage of the multi-level converter power submodule, U2 is the maximum operating voltage of the redundant power supply and energy acquisition module, wherein i is an integer greater than or equal to 1 and less than or equal to n.

7. The resistor voltage division control redundant power supply circuit according to claim 1, wherein The ratio of the series resistance value of the k-th voltage division resistor to the n-th voltage division resistor to the sum of the resistance values of the n voltage division resistors is less than or equal to the ratio of the maximum working voltage of the redundant power supply energy extraction module to the pre-charging voltage of the multi-level converter power sub-module.

8. The resistor voltage division control redundant power supply circuit according to claim 1, wherein The ratio of the series resistance value of the j-th voltage division resistor to the n-th voltage division resistor to the series resistance value of the k-th voltage division resistor to the n-th voltage division resistor is less than or equal to the ratio of the withstand voltage of the energy storage capacitor of the bypass switch to the maximum working voltage of the redundant power supply energy extraction module.

9. The resistor voltage division controlled redundant power supply circuit according to claim 1, characterized in that: The bypass switch includes: A fast mechanical switch, which is connected in parallel with the power semiconductor unit; The energy storage capacitor has a positive electrode connected to the other end of the second current-passing unit, and a negative electrode connected to the negative electrode of the high-voltage DC capacitor; The bypass switch control coil has one end connected to the other end of the second current-passing unit, and the other end is used to control the fast mechanical switch.

10. The resistor voltage division controlled redundant power supply circuit according to claim 1, characterized in that: The multilevel converter power submodule further comprises: A control board, a first end of which is connected to a third end of the redundant power supply energy acquisition module, the redundant power supply energy acquisition module is used to supply power to the control board, and a second end of the control board is connected to a power semiconductor unit of the multilevel converter power submodule to control the power semiconductor unit; The high-voltage power supply board is connected to the high-voltage DC capacitor, the control board and the energy storage capacitor of the bypass switch respectively, so as to draw power from the high-voltage DC capacitor and supply power to the control board and the energy storage capacitor of the bypass switch.

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