A converter unit, a converter and a control method

Abstract

The application discloses a current conversion unit, a current converter and a control method, which comprise a power conversion circuit, a driving power supply, a direct current discharge circuit and a controller; the bridge arm switch tube of the power conversion circuit is an IGCT; the driving power supply is used for providing driving for the IGCT; the power conversion circuit is connected with a direct current bus; the direct current discharge circuit is connected with the direct current bus; the controller is used for controlling at least part of the IGCT corresponding to the driving power supply which is not powered off to be turned off, controlling the direct current discharge circuit to discharge the direct current bus, and controlling the IGCT in a normal bridge arm to discharge the direct current bus when the voltage of the direct current bus is less than or equal to a preset voltage; and the driving power supply corresponding to all the IGCT in the normal bridge arm is normal. The IGCT current converter provided by the application can guarantee the safety of the IGCT when the driving power supply is powered off, and can also quickly discharge the energy of the direct current bus, so that the voltage of the direct current bus is quickly reduced.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a converter unit, converter, and control method. Background Technology

[0002] Pumped storage, offshore wind power, and high-power variable frequency drives are placing higher demands on the power rating of converters. Research and development of 10+ MW and even tens of MW power electronic converters have become a hot topic in the industry. Integrated gate-commutated thyristors (IGCTs) offer significant advantages such as high blocking voltage, strong current carrying capacity, low conduction losses, short-circuit failure resistance, and high reliability, making them particularly suitable for medium-voltage, high-power power conversion scenarios.

[0003] IGCTs are currently being used in medium-voltage megawatt-level AC-DC-AC converters. For example, two-level AC-DC-AC converters based on IGCTs are suitable for applications such as motor drives and wind power grid connection.

[0004] IGCTs require a driving power supply to operate. However, in practical applications, the driving power supply may fail or lose power due to fault protection, failing to provide the required driving power to the IGCT. In this case, the IGCT cannot perform normal switching operations. Since the IGCT cannot withstand the DC bus voltage, it may fail and be damaged, leading to faults such as bridge arm shoot-through. Summary of the Invention

[0005] In view of this, this application provides a converter unit, converter and control method that can protect the IGCT in a timely manner when the drive power supply of the IGCT fails.

[0006] This application provides a converter unit, including: a power conversion circuit, a drive power supply, a DC discharge circuit, and a controller; the bridge arm switching transistor of the power conversion circuit is an IGCT; the drive power supply is used to provide drive for the IGCT; the power conversion circuit is connected to the DC bus; the DC discharge circuit is connected to the DC bus; the controller is used to control at least some IGCTs corresponding to the drive power supply that is not powered off to disconnect when at least one drive power supply is powered off, and to control the DC discharge circuit to discharge to the DC bus; when the DC bus voltage is less than or equal to a preset voltage, it controls the IGCTs in the normal bridge arm to conduct to discharge to the DC bus, and the drive power supplies corresponding to all IGCTs in the normal bridge arm are normal.

[0007] Preferably, the DC discharge circuit includes: a switching transistor and a resistor connected in series; and a controller, specifically used to control all IGCTs corresponding to the driving power supply that has not lost power to disconnect, control the switching transistor to close, and enable the DC discharge circuit to discharge to the DC bus.

[0008] Preferably, it further includes: a chopper circuit; the chopper circuit is connected to the DC bus; and a controller, which is also used to control the chopper circuit to chop and discharge the DC bus when the drive power supply fails.

[0009] Preferably, the number of IGCTs is greater than the number of drive power supplies, with one drive power supply used to drive multiple IGCTs.

[0010] Preferably, the number of IGCTs is the same as the number of drive power supplies, and there is a one-to-one correspondence between IGCTs and drive power supplies.

[0011] Preferably, the power conversion circuit includes: an AC-CDC circuit and a DC-AC circuit; the bridge arm switching transistors of the AC-CDC circuit and the bridge arm switching transistors of the DC-AC circuit both include IGCTs; the output terminal of the AC-CDC circuit is connected to the DC bus, and the input terminal of the DC-AC circuit is connected to the DC bus.

[0012] Preferably, the AC / DC circuit is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series; the DC / AC circuit is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series. or, The AC / DC circuit is a three-phase half-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes an IGCT; the DC / AC circuit is a three-phase half-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes an IGCT.

[0013] Preferably, the controller is also used to control the input terminal of the AC-CDC circuit to disconnect from the outside world and the output terminal of the DC-AC circuit to disconnect from the power supply when the drive power supply corresponding to the IGCT is de-energized.

[0014] Preferably, the power conversion circuit includes: an ACCDC circuit; the output terminal of the ACCDC circuit is connected to the DC bus; the ACCDC circuit is a three-phase full-bridge circuit, the three-phase full-bridge circuit includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series; or, The ACDC circuit is a three-phase half-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes an IGCT.

[0015] Preferably, the power conversion circuit includes: a DCAC circuit; the input terminal of the DCAC circuit is connected to the DC bus; the DCAC circuit is a three-phase full-bridge circuit, the three-phase full-bridge circuit includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series. or, The DCAC circuit is a three-phase half-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes an IGCT.

[0016] Preferably, the power conversion circuit is a single-phase full-bridge circuit or a single-phase half-bridge circuit. This application also provides a converter including at least one converter unit as described above; when there are multiple converter units, the multiple converter units are cascaded together.

[0017] This application also provides a control method for a converter unit, which includes a power conversion circuit, a drive power supply, and a DC discharge circuit. The bridge arm switching transistors of the power conversion circuit are IGCTs. The drive power supply provides drive for the IGCTs. When at least one drive power supply fails, at least some IGCTs corresponding to the drive power supplies that have not failed are controlled to disconnect. The DC discharge circuit is controlled to discharge to the DC bus. When the DC bus voltage is less than or equal to a preset voltage, the IGCTs in the normal bridge arm are controlled to conduct and discharge to the DC bus. The drive power supplies corresponding to all IGCTs in the normal bridge arm are normal.

[0018] Preferably, controlling the DC discharge circuit to discharge to the DC bus specifically includes: controlling the switching transistor in the DC discharge circuit to close, so that the DC discharge circuit discharges to the DC bus; the DC discharge circuit includes: a switching transistor and a resistor connected in series.

[0019] Preferably, the converter unit further includes: a chopper circuit; the chopper circuit is connected to the DC bus; the method further includes: When the drive power supply fails, the control chopper circuit performs chopping to discharge the DC bus.

[0020] Therefore, this application has the following beneficial effects: The converter unit provided in this application embodiment, when one drive power supply fails, in order to protect the IGCT, first disconnects some or all of the IGCTs corresponding to the remaining drive power supplies. The energy of the DC bus is then discharged through the DC discharge circuit, causing the DC bus voltage to drop. When the DC bus voltage drops to a preset voltage, the corresponding current is the safe current that the IGCT can withstand. Only then is the normal bridge arm controlled to conduct, thereby constructing more DC bus discharge circuits. Since the IGCT itself has a large current-carrying capacity, the DC bus can be short-circuited by closing the IGCT of the normal bridge arm, thus quickly discharging the saved DC bus voltage energy without causing the IGCT device to fail due to overcurrent. Therefore, the IGCT converter provided in this application embodiment can ensure the safety of the IGCT and quickly discharge the DC bus energy when the drive power supply fails, resulting in a rapid drop in the DC bus voltage. Attached Figure Description

[0021] Figure 1A schematic diagram of a converter provided in an embodiment of this application; Figure 2 A schematic diagram of an equivalent IGCT provided in an embodiment of this application; Figure 3 A schematic diagram of another converter provided in an embodiment of this application; Figure 4 A topology diagram of another converter provided in the embodiments of this application; Figure 5 This application provides another converter topology diagram as an embodiment of the present application; Figure 6 A schematic diagram of the DC bus voltage discharge process provided in the embodiments of this application; Figure 7 A flowchart of a converter control method provided in an embodiment of this application. Detailed Implementation

[0022] To enable those skilled in the art to better understand and implement the technical solutions provided in the embodiments of this application, the application scenarios of the IGCT converter unit are first described below with reference to the accompanying drawings. It should be understood that the IGCT converter unit provided in the embodiments of this application can be applied to various scenarios, such as motor drives, for example, motor drives in rail transit. In addition, the IGCT converter unit can also be applied to wind turbine generator sets. Furthermore, it can also be applied to pumped storage and other applications.

[0023] This application does not specifically limit the topology type of the IGCT converter unit; for example, it can be a rectifier, an inverter, or an AC-DC-AC converter unit. The following describes a specific implementation of an AC-DC-AC converter unit applied to an AC-DC-AC converter unit.

[0024] See Figure 1 The figure is a schematic diagram of an IGCT converter unit provided in an embodiment of this application.

[0025] The IGCT converter unit provided in this application embodiment has an AC-DC-AC converter unit topology. The power conversion circuit of the IGCT converter unit includes: an AC-DC circuit 100 and a DC-AC circuit 200. Both the bridge arm switching transistors of the ACDC circuit 100 and the bridge arm switching transistors of the DCAC circuit include IGCT. The output of the AC / DC circuit 100 is connected to the DC bus, and the input of the DC / AC circuit is also connected to the DC bus. The DC bus includes the positive DC bus BUS+ and the negative DC bus BUS-.

[0026] The ACDC circuit 100 is a three-phase full-bridge circuit. A three-phase full-bridge circuit includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series, such as... Figure 1 As shown, one bridge arm 10 includes two IGCTs connected in series. The DCAC circuit 200 is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series.

[0027] Figure 1 In the example, the input terminal of the AC-DC circuit 100 is used to connect the motor M through the first set of circuit breakers Sm, and the output terminal of the DC-AC circuit 200 is used to connect the AC power grid G ​​through the second set of circuit breakers Sg.

[0028] The IGCT is a hard-driven circuit, and its di / dt level is mainly affected by the external circuit parameters. During the IGCT turn-on and diode turn-off, the diode generates a large reverse recovery current. To protect the diode, each bridge arm is equipped with a buffer absorption circuit 20 consisting of a resistor, inductor, capacitor, and diode (RLCD) to limit the di / dt during the IGCT turn-on process, absorb turn-off voltage spikes, and also limit the rate of rise of fault current.

[0029] See Figure 2 This figure is an equivalent schematic diagram of IGCT provided in the embodiments of this application.

[0030] The IGCT has a gate (G), anode (A), and cathode (K). For the IGCT to operate, a drive power supply is required. When the IGCT is off, the drive power supply must provide a certain reverse bias voltage to the IGCT gate and cathode to ensure reliable IGCT turn-off.

[0031] However, in practical applications, the drive power supply may fail due to its own failure or fault protection (overvoltage, overcurrent, etc.), and thus fail to provide the required gate cathode power to the IGCT. In this case, the IGCT cannot perform the corresponding switching actions according to the drive signals given by the controller. More importantly, the IGCT cannot withstand high DC bus voltages, which may lead to IGCT failure and damage, and consequently cause faults such as bridge arm shoot-through.

[0032] To prevent damage to the IGCT from excessively high DC bus voltage, a DC discharge circuit is used to reduce the DC bus voltage. However, simply discharging through the DC discharge circuit results in a slow discharge rate, which gradually decreases with increasing discharge time, conforming to the first-order inertial time-domain characteristics. Therefore, it is not possible to reduce the DC bus voltage to below the IGCT's safe voltage in a timely manner.

[0033] In order to protect the IGCT when the drive power supply fails, this embodiment of the application takes into account the large current carrying capacity of the IGCT and the safe discharge effect of the DC discharge circuit, so as to quickly and safely reduce the DC bus voltage after the drive power supply fails, thereby protecting the IGCT device and the entire IGCT converter unit.

[0034] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0035] See Figure 3 The figure is a schematic diagram of another IGCT converter unit provided in an embodiment of this application.

[0036] The integrated gate commutated thyristor (IGCT) converter unit provided in this application includes: a power conversion circuit, a drive power supply (not shown in the figure), a DC discharge circuit 300, and a controller 1000.

[0037] The bridge arm switching transistor of the power conversion circuit is an IGCT; the drive power supply is used to drive the IGCT.

[0038] The power conversion circuit is connected to the DC bus; the DC discharge circuit 300 is also connected to the DC bus. This embodiment of the application uses a power conversion circuit including an AC-CDC100 and a DC-AC circuit 200 as an example. The input terminal of the AC-CDC100 is connected to the motor M via a first circuit breaker Sm, and the output terminal of the AC-CDC100 is connected to the DC bus. The input terminal of the DC-AC circuit 200 is connected to the DC bus, and the output terminal of the DC-AC circuit 200 is connected to the AC power grid G. It should be understood that the input and output terminals are relative concepts; the AC-CDC100 and DC-AC circuit 200 can also be bidirectional conversion circuits, meaning power can flow bidirectionally. Alternatively, the power conversion circuit provided in this embodiment may also include only the AC-CDC100; see [link to relevant documentation]. Figure 4 This illustrates another topology of the IGCT converter unit. The power conversion circuit includes: an ACCDC circuit 100; the output of the ACCDC circuit 100 is connected to the DC bus; the ACCDC circuit 100 is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series.

[0039] Alternatively, the power conversion circuit provided in this application embodiment may also include only the DCAC circuit 200, see [link to relevant documentation]. Figure 5 The diagram shows another topology of the IGCT converter unit. The power conversion circuit includes: a DCAC circuit 200; the input terminal of the DCAC circuit 200 is connected to the DC bus; the DCAC circuit 200 is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series.

[0040] Figure 4 and Figure 5 The topology of the power conversion circuit and Figure 3 There are some differences, but the rest of the architecture is the same, so I won't go into details here.

[0041] The controller 1000 is used to control all IGCTs to disconnect when the drive power supply fails, control the DC discharge circuit to discharge to the DC bus, and control the IGCTs in the normal bridge arm to conduct to discharge to the DC bus when the DC bus voltage is less than or equal to the preset voltage. The drive power supply corresponding to all IGCTs in the normal bridge arm is normal.

[0042] When the converter unit is applied to a wind turbine generator set, the DC discharge circuit can be directly implemented using the crowbar circuit in the wind turbine generator set, requiring a separate DC discharge circuit. It should be understood that a separate DC discharge circuit can also be configured, allowing both the crowbar circuit and the DC discharge circuit to discharge the DC bus voltage.

[0043] The embodiments of this application do not specifically limit the specific value of the preset voltage, but can obtain it through simulation testing based on the voltage level of the DC bus and the current withstand capability of the IGCT.

[0044] The controller monitors the status of the drive power supply for each IGCT. If the drive power supply of any IGCT fails, the controller will receive a corresponding fault signal. This embodiment does not specify the exact method used to detect drive power failure.

[0045] When one drive power supply fails, to protect the IGCT, all IGCTs are first disconnected. Energy from the DC bus is then discharged through the DC discharge circuit, causing the DC bus voltage to drop. When the DC bus voltage drops to a preset voltage, the corresponding current is the safe current that the IGCT can withstand. Only then is the normal bridge arm turned on, thus creating more DC bus discharge loops. Because the IGCT itself has a large current-carrying capacity, the DC bus can be short-circuited by closing the IGCT in the normal bridge arm, thereby quickly dissipating the saved DC bus voltage energy without causing overcurrent failure of the IGCT devices. Therefore, the IGCT converter unit provided in this application can ensure the safety of the IGCT and quickly dissipate DC bus energy when the drive power supply fails, resulting in a rapid drop in DC bus voltage.

[0046] When the DC bus voltage drops below the preset voltage Vsafe (determined by the specific IGCT specification), meaning that the IGCT's drive power supply is de-energized at this preset voltage, the IGCT can still withstand the corresponding safe current. Disconnect all IGCTs, and then power down the entire converter unit for maintenance.

[0047] The input terminal of the ACDC circuit 100 is used to connect the motor through the first set of circuit breakers Sm, and the output terminal of the DCAC circuit 200 is used to connect to the AC power grid through the second set of circuit breakers Sg. The controller is also used to control both the first set of circuit breakers Sm and the second set of circuit breakers Sg to open when the drive power supply corresponding to the IGCT fails, thereby blocking the external energy source from supplying energy to the DC bus. The above is only an example using the first and second sets of circuit breakers; it should be understood that other types of switches can also be used for connection, switching the energy path by controlling the switch to open. For example, other types of switches can be contactors or relays.

[0048] The IGCT converter unit provided in this application embodiment has a greater number of IGCTs than the number of drive power supplies, with one drive power supply providing power to multiple IGCTs. For example, IGCTs in the same bridge arm share the same drive power supply. Taking the first bridge arm in the ACDC circuit 100 as an example, Tma1 and Tma2 in the first bridge arm can share a single drive power supply. In this case, when the drive power supply fails, the corresponding IGCTs cannot perform normal switching operations. Another implementation method is that the number of IGCTs is the same as the number of drive power supplies, with a one-to-one correspondence between IGCTs and drive power supplies, meaning each IGCT corresponds to a separate drive power supply.

[0049] The IGCT converter unit provided in this application embodiment is not specifically limited to the specific structure of the DC discharge circuit, as long as it can discharge the energy of the DC bus and reduce the DC bus voltage, for example... Figure 3 One provided DC discharge circuit includes a switching transistor Tc and a resistor Rc connected in series.

[0050] The controller 300 is specifically used to control the closing of the switching transistor Tc, so that the DC discharge circuit 300 discharges to the DC bus. When the switching transistor Tc is closed, the resistor Rc consumes energy, and the DC bus voltage decreases.

[0051] The embodiments of this application do not specifically limit the type of switching transistor Tc. For example, Tc can also be an IGCT or other types of switching transistors.

[0052] The following is combined with Figure 3 This section presents a specific working example; for ease of understanding, please refer to [link / reference]. Figure 6 The figure is a schematic diagram of the DC bus voltage discharge process provided in the embodiment of this application.

[0053] Figure 6 The horizontal axis represents time t, and the vertical axis represents the DC bus voltage Vbus. Vshoot is the preset voltage, and Vsafe is the safety voltage.

[0054] The AC / DC circuit is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series; the DC / AC circuit is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series.

[0055] Before time t0, the IGCT converter unit was operating normally, and the DC bus voltage was the rated voltage VN. At time t0, the controller detected a power failure in the drive power supply of Tma1. The controller first disconnected all IGCTs, and disconnected Sm and Sg, and turned on the switch Tc in the DC discharge circuit to discharge the DC bus, causing the DC bus voltage Vbus to begin to drop.

[0056] At time t1, the DC bus voltage Vbus drops to Vshoot. The controller then turns on Tmb1, Tmb2, Tmc1, Tmc2, Tga1, Tga2, Tgb1, Tgb2, Tgc1, and Tgc2 in the normal bridge arms. This causes the IGCTs to form a DC bus short-circuit loop, accelerating the DC bus discharge speed. Eventually, the DC bus voltage Vbus drops to Vsafe. At this point, the corresponding current is the safe current that the IGCTs can withstand. All IGCTs are then disconnected, and the system is powered off for maintenance.

[0057] It should be understood that due to a power failure in the drive power supply of Tma1, the bridge arm where Tma1 is located is not included when the normal bridge arm is turned on.

[0058] The above embodiments use a DC discharge circuit to supply DC bus voltage. In addition, the converter unit may also include a chopper circuit connected to the DC bus. The controller is also used to control the chopper circuit to discharge the DC bus when the drive power supply fails. That is, the chopper circuit and the DC discharge circuit work together to discharge the DC bus.

[0059] The embodiments of this application do not specifically limit the specific implementation of the chopper circuit; for example, it can be a DC-DC circuit.

[0060] The IGCT converter unit provided in this application embodiment, through the cooperation of the bridge arm IGCT and the DC discharge circuit, can quickly and safely discharge the DC bus, ensuring the protection of the IGCT device and the active protection of the IGCT converter unit after the drive power supply fails.

[0061] It should be understood that the converter unit provided in the above embodiments can be used independently as a converter, or as a power module in a high-power converter. The high-power converter includes multiple converter units described above, and multiple converter units are cascaded together. When the drive power supply of the IGCT in the converter unit fails, the technical solution provided in the embodiments of this application also applies.

[0062] Based on the IGCT converter unit provided in the above embodiments, this application also provides a control method for the IGCT converter unit, which will be described in detail below with reference to the accompanying drawings.

[0063] See Figure 7 The figure is a flowchart of a control method for an IGCT converter unit provided in an embodiment of this application.

[0064] The control method for the IGCT converter unit provided in this application embodiment includes a power converter unit circuit, a drive power supply, and a DC discharge circuit; the bridge arm switching transistor of the power conversion circuit is an IGCT; and the drive power supply provides drive for the IGCT. S701: When the drive power supply fails, it controls all IGCTs to disconnect and controls the DC discharge circuit to discharge to the DC bus. Controlling the DC discharge circuit to discharge to the DC bus specifically includes: The switching transistor in the DC discharge circuit is closed to allow the DC discharge circuit to discharge to the DC bus; the DC discharge circuit includes a switching transistor and a resistor connected in series.

[0065] S702: When the DC bus voltage is less than or equal to the preset voltage, the IGCT in the normal bridge arm is controlled to conduct to discharge the DC bus, and the drive power supply corresponding to all IGCTs in the normal bridge arm is normal.

[0066] When one drive power supply fails, to protect the IGCT, all IGCTs are first disconnected. Energy from the DC bus is then discharged through a DC discharge circuit, causing the DC bus voltage to drop. When the voltage drops to a preset level, the corresponding current is the safe current that the IGCT can withstand. Only then is the normal bridge arm turned on, thus creating more DC bus discharge loops. Because the IGCT itself has a large current-carrying capacity, the DC bus can be short-circuited by closing the IGCT in the normal bridge arm, thereby quickly dissipating the saved DC bus voltage energy without causing overcurrent failure of the IGCT devices. Therefore, the control method for the IGCT converter unit provided in this application can ensure the safety of the IGCT and quickly dissipate DC bus energy when the drive power supply fails, resulting in a rapid drop in DC bus voltage.

[0067] The control method provided in this application embodiment, through the cooperation of the bridge arm IGCT and the DC discharge circuit, enables the DC bus to discharge quickly and safely, ensuring the protection of the IGCT device and the active protection of the IGCT converter unit after the drive power supply fails.

[0068] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0069] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A converter unit, characterized in that, include: Power conversion circuit, drive power supply, DC discharge circuit and controller; The bridge arm switching transistor of the power conversion circuit is an IGCT; the driving power supply is used to provide drive for the IGCT. The power conversion circuit is connected to the DC bus; the DC discharge circuit is connected to the DC bus. The controller is configured to, when at least one drive power supply fails, control at least some IGCTs corresponding to the drive power supply that has not failed to disconnect, control the DC discharge circuit to discharge the DC bus, and control the IGCTs in the normal bridge arm to conduct to discharge the DC bus when the DC bus voltage is less than or equal to a preset voltage, and the drive power supply corresponding to all IGCTs in the normal bridge arm is normal.

2. The converter unit according to claim 1, characterized in that, The DC discharge circuit includes a switching transistor and a resistor connected in series; The controller is specifically used to disconnect all IGCTs corresponding to the drive power supply that has not lost power, and to close the switching transistor so that the DC discharge circuit discharges to the DC bus.

3. The converter unit according to claim 2, characterized in that, Also includes: Chopper circuit; The chopper circuit is connected to the DC bus; The controller is also configured to control the chopper circuit to chop and discharge the DC bus when the drive power supply fails.

4. The converter unit according to claim 1, characterized in that, The number of IGCTs is greater than the number of driving power supplies, and one driving power supply is used to drive multiple IGCTs.

5. The converter unit according to claim 1, characterized in that, The number of IGCTs is the same as the number of driving power supplies, and there is a one-to-one correspondence between the IGCTs and the driving power supplies.

6. The converter unit according to any one of claims 1-5, characterized in that, The power conversion circuit includes: an AC-CDC circuit and a DC-AC circuit; Both the bridge arm switching transistors of the AC-CDC circuit and the bridge arm switching transistors of the DC-AC circuit include IGCTs. The output terminal of the AC-CDC circuit is connected to the DC bus, and the input terminal of the DC-AC circuit is connected to the DC bus.

7. The converter unit according to claim 6, characterized in that, The AC / DC circuit is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series; the DC / AC circuit is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series. or, The AC / DC circuit is a three-phase half-bridge circuit, which includes three bridge arms, each of which includes one IGCT; the DC / AC circuit is a three-phase half-bridge circuit, which includes three bridge arms, each of which includes one IGCT.

8. The converter unit according to claim 7, characterized in that, The controller is also used to control the input terminal of the AC-CDC circuit to disconnect from the outside world and the output terminal of the DC-AC circuit to disconnect from the power supply when the drive power supply corresponding to the IGCT is de-energized.

9. The converter unit according to any one of claims 1-5, characterized in that, The power conversion circuit includes an AC-CDC circuit; the output terminal of the AC-CDC circuit is connected to the DC bus. The ACDC circuit is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series. or, The ACDC circuit is a three-phase half-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes one IGCT.

10. The converter unit according to any one of claims 1-5, characterized in that, The power conversion circuit includes a DCAC circuit; the input terminal of the DCAC circuit is connected to the DC bus. The DCAC circuit is a three-phase full-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes two IGCTs connected in series. or, The DCAC circuit is a three-phase half-bridge circuit, which includes three bridge arms, and each of the three bridge arms includes one IGCT.

11. The converter unit according to any one of claims 1-5, characterized in that, The power conversion circuit is a single-phase full-bridge circuit or a single-phase half-bridge circuit.

12. A converter, characterized in that, Includes at least one converter unit as described in any one of claims 1-11; When there are multiple converter units, the multiple converter units are cascaded together.

13. A control method for a converter unit, characterized in that, The converter unit includes a power conversion circuit, a drive power supply, and a DC discharge circuit; the bridge arm switching transistor of the power conversion circuit is an IGCT; the drive power supply provides drive for the IGCT. When at least one drive power supply fails, at least a portion of the IGCTs corresponding to the drive power supply that has not failed are disconnected; the DC discharge circuit is controlled to discharge to the DC bus. When the DC bus voltage is less than or equal to the preset voltage, the IGCT in the normal bridge arm is turned on to discharge the DC bus, and the drive power supply corresponding to all the IGCTs in the normal bridge arm is normal.

14. The control method according to claim 13, characterized in that, Controlling the DC discharge circuit to discharge to the DC bus specifically includes: The switching transistor in the DC discharge circuit is controlled to close, so that the DC discharge circuit discharges to the DC bus; the DC discharge circuit includes a switching transistor and a resistor connected in series.

15. The control method according to claim 14, characterized in that, The converter unit further includes a chopper circuit; the chopper circuit is connected to the DC bus. The method further includes: When the drive power supply fails, the chopper circuit is controlled to chop and discharge the DC bus.

Images