Bypass circuit of converter, unit control board and converter

Abstract

The utility model provides a bypass circuit of a converter, a unit control board and the converter. The converter comprises a plurality of cascade unit modules, and each cascade unit module comprises a supporting capacitor. The bypass circuit comprises a power supply circuit, a control circuit and a switching circuit. The power supply circuit and the control circuit are connected with the supporting capacitor in parallel. The power supply circuit at least comprises a first power supply circuit and a second power supply circuit, in response to the closing operation of the switching circuit, after the first power supply circuit supplies power to a trigger circuit in the control circuit, the second power supply circuit supplies power to an execution circuit in the control circuit; the trigger circuit is used for starting the execution circuit, and the execution circuit is used for closing the contactor to bypass the cascade unit module. According to an exemplary embodiment, a reliable closing power supply, a closing control loop power supply and a simple control circuit are provided for the bypass contactor.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of energy storage, and particularly relates to a bypass circuit of a converter, a unit control board and a converter. BACKGROUND

[0002] The cascade multi-level converter with the bypass function usually uses a contactor as a bypass device of the cascade multi-level converter. The vacuum contactor can be manually opened and closed, electrically controlled to be closed and permanently magnetically kept to be opened, and has the advantages of small size, small closing power supply capacity, simple control circuit and mechanical keeping of closing.

[0003] In the related art, the bypass circuit of the converter has high hardware cost and poor adaptability after the circuit is determined.

[0004] It should be noted that the statements herein only provide background information related to the present disclosure and do not necessarily constitute prior art. CONTENT OF THE UTILITY MODEL

[0005] In view of the above problems, a bypass circuit of a converter, a unit control board and a converter are proposed to overcome the above problems or at least partially solve the above problems.

[0006] The embodiments of the present disclosure adopt the following technical solutions:

[0007] In a first aspect, a bypass circuit of a converter is provided, the converter comprising a plurality of cascaded unit modules, each of the cascaded unit modules comprising a support capacitor; the bypass circuit comprising: a power supply circuit, a control circuit, a switching circuit, the power supply circuit and the control circuit being connected in parallel with the support capacitor; the power supply circuit comprising at least a first power supply circuit and a second power supply circuit, in response to the closing operation of the switching circuit, the first power supply circuit supplies power to a trigger circuit in the control circuit, and then the second power supply circuit supplies power to an execution circuit in the control circuit, the trigger circuit is used to start the execution circuit, and the execution circuit is used to close a contactor so that the cascaded unit module is bypassed.

[0008] Preferably, the power supply circuit further comprises a first resistor, a first diode and a second diode, and the first resistor, the first diode and the second diode are connected in series and connected in parallel with the support capacitor.

[0009] The first power supply circuit is connected in parallel with the second diode, and the second power supply circuit is connected in parallel with the series circuit of the first diode and the second diode.

[0010] Preferably, the first power supply circuit comprises a first capacitor, the second power supply circuit comprises a third capacitor and a fifth resistor, and the third capacitor and the fifth resistor are connected in parallel.

[0011] Preferably, the power supply circuit further comprises a third diode, a second resistor and a second capacitor, which are connected in series and then connected in series with the fifth resistor.

[0012] Preferably, the control circuit comprises a trigger circuit and an execution circuit, the trigger circuit comprises a fully-controlled power electronic switch, the fully-controlled power electronic switch comprises an IGBT, a first end of the IGBT is connected with one end of the first capacitor through a third resistor, and a second end of the IGBT is connected with the other end of the first capacitor.

[0013] Preferably, the execution circuit comprises a control coil and a fourth diode, the fourth diode is connected with the control coil in parallel, the control coil is connected with a third end of the IGBT through a fourth resistor, and a second end of the control coil is connected with one end of the second capacitor.

[0014] Preferably, the power supply circuit further comprises a normally-closed auxiliary contact, which is connected with the second capacitor in parallel.

[0015] Preferably, the switch circuit comprises a relay normally-open contact, which is arranged between the third resistor and the first capacitor.

[0016] In a second aspect, a unit control panel is provided, comprising the bypass circuit according to any one of the first aspect.

[0017] In a third aspect, a converter is provided, comprising the unit control panel according to the second aspect.

[0018] The above at least one technical solution adopted by the exemplary embodiments can achieve the following beneficial effects:

[0019] According to the exemplary embodiments of the present disclosure, the bypass circuit of the converter provides reliable closing power, closing control loop power and simple control circuit; the bypass circuit uses a small number of components, the components are low in material cost and easy to obtain.

[0020] It should be understood that the summary section is not intended to identify key or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description of some embodiments thereof, taken in conjunction with the accompanying drawings in which:

[0022] Figure 1 FIG. 1 is a schematic diagram of a bypass circuit of a converter according to an exemplary embodiment of the present disclosure;

[0023] Figure 2 Circuit diagram for bypass circuit of the converter in the embodiments of the present disclosure;

[0024] Figure 3 Circuit diagram for power supply circuit in the bypass circuit of the converter in the embodiments of the present disclosure;

[0025] Figure 4 Circuit schematic diagram of the unit control board in the embodiments of the present disclosure. DETAILED DESCRIPTION

[0026] The principles of the present disclosure will now be described with reference to some embodiments. It should be understood that the description of these embodiments is merely intended to illustrate the present disclosure and help the person skilled in the art understand and implement the present disclosure, and does not impose any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in a manner different from that described below.

[0027] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0028] The reference in the present disclosure to "one embodiment", "an embodiment", "exemplary embodiment", etc. indicates that a described embodiment can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an example embodiment, it is submitted that such a feature, structure, or characteristic can be used in connection with other embodiments whether or not explicitly described.

[0029] It should be understood that although the terms "first" and "second" and the like can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the example embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the associated terms.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" "comprising," "includes" "including," "has" "having" "has" "having," "includes" and / or "including" when used herein, specify the presence of stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0031] As used in the present disclosure, the term "circuitry" can refer to one or more or all of the following:

[0032] (a) hardware-only circuit implementations (such as implementations in analog and / or digital circuitry)

[0033] (b) combinations of hardware circuits and software, such as (as applicable):

[0034] (i) combinations of analog and / or digital hardware circuits with software / firmware

[0035] (ii) any portions of hardware processor(s) with software (including digital signal processors); and

[0036] (c) hardware circuit(s) and / or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but is not a software per se.

[0037] This definition of circuitry applies to all uses of this term in this disclosure, including in any claims. As a further example, as used in this disclosure, the term circuitry also includes an implementation that is a combination of hardware circuits and software, such as (as applicable): a combination of a general purpose hardware circuit(s) with software / firmware (which combination is a type of hardware circuit), software, and memory that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

[0038] The cascaded multilevel converter has the advantages of high output voltage level, high output power level, small output current harmonic content, modular structure, high redundancy, easy expansion, etc., and is widely used in high-voltage frequency converters, cascaded energy storage converters, high-voltage static var generators, high-voltage active filters, AC flexible power transmission and high-voltage DC power transmission, etc.

[0039] The cascade multi-level converter generally adopts single-phase full-bridge or half-bridge topology as the core topology of the power electronic of the cascade unit module, is composed of a plurality of unit modules in cascade to form a single-phase converter, and is connected in star or angle to form a three-phase converter. The cascade multi-level converter has a large number of power devices, so that the fault points are increased; and the fault of the power device of the cascade unit module will affect the normal work of the converter.

[0040] In order to realize high reliability of the cascade multi-level converter, the AC output end of the cascade unit module is connected in parallel with a bypass device, which bypasses the cascade unit module when a fault occurs, so as to ensure the normal operation of the cascade multi-level converter.

[0041] The common bypass technical solutions include: anti-parallel thyristor or bidirectional thyristor, rectifier bridge thyristor, reverse series IGBT, anti-parallel IGBT series diode, anti-parallel diode series thyristor, contactor, etc.

[0042] When the bypass technical solution takes power electronic devices as the core components, not only a special control circuit needs to be configured to realize the bypass function, but also a heat dissipation device needs to be configured to ensure that the power electronic devices work in the allowable temperature range, and the selection of the semi-controlled power electronic devices also has the problem of current discontinuity.

[0043] The bypass technical solution of the cascade multi-level converter takes the contactor as the core component, and is applied to the power supply mode of the high-voltage frequency converter, which includes:

[0044] 1. The input side of the single-phase isolation transformer is connected with the AC input end of the cascade unit module, and the output of the single-phase isolation transformer is directly used for the power supply of the control coil of the contactor.

[0045] 2. The input side of the single-phase isolation transformer is connected with the AC input end of the cascade unit module, the output side of the single-phase isolation transformer is connected with the input end of the AC / DC conversion circuit, and the output of the AC / DC conversion circuit is used for the power supply of the control coil of the contactor.

[0046] The contactor power supply mode applied to the high-voltage frequency converter, high-voltage static var generator and the like includes:

[0047] 1. The DC support capacitor voltage of the cascade unit module is converted by the power module to be used for the power supply of the control coil of the contactor;

[0048] 2. The DC support capacitor voltage of the cascade unit module is converted by the auxiliary source circuit to be used for the power supply of the control coil of the contactor and the power supply of the unit module control panel.

[0049] The above technical solutions have the following disadvantages:

[0050] 1. Single-phase isolation transformer power supply mode or single-phase isolation transformer plus AC / DC conversion circuit power supply mode, higher material cost;

[0051] 2. Power supply module or auxiliary source circuit parallel to the DC support capacitor of the cascaded unit module, high material cost, the output of the power supply module or auxiliary source circuit is not easy to adjust, poor adaptability.

[0052] In the exemplary embodiments of the present disclosure, in view of the high cost of the bypass circuit of the converter in the related art, the circuit is not easy to adjust and has poor adaptability, a universal bypass circuit of the converter is designed, which reduces the complexity of the circuit, reduces the cost of the circuit, and improves the adaptability of the circuit through the combination of the power supply circuit and the control circuit.

[0053] The technical solutions provided by the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0054] The bypass circuit of the converter, the unit control board and the converter are provided. Figure 1 As shown in the schematic diagram of the bypass circuit of the converter 100 in the embodiments of the present disclosure, the converter includes a plurality of cascaded unit modules 110, each of which includes a support capacitor; the bypass circuit includes a power supply circuit 120, a control circuit 130 and a switch circuit 140, the power supply circuit 120 and the control circuit 130 are connected in parallel with the support capacitor; the power supply circuit 120 includes at least a first power supply circuit 1201 and a second power supply circuit 1202, in response to the closing operation of the switch circuit 140, the first power supply circuit 1201 supplies power to the trigger circuit 1301 in the control circuit, and then the second power supply circuit 1202 supplies power to the execution circuit 1302 in the control circuit, the trigger circuit is used to start the execution circuit, and the execution circuit is used to close the contactor so that the cascaded unit module is bypassed. Wherein, the support capacitor is a DC support capacitor C0, as shown in Figure 3 .

[0055] As Figure 2 , Figure 3As shown, the power supply circuit further comprises a first resistor R1, a first diode D1 and a second diode D2, which are connected in series and connected in parallel with the (DC) support capacitor; the first power supply circuit 1201 is connected in parallel with the second diode D2, and the second power supply circuit 1202 is connected in parallel with the series circuit of the first diode D1 and the second diode D2. Among them, the first diode D1 and the second diode D2 are voltage stabilizing diodes. The first diode D1 and the second diode D2 are reversely connected in the circuit. R1 is a current limiting resistor, D1 is a voltage stabilizing diode, and C1 is an energy storage capacitor. The DC support capacitor C0 charges the energy storage capacitor C1 through the current limiting resistor R1 and the voltage stabilizing diode D1. The breakdown voltage of D1 is greater than that of D2.

[0056] With reference to the foregoing Figure 2 , the first power supply circuit 1201 comprises a first capacitor C1, the second power supply circuit 1202 comprises a third capacitor C3 and a fifth resistor R5, and the third capacitor C3 and the fifth resistor R5 are connected in parallel. The power supply circuit 120 further comprises a third diode D3, a second resistor R2 and a second capacitor C2, which are connected in series and connected in series with the fifth resistor R5. Among them, C2 is a fire extinguishing capacitor, which is used to avoid the contactor's normally closed contact from firing when it is converted to a normally open contact, D3 is an anti-reverse diode, R2 is a current limiting resistor, and C3 is an energy storage capacitor. The DC support capacitor C0 charges the energy storage capacitor C3 through the current limiting resistor R1, the anti-reverse diode D3, the current limiting resistor R2 and the normally closed auxiliary contact of the bypass contactor KM1.

[0057] The control circuit 130 comprises a trigger circuit 1301 and an execution circuit 1302, the trigger circuit 1301 comprises an all-controlled power electronic switch (IGBT) Q1, the first end of the IGBT is connected with one end of the first capacitor C1 through a third resistor R3, and the second end of the IGBT is connected with the other end of the first capacitor C1.

[0058] The execution circuit 1302 includes a control coil (contactor KM1) and a fourth diode D4 connected in parallel with the control coil, the control coil is connected with the third end of the IGBT through a fourth resistor R4, and the second end of the control coil is connected with one end of the second capacitor C2. The power supply circuit 120 further includes a normally closed auxiliary contact (KM1) connected in parallel with the second capacitor C2. The switching circuit 140 includes a normally open contact of a relay (KA1) arranged between the third resistor R3 and the first capacitor C1. Wherein, Q1 is a full-controlled power electronic switch (IGBT), C3 is an energy storage capacitor, and R4 is a current limiting resistor. When the relay control circuit controls the relay KA1 to close, the energy storage capacitor C1 applies a gate voltage to the full-controlled power electronic switch Q1 through the current limiting resistor R3, the full-controlled power electronic switch Q1 is turned on, the energy storage capacitor C3 applies a closing voltage to the closing coil of the bypass contactor KM1 through the current limiting resistor R4 and the full-controlled power electronic switch Q1, the current limiting resistor R4 limits the closing current of the closing coil, and the normally open main contact of the bypass contactor KM1 is closed and kept in a closed state.

[0059] It can be understood that in the bypass circuit in the disclosed embodiment, the power supply circuit and the control circuit are connected in parallel at the positive bus end and the negative bus end of the support capacitor of the cascaded unit module, a voltage dividing resistor and two voltage stabilizing diodes with different breakdown voltages are connected in series for voltage division, the energy storage capacitor connected in parallel at the two ends of the voltage stabilizing diode with a low breakdown voltage stores energy as a power supply for the closing control loop of the bypass contactor, the voltage stabilizing diode with a high breakdown voltage and the voltage stabilizing diode with a low breakdown voltage are connected in series and charge the energy storage capacitor through the current limiting resistor to store energy as a power supply for the closing coil of the bypass contactor, the closing control loop of the bypass contactor selects a full-controlled power electronic device as a switch connected in series between the closing power supply of the contactor and the coil of the contactor, and the power supply circuit and the control circuit of the bypass contactor have a small number of components and low material cost, and can provide a reliable closing power supply, a closing control loop power supply and a simple control circuit for the bypass contactor.

[0060] In the disclosure, the working principle of the power supply circuit 120 is as follows:

[0061] 1. When the (cascaded multi-level) converter is in a shutdown state, the terminal voltage U C0 of the DC support capacitor C0 of the converter is 0V, the terminal voltage U C1 of the energy storage capacitor C1 of the power supply circuit of the bypass contactor is 0V, and the terminal voltage U C3 of the energy storage capacitor C3 is 0V.

[0062] 2. When the cascaded multi-level converter is switched from the shutdown state to the running state, the terminal voltage U C0 of the DC support capacitor C0 of the converter gradually rises from 0V to the working voltage set by the converter:

[0063] 2.1 The terminal voltage U of the DC support capacitor C0 of the converter C0 During the process of gradually increasing the voltage from 0V to the operating voltage set by the converter, the DC support capacitor C0 charges the energy storage capacitor C1 through the current-limiting resistor R1 and the Zener diode D1. The terminal voltage U of the energy storage capacitor C1... C1 The voltage U at the terminals of the energy storage capacitor C1 gradually increases; C1 Higher than the breakdown voltage V of Zener diode D2 BR(D2) At this time, the Zener diode D2 remains in the breakdown state, and the voltage across the energy storage capacitor C1 and the Zener diode D2 remains at V. BR(D2) The terminal voltage U of the energy storage capacitor C1 C1 It is within the allowable gate turn-on voltage range of the power electronic switching device Q1.

[0064] 2.2 The terminal voltage U of the DC support capacitor C0 of the converter C0 During the process of gradually increasing the voltage from 0V to the operating voltage set by the converter, the DC support capacitor C0 charges the energy storage capacitor C3 through the normally closed auxiliary contact of the current limiting resistor R1, the reverse protection diode D3, the current limiting resistor R2, and the bypass contactor KM1. The terminal voltage U of the energy storage capacitor C3... C3 The voltage U across the current-limiting resistor R1 gradually increases; R1 The voltage drop V of the anti-reverse diode D3 D3 The terminal voltage U of the current-limiting resistor R2 R2 and the terminal voltage U of the energy storage capacitor C3 C3 The sum is higher than the breakdown voltage V of the Zener diode D1. BR(D1) And the breakdown voltage V of Zener diode D2 BR(D2) When the sum is equal, Zener diodes D1 and D2 remain in a breakdown state, and the voltage across the series connection of Zener diodes D1 and D2 remains V. BR(D1) With V BR(D2) The sum of the terminal voltages U of the energy storage capacitor C3. C3 The voltage U at the terminals of the energy storage capacitor C3 no longer increases. C3 It is within the closing voltage range required by the bypass contactor KM1.

[0065] 3. When a cascaded multilevel converter switches from operating to shutdown mode, the voltage U across the DC support capacitor C0 of the converter... C0 Gradually reduce the rated operating voltage to 0V:

[0066] 3.1 The terminal voltage U of the DC support capacitor C0 C0 Higher than the breakdown voltage V of Zener diode D1 BR(D1) and the breakdown voltage V of the Zener diode D2 BR(D2) During the summation phase, the terminal voltage U of the energy storage capacitor C3C3 The terminal voltage U of the DC support capacitor C0 remains unchanged C0 The terminal voltage U of the DC support capacitor C0 remains unchanged BR(D1) The terminal voltage U of the DC support capacitor C0 remains unchanged BR(D2) The terminal voltage U of the DC support capacitor C0 remains unchanged C3 The terminal voltage U of the DC support capacitor C0 remains unchanged

[0067] 3.2、The terminal voltage U of the DC support capacitor C0 remains unchanged C0 The terminal voltage U of the DC support capacitor C0 remains unchanged BR(D2) The terminal voltage U of the DC support capacitor C0 remains unchanged C1 The terminal voltage U of the DC support capacitor C0 remains unchanged C0 The terminal voltage U of the DC support capacitor C0 remains unchanged BR(D2) The terminal voltage U of the DC support capacitor C0 remains unchanged C1 The terminal voltage U of the DC support capacitor C0 remains unchanged

[0068] In the present disclosure, the working principle of the control circuit 130 is as follows:

[0069] 1. When the cascaded multilevel converter is normally running, the bypass contactor of the converter always remains open, the bypass contactor control signal issued by the controller of the converter to the unit control board is an open signal, the unit control board decodes the bypass contactor control signal issued by the controller, and the relay control circuit controls the relay KA1 to remain open, and the normally open contact of the relay KA1 remains open.

[0070] 2. When the controller detects that the cascaded unit module has a bypass fault during the running of the cascaded multilevel converter, the controller issues a closed contactor control signal to the unit control board, the unit control board decodes the bypass contactor control signal issued by the controller, and the relay control circuit controls the relay KA1 to close, the energy storage capacitor C1 applies a gate voltage to the full-control power electronic switch Q1 through the current-limiting resistor R3, the full-control power electronic switch Q1 is turned on, the energy storage capacitor C3 applies a closed voltage to the closed coil of the bypass contactor KM1 through the current-limiting resistor R4 and the full-control power electronic switch Q1, the current-limiting resistor R4 limits the closed current of the closed coil, the normally open main contact of the bypass contactor KM1 is closed and remains closed, the bypass contactor KM1 bypasses the faulty unit, and the cascaded multilevel converter continues to run.

[0071] 3. The contactor KM1 state detection circuit of the unit control detects the state of the contactor KM1 and uploads the state information to the controller.

[0072] It is understandable that the power supply and control circuits for the bypass circuit of the bypass contactor are connected in parallel to the positive and negative bus terminals of the DC support capacitor in the cascaded unit module, using two Zener diodes with different breakdown voltages connected in series for voltage division. A storage capacitor is connected in parallel across the low-breakdown-voltage Zener diode to store energy, which serves as the control power supply for the fully controlled power electronic switch in the bypass contactor's closing control circuit. The voltage divided by the high-breakdown-voltage diode and the low-breakdown-voltage diode is used to charge the storage capacitor through a current-limiting resistor, storing energy to power the bypass contactor's closing coil. The closing control switch of the bypass contactor uses a fully controlled power electronic device. Fully controlled power electronic devices have low gate drive voltages and require less power supply capacity. The power supply and control circuits provide a reliable closing power supply, a closing control circuit power supply, and a simple control circuit for the bypass contactor. The bypass circuit uses fewer components, and the component materials are inexpensive and readily available. The two power supply voltages of the power supply and control circuits are easy to adjust; simply adjust the selection of the Zener diodes and the operating voltage of the storage capacitor.

[0073] This disclosure also provides a unit control board including bypass circuitry as described in any of the first aspects. Figure 4 As shown, the bypass circuit is integrated on the unit control board and interacts with the converter controller. The operation of the unit control board can be found in the preceding description.

[0074] This disclosure also provides a converter including the aforementioned unit control board. For other parts of the converter, please refer to the prior art; details will not be elaborated here.

[0075] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0076] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0077] In the present application, unless specifically stated and limited otherwise, a first feature "on" or "under" a second feature can be directly in contact with the second feature, or indirectly in contact with the second feature through an intermediate medium. Also, a first feature "over", "above" and "on top of" a second feature can mean the first feature is directly above or obliquely above the second feature, or simply means the first feature is horizontally higher than the second feature. A first feature "under", "below" and "underneath" a second feature can mean the first feature is directly below or obliquely below the second feature, or simply means the first feature is horizontally lower than the second feature.

[0078] Any process or method descriptions or blocks in flow charts described herein and elsewhere can be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logic functions or steps in the process. Alternate implementations are included within the scope of the preferred embodiments of the present application in which additional functionality can be added or some functionality can be removed, by adding, removing or modifying some steps of the processes described and / or described in flow chart form.

[0079] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the particular feature, structure, material or characteristic being described is included in at least one embodiment or example of the present application. The illustrative appearance of the above terms in various places in the description are not necessarily intended to refer to the same embodiment or example. Also, the particular features, structures, materials or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0080] Although the embodiments of the present application have been shown and described above, it is to be understood that the above-described embodiments are exemplary only, and are not to be taken as limiting the present application, and that changes, modifications, substitutions and variations can be made within the scope of the present application by those skilled in the art without departing from the spirit of the present application.

Claims

1. A bypass circuit for a power converter, the bypass circuit comprising: The converter comprises a plurality of cascaded unit modules, each of which comprises a support capacitor; The bypass circuit comprises: a power supply circuit, a control circuit, and a switch circuit, the power supply circuit and the control circuit being connected in parallel with the support capacitor; The power supply circuit comprises at least a first power supply circuit and a second power supply circuit, In response to the closing operation of the switch circuit, the first power supply circuit supplies power to a trigger circuit in the control circuit, and then the second power supply circuit supplies power to an execution circuit in the control circuit, the trigger circuit being used to start the execution circuit, and the execution circuit being used to close a contactor so that the cascaded unit module is bypassed.

2. The bypass circuit of claim 1, wherein, The power supply circuit further comprises a first resistor, a first diode, and a second diode, which are connected in series and connected in parallel with the support capacitor; The first power supply circuit is connected in parallel with the second diode, and the second power supply circuit is connected in parallel with the series circuit of the first diode and the second diode.

3. The bypass circuit of claim 2, wherein, The first power supply circuit comprises a first capacitor, and the second power supply circuit comprises a third capacitor and a fifth resistor, which are connected in parallel.

4. The bypass circuit of claim 3, wherein, The power supply circuit further comprises a third diode, a second resistor, and a second capacitor, which are connected in series and connected in series with the fifth resistor.

5. The bypass circuit of claim 4, wherein, The control circuit comprises a trigger circuit and an execution circuit, the trigger circuit comprising a fully controlled power electronic switch, and the fully controlled power electronic switch comprising an IGBT, a first end of the IGBT being connected to one end of the first capacitor through a third resistor, and a second end of the IGBT being connected to the other end of the first capacitor.

6. The bypass circuit of claim 5, wherein, The execution circuit comprises a control coil and a fourth diode, the fourth diode being connected in parallel with the control coil, the control coil being connected to a third end of the IGBT through a fourth resistor, and a second end of the control coil being connected to one end of the second capacitor.

7. The bypass circuit of claim 4, wherein, The power supply circuit further comprises a normally closed auxiliary contact, which is connected in parallel with the second capacitor.

8. The bypass circuit of claim 5, wherein, The switch circuit comprises a relay normally open contact, which is arranged between the third resistor and the first capacitor.

9. A unit control board characterized by, The bypass circuit comprises a plurality of cascaded unit modules, each of which comprises a support capacitor; 10. A current transformer, characterized by The unit control board comprises a power supply circuit, a control circuit, and a switch circuit, the power supply circuit and the control circuit being connected in parallel with the support capacitor; The power supply circuit comprises at least a first power supply circuit and a second power supply circuit, In response to the closing operation of the switch circuit, the first power supply circuit supplies power to a trigger circuit in the control circuit, and then the second power supply circuit supplies power to an execution circuit in the control circuit, the trigger circuit being used to start the execution circuit, and the execution circuit being used to close a contactor so that the cascaded unit module is bypassed. The power supply circuit further comprises a first resistor, a first diode, and a second diode, which are connected in series and connected in parallel with the support capacitor; The first power supply circuit is connected in parallel with the second diode, and the second power supply circuit is connected in parallel with the series circuit of the first diode and the second diode. The first power supply circuit comprises a first capacitor, and the second power supply circuit comprises a third capacitor and a fifth resistor, which are connected in parallel. The power supply circuit further comprises a third diode, a second resistor, and a second capacitor, which are connected in series and connected in series with the fifth resistor. The control circuit comprises a trigger circuit and an execution circuit, the trigger circuit comprising a fully controlled power electronic switch, and the fully controlled power electronic switch comprising an IGBT, a first end of the IGBT being connected to one end of the first capacitor through a third resistor, and a second end of the IGBT being connected to the other end of the first capacitor. The execution circuit comprises a control coil and a fourth diode, the fourth diode being connected in parallel with the control coil, the control coil being connected to a third end of the IGBT through a fourth resistor, and a second end of the control coil being connected to one end of the second capacitor. The power supply circuit further comprises a normally closed auxiliary contact, which is connected in parallel with the second capacitor. The switch circuit comprises a relay normally open contact, which is arranged between the third resistor and the first capacitor.

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