Resistive voltage division control redundant power supply circuit for multilevel converter power submodules

Abstract

The application provides a resistance voltage division control redundant power supply circuit for a multi-level converter power sub-module, and relates to the technical field of power supply of a multi-level converter power sub-module. The resistance voltage division control redundant power supply circuit comprises: n voltage division resistors and a high-voltage direct-current capacitor connected in parallel in series connection; a first current flow unit, one end of which is connected to the connection point of the (k-1)th voltage division resistor and the kth voltage division resistor; a second current flow unit, one end of which is connected to the connection point of the (j-1)th voltage division resistor and the jth voltage division resistor, and the other end of which is connected to an energy storage capacitor of a bypass switch; a resistance voltage division control branch, one end of which is connected to one end of the first current flow unit, and the other end of which is connected to the negative electrode of the high-voltage direct-current capacitor; and a redundant power supply energy taking module, two ends of which are respectively connected to the other end of the first current flow 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, the application realizes the start of redundant power supply, avoids the occurrence of black module failure, and improves the system reliability.

Description

Technical Field

[0001] This application relates to the field of power supply technology for multilevel converter power submodules, and more specifically, to a resistor divider control redundant power supply circuit for multilevel converter power submodules. Background Technology

[0002] Modular multilevel converters (MMCs), with their superior performance, modular structure, easy expansion, low AC output harmonic content, low switching losses, and transformer-free operation, are widely used in high-capacity high-voltage transmission equipment such as flexible DC transmission converters, unified power flow controllers, and static var generators.

[0003] Multilevel converters can withstand high voltages through the series voltage equalization of multiple power submodules. An explosion caused by an overvoltage or overcurrent fault in a single power submodule can spread to surrounding submodules, expanding the damage area and potentially causing a system-wide shutdown. Therefore, mechanical bypass switches are typically configured at the AC ports of the power submodules. When a power submodule fails, the bypass switch immediately activates, disconnecting the faulty submodule from the system and confining the loss to that single submodule. The timely and reliable activation of the bypass switch depends on bypass commands issued by the control board. Due to lifespan limitations, aging, failure, or other external factors, the high-voltage power supply board may fail to supply power to the control board, rendering it inoperable and unable to issue bypass commands. Therefore, improving the power supply reliability of the control board is crucial for the overall operational reliability of the modular multilevel converter. Currently, there is considerable research on improving the power supply reliability of the control board, such as dual high-voltage power supply boards and cross-powering adjacent power submodules. However, this inevitably increases the number of hardware boards and equipment costs.

[0004] Some scholars have proposed a patented solution for self-triggering bypass switches: Invention patent CN107147305B proposes a self-triggering circuit for bypass switches in multi-level converter submodules. The bypass switch energy storage capacitor is charged through the AC terminal of the power submodule. However, if the power board has failed before the system starts up, the bypass switch closing coil will short-circuit the bypass switch energy storage capacitor connected in parallel with it. Therefore, the energy storage capacitor cannot be charged and cannot provide the energy required for the bypass switch to close.

[0005] The invention patent CN108111007A proposes a power module redundant energy supply circuit and a control method. The invention realizes the action of the bypass switch by breaking down the voltage regulator tube when the power panel fails. However, this solution requires a large number of high-voltage switches, has complex control logic, high cost, poor practicability, and if a power sub-module becomes a black module, the action of the bypass switch cannot be completed, which will cause the loss to further expand to surrounding power sub-modules;

[0006] The invention patent CN109274256B proposes a redundant energy supply circuit and a control method for power modules based on breakdown diodes. When a fault occurs on the power board of the power module, the redundant energy supply circuit provides the energy required for closing the bypass switch and supplies power to the control board of the power module, ensuring reliable closing of the bypass switch. However, this solution is limited by the overall power of the voltage dividing resistors, the working voltage range of the power module and the working voltage range of the bypass switch, resulting in a high starting operating point of the redundant power supply and a large monitoring blind area. SUMMARY OF THE INVENTION

[0007] In order to solve at least one of the above problems, the present application proposes a resistance voltage division controlled redundant power supply circuit for power sub-modules of a multi-level converter.

[0008] According to a first aspect of the present application, at least one embodiment of the present application provides a resistance voltage division controlled redundant power supply circuit for a power sub-module of a multi-level converter, the power sub-module of the multi-level converter comprises: a power semiconductor unit, a high-voltage DC capacitor and a bypass switch, and the resistance voltage division controlled redundant power supply circuit comprises: n voltage dividing resistors, wherein the n voltage dividing resistors connected in series are connected in parallel with the high-voltage DC capacitor, and n is an integer greater than or equal to 3; a first current passing 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 passing 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, wherein 1<k<j≤n, and both k and j are integers; a resistance voltage division control branch, one end of which is connected to the one end of the first current passing unit, and the other end of which is connected to the negative electrode of the high-voltage DC capacitor; a redundant power supply energy-taking module, the first end of which is connected to the other end of the first current passing 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 resistance voltage division control branch comprises: a controllable voltage dividing resistor, one end of which is connected to the one end of the first current passing 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 this application, the resistor voltage divider control branch includes: m resistor voltage divider control sub-branches connected in parallel, where m is an integer greater than or equal to 2. Each of the m resistor voltage divider control sub-branches includes: a controllable voltage divider resistor, one end of which is connected to one end of the first current-carrying unit; and a voltage divider control switch, one end of which is connected to the other end of the controllable voltage divider resistor, and the other end of which is connected to the negative terminal of the high-voltage DC capacitor.

[0011] For example, in some embodiments of this application, the voltage divider control switch of each of the m resistor voltage divider control sub-branches is used to close in segments according to control commands, so as to smoothly change the input voltage of the redundant power supply module.

[0012] For example, in some embodiments of this application, the control command is used to control the voltage divider control switch to close when the voltage of the redundant power supply energy harvesting module is a first set threshold, or to control the voltage divider control switch to close after the first time after the pre-charging of the multilevel converter power submodule is completed.

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

[0014]

[0015] Among them, R i R is the resistance value of the i-th voltage divider resistor. x U1 is the total resistance of the controllable voltage divider resistors, U2 is the maximum operating voltage of the multilevel converter power submodule, and U2 is the maximum operating voltage of the redundant power supply energy harvesting 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 this application, the ratio of the series resistance of the k-th to n-th voltage divider resistors to the sum of the resistances of the n voltage divider resistors is less than or equal to the ratio of the maximum operating voltage of the redundant power supply module to the pre-charge voltage of the multilevel converter power submodule.

[0017] For example, in some embodiments of this application, the ratio of the series resistance of the j-th voltage divider resistor to the n-th voltage divider resistor to the series resistance of the k-th voltage divider resistor to the n-th voltage divider 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 module.

[0018] For example, in some embodiments of this application, the bypass switch includes: a fast mechanical switch connected in parallel with the power semiconductor unit; the energy storage capacitor, with its positive terminal connected to the other end of the second current-carrying unit and its negative terminal connected to the negative terminal of the high-voltage DC capacitor; and 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 this application, the multilevel converter power submodule further includes: a control board, the first end of which is connected to the third end of the redundant power supply module, the redundant power supply module being used to supply power to the control board, and the second end of the control board being connected to the power semiconductor unit of the multilevel converter power submodule to control the power semiconductor unit; and a high-voltage power supply board, which is 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 example embodiments, this application provides a resistor divider control redundant power supply circuit for a power submodule of a multilevel converter. By utilizing the segmented switching of controllable voltage divider resistors, it solves the problem of insufficient power in the resistor divider redundant power harvesting circuit under low DC capacitor voltage, and achieves balanced control of the power module's input voltage amplitude limitation and output power regulation. By adding a resistor divider control branch to the redundant power supply branch, it greatly improves the input power and operating voltage range of the redundant power supply power harvesting module, reduces the operating blind zone of the redundant power supply, realizes redundant power supply of the control board under low-voltage pre-charging conditions, and improves the overall operational reliability.

[0021] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0022] The above and other objects, features, and advantages of this application will become more apparent from the detailed description of exemplary embodiments with reference to the accompanying drawings. The drawings described below are merely some embodiments of this application and are not intended to limit the scope of this application.

[0023] Figure 1 This paper shows the schematic diagram of the resistor divider control redundant power supply circuit of the multilevel converter power submodule of this application;

[0024] Figure 2 This diagram shows a resistor divider control redundant power supply circuit for the multilevel converter power submodule of this application.

[0025] Figure 3 This diagram shows the schematic of the resistor divider control redundant power supply circuit of this application;

[0026] Figure 4 This is a schematic diagram of a half-bridge power submodule composed of two power devices;

[0027] Figure 5 This is a schematic diagram of a full-bridge power submodule consisting of four power devices. Detailed Implementation

[0028] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0029] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. 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 do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

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

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

[0033] Figure 1 The schematic diagram shows the resistor divider control redundant power supply circuit of the multilevel converter power submodule of this application.

[0034] like Figure 1 As shown, the multilevel converter power submodule includes a bypass switch 101, a power semiconductor unit 102, and a high-voltage DC capacitor 103. 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 terminal 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 configuration, such as... Figure 4 As shown; or using at least four power semiconductor devices in a full-bridge configuration, such as Figure 5 As shown.

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

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

[0038] Each voltage divider resistor has two terminals: the terminal closest to the positive terminal of the high-voltage DC capacitor 103 is the upper terminal, and the terminal closest to the negative terminal of the high-voltage DC capacitor 103 is the lower terminal. When connected in series, the upper terminal of the first voltage divider resistor R1 is connected to the positive terminal of the high-voltage DC capacitor 103, and the lower terminal of the nth voltage divider resistor Rn is connected to the negative terminal of the high-voltage DC capacitor 103.

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

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

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

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

[0043] According to some embodiments, the voltage divider control switch of each of the m resistor voltage divider control sub-branches is used to close in segments according to control commands to smoothly change the input voltage of the redundant power supply energy harvesting module.

[0044] After the pre-charging of the multilevel converter power submodule is completed, during the transition of the multilevel converter power submodule to normal operation, the voltage divider control switches of the m resistor voltage divider control sub-branches are closed in stages. The control command is used to control the voltage divider control switches to close when the voltage of the redundant power supply energy harvesting module is at a first set threshold, or to control the voltage divider control switches to close immediately after the pre-charging of the multilevel converter power submodule is completed.

[0045] During the transition from uncontrolled charging of the multilevel converter power submodule to normal operation, the AC / DC grid charges the high-voltage DC capacitor. In the initial state, no voltage divider control switch is closed in the resistor voltage divider control redundant power supply circuit, and the voltage of the high-voltage DC capacitor increases monotonically. The redundant power supply energy harvesting module draws power from the high-voltage DC capacitor.

[0046] When the voltage of the redundant power supply energy-taking module rises to a first set threshold, a first voltage division control switch is switched on at this time, and the corresponding resistance voltage division control sub-branch is conducted. The controllable voltage dividing resistors of the resistance voltage division control sub-branches are connected in parallel, so that the voltage division ratio is reduced, the voltage divided by the redundant power supply energy-taking module is reduced, and the redundant power supply energy-taking module continues to take power from the high-voltage DC capacitor; as the charging continues, when the voltage of the redundant power supply energy-taking module reaches the first set threshold for the second time, a voltage division control switch of another resistance voltage division control sub-branch is switched on again, and the controllable voltage dividing resistor of the resistance voltage division control sub-branch is connected in parallel, so that the voltage division ratio is further reduced, the voltage divided by the redundant power supply energy-taking module is reduced again, and the redundant power supply energy-taking module continues to take power from the high-voltage DC capacitor; when the voltage of the redundant power supply energy-taking module reaches the first set threshold, the resistance voltage division control sub-branches are switched on successively, so as to ensure that the voltage divided by the redundant power supply energy-taking module is always lower than the first set threshold. The above process of switching on voltage division control switches continues until the power sub-modules of the multi-level converter enter normal operation or until all voltage division control switches are closed.

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

[0048] For another example, the method of switching on voltage division control switches (that is, the method of controlling voltage division control switches to close) may be as follows: within a certain period of time after the pre-charging of the power sub-module of the multi-level converter is completed, the voltage division control switch 1 is closed at a first interval, the voltage division control switch 2 is closed at a second interval, ..., the voltage division control switch n is closed at an n-th interval. Wherein, the first time interval, the second time interval, ..., the n-th time interval can be set by oneself. For example, the first time interval, the second time interval, ..., the n-th time interval are all 10ms, which is only used as an example in the present application, but not limited thereto.

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

[0050] According to some embodiments, the first current passing unit 2031 and the second current passing unit 2032 comprise one or more of diodes, fast mechanical switches, relays, semiconductor controllable devices and / or electronic switches.

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

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

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

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

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

[0056] According to some embodiments, switching power converters have advantages such as high energy conversion efficiency and small size, and the redundant power supply energy harvesting module 204 is preferably a switching power converter. Isolated switching power converters include flyback converters, forward converters, etc.; non-isolated switching power converters include Buck converters, etc.

[0057] According to the example embodiment, the multilevel converter power submodule also includes: a control board 30 and a high-voltage power supply board 40.

[0058] The first terminal of the control board 30 is connected to the third terminal of the redundant power supply module 204, which supplies power to the control board. The second terminal of the control board 30 is connected to the power semiconductor unit 102 of the multilevel converter power submodule to control the power semiconductor unit.

[0059] The control board 30 includes a voltage sampling circuit 301, a control core unit 302, and a drive module 303. One end of the voltage sampling circuit 301 is connected to the positive terminal 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 drive module 303, and the other end of the drive module 303 is connected to the semiconductor power unit 102.

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

[0061] The resistor-divider control redundant power supply circuit, by making reasonable use of the voltage divider resistors, enables the high-voltage DC capacitor to provide redundant power to the energy storage capacitor of the bypass switch and the control board through the current-carrying unit. This solves the problem of the coupling design between the energy storage capacitor withstand voltage of the bypass switch and the input voltage of the redundant power supply energy harvesting module. By adding a resistor-divider control branch to the resistor-divider control redundant power supply circuit, the input power and operating voltage range of the redundant power supply energy harvesting module are greatly improved, the working dead zone of the redundant power supply is reduced, and redundant power supply of the control board is realized under the resistor-divider control condition, thereby improving the overall operational reliability.

[0062] According to some embodiments, the series resistance of the k-th voltage divider resistor connected to one end of the first current-carrying unit 2031 is defined as Ra; the series resistance of the k-th voltage divider resistor to the n-th voltage divider resistor is defined as Rb; and the parallel resistance of Rb and the connected controllable voltage divider resistor Rx is defined as Rc. The ratio of the resistance of Rc to the resistance of Rc+Ra must be less than or equal to the ratio of the maximum operating voltage of the redundant power supply energy harvesting module to the maximum operating voltage of the multilevel converter power submodule.

[0063]

[0064] Among them, R i R is the resistance value of the i-th voltage divider resistor, where i is an integer greater than or equal to 1 and less than or equal to n. x U1 represents the total resistance of the controllable voltage divider resistors in the system; U2 represents the maximum operating voltage of the multilevel converter power submodule and U2 represents the maximum operating voltage of the redundant power supply energy harvesting module.

[0065] According to some embodiments, the ratio of the series resistance of the kth voltage divider resistor connected to one end of the first current-passing unit 2031 to the nth voltage divider resistor to the sum of the series resistances of all voltage divider resistors needs to be less than or equal to the ratio of the maximum operating voltage of the redundant power supply energy harvesting module to the pre-charge voltage of the multilevel converter power submodule.

[0066]

[0067] U3 is the pre-charge voltage of the power submodule.

[0068] According to some embodiments, the ratio of the series resistance of the j-th voltage divider resistor connected to one end of the second flow unit 2032 to the series resistance of the k-th voltage divider resistor to the n-th voltage divider 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 harvesting module.

[0069]

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

[0071] This application provides a resistor-divider control redundant power supply circuit for a multilevel converter power submodule. By rationally utilizing the voltage divider resistors, redundant power supply is achieved from the high-voltage DC capacitor to the energy storage capacitor of the bypass switch and the control board through the current-carrying unit. The addition of multi-stage voltage divider resistors solves the design challenge of coupling the energy storage capacitor's withstand voltage and the input voltage of the redundant power supply. The addition of a resistor-divider control branch significantly improves the input power and operating voltage range of the redundant power supply module, reduces the dead zone of the redundant power supply, and achieves redundant power supply for the control board under low-voltage pre-charging conditions. From the end of the pre-charging phase to the normal operation of the multilevel converter power submodule, the input voltage of the redundant power supply module adapts to the operating voltage of the multilevel converter power submodule by segmented switching of the voltage divider control switches Q1 to Qm, thus completing the redundant power supply for the entire process from low-voltage pre-charging to operation of the multilevel converter power submodule.

[0072] It should be clearly understood that this application describes how specific examples are formed and used, but this application is not limited to any details of these examples. Rather, based on the teachings of the disclosure of this application, these principles can be applied to many other embodiments.

[0073] Furthermore, it should be noted that the above figures are merely illustrative representations of the processes included in the method according to exemplary embodiments of this application, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0074] Exemplary embodiments of this application have been specifically shown and described above. It should be understood that this application is not limited to the detailed structures, arrangements, or implementation methods described herein; rather, this application is intended to cover various modifications and equivalent arrangements that fall within the objectives and scope of the appended claims.

Claims

1. A resistor-divider controlled redundant power supply circuit for a power submodule of a multilevel converter, characterized in that, The power submodule of the multilevel converter comprises: a power semiconductor unit, a high-voltage DC capacitor and a bypass switch, and the resistance voltage division control redundant power supply circuit comprises: n voltage dividing resistors, wherein the n voltage dividing resistors connected in series are connected in parallel with the high-voltage DC capacitor, and 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, wherein 1<k<j≤n, and both k and j are integers; a resistance voltage division control branch, one end of which is connected to said 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-taking module, wherein a first end of the redundant power supply energy-taking module is connected to the other end of the first current-carrying unit, and a second end of the redundant power supply energy-taking module is connected to the negative electrode of the high-voltage DC capacitor; The resistance voltage division control branch comprises: m resistance voltage division control sub-branches connected in parallel, wherein m is an integer greater than or equal to 2, and each of the m resistance voltage division control sub-branches comprises: a controllable voltage dividing resistor, one end of which is connected to said 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; the voltage division control switch of each resistance voltage division control sub-branch among the m resistance voltage division control sub-branches is configured to be closed in sections according to a control instruction, so as to smoothly change the input voltage of the redundant power supply energy-taking module; the control instruction is configured to control the voltage division control switch to close when the voltage of the redundant power supply energy-taking module reaches a first set threshold, or to control the voltage division control switch to close after a first time since the pre-charging of the power submodule of the multilevel converter is completed; the resistance value of the投入 controllable voltage dividing resistors satisfies the following formula: in, R i For the first i The resistance value of each voltage divider resistor, R x This represents the total resistance of the controllable voltage divider resistors that are applied. U 1 represents the maximum operating voltage of the power submodule of the multilevel converter. U 2 represents the maximum operating voltage of the redundant power supply module, where i is an integer greater than or equal to 1 and less than or equal to n; the ratio of the series resistance value from the k-th voltage dividing resistor to the n-th voltage dividing resistor to the sum of the resistance values of the n voltage dividing resistors is less than or equal to the ratio of the maximum working voltage of the redundant power supply energy-taking module to the pre-charging voltage of the power submodule of the multilevel converter; the ratio of the series resistance value from the j-th voltage dividing resistor to the n-th voltage dividing resistor to the series resistance value from 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 working voltage of the redundant power supply energy-taking module.

2. The resistor-divider-controlled redundant power supply circuit as described in claim 1, characterized in that, The bypass switch comprises: a fast mechanical switch connected in parallel with the power semiconductor unit; the energy storage capacitor, wherein the positive electrode of the energy storage capacitor is connected to the other end of the second current-carrying unit, and the negative electrode of the energy storage capacitor is connected to the negative electrode of the high-voltage DC capacitor; a bypass switch control coil, one end of which is connected to the other end of the second current-carrying unit, and the other end of which is configured to control the fast mechanical switch.

3. The resistor-divider-controlled redundant power supply circuit as described in claim 1, characterized in that, The power submodule of the multilevel converter further comprises: The control board has a first terminal connected to the third terminal of the redundant power supply module, which supplies power to the control board. The second terminal of the control board is connected to the power semiconductor unit of the multilevel converter power submodule to control the power semiconductor unit. A 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 energy storage capacitor of the control board and the bypass switch.

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