Control method of dual controllable overvoltage through circuit for power module

Abstract

The invention provides a control method of a dual controllable overvoltage straight-through circuit for a power module, and the method comprises the steps: enabling a lower tube to forcibly trigger a circuit to generate a first trigger current when the voltage of a DC capacitor reaches a preset first voltage fixed value, and enabling the first trigger current to control the conduction of a lower tube, and completing the weak opening of the lower tube; when the voltage of the direct-current capacitor is lower than a preset second voltage fixed value, the anti-parallel diodes of the lower tube and the upper tube form a path, the direct-current capacitor discharges quickly, and the lower tube keeps current to pass through; when the voltage of the direct-current capacitor is higher than the second voltage fixed value, the upper tube forcibly triggers the circuit to generate second trigger current, the second trigger current enables the upper tube to be conducted, the upper tube and the lower tube form a path, the direct-current capacitor discharges quickly, and the lower tube keeps current to pass through. According to the embodiment of the invention, the overvoltage problem of the fault power module in the current flexible DC power transmission system is solved.

Description

Technical Field

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

[0002] In a flexible DC 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 adding redundant modules is usually adopted. When a power module fails, the faulty power module can be removed through bypass operation to ensure 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 make bypass operation impossible. In this case, the faulty power module will be continuously charged by the external current, and the voltage will continue to rise, eventually endangering the capacitor safety of the power module and the safety of the power system.

[0004] At present, the module is usually bypassed by breaking down the lower tube of the power module, but the way to break down the lower tube is usually thermal breakdown or overcurrent breakdown. However, these two methods are highly dependent on the type of device and external electrical conditions and cannot form a stable and reliable bypass effect. Summary of the invention

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

[0006] According to one aspect of the present application, a control method for a dual controllable overvoltage pass-through circuit for a power module is proposed, wherein the power module includes a bridge structure and a DC capacitor, wherein the DC capacitor is connected in parallel to both ends of the bridge structure, wherein a power device between the midpoint of the bridge structure and the negative electrode of the DC capacitor is defined as a lower tube, and a power device between the midpoint of the bridge structure and the positive electrode of the DC capacitor is defined as an upper tube, wherein diodes are connected in anti-parallel to the upper tube and the lower tube, respectively, and wherein the dual controllable overvoltage pass-through circuit includes a lower tube forced trigger circuit electrically connected between the positive electrode of the DC capacitor and the gate of the lower tube and an upper tube forced trigger circuit electrically connected between the positive electrode of the DC capacitor and the gate of the upper tube, wherein the control method includes: when the When the voltage of the DC capacitor reaches a preset first voltage setting value, the lower tube forced trigger circuit generates a first trigger current, the first trigger current controls the lower tube to be turned on, completes the weak opening of the lower tube, and the first trigger current simultaneously controls the upper tube forced trigger circuit to switch the state; when the voltage of the DC capacitor is lower than the preset second voltage setting value, the anti-parallel diodes of the lower tube and the upper tube form a path, the DC capacitor discharges quickly, and the lower tube keeps the current passing; when the voltage of the DC capacitor is higher than the second voltage setting value, the upper tube forced trigger circuit generates a second trigger current, the second trigger current turns on the upper tube, the upper tube and the lower tube form a path, the DC capacitor discharges quickly, and the lower tube keeps the current passing.

[0007] According to some embodiments, the lower tube forced trigger circuit includes a first overvoltage protection unit, the first overvoltage protection unit includes one or more transient voltage suppression diodes, Zener diodes or BOD devices connected in series, and the action voltage of the first overvoltage protection unit is the first voltage constant.

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

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

[0010] According to some embodiments, the upper tube forced trigger circuit includes a second overvoltage protection unit and a third overvoltage protection unit, wherein the second overvoltage protection unit and the third overvoltage protection unit each include one or more transient voltage suppression diodes, Zener diodes or BOD devices connected in series; the action voltage of the second overvoltage protection unit is the second voltage constant, and the action voltage of the third overvoltage protection unit is the third voltage constant.

[0011] According to some embodiments, the upper tube forced trigger circuit further includes a second series resistor-capacitor network and a third series resistor-capacitor network, which are respectively connected in series with the second overvoltage protection unit and the third overvoltage protection unit.

[0012] According to some embodiments, two ends of the third overvoltage protection unit are connected in parallel to a controllable switch, the controllable switch is in a normally open state, and is closed according to a signal from the lower tube forced trigger circuit.

[0013] According to some embodiments, the controllable switch includes a switching transistor, and the second series resistor-capacitor network is directly or via a current-limiting resistor in parallel with an optocoupler receiving side or a light receiving device, wherein: the collector and emitter of the switching transistor are electrically connected to the two ends of the third overvoltage protection unit; the base of the switching transistor is electrically connected to the first end of the optocoupler receiving side or the light receiving device; the second end of the optocoupler receiving side or the light receiving device is connected to the second overvoltage protection circuit via a resistor, or is connected to the gate of the upper tube.

[0014] According to some embodiments, when the voltage of the DC capacitor reaches the first voltage setting value and the first trigger current controls the lower tube to be turned on, the optocoupler receiving side or the light receiving device is turned on.

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

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

[0017] According to some embodiments, the power module also includes: a lower tube drive shutdown branch, which is electrically connected to the lower tube forced trigger circuit through a first control network, and the trigger current generated by the lower tube forced trigger circuit can disconnect the lower tube drive shutdown branch; an upper tube drive shutdown branch, which is electrically connected to the upper tube forced trigger circuit through a second control network, and the trigger current generated by the upper tube forced trigger circuit can disconnect the upper tube drive shutdown branch.

[0018] According to some embodiments, the lower tube driving shutdown branch includes a first transistor, the emitter of the first transistor is electrically connected to the gate of the lower tube, and the collector is electrically connected to a negative power supply or the negative electrode of the DC capacitor, or a reference ground potential; the upper tube driving shutdown branch includes a second transistor, the emitter of the second transistor is electrically connected to the gate of the upper tube, and the collector is electrically connected to a negative power supply or the negative electrode of the DC capacitor, or a reference ground potential.

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

[0020] According to some embodiments, the lower tube and the upper tube respectively include multiple compound triode branches, and the control method also includes: when some of the compound triode branches are turned on, the load current of the power module is transferred to the turned-on compound triode branches, causing the turned-on compound triode branches to overcurrent or 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 tube to the lower tube, the reverse diode in parallel with the lower tube causes recovery failure, and the lower tube forms a short circuit failure.

[0021] According to some embodiments, the power module also includes a lower tube driving circuit, which includes: a control power supply; a black start branch, connected in parallel between the gate and cathode of the lower tube, and including: 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, including an energy storage capacitor and a discharge system connected in parallel with the excitation coil, the discharge system being turned on 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.

[0022] According to the embodiments of the present application, the lower tube and the upper tube are double-triggered simultaneously to form a reliable direct short-circuit effect, thereby solving the overvoltage problem of the faulty power module in the current flexible direct current transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. By describing the exemplary embodiments in detail with reference to the drawings, the above and other objectives, features and advantages of the present application will become more apparent.

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

[0025] Figure 2 A schematic diagram of setting a voltage constant for a dual controllable overvoltage pass-through circuit control method for a power module according to an exemplary embodiment of the present application is shown.

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

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

[0028] Figure 5 A schematic diagram of a driving shutdown branch structure of a dual controllable overvoltage pass-through circuit for a power module according to an exemplary embodiment of the present application is shown.

[0029] Figure 6 A schematic diagram of a driving shutdown branch structure of a dual controllable overvoltage pass-through circuit for a power module according to an exemplary embodiment of the present application is shown.

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

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

[0032] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. In the figures, the same figures show the same or similar parts, and thus their repeated description will be omitted.

[0033] The described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or other modes, components, materials, devices or operations may be adopted. In these cases, known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0034] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0035] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0036] The specific embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0037] Figure 1 A device block diagram of a dual controllable overvoltage pass-through circuit for a power module according to an exemplary embodiment of the present application is shown. Figure 1 The double controllable overvoltage pass-through circuit includes a lower tube forced trigger circuit 101 and an upper tube forced trigger circuit 103 .

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

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

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

[0041] According to an embodiment of the present application, the lower tube forced trigger circuit 101 includes a first overvoltage protection unit, wherein the first overvoltage protection unit includes one or more series-connected transient voltage suppression diodes, voltage regulator tubes or BOD devices.

[0042] In some embodiments, the bottom tube forced trigger circuit 101 further includes 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 directly or via a current limiting resistor in parallel with the light-emitting side of the optocoupler or the light-emitting device.

[0043] In some other embodiments, the upper tube forced trigger circuit 103 includes a second overvoltage protection unit and a third overvoltage protection unit, wherein the second overvoltage protection unit and the third overvoltage protection unit each include one or more series-connected transient voltage suppression diodes, voltage regulators or BOD devices.

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

[0045] In a specific embodiment, two ends of the third overvoltage protection unit are connected in parallel to a controllable switch, which is in a normally open state and is closed according to a signal from the lower tube forced trigger circuit 101 .

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

[0047] According to an embodiment of the present application, the power module further includes 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 trigger circuit 101 through a first control network, and the trigger current generated by the lower tube forced trigger circuit 101 can disconnect the lower tube drive shutdown branch; the upper tube drive shutdown branch is electrically connected to the upper tube forced trigger circuit 103 through a second control network, and the trigger current generated by the upper tube forced trigger circuit 103 can disconnect the upper tube drive shutdown branch.

[0048] In some embodiments, the lower tube driving shutdown branch includes a first transistor, the emitter of the first transistor is electrically connected to the gate of the lower tube, and the collector is electrically connected to a negative power supply or a negative electrode of a DC capacitor, or a reference ground potential; the upper tube driving shutdown branch includes a second transistor, the emitter of the second transistor is electrically connected to the gate of the upper tube, and the collector is electrically connected to a negative power supply or a negative electrode of a DC capacitor, or a reference ground potential.

[0049] According to some other embodiments, the first control network includes a resistor-capacitor network, and the lower tube forced trigger circuit forms a high level or a low level through the trigger current generated; and / or the second control network includes a resistor-capacitor network, and the upper tube forced trigger circuit forms a high level or a low level through the trigger current generated.

[0050] According to an embodiment of the present application, the lower tube forced trigger circuit 101 and the lower tube are arranged on the same driving circuit board; and / or the upper tube forced trigger circuit 103 and the upper tube are arranged on the same driving circuit board.

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

[0052] In some other embodiments, the power module further includes a lower tube driving circuit, and the lower tube driving circuit includes a control power supply, a black start branch, and a black start additional control circuit.

[0053] In some embodiments, the black start branch is connected in parallel between the gate and cathode of the lower tube, and the black start branch includes an excitation switch, an excitation coil and a normally closed node, wherein 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, and the discharge system is turned on 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, the lower tube and the upper tube are double-triggered simultaneously to form a reliable direct short-circuit effect, thereby solving the overvoltage problem of the faulty power module in the current flexible DC transmission system.

[0056] Figure 3 A flow chart of a control method for a dual controllable overvoltage pass-through circuit for a power module according to an exemplary embodiment of the present application is shown. Figure 3 As shown, when an abnormality occurs in the power module, the upper tube and the lower tube are in a locked state, and then the voltage of the DC capacitor in the power module increases.

[0057] In a specific embodiment, the upper tube or the lower tube includes an IGCT or an IGBT.

[0058] When the voltage of the DC capacitor reaches the first voltage setting value, the lower tube forced trigger circuit generates a first trigger current. The first trigger current controls the lower tube to be turned on, completes the weak turn-on of the lower tube, establishes a charging loop for the upper tube gate of the upper tube forced trigger circuit, and controls the switching state of the upper tube forced trigger circuit, that is, turns on the optocoupler 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 setting value, the anti-parallel diodes of the lower tube and the upper tube form a path, the DC capacitor discharges quickly, and the lower tube keeps the current passing.

[0060] When the voltage of the DC capacitor is higher than the second voltage setting value, the upper tube forces the trigger circuit to generate a second trigger current. The second trigger current turns on the upper tube, and a path is formed between the upper tube and the lower tube. The DC capacitor discharges quickly, and the lower tube keeps the current passing.

[0061] according to Figure 3 The embodiment of the invention proposes two control methods to make the lower tube short-circuit and fail, one of which is to control the lower tube to be turned on and form a direct connection with the anti-parallel diode of the upper tube; the other is to control the upper tube and the lower tube to be turned on together to form a direct connection. Among them, the prerequisites for turning on the upper tube include: the DC capacitor voltage reaches the first overvoltage setting value, the lower tube is successfully turned on, and the upper tube forced trigger circuit is established as a charging loop for the upper tube gate; the second overvoltage protection unit of the upper tube forced trigger circuit is successfully removed, and the overvoltage protection action threshold is lowered; the DC capacitor voltage reaches the second overvoltage setting value, and the upper tube forced trigger circuit is activated to turn on the upper tube.

[0062] Figure 4 A schematic diagram of a dual controllable overvoltage pass-through circuit for a power module according to an exemplary embodiment of the present application is shown.

[0063] like Figure 4 As shown, the lower tube forced trigger circuit includes a first overvoltage protection unit, and the first overvoltage protection unit action voltage is preset to a first voltage constant. The first overvoltage protection unit is composed of one or more series-connected transient voltage suppression diodes, or voltage regulators, or BOD devices.

[0064] In some embodiments, the bottom tube forced trigger circuit is further connected in series with a resistor-capacitor network and then connected to the bottom tube gate.

[0065] In some other embodiments, both ends of the RC network are connected in parallel to the light-emitting side of the optocoupler or the light-emitting device U1 - 1 directly or via a current-limiting resistor R1 .

[0066] like Figure 4As shown, the upper tube forced trigger circuit includes a second overvoltage protection unit and a third overvoltage protection unit, and the second overvoltage protection unit and the third overvoltage protection unit are both composed of a plurality of series-connected transient voltage suppression diodes, or voltage regulators, or BOD devices. The second overvoltage protection unit action voltage is preset to be a second voltage constant, and the third overvoltage protection unit action voltage is preset to be a third voltage constant.

[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 gate of the upper tube.

[0068] like Figure 4 As shown, the controllable switch Q1 is connected in parallel at both ends of the third overvoltage protection unit; in a specific embodiment, the controllable switch Q1 is in a normally open state, and is closed after receiving a signal from the lower tube forced trigger circuit.

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

[0070] According to some embodiments, the lower tube forced trigger circuit is disposed on a driving circuit board of the lower tube; and the upper tube forced trigger circuit is disposed on a driving circuit board of the upper tube.

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

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

[0073] Figure 5 and Figure 6 The schematic diagrams of the drive shutoff branch structure of a dual controllable overvoltage pass-through circuit for a power module according to an exemplary embodiment of the present application are respectively shown. Figure 5 or Figure 6 The driver shutdown branch shown can be used for the upper tube driver shutdown branch or the lower tube driver shutdown branch.

[0074] As mentioned above, the lower tube forced trigger circuit is also connected to the lower tube drive shutdown branch through the first control network; the upper tube forced trigger circuit is also connected to the upper tube drive shutdown branch through the second control network. The trigger currents generated by the upper tube forced trigger circuit and the lower tube forced trigger circuit respectively disconnect the corresponding drive shutdown branches. Figure 5 or Figure 6As shown, the first control network or the second control network includes a resistor-capacitor structure, which generates a high level through the trigger current of the upper tube forced trigger circuit or the lower tube forced trigger circuit, or controls the transistor structure through a resistor-capacitor structure, which generates a low level through the trigger current, so that the cathode potential of the upper tube or the lower tube is fixed.

[0075] like Figure 5 As shown, the drive shutoff branch structure of the lower tube and the upper tube is PNP; Figure 6 As shown, the driving turn-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 schematic diagram of a weak turn-on principle for a power module according to an exemplary embodiment of the present application is shown. Figure 7 As shown, the upper tube T2 and the lower tube T1 are both IGCTs, D1 and D2 are diodes connected in anti-parallel thereto respectively, and T1 and T2 are internally connected in parallel by a composite triode structure consisting of multiple PNP transistors (Q1-1) and NPN transistors (Q1-2); the emitter of Q1-1 is defined as the IGCT anode, the emitter of Q1-2 is defined as the IGCT cathode, and the base of Q1-2 is defined as the IGCT gate.

[0077] Below Figure 7 Taking the example, a control method for realizing the conduction of the lower tube by using the lower tube forced trigger circuit and the load current and further forming the short circuit failure of the lower tube is described in detail.

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

[0079] When the DC capacitor voltage rises to the first voltage setting 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 Q1-2 gate equivalent capacitor Cgk of the IGCT lower tube. When the Q1-2 gate voltage exceeds its turn-on voltage, Q1-2 is turned on, and then Q1-1 is turned on. Since the current of Is1 is small and the rising rate is insufficient, only part of the Q1-1 / Q1-2 composite transistor can be turned on;

[0080] When the load current is transferred to the turned-on compound triode branch, the turned-on compound triode branch overcurrent or overheating melts, resulting in a short circuit failure; when the load current is large or the rate of change is large, the load current is transferred from the anti-parallel diode D2 of the upper tube T2 to the lower tube T1, causing the diode D1 to reverse recover and fail, forming a direct short circuit with the turned-on compound triode branch, the DC capacitor voltage drops rapidly, and the lower tube T1 fails in a short circuit.

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

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

[0083] like Figure 8 As shown, 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 electrode of the DC capacitor; the discharge system is turned on when the voltage on the energy storage capacitor increases to the threshold of the energy storage capacitor, energizes the excitation coil, and opens the normally closed node Ks.

[0084] According to some embodiments, the driving circuit controls the power supply Vcc to be closed after reaching the start-up value of the control power supply, so as to excite the excitation coil Xs and open the normally closed node Ks.

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

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

[0087] It should be noted here that although Figure 8 The black start additional control process shown is based on the example of tube T1. Figure 8 The black start additional control process shown is also applicable to the upper tube, which will not be described in detail here.

[0088] In addition, it should be noted that Figure 8 The off switches Coff and Doff in Figure 5 or Figure 6 The drive shut-off branch structure.

[0089] The embodiments of the present application are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application. At the same time, changes or deformations made by those skilled in the art based on the ideas of the present application, the specific implementation methods and the scope of application of the present application, all belong to the scope of protection of the present application. In summary, the content of this specification should not be construed as a limitation on the present application.

Claims

1. A control method for a dual controllable overvoltage pass-through circuit for a power module, characterized in that: The power module includes a bridge structure and a DC capacitor, wherein the DC 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 DC capacitor is defined as a lower tube, and the power device between the midpoint of the bridge structure and the positive electrode of the DC capacitor is defined as an upper tube. The upper tube and the lower tube are respectively connected with anti-parallel diodes. The double controllable overvoltage direct-through circuit includes a lower tube forced trigger circuit electrically connected between the positive electrode of the DC capacitor and the gate of the lower tube and an upper tube forced trigger circuit electrically connected between the positive electrode of the DC capacitor and the gate of the upper tube. The control method comprises: When the voltage of the DC capacitor reaches a preset first voltage value, the lower tube forced trigger circuit generates a first trigger current, and the first trigger current controls the lower tube to be turned on, thereby completing the weak turn-on of the lower tube; When the voltage of the DC capacitor is lower than a preset second voltage value, the anti-parallel diodes of the lower tube and the upper tube form a path, the DC capacitor discharges quickly, and the lower tube keeps the current passing; When the voltage of the DC capacitor is higher than the second voltage setting value, the upper tube forces the trigger circuit to generate a second trigger current, the second trigger current turns on the upper tube, the upper tube and the lower tube form a path, the DC capacitor discharges quickly, and the lower tube keeps current passing.

2. The control method according to claim 1, characterized in that: The lower tube forced trigger circuit includes a first overvoltage protection unit, which includes one or more transient voltage suppression diodes, voltage regulators or BOD devices connected in series, and the action voltage of the first overvoltage protection unit is the first voltage constant.

3. The control method according to claim 2, characterized in that: The lower tube forced trigger circuit also includes an optocoupler light-emitting side or a light-emitting device electrically connected in series with the first overvoltage protection unit.

4. The control method according to claim 3, characterized in that: The lower tube forced trigger circuit also includes a first series resistor-capacitor network connected in series with the first overvoltage protection unit. The first series resistor-capacitor network is directly or via a current limiting resistor in parallel with the light-emitting side of the optocoupler or the light-emitting device.

5. The control method according to claim 4, characterized in that: The upper tube forced trigger circuit includes a second overvoltage protection unit and a third overvoltage protection unit, wherein: The second overvoltage protection unit and the third overvoltage protection unit each include one or more transient voltage suppression diodes, voltage regulators or BOD devices connected in series; The action voltage of the second overvoltage protection unit is the second voltage constant, and the action voltage of the third overvoltage protection unit is the third voltage constant.

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

7. The control method according to claim 6, characterized in that: Two ends of the third overvoltage protection unit are connected in parallel to a controllable switch, the controllable switch is in a normally open state, and is closed according to a signal from the lower tube forced trigger circuit.

8. The control method according to claim 7, characterized in that: The controllable switch includes a switching transistor, and the second series resistor-capacitor network is directly or via a current-limiting resistor in parallel with the optical coupler receiving side or the light receiving device, wherein: The collector and emitter of the switching transistor are electrically connected to two ends of the third overvoltage protection unit; The base of the switching transistor is electrically connected to the receiving side of the optical coupler or the first end of the light receiving device; The receiving side of the optocoupler or the second end of the light receiving device is connected to the second overvoltage protection circuit via a resistor, or is connected to the gate of the upper tube.

9. The control method according to claim 8, characterized in that: When the voltage of the DC capacitor reaches the first voltage constant and the first trigger current controls the lower tube to be turned on, the optocoupler receiving side or the light receiving device is turned on.

10. The control method according to claim 9, characterized in that: The lower tube forced trigger circuit and the lower tube are arranged on the same driving circuit board; and / or The upper tube forced trigger circuit and the upper tube are arranged on the same driving circuit board.

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

12. The control method according to claim 11, characterized in that: The power module further comprises: A lower tube driving shutdown branch is electrically connected to the lower tube forced trigger circuit through a first control network, and a trigger current generated by the lower tube forced trigger circuit can disconnect the lower tube driving shutdown branch; The upper tube driving shutdown branch is electrically connected to the upper tube forced trigger circuit through a second control network, and the trigger current generated by the upper tube forced trigger circuit can disconnect the upper tube driving shutdown branch.

13. The control method according to claim 12, characterized in that: The lower tube driving shutdown branch comprises a first triode, the emitter of the first triode is electrically connected to the gate of the lower tube, and the collector is electrically connected to a negative power supply or a negative electrode of the DC capacitor, or a reference ground potential; The upper tube driving shutdown branch comprises a second triode, the emitter of the second triode is electrically connected to the gate of the upper tube, and the collector is electrically connected to a negative power supply or the negative electrode of the DC capacitor, or a reference ground potential.

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

15. The control method according to claim 14, characterized in that: The lower tube and the upper tube respectively include a plurality of composite triode branches, and the control method further includes: When part of the composite triode branches are turned on, the load current of the power module is transferred to the composite triode branches that are turned on, causing the composite triode branches to over-current or overheat and melt, resulting in a short circuit failure; When the load current of the power module is transferred from the anti-parallel diode of the upper tube to the lower tube, the reverse diode connected in parallel with the lower tube fails to recover, and the lower tube fails to short circuit.

16. The control method according to claim 15, characterized in that: The power module further includes a lower tube driving circuit, and the lower tube driving circuit includes: Control power supply; The black start branch is connected in parallel between the gate and cathode of the lower tube and comprises: Excitation switch; An excitation coil, controlled by the excitation switch; A normally closed node, controlled by the excitation coil; The black start additional control circuit comprises an energy storage capacitor and a discharge system connected in parallel with the excitation coil. The discharge system is turned on 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.

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