Control method for double controllable overvoltage pass-through circuit of power module

Abstract

The application provides a control method of a double-controllable overvoltage pass-through circuit for a power module, which comprises the following steps: when the voltage of a direct-current capacitor reaches a preset first voltage value, a first trigger current is generated by a lower tube forced trigger circuit, the first trigger current controls the lower tube to be turned on, and the weak opening of the lower tube is completed; when the voltage of the direct-current capacitor is lower than a preset second voltage value, a reverse-parallel diode of the lower tube and an upper tube forms a pass-through path, the direct-current capacitor is rapidly discharged, and the lower tube keeps current passing; and when the voltage of the direct-current capacitor is higher than the second voltage value, a second trigger current is generated by an upper tube forced trigger circuit, the second trigger current makes the upper tube turned on, the upper tube and the lower tube form a pass-through path, the direct-current capacitor is rapidly discharged, and the lower tube keeps current passing. According to the embodiment of the application, the overvoltage problem of a fault power module in a flexible direct-current power transmission system is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power systems, in particular, to a control method of a double controllable overvoltage pass-through circuit for a power module. BACKGROUND

[0002] In a flexible DC power transmission system, as the number of power modules increases, the reliability of the system will be affected by module failure. In order to improve the reliability of the power system, the method of increasing redundant modules is usually adopted. When a power module fails, the faulty power module can be removed by bypass operation, thereby ensuring the continuous operation of the power system.

[0003] If the fault causes the power module to be not fully charged, the power module will lose external communication, and the control power supply is not ready, which will lead to the bypass operation being unable to be performed. In this case, the faulty power module will be continuously charged by external current, and the voltage will continue to rise, eventually endangering the safety of the power module capacitor and the power system.

[0004] At present, the lower tube of the power module is usually broken down to bypass the module, but the way to break down the lower tube usually adopts thermal breakdown or overcurrent breakdown, but these two methods are greatly dependent on the type of device and external electrical conditions, and cannot form a stable and reliable bypass effect. SUMMARY

[0005] The present application proposes a control method of a double controllable overvoltage pass-through circuit for a power module to solve the overvoltage problem of the faulty power module in the current flexible DC power transmission system.

[0006] According to one aspect of this application, a control method for a dual controllable overvoltage shoot-through circuit for a power module is proposed. The power module includes a bridge structure and a DC capacitor. The DC capacitor is connected in parallel across the two ends of the bridge structure. A power device between the midpoint of the bridge structure and the negative terminal of the DC capacitor is defined as the lower transistor, and a power device between the midpoint of the bridge structure and the positive terminal of the DC capacitor is defined as the upper transistor. The upper transistor and the lower transistor are respectively connected in anti-parallel diodes. The dual controllable overvoltage shoot-through circuit includes a lower transistor forced trigger circuit electrically connected between the positive terminal of the DC capacitor and the gate of the lower transistor, and an upper transistor forced trigger circuit electrically connected between the positive terminal of the DC capacitor and the gate of the upper transistor. The control method includes: when the... When the voltage of the DC capacitor reaches a preset first voltage setting, the lower transistor forced trigger circuit generates a first trigger current. The first trigger current controls the lower transistor to turn on, completing the weak turn-on of the lower transistor. The first trigger current simultaneously controls the upper transistor forced trigger circuit to switch modes. When the voltage of the DC capacitor is lower than a preset second voltage setting, the anti-parallel diodes of the lower and upper transistors form a path, the DC capacitor discharges rapidly, and the lower transistor maintains current flow. When the voltage of the DC capacitor is higher than the second voltage setting, the upper transistor forced trigger circuit generates a second trigger current. The second trigger current turns on the upper transistor, the upper and lower transistors form a path, the DC capacitor discharges rapidly, and the lower transistor maintains current flow.

[0007] According to some embodiments, the lower transistor forced triggering circuit includes a first overvoltage protection unit, which includes one or more transient voltage suppression diodes, Zener diodes, or BOD devices connected in series, and the operating voltage of the first overvoltage protection unit is the first voltage setpoint.

[0008] According to some embodiments, the lower tube forced triggering circuit further includes an optocoupler light-emitting side or a light-emitting device that is connected in series with the first overvoltage protection unit.

[0009] According to some embodiments, the lower tube forced triggering circuit further includes a first series RC network connected in series with the first overvoltage protection unit, and the first series RC network is directly or in parallel with the optocoupler light-emitting side or the light-emitting device via a current-limiting resistor.

[0010] According to some embodiments, the upper-side forced triggering circuit includes a second overvoltage protection unit and a third overvoltage protection unit, wherein both the second overvoltage protection unit and the third overvoltage protection unit include one or more transient voltage suppression diodes, Zener diodes, or BOD devices connected in series; the operating voltage of the second overvoltage protection unit is the second voltage setpoint, and the operating voltage of the third overvoltage protection unit is the third voltage setpoint.

[0011] According to some embodiments, the upper tube forced triggering circuit further comprises a second series R-C network and a third series R-C network, which are connected in series with the second overvoltage protection unit and the third overvoltage protection unit respectively.

[0012] According to some embodiments, a controllable switch is connected in parallel across the third overvoltage protection unit, which is in an open state and is closed according to a signal from the lower tube forced triggering circuit.

[0013] According to some embodiments, the controllable switch comprises a switching triode, and the second series R-C network is connected in parallel with a light-accepting side of a photo-coupler or a light-receiving device directly or through a current-limiting resistor, wherein: the collector and emitter of the switching triode are electrically connected across the third overvoltage protection unit; the base of the switching triode is electrically connected to a first end of the light-accepting side of the photo-coupler or the light-receiving device; and a second end of the light-accepting side of the photo-coupler or the light-receiving device is connected to the second overvoltage protection circuit through a resistor, or to the gate of the upper tube.

[0014] According to some embodiments, when the voltage of the direct-current capacitor reaches the first voltage set value and the first triggering current controls the lower tube to be turned on, the light-accepting side of the photo-coupler or the light-receiving device is turned on.

[0015] According to some embodiments, the lower tube forced triggering circuit and the lower tube are arranged on the same drive circuit board; and / or the upper tube forced triggering circuit and the upper tube are arranged on the same drive circuit board.

[0016] According to some embodiments, the first voltage set value is higher than the second voltage set value and the operating voltage of the power module, and is lower than the sum of the second voltage set value and the third voltage set value.

[0017] According to some embodiments, the power module further comprises: a lower tube drive turn-off branch electrically connected to the lower tube forced triggering circuit through a first control network, and a triggering current generated by the lower tube forced triggering circuit can cause the lower tube drive turn-off branch to be turned off; and an upper tube drive turn-off branch electrically connected to the upper tube forced triggering circuit through a second control network, and a triggering current generated by the upper tube forced triggering circuit can cause the upper tube drive turn-off branch to be turned off.

[0018] According to some embodiments, the lower tube drive turn-off branch comprises a first triode, the emitter of which is electrically connected to the gate of the lower tube, and the collector of which is electrically connected to a negative power supply or the negative electrode of the direct-current capacitor, or a reference ground potential; and the upper tube drive turn-off branch comprises a second triode, the emitter of which is electrically connected to the gate of the upper tube, and the collector of which is electrically connected to a negative power supply or the negative electrode of the direct-current capacitor, or a reference ground potential.

[0019] According to some embodiments, the first control network comprises a resistance-capacitance network, and the lower forced trigger circuit forms a high level or a low level through a generated trigger current; and / or the second control network comprises a resistance-capacitance network, and the upper forced trigger circuit forms a high level or a low level through a generated trigger current.

[0020] According to some embodiments, the lower pipe and the upper pipe respectively comprise a plurality of composite triode branches, and the control method further comprises: when part of the composite triode branches are turned on, the load current of the power module is transferred to the turned-on composite triode branches, causing the turned-on composite triode branches to overheat and melt, forming a short-circuit failure; when the load current of the power module is transferred from the anti-parallel diode of the upper pipe to the lower pipe, the reverse diode parallel to the lower pipe recovers failure, and the lower pipe forms a short-circuit failure.

[0021] According to some embodiments, the power module further comprises a lower pipe driving circuit, and the lower pipe driving circuit comprises: a control power supply; a black start branch connected in parallel between the gate and the cathode of the lower pipe, and comprising: an excitation switch; an excitation coil controlled by the excitation switch; a normally closed node controlled by the excitation coil; a black start additional control circuit comprising an energy storage capacitor connected in parallel with the excitation coil and a discharge system, the discharge system being turned on when the voltage of the energy storage capacitor rises to a threshold value of the energy storage capacitor, so as to energize the excitation coil and open the normally closed node.

[0022] According to the embodiments of the present application, by simultaneously triggering the lower pipe and the upper pipe, a reliable straight-through short-circuit effect is formed, thereby solving the problem of overvoltage of the fault power module in the current flexible direct current power transmission system. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. The above and other objects, features and advantages of the present application will become more apparent through detailed description of example embodiments with reference to the accompanying drawings.

[0024] Figure 1 A device block diagram of a double-controllable overvoltage straight-through circuit for a power module according to an example embodiment of the present application is shown.

[0025] Figure 2 A voltage setting diagram of a double-controllable overvoltage straight-through circuit control method for a power module according to an example embodiment of the present application is shown.

[0026] Figure 3 A control method flow chart of a double-controllable overvoltage straight-through circuit for a power module according to an example embodiment of the present application is shown.

[0027] Figure 4 A schematic diagram of a double controllable over-voltage pass-through circuit for a power module is shown according to an example embodiment of the present application.

[0028] Figure 5 A schematic diagram of a drive turn-off branch structure of a double controllable over-voltage pass-through circuit for a power module is shown according to an example embodiment of the present application.

[0029] Figure 6 A schematic diagram of a drive turn-off branch structure of a double controllable over-voltage pass-through circuit for a power module is shown according to an example embodiment of the present application.

[0030] Figure 7 A schematic diagram of a weak turn-on principle for a power module is shown according to an example embodiment of the present application.

[0031] Figure 8 A schematic diagram of a black start additional control principle for a power module is shown according to an example embodiment of the present application. DETAILED DESCRIPTION

[0032] Example embodiments now will be described more fully hereinafter with reference to the accompanying drawings. Example embodiments, however, can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example embodiments to those skilled in the art. In the drawings, the same reference numbers indicate similar or same elements, and repetitive descriptions can be omitted.

[0033] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the

[0034] The flow charts shown in the figures are merely examples and do not necessarily include all of the steps or operations, nor do they necessarily need to be performed in the order shown. For example, some operations / steps can be combined, or divided into sub-operations / steps, and thus the actual order can vary from what is shown. The flow charts can also include more steps or operations than shown, or fewer steps or operations.

[0035] The terms "first", "second", and the like in the description and in the claims of the present application and above-described drawings are intended to distinguish different objects, not to describe a particular sequential order. Moreover, the terms "comprises", "comprising", and the like are intended to encompass non-exclusive inclusions. For example, processes, methods, articles, or apparatuses that comprise a list of steps or elements do not necessarily comprise the listed steps or elements only, but can optionally further comprise other steps or elements not expressly listed or inherent to such processes, methods, articles, or apparatuses.

[0036] The specific embodiments according to the present application are explained hereinafter in detail with reference to the accompanying drawings.

[0037] Figure 1 A device block diagram of a dual controllable over-voltage pass-through circuit for a power module according to an example embodiment of the present application is shown in FIG. 1. Figure 1 The dual controllable over-voltage pass-through circuit shown in FIG. 1 includes a lower tube forced triggering circuit 101 and an upper tube forced triggering circuit 103.

[0038] In embodiments of the present application, Figure 1 The power module in FIG. 1 includes a bridge structure and a DC capacitor, wherein the DC capacitor is connected in parallel to both ends of the bridge structure, and a power device between the midpoint of the bridge structure and the negative pole of the DC capacitor is defined as a lower tube, and a power device between the midpoint of the bridge structure and the positive pole of the DC capacitor is defined as an upper tube. Wherein the upper tube and the lower tube are respectively anti-parallel to diodes.

[0039] According to embodiments of the present application, the lower tube forced triggering circuit 101 is electrically connected between the positive pole of the DC capacitor and the gate of the lower tube; and the upper tube forced triggering circuit 103 is electrically connected between the positive pole of the DC capacitor and the gate of the upper tube.

[0040] In specific embodiments, the bridge structure includes a half-bridge or full-bridge structure composed of multiple integrated gate-commutated thyristors (IGCT) or / and insulate-gate bipolar transistors (IGBT). In some embodiments, the midpoint of the half-bridge and the negative pole of the DC capacitor, or the two midpoints of the full-bridge constitute the AC port of the power module.

[0041] According to embodiments of the present application, the lower tube forced triggering circuit 101 includes a first over-voltage protection unit. Wherein the first over-voltage protection unit includes one or more transient voltage suppression diodes, voltage stabilizing tubes or BOD devices connected in series.

[0042] In some embodiments, the lower tube forced triggering circuit 101 further comprises a first series resistor-capacitor network. The first series resistor-capacitor network is connected in series with the first overvoltage protection unit. In some embodiments, the first series resistor-capacitor network is connected in parallel with the light-emitting side or the light-emitting device of the optocoupler directly or through a current-limiting resistor.

[0043] In other embodiments, the upper tube forced triggering circuit 103 comprises a second overvoltage protection unit and a third overvoltage protection unit. The second overvoltage protection unit and the third overvoltage protection unit each comprise one or more series-connected transient voltage suppression diodes, zener diodes, or BOD devices.

[0044] In some embodiments, the upper tube forced triggering circuit 103 further comprises a second series resistor-capacitor network and a third series resistor-capacitor network, which are connected in series with the second overvoltage protection unit and the third overvoltage protection unit, respectively.

[0045] In specific embodiments, a controllable switch is connected in parallel across the third overvoltage protection unit. The controllable switch is in an open state and is closed according to a signal from the lower tube forced triggering circuit 101.

[0046] In some embodiments, the controllable switch comprises a switching triode, and the second series resistor-capacitor network is connected in parallel with the light-receiving side or the light-receiving device of the optocoupler directly or through a current-limiting resistor. The collector and the emitter of the switching triode are electrically connected across the third overvoltage protection unit. The base of the switching triode is electrically connected to a first end of the light-receiving side or the light-receiving device of the optocoupler. A second end of the light-receiving side or the light-receiving device of the optocoupler is connected to the second overvoltage protection circuit through a resistor, or to the gate of the upper tube.

[0047] According to embodiments of the present application, the power module further comprises a lower tube drive shutdown branch and an upper tube drive shutdown branch. The lower tube drive shutdown branch is electrically connected to the lower tube forced triggering circuit 101 through a first control network. The trigger current generated by the lower tube forced triggering circuit 101 can cause the lower tube drive shutdown branch to be disconnected. The upper tube drive shutdown branch is electrically connected to the upper tube forced triggering circuit 103 through a second control network. The trigger current generated by the upper tube forced triggering circuit 103 can cause the upper tube drive shutdown branch to be disconnected.

[0048] In some embodiments, the lower tube drive shutdown branch comprises a first triode, the emitter of which is electrically connected to the gate of the lower tube, and the collector of which is electrically connected to the negative of the negative power supply or the DC capacitor, or the reference ground potential. The upper tube drive shutdown branch comprises a second triode, the emitter of which is electrically connected to the gate of the upper tube, and the collector of which is electrically connected to the negative of the negative power supply or the DC capacitor, or the reference ground potential.

[0049] According to other embodiments, the first control network includes an RC network, and the lower transistor forced trigger circuit generates a high or low level through the generated trigger current; and / or the second control network includes an RC network, and the upper transistor forced trigger circuit generates a high or low level through the generated trigger current.

[0050] According to embodiments of this application, the lower MOSFET forced trigger circuit 101 is disposed on the same drive circuit board as the lower MOSFET; and / or the upper MOSFET forced trigger circuit 103 is disposed on the same drive circuit board as the upper MOSFET.

[0051] In a specific embodiment, the operating voltage of the first overvoltage protection unit is a first voltage setpoint, the operating voltage of the second overvoltage protection unit is a second voltage setpoint, and the operating voltage of the third overvoltage protection unit is a third voltage setpoint. The first voltage setpoint is higher than the second voltage setpoint and higher than the operating voltage of the power module; the first voltage setpoint is lower than the sum of the second and third voltage setpoints. Figure 2 The diagram shows a voltage setpoint setting for a dual controllable overvoltage pass-through circuit control method for a power module. The first voltage setpoint is set to 5800~6000V, the second voltage setpoint is set to 5000~5200V, and the sum of voltage setpoint 2 and voltage setpoint 3 is set to 6200~6500V.

[0052] In other embodiments, the power module further includes a lower transistor drive circuit, which includes a control power supply, a black start branch, and a black start additional control circuit.

[0053] In some embodiments, a black-start branch is connected in parallel between the gate and cathode of the lower tube. The black-start branch includes an excitation switch, an excitation coil, and a normally closed node. The excitation coil is controlled by the excitation switch, and the normally closed node is controlled by the excitation coil.

[0054] In other embodiments, the black-start additional control circuit includes an energy storage capacitor and a discharge system connected in parallel with the excitation coil. The discharge system conducts when the voltage of the energy storage capacitor rises to a threshold value of the energy storage capacitor, thereby energizing the excitation coil and opening the normally closed node.

[0055] exist Figure 1 In the illustrated embodiment, by simultaneously triggering both the lower and upper tubes to form a reliable direct-through short circuit effect, the overvoltage problem of faulty power modules in current flexible DC transmission systems is solved.

[0056] Figure 3 A flowchart illustrating a control method for a dual controllable overvoltage shoot-through circuit for a power module according to an example embodiment of this application is shown, such as... Figure 3 As shown, when the power module malfunctions, the upper and lower transistors are locked, and then the voltage of the DC capacitor in the power module rises.

[0057] In specific embodiments, the upper tube or the lower tube comprises an IGCT or an IGBT.

[0058] When the voltage of the DC capacitor reaches the first voltage set value, the lower tube forced trigger circuit generates a first trigger current, the first trigger current controls the lower tube to turn on, completes the weak opening of the lower tube, establishes the charging circuit of the upper tube forced trigger circuit for the gate of the upper tube, and controls the switching form of the upper tube forced trigger circuit, that is, turns on the light coupling receiving side or the light receiving device in the upper tube forced trigger circuit.

[0059] When the voltage of the DC capacitor is lower than the second voltage set value, the anti-parallel diode of the lower tube and the upper tube forms a path, the DC capacitor is quickly discharged, and the current through the lower tube is maintained.

[0060] When the voltage of the DC capacitor is higher than the second voltage set value, the upper tube forced trigger circuit generates a second trigger current, the second trigger current makes the upper tube turn on, the lower tube and the upper tube form a path, the DC capacitor is quickly discharged, and the current through the lower tube is maintained.

[0061] According to Figure 3 embodiments, two control methods for short-circuit failure of the lower tube are proposed, one of which is to control the lower tube to open and form a straight path with the anti-parallel diode of the upper tube; the other is to control the upper tube and the lower tube to open together to form a straight path. The prerequisite for the opening of the upper tube includes: the DC capacitor voltage reaches the first overvoltage set value, the lower tube successfully opens, and the charging circuit of the upper tube forced trigger circuit for the gate of the upper tube is established; the second overvoltage protection unit of the upper tube forced trigger circuit successfully removes, and the overvoltage protection action threshold is lowered; the DC capacitor voltage reaches the second overvoltage set value, and the upper tube forced trigger circuit acts to open the upper tube.

[0062] Figure 4 A schematic diagram of a double-controllable overvoltage straight-through circuit for a power module according to an example embodiment of the application is shown.

[0063] As shown in Figure 4 , the lower tube forced trigger circuit includes a first overvoltage protection unit, and the first overvoltage protection unit is preset to have a first overvoltage protection unit action voltage of a first voltage set value. The first overvoltage protection unit is composed of one or more transient voltage suppression diodes, or voltage stabilizing tubes, or BOD devices in series.

[0064] In some embodiments, the lower tube forced trigger circuit is further connected to the gate of the lower tube in series with a resistance-capacitance network.

[0065] In other embodiments, the resistance-capacitance network is directly connected in parallel with the light coupling light-emitting side or the light-emitting device U1-1 across the resistor R1.

[0066] As shown in Figure 4As shown, the upper-side forced trigger circuit includes a second overvoltage protection unit and a third overvoltage protection unit, both of which are composed of multiple transient voltage suppression diodes, Zener diodes, or BOD devices connected in series. The preset operating voltage of the second overvoltage protection unit is a second voltage setting value, and the preset operating voltage of the third overvoltage protection unit is a third voltage setting value.

[0067] In some embodiments, the second overvoltage protection unit and the third overvoltage protection unit are further connected in series with a resistor-capacitor network and then connected to the upper gate.

[0068] like Figure 4 As shown, the controllable switch Q1 is connected in parallel across the three overvoltage protection units. In a specific embodiment, the controllable switch Q1 is normally open and closes after receiving a signal from the lower tube forced trigger circuit.

[0069] See Figure 4 The controllable switch Q1 is a switching transistor, in which its collector and emitter are connected to the two ends of the third overvoltage protection unit; its base is connected to the optocoupler receiver or the light receiving device U1-2. One end of the optocoupler receiver or the light receiving device U1-2 is connected to the second overvoltage protection circuit via resistor R2, and is also electrically connected to the gate of the upper transistor.

[0070] According to some embodiments, the lower MOSFET forced trigger circuit is disposed on the lower MOSFET's drive circuit board; the upper MOSFET forced trigger circuit is disposed on the upper MOSFET's drive circuit board.

[0071] In some embodiments, the lower tube forced triggering circuit is electrically connected to the upper tube forced triggering circuit via an optical fiber.

[0072] According to some embodiments, the first voltage setting is higher than the second voltage setting and higher than the power module operating voltage; the first voltage setting is lower than the sum of the second voltage setting and the third voltage setting.

[0073] Figure 5 and Figure 6 Schematic diagrams of the drive-off branch structure of a dual controllable overvoltage shoot-through circuit for a power module according to an example embodiment of this application are shown. Figure 5 or Figure 6 The drive-off branch shown can be used for either the upper MOSFET drive-off branch or the lower MOSFET drive-off branch.

[0074] As mentioned earlier, the lower MOSFET forced trigger circuit is also connected to the lower MOSFET drive turn-off branch through the first control network; the upper MOSFET forced trigger circuit is also connected to the upper MOSFET drive turn-off branch through the second control network. The trigger currents generated by the upper and lower MOSFET forced trigger circuits respectively disconnect their corresponding drive turn-off branches. Figure 5 or Figure 6As shown, the first control network or the second control network comprises a resistor-capacitor structure, a high level is generated by a trigger current of the upper tube forced trigger circuit or the lower tube forced trigger circuit, or a low level is generated by a trigger current through the resistor-capacitor control triode structure, so that the cathode potential of the upper tube or the lower tube is fixed.

[0075] As shown, the drive-off branch structure of the lower tube and the upper tube is PNP; as shown, Figure 5 Figure 6 As shown, the drive-off branch structure of the lower tube and the upper tube is N-MOS. The emitter (source) is connected to the gate of the upper tube or the lower tube, and the collector (drain) is connected to the negative power supply or the negative electrode of the capacitor or the reference ground potential.

[0076] Figure 7 A weak turn-on principle diagram for a power module is shown according to an example embodiment of the present application, as shown in Figure 7 The upper tube T2 and the lower tube T1 are both IGCTs, D1 and D2 are diodes connected in anti-parallel with the IGCTs, and T1 and T2 are both composed of a plurality of PNP transistors (Q1-1) and NPN transistors (Q1-2) connected in parallel in a composite triode structure; the emitter of Q1-1 is defined as the anode of the IGCT, the emitter of Q1-2 is defined as the cathode of the IGCT, and the base of Q1-2 is defined as the gate of the IGCT.

[0077] The following will take Figure 7 as an example to describe in detail a control method for realizing the conduction of the lower tube by the lower tube forced trigger circuit and the load current, and further forming the short-circuit failure of the lower tube.

[0078] First, all IGCT devices of the power module are in the off state, the load current IL flows into the power module, and the DC capacitor is charged through the anti-parallel diode D2 of the upper tube T2.

[0079] When the DC capacitor voltage rises to a first voltage set value, the first overvoltage protection unit of the lower tube forced trigger circuit breaks down, forming a trigger current Is1. The trigger current Is1 charges the equivalent capacitor Cgk of the Q1-2 gate of the IGCT lower tube. When the Q1-2 gate voltage exceeds its turn-on voltage, Q1-2 turns on, and Q1-1 turns on at the same time. Since the current Is1 is small and the rising rate is not enough, only part of the Q1-1 / Q1-2 composite triode can be turned on.

[0080] When the load current shifts to the conducting composite triode branch, the conducting composite triode branch melts due to overcurrent or overheating, forming a short-circuit failure. When the load current is large or has a large change rate, the load current shifts from the anti-parallel diode D2 of the upper tube T2 to the lower tube T1, causing the diode D2 to fail in reverse recovery, forming a straight-through short circuit with the conducting composite triode branch, and the DC capacitor voltage rapidly decreases, and the lower tube T1 forms a short-circuit failure. ​

[0081] Figure 8 A black start additional control principle diagram for a power module is shown according to an example embodiment of the present application.

[0082] As shown in Figure 8 , the lower tube T1 includes an IGCT composite triode branch, a drive circuit, a control power supply Vcc, a black start branch connected in parallel between the gate and the cathode of the IGCT composite triode branch, and a black start additional control circuit. The black start circuit includes a normally closed node Ks, which is controlled by an excitation coil Xs, and the excitation coil Xs is controlled by an excitation switch Qs.

[0083] As shown in Figure 8 , the black start additional control circuit includes an energy storage capacitor Cs and a discharge system connected in parallel with the excitation coil Xs, wherein the energy storage capacitor is connected between the IGCT gate and the negative pole of the DC capacitor; the discharge system is turned on when the voltage on the energy storage capacitor rises to the threshold value of the energy storage capacitor, and the excitation coil is energized to open the normally closed node Ks.

[0084] According to some embodiments, the drive circuit controls the control power supply Vcc to reach the start value of the control power supply, and then closes to excite the excitation coil Xs and open the normally closed node Ks.

[0085] According to some embodiments, the drive circuit further includes an on switch Qon and an off switch Qoff. The on switch Qon is connected in series with an on inductor and then connected to the IGCT gate; the off switch Qoff is connected in parallel between the IGCT gate and the cathode in series with an off capacitor.

[0086] According to some embodiments, when the control power supply Vcc is abnormal or does not reach its start threshold, the trigger current Is1 charges the energy storage capacitor Cs, and when the voltage on the energy storage capacitor Cs rises to its threshold value, the triode Qs3 is turned on, and then the triode Qs2 is turned on, the energy storage capacitor Cs energizes the excitation coil Xs, and the normally closed node Ks is opened.

[0087] It should be noted that although the black start additional control process shown in Figure 8 is taken as an example of the lower tube T1, Figure 8 the black start additional control process shown in is also applicable to the upper tube, and will not be described one by one.

[0088] Figure 8 In addition, it should be noted that Figure 5 the off switch Coff and Doff in Figure 6 may adopt the drive off branch structure of .

[0089] The above has carried out the detailed introduction to the embodiment of the application, the principle and implementation mode of the application have been described by applying specific examples in this paper, the above embodiment description is only used for helping understanding the method of the application and its core idea. At the same time, the changes or deformations made by the person skilled in the art on the basis of the specific implementation mode and the application range of the application according to the idea of the application all belong to the protection scope of the application. In summary, the content of the specification should not be understood as the limitation of the application.

Claims

1. A control method of a dual controllable overvoltage pass-through circuit for a power module, characterized by, The power module comprises a bridge structure and a direct current capacitor, the direct current capacitor is connected in parallel to both ends of the bridge structure, The power device between the midpoint of the bridge structure and the negative electrode of the direct current capacitor is defined as a lower tube, the power device between the midpoint of the bridge structure and the positive electrode of the direct current capacitor is defined as an upper tube, the upper tube and the lower tube are respectively anti-parallelly connected with diodes, the upper tube and the lower tube are IGCTs, and the upper tube and the lower tube are respectively composed of a plurality of PNP transistors and NPN transistors in a composite triode structure. The double-controllable overvoltage pass-through circuit comprises a lower tube forced triggering circuit electrically connected between the positive electrode of the direct current capacitor and the gate electrode of the lower tube and an upper tube forced triggering circuit electrically connected between the positive electrode of the direct current capacitor and the gate electrode of the upper tube. The control method comprises: When the power module is abnormal, the upper tube and the lower tube are in a latching state, and then the voltage of the direct current capacitor in the power module is increased; When the voltage of the direct current capacitor reaches a preset first voltage value, the lower tube forced triggering circuit generates a first trigger current, the first trigger current controls the lower tube to be turned on, the weak opening of the lower tube is completed, the charging circuit of the upper tube forced triggering circuit for the gate electrode of the upper tube is established, and the weak opening of the lower tube means that only part of the composite triode is turned on due to the small current and insufficient rising rate of the trigger current; When the voltage of the direct current capacitor is lower than a preset second voltage value, when the load current is transferred to the turned-on composite triode branch, the turned-on composite triode branch is overcurrent or overheated and fused to form a short circuit failure; when the load current is large or has a large change rate, the load current is transferred from the anti-parallel diode D2 of the upper tube to the lower tube, which causes the diode D2 to fail in reverse recovery and forms a pass-through short circuit with the turned-on composite triode branch, the voltage of the direct current capacitor rapidly decreases, and the lower tube forms a short circuit failure; When the voltage of the direct current capacitor is higher than the second voltage value, the upper tube forced triggering circuit generates a second trigger current, the second trigger current turns on the upper tube, the upper tube and the lower tube form a pass-through, the direct current capacitor is rapidly discharged, and the lower tube keeps current passing.

2. The control method according to claim 1, characterized by, The lower tube forced triggering circuit comprises a first overvoltage protection unit, the first overvoltage protection unit comprises one or more transient voltage suppression diodes, voltage stabilizing tubes or BOD devices connected in series, and the action voltage of the first overvoltage protection unit is the first voltage value.

3. The control method according to claim 2, characterized by, The lower tube forced triggering circuit further comprises a light emitting side of an optical coupler or a light emitting device connected in series with the first overvoltage protection unit.

4. The control method according to claim 3, characterized by, The lower tube forced triggering circuit further comprises a first series resistance-capacitance network connected in series with the first overvoltage protection unit, and the first series resistance-capacitance network is connected in parallel with the light emitting side of the optical coupler or the light emitting device directly or through a current limiting resistor.

5. The control method according to claim 4, characterized by The upper tube forced triggering circuit comprises a second overvoltage protection unit and a third overvoltage protection unit, wherein The second overvoltage protection unit and the third overvoltage protection unit each comprise one or more transient voltage suppression diodes, voltage stabilizing tubes or BOD devices connected in series. The action voltage of the second overvoltage protection unit is the second voltage constant value, and the action voltage of the third overvoltage protection unit is the third voltage constant value.

6. The control method according to claim 5, characterized by The upper tube forced triggering circuit further comprises a second series resistor-capacitor network and a third series resistor-capacitor network, which are connected in series with the second overvoltage protection unit and the third overvoltage protection unit, respectively.

7. The control method according to claim 6, characterized by A controllable switch is connected in parallel across the third overvoltage protection unit, and the controllable switch is in an open state and is closed according to a signal from the lower tube forced triggering circuit.

8. The control method according to claim 7, characterized by, The controllable switch comprises a switching triode, and the second series resistor-capacitor network is connected in parallel with a light-accepting side of a photo-coupler or a light-receiving device directly or through a current-limiting resistor, wherein: The collector and the emitter of the switching triode are electrically connected across the third overvoltage protection unit; The base of the switching triode is electrically connected to a first end of the light-accepting side of the photo-coupler or the light-receiving device; A second end of the light-accepting side of the photo-coupler or the light-receiving device is connected to the second overvoltage protection circuit through a resistor, or is connected to a gate of the upper tube.

9. The control method according to claim 8, characterized by, When the voltage of the direct-current capacitor reaches the first voltage constant value and the first trigger current controls the lower tube to be turned on, the light-accepting side of the photo-coupler or the light-receiving device is turned on.

10. The control method according to claim 9, wherein: The lower tube forced triggering circuit and the lower tube are arranged on the same drive circuit board; and / or The upper tube forced triggering circuit and the upper tube are arranged on the same drive circuit board.

11. The control method according to claim 10, wherein: The first voltage constant value is higher than the second voltage constant value and is higher than an operating voltage of the power module; The first voltage constant value is lower than the sum of the second voltage constant value and the third voltage constant value.

12. The control method according to claim 11, characterized by, The power module further comprises: A lower tube drive turn-off branch, which is electrically connected to the lower tube forced triggering circuit through a first control network, and a trigger current generated by the lower tube forced triggering circuit can make the lower tube drive turn-off branch be disconnected; An upper tube drive turn-off branch, which is electrically connected to the upper tube forced triggering circuit through a second control network, and a trigger current generated by the upper tube forced triggering circuit can make the upper tube drive turn-off branch be disconnected.

13. The control method according to claim 12, wherein: The lower tube drive turn-off branch comprises a first triode, and an emitter of the first triode is electrically connected to a gate of the lower tube, and a collector of the first triode is electrically connected to a negative power supply or a negative electrode of the direct-current capacitor, or a reference ground potential; The upper tube drive turn-off branch comprises a second triode, and an emitter of the second triode is electrically connected to a gate of the upper tube, and a collector of the second triode is electrically connected to a negative power supply or a negative electrode of the direct-current capacitor, or a reference ground potential.

14. The control method according to claim 13, wherein: The first control network comprises a resistor-capacitor network, and the lower tube forced triggering circuit forms a high level or a low level through a trigger current generated by the lower tube forced triggering circuit; and / or The second control network comprises a resistor-capacitor network, and the upper tube forced triggering circuit forms a high level or a low level through a trigger current generated by the upper tube forced triggering circuit.

15. The control method according to claim 14, characterized by, The power module further comprises a lower tube drive circuit, and the lower tube drive circuit comprises: A control power supply; A black start branch is connected in parallel between the gate electrode and the cathode electrode of the lower tube and comprises: a magnetizing switch; a magnetizing coil controlled by the magnetizing switch; a normally closed node controlled by the magnetizing coil; a black start additional control circuit comprising an energy storage capacitor connected in parallel with the magnetizing coil and a discharge system, which is turned on when the voltage of the energy storage capacitor rises to a threshold value of the energy storage capacitor, thereby energizing the magnetizing coil, and the normally closed node is opened.

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