Power semiconductor device series voltage equalization circuit and power electronic converter

Abstract

The application relates to a power semiconductor device series voltage equalization circuit and a power electronic converter, the power semiconductor device series voltage equalization circuit comprising: a power semiconductor device series circuit, the power semiconductor device series circuit comprising a plurality of power semiconductor devices connected in series; a voltage equalization circuit, the voltage equalization circuit comprising a plurality of voltage equalization units, each voltage equalization unit being connected in parallel with each power semiconductor device and used for equalizing the voltage across each power semiconductor device; and a voltage clamping circuit, the voltage clamping circuit being connected in parallel with the power semiconductor device series circuit, the voltage clamping circuit comprising a plurality of voltage clamping units connected in parallel, the plurality of voltage clamping units being used for equalizing the voltage across each power semiconductor device during a power semiconductor device turn-off transient. The power semiconductor device series voltage equalization circuit can effectively improve the problem of voltage imbalance during power semiconductor device series connection.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a series voltage equalization circuit for power semiconductor devices and a power electronic converter. Background Technology

[0002] With the development of modern power electronics technology, the demand for high-voltage applications in high-voltage inverters, high-voltage direct current transmission systems and other applications is constantly increasing. However, the application and development of individual power semiconductor devices are limited by the influence of process and performance. Therefore, series connection of power semiconductor devices is an important way to solve and realize high-voltage, high-capacity power electronic converters. However, the individual performance differences of power semiconductor devices and the differences in stray parameters of the circuit will cause uneven voltage division in series connection. If not controlled, it may lead to damage to the power semiconductor devices.

[0003] In the prior art, voltage equalization of power semiconductor devices can be achieved by using a voltage equalization circuit composed of parallel resistors and capacitors or by using parallel resistors in each power semiconductor device. However, the voltage equalization effect in the prior art is not ideal. Summary of the Invention

[0004] Therefore, it is necessary to provide a power semiconductor device series voltage equalization circuit and power electronic converter that can effectively improve the problem of voltage imbalance in the series connection of power semiconductor devices.

[0005] In a first aspect, embodiments of this application provide a series voltage equalization circuit for power semiconductor devices, comprising: a series circuit for power semiconductor devices, the series circuit including a plurality of power semiconductor devices connected in series; a voltage equalization circuit including a plurality of voltage equalization units, each voltage equalization unit being connected in parallel with each power semiconductor device, for equalizing the voltage across each power semiconductor device; and a voltage clamping circuit, the voltage clamping circuit being connected in parallel with the series circuit for power semiconductor devices, the voltage clamping circuit including a plurality of parallel voltage clamping units, the plurality of parallel voltage clamping units being used to equalize the voltage across each power semiconductor device during a power semiconductor device turn-off transient.

[0006] In one embodiment, the voltage clamping unit is configured to be in a high impedance state when the voltage across the voltage clamping unit does not exceed a preset operating voltage, and in a low impedance state when the voltage across the voltage clamping unit exceeds the preset operating voltage.

[0007] In one embodiment, the plurality of parallel voltage clamping units include: passive clamping units, and / or, active clamping units.

[0008] In one embodiment, the active clamping unit includes a transition diode, a gate resistor, a power dissipation resistor, and a thyristor. The anode of the transition diode is connected to the first terminal of the gate resistor and the gate of the thyristor. The cathode of the transition diode is connected to the first terminal of the power dissipation resistor to form a first output port. The second terminal of the power dissipation resistor is connected to the anode of the thyristor. The cathode of the thyristor is connected to the second terminal of the gate resistor to form a second output port. When the voltage across the active clamping unit exceeds the operating voltage of the transition diode, the transition diode is reverse-broken down and generates a current injected into the gate of the thyristor, causing the active clamping unit to be in a low-impedance state.

[0009] In one embodiment, if the multiple parallel voltage clamping units include active clamping units and passive clamping units, the first output ports of each active clamping unit are interconnected and connected to the first terminal of the power semiconductor device series circuit and the first terminal of each passive clamping unit, and the second output ports of each active clamping unit are interconnected and connected to the second terminal of the power semiconductor device series circuit and the second terminal of each passive clamping unit.

[0010] In one embodiment, at least two of the multiple parallel voltage clamping units have the same operating voltage, or at least two of the multiple parallel voltage clamping units have different operating voltages.

[0011] In one embodiment, each voltage equalization unit includes a dynamic voltage equalization unit and a static voltage equalization unit, with the dynamic voltage equalization unit connected in parallel with the static voltage equalization unit. The dynamic voltage equalization unit is used to slow down the rate of change of voltage across the power semiconductor device during the power semiconductor device's turn-on and turn-off transients, so as to equalize the dynamic voltage across each power semiconductor device. The static voltage equalization unit is used to balance the leakage current of the power semiconductor device when the power semiconductor device is turned off, so as to equalize the static voltage across each power semiconductor device.

[0012] In one embodiment, the dynamic voltage equalization unit includes a capacitor and a first resistor, with the capacitor and the first resistor connected in series; the static voltage equalization unit includes a second resistor, the value of which is less than the equivalent impedance when the power semiconductor device is blocked.

[0013] In one embodiment, in a series circuit of power semiconductor devices, each power semiconductor device is connected in reverse parallel with a diode to block and control the forward current and forward voltage.

[0014] In a second aspect, this application provides a power electronic converter that includes a series voltage equalization circuit of power semiconductor devices as described in any one of the first aspects above.

[0015] The aforementioned series voltage equalization circuit for power semiconductor devices includes a series circuit of power semiconductor devices, a voltage equalization circuit, and a voltage clamping circuit. The series circuit of power semiconductor devices includes multiple power semiconductor devices connected in series. The voltage equalization circuit includes multiple voltage equalization units, each connected in parallel with each power semiconductor device, used to equalize the voltage across each power semiconductor device. The voltage clamping circuit is connected in parallel with the series circuit of power semiconductor devices and includes multiple parallel voltage clamping units. These multiple parallel voltage clamping units are used to equalize the voltage across each power semiconductor device during the power semiconductor device turn-off transient. In this way, the voltage equalization circuit improves the static and dynamic voltage imbalance problems when power semiconductor devices are connected in series. At the same time, by connecting multiple parallel voltage clamping units, the voltage across the power semiconductor device can be clamped during the power semiconductor device turn-off transient, which can improve the voltage clamping effect of the voltage clamping circuit and further improve the voltage division imbalance problem during the series connection of power semiconductor devices. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of a series voltage equalization circuit for power semiconductor devices provided in one embodiment;

[0018] Figure 2 An active clamping unit structure is provided as one embodiment;

[0019] Figure 3 A schematic diagram of a voltage clamping circuit when two active clamping units are connected in parallel, as provided in one embodiment;

[0020] Figure 4 A schematic diagram of a voltage clamping circuit with one active clamping unit and one passive clamping unit connected in parallel, provided for one embodiment;

[0021] Figure 5 One embodiment provides a voltage equalization unit structure;

[0022] Figure 6 A schematic diagram of a series voltage equalization circuit for power semiconductor devices is provided for another embodiment;

[0023] Figure 7 A schematic diagram of a series voltage equalization circuit for power semiconductor devices is provided for another embodiment;

[0024] Figure 8A schematic diagram of a series voltage equalization circuit for power semiconductor devices provided in another embodiment.

[0025] Explanation of reference numerals in the attached figures:

[0026] 10. Series voltage equalization circuit for power semiconductor devices; 100. Series circuit for power semiconductor devices; 110. Power semiconductor device; 111. Diode; 200. Voltage equalization circuit; 210. Voltage equalization unit; 211. Dynamic voltage equalization unit; 212. Static voltage equalization unit; 213. Capacitor; 214. First resistor; 215. Second resistor; 300. Voltage clamping circuit; 310. Voltage clamping unit; 311. Passive clamping unit; 312. Active clamping unit; 313. Turnaround diode; 314. Gate resistor; 315. Energy dissipation resistor; 316. Thyristor; 300'. Branch voltage clamping circuit. Detailed Implementation

[0027] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0029] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0030] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0031] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0032] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0033] With the development of modern power electronics technology, the demand for high-voltage applications in high-voltage inverters, high-voltage direct current transmission systems and other applications is constantly increasing. However, the application and development of individual power semiconductor devices are limited by the influence of process and performance. Therefore, series connection of power semiconductor devices is an important way to solve and realize high-voltage, high-capacity power electronic converters. However, the individual performance differences of power semiconductor devices and the differences in stray parameters of the circuit will cause uneven voltage division in series connection. If not controlled, it may lead to damage to the power semiconductor devices.

[0034] In the prior art, voltage equalization of power semiconductor devices can be achieved by using a voltage equalization circuit composed of parallel resistors and capacitors or by using parallel resistors in each power semiconductor device. However, the voltage equalization effect in the prior art is not ideal.

[0035] In view of this, embodiments of this application provide a power semiconductor device series voltage equalization circuit that can effectively improve the problem of voltage imbalance during the series connection of power semiconductor devices.

[0036] In one exemplary embodiment, such as Figure 1 As shown, a power semiconductor device series voltage equalization circuit 10 is provided. The power semiconductor device series voltage equalization circuit 10 includes a power semiconductor device series circuit 100, a voltage equalization circuit 200, and a voltage clamping circuit 300. The power semiconductor device series circuit 100 includes a plurality of power semiconductor devices 110 connected in series. The voltage equalization circuit 200 includes a plurality of voltage equalization units 210, each voltage equalization unit 210 being connected in parallel with each power semiconductor device 110, for equalizing the voltage across each power semiconductor device 110. The voltage clamping circuit 300 is connected in parallel with the power semiconductor device series circuit 100, and the voltage clamping circuit 300 includes a plurality of parallel voltage clamping units 310, which are used to equalize the voltage across each power semiconductor device 110 during the power semiconductor device 110 turn-off transient.

[0037] Optionally, the power semiconductor device 110 can be a high-power electronic device used for power conversion and circuit control, serving as a bridge between low-voltage control and high-voltage operation. It is mainly used for functions such as frequency conversion, voltage conversion, current conversion, power amplification, and power management. The power semiconductor device 110 may include thyristors, insulated gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), or integrated gate commutated thyristors (IGCTs), etc.

[0038] Optionally, the power semiconductor device series circuit 100 can be two or more power semiconductor devices 110 connected sequentially in the same circuit to improve the overall voltage and power capacity. The series-connected power semiconductor devices 110 can distribute the voltage and improve the voltage withstand capability of the overall circuit. In this application embodiment, there are no limitations on the number, type and model of the power semiconductor devices 110, which can be selected according to the actual situation. For example, when n power semiconductor devices 110 are connected in series, the first power semiconductor device is the stage with the highest potential in the power semiconductor device series circuit 100, and the nth power semiconductor device is the stage with the lowest potential in the power semiconductor device series circuit 100.

[0039] Optionally, due to individual performance differences of the power semiconductor devices 110 and stray parameter differences in the cooperating circuit, the voltage division of the series circuit 110 of the power semiconductor devices will be unbalanced. When the power semiconductor device 110 is in the on or off state, the voltage of the power semiconductor device 110 remains stable, but there is static voltage imbalance. For example, taking the power semiconductor device as a MOSFET, the static imbalance is mainly caused by the inconsistency of leakage current parameters between the MOSFETs. When the power semiconductor device 110 is in the turn-on transient or turn-off transient state, the voltage of the power semiconductor device 110 changes drastically, and there is dynamic voltage imbalance. Therefore, it is necessary to connect a voltage equalization unit in parallel across each power semiconductor device 110 to balance the voltage across each power semiconductor device 110.

[0040] Optionally, the equalizing unit can be a static equalizing unit and / or a dynamic equalizing unit, and this application embodiment does not limit this.

[0041] Optionally, when the power semiconductor device 110 is in the turn-off transient state, the inductor current in the branch where the power semiconductor device 110 is located is interrupted, causing the voltage across the power semiconductor device 110 to rise rapidly, which exacerbates the voltage imbalance among the power semiconductor devices 110. At the same time, the power semiconductor device 110 is at risk of overvoltage breakdown failure. Therefore, a voltage clamping circuit 300 needs to be connected in parallel across the series circuit 100 of the power semiconductor devices. The equivalent impedance of the voltage clamping circuit 300 decreases as the voltage across the power semiconductor device 110 rises, which can limit the further rise of the voltage across the power semiconductor device 110 during the turn-off transient state, allowing other power semiconductor devices in the series branch to withstand the voltage, thereby making the voltages across each device closer and balancing the voltages across the power semiconductor devices 110.

[0042] Optionally, the voltage clamping circuit 300 can be implemented by connecting multiple voltage clamping units 310 in parallel. In this way, the voltage clamping circuit 300 can have multi-level impedance adjustment and redundancy backup capabilities, which can improve the voltage clamping effect of the voltage clamping circuit and further improve the problem of voltage imbalance in the series connection of power semiconductor devices.

[0043] The aforementioned series voltage equalization circuit for power semiconductor devices includes a series circuit of power semiconductor devices, a voltage equalization circuit, and a voltage clamping circuit. The series circuit of power semiconductor devices includes multiple power semiconductor devices connected in series. The voltage equalization circuit includes multiple voltage equalization units, each connected in parallel with each power semiconductor device, used to equalize the voltage across each power semiconductor device. The voltage clamping circuit is connected in parallel with the series circuit of power semiconductor devices and includes multiple parallel voltage clamping units. These multiple parallel voltage clamping units are used to equalize the voltage across each power semiconductor device during the power semiconductor device turn-off transient. In this way, the voltage equalization circuit improves the static and dynamic voltage imbalance problems when power semiconductor devices are connected in series. At the same time, by connecting multiple parallel voltage clamping units, the voltage across the power semiconductor device can be clamped during the power semiconductor device turn-off transient, which can improve the voltage clamping effect of the voltage clamping circuit and further improve the voltage division imbalance problem during the series connection of power semiconductor devices.

[0044] In an exemplary embodiment, the voltage clamping unit 310 is configured to be in a high impedance state when the voltage across the voltage clamping unit 310 does not exceed a preset operating voltage, and to be in a low impedance state when the voltage across the voltage clamping unit 310 exceeds the preset operating voltage.

[0045] Optionally, when the power semiconductor device 110 is in the off transient state, the voltage across the power semiconductor device 110 rises rapidly, causing the voltage across the voltage clamping unit 310 to exceed the preset operating voltage. At this time, the voltage clamping unit 310 is in a low impedance state, which can absorb energy and limit the voltage across the power semiconductor device 110 from rising further.

[0046] Optionally, at least two of the multiple parallel voltage clamping units have the same operating voltage, or at least two of the multiple parallel voltage clamping units have different operating voltages.

[0047] Optionally, when the voltage across the voltage clamping unit 310 exceeds the preset operating voltage, if at least two voltage clamping units 310 have the same operating voltage, then these at least two voltage clamping units 310 are in a low impedance state, the equivalent parallel impedance of the voltage clamping circuit 300 is reduced, and the fact that at least two voltage clamping units 310 have the same operating voltage achieves redundancy in the voltage clamping circuit 300, improving the energy absorption and voltage clamping effect. At the same time, it avoids the risk of overheating and explosion caused by absorbing energy when there is only one voltage clamping unit 310, which can improve the safety of the voltage clamping circuit.

[0048] Optionally, when the voltage across the voltage clamping unit 310 exceeds the preset operating voltage, if the operating voltages of at least two voltage clamping units 310 are different, the voltage clamping unit with the lower operating voltage is in a low-impedance state, and the voltage clamping unit with the higher operating voltage is in a high-impedance state. The voltage clamping unit in the low-impedance state absorbs energy to achieve voltage clamping. When the voltage clamping unit in the low-impedance state cannot complete voltage clamping, the voltage clamping unit with the higher operating voltage is in a low-impedance state to reduce the equivalent parallel impedance of the voltage clamping circuit, thereby realizing 300-step clamping of the voltage clamping circuit and improving the effect of energy absorption and voltage clamping.

[0049] In one exemplary embodiment, the plurality of parallel voltage clamping units 310 include: a passive clamping unit 311, and / or an active clamping unit 312.

[0050] Optionally, the voltage clamping circuit 300 can be implemented by multiple passive clamping units 311 connected in parallel, or by multiple active clamping units 312 connected in parallel, or by multiple passive clamping units 311 and multiple active clamping units 312 connected in parallel. This application embodiment does not limit the type and model of the voltage clamping units.

[0051] Optionally, the passive clamping unit 311 can be a voltage-controlled variable resistor device, wherein a voltage-controlled variable resistor device is a component whose resistance value changes with the control voltage, and can adjust its own resistance value according to the externally applied voltage, thereby affecting the circuit or voltage distribution in the circuit.

[0052] Optionally, the passive clamping unit 311 may include a surge arrester, a surge tube, a Zener diode, or a transient suppression diode, etc., wherein the surge arrester is a varistor, that is, the resistance of the surge arrester changes with the voltage across its terminals, and the surge tube is a gas discharge tube, which forms a short-circuit arc when the voltage across its terminals breaks down the insulating gas, thereby releasing energy.

[0053] Optional, such as Figure 2 As shown, the active clamping unit 312 includes a transition diode 313, a gate resistor 314, a power dissipation resistor 315, and a thyristor 316. The anode of the transition diode 313 is connected to the first terminal of the gate resistor 314 and the gate of the thyristor 316. The cathode of the transition diode 313 is connected to the first terminal of the power dissipation resistor 315, forming a first output port. The second terminal of the power dissipation resistor 315 is connected to the anode of the thyristor 316, and the cathode of the thyristor 316 is connected to the second terminal of the gate resistor 314, forming a second output port. When the voltage across the active clamping unit 312 exceeds the operating voltage of the transition diode 313, the transition diode 313 is reverse-broken down, generating a current injected into the gate of the thyristor 316, thus putting the active clamping unit 312 in a low-impedance state.

[0054] Optionally, when the voltage across the active clamping unit 312 does not exceed the operating voltage of the transition diode 313, the gate of the thyristor 316 is connected to its own cathode through the gate resistor, the thyristor 316 remains in a blocking state, and the active clamping unit 312 is in a high-impedance state; when the voltage across the active clamping unit 312 exceeds the operating voltage of the transition diode 313, the transition diode 313 is reverse-broken down and generates a current injected into the gate of the thyristor 316, the thyristor 316 is turned on, and the energy-dissipating resistor 315 is connected in parallel between the first output port and the second output port of the active clamping unit 312, the equivalent parallel impedance of the two output ports changes from high to low, so that the active clamping unit 312 is in a low-impedance state.

[0055] For example, such as Figure 3As shown, taking the voltage clamping circuit 300 consisting of two active clamping units 312 connected in parallel as an example, the first output ports of the two active clamping units 312 are interconnected, and the second output ports are interconnected. When the voltage across the active clamping unit 312 exceeds the operating voltage of the transition diode 313, and when the operating voltages of the transition diodes 313 in the two active clamping units 312 are the same, redundancy of the voltage clamping circuit 300 is achieved, improving energy absorption and voltage clamping effect, and avoiding the risk of overheating and explosion. At the same time, the active clamping unit 312 where the transition diode 313 with the lower operating voltage is located is initially in a low-impedance state, while the active clamping unit where the transition diode 313 with the higher operating voltage is located remains in a high-impedance state. Energy absorption and voltage clamping are performed by the active clamping unit 312 in the low-impedance state. When the active clamping unit 312 in the low-impedance state cannot complete voltage clamping, the active clamping unit where the transition diode 313 with the higher operating voltage is located is again in a low-impedance state, further reducing the parallel equivalent impedance, realizing stepped clamping, and improving the energy absorption and voltage clamping effect.

[0056] Optionally, since the thyristor 316 in the active clamping unit 312 has a fast dynamic response speed, good consistency of each component and simple selection, the operating voltage consistency of the active clamping unit 312 can be guaranteed, which can further improve the safety of power semiconductor devices under all operating conditions.

[0057] Optionally, if the multiple parallel voltage clamping units 310 include active clamping units 312 and passive clamping units 311, the first output ports of each active clamping unit 312 are interconnected and connected to the first terminal of the power semiconductor device series circuit 100 and the first terminal of each passive clamping unit 311, and the second output ports of each active clamping unit 312 are interconnected and connected to the second terminal of the power semiconductor device series circuit 100 and the second terminal of each passive clamping unit 311, the embodiments of this application do not limit the number and connection order of voltage clamping units.

[0058] For example, such as Figure 4As shown, taking the voltage clamping circuit 300 consisting of one active clamping unit 312 and one passive clamping unit 311 connected in parallel as an example, the passive clamping unit 311 can be a surge arrester. The state of the passive clamping unit 311 is determined by the voltage across the passive clamping unit 311 and the operating voltage of the surge arrester. When the voltage across the passive clamping unit 311 exceeds the operating voltage of the surge arrester, the passive clamping unit 311 is in a low-impedance state. When the voltage across the passive clamping unit 311 does not exceed the operating voltage of the surge arrester, the passive clamping unit 311 is in a low-impedance state. 1. It is in a high impedance state; similarly, the operating voltage of the surge arrester and the operating voltage of the transition diode 313 can be the same or different. That is, when the operating voltages of the passive clamping unit 311 and the active clamping unit 312 are the same, the redundancy of the voltage clamping circuit 300 is realized, the energy absorption and voltage clamping effect are improved, and the risk of overheating and explosion is avoided. When the operating voltages of the passive clamping unit 311 and the active clamping unit 312 are different, the step clamping of the voltage clamping circuit 300 is realized, and the energy absorption and voltage clamping effect are improved.

[0059] In an exemplary embodiment, each voltage equalization unit 210 includes a dynamic voltage equalization unit 211 and a static voltage equalization unit 212, with the dynamic voltage equalization unit 211 and the static voltage equalization unit 212 connected in parallel. The dynamic voltage equalization unit 211 is used to slow down the rate of change of the voltage across the power semiconductor device 110 during the turn-on and turn-off transients, so as to equalize the dynamic voltage across each power semiconductor device 110. The static voltage equalization unit 212 is used to balance the leakage current of the power semiconductor device 110 when the power semiconductor device 110 is blocked, so as to equalize the static voltage across each power semiconductor device 110.

[0060] Optional, such as Figure 5 As shown, the dynamic voltage equalization unit 211 includes a capacitor 213 and a first resistor 214, with the capacitor 213 and the first resistor 214 connected in series; the static voltage equalization unit 212 includes a second resistor 215, the resistance of which is less than the equivalent impedance of the power semiconductor device 110 when it is blocked.

[0061] Optionally, when the power semiconductor device 110 is in a turn-off transient state, the voltage across the power semiconductor device 110 rises and charges the capacitor 213 through the first resistor 214. The dynamic voltage equalization unit 211 provides an additional current path, reducing the equivalent input impedance across the power semiconductor device 110 and the rate of voltage rise. When the power semiconductor device 110 is in a turn-on transient state, the voltage across the power semiconductor device 110 drops and discharges the capacitor 213 through the first resistor 214. The dynamic voltage equalization unit 211 provides an additional current source, reducing the equivalent output impedance across the power semiconductor device 110 and the rate of voltage drop.

[0062] Optionally, the resistance value of the second resistor 215 of the static voltage equalization unit 212 is much smaller than the equivalent impedance of the power semiconductor device 110 when it is blocked, so as to balance the leakage current of the power semiconductor device 110 when it is blocked, thereby balancing the static voltage of each power semiconductor device 110.

[0063] The aforementioned voltage equalization units include dynamic voltage equalization units and static voltage equalization units, with the dynamic voltage equalization units connected in parallel with the static voltage equalization units. The dynamic voltage equalization unit is used to slow down the rate of change of voltage across the power semiconductor devices during the turn-on and turn-off transients, so as to equalize the dynamic voltage across each power semiconductor device. The static voltage equalization unit is used to balance the leakage current of the power semiconductor devices when the power semiconductor devices are turned off, so as to equalize the static voltage across each power semiconductor device, which can improve the problem of voltage imbalance during the series connection of power semiconductor devices.

[0064] In one exemplary embodiment, such as Figure 6 As shown, in the series circuit 100 of power semiconductor devices, each power semiconductor device 110 is connected in reverse parallel with a diode 111 to block and control the forward current and forward voltage.

[0065] For example, Figure 6 Taking the power semiconductor device 110 as an example of an asymmetric IGCT device, the voltage clamping circuit 300 is implemented by two active clamping units connected in parallel.

[0066] Optionally, in the above embodiments, the power semiconductor device is based on the power semiconductor device 110 with a reverse parallel diode 111. The anode of the diode 111 is connected to the cathode of the power semiconductor device 110, and the cathode of the diode 111 is connected to the anode of the power semiconductor device 110. This can block and control the forward current and forward voltage. When there is a reverse current or reverse voltage in the power semiconductor device 110, the diode 111 conducts, and a circuit is formed between the diode 111 and the power semiconductor device 110 to prevent the voltage equalization circuit 200 and the voltage clamping circuit 300 from conducting.

[0067] In one possible implementation, such as Figure 7As shown, taking the power semiconductor device series circuit 100, which is a unipolar series circuit composed of one power semiconductor device, as an example, the voltage clamping circuit 300 is implemented by one active clamping unit and one passive clamping unit connected in parallel. Each power semiconductor device 110 can also be connected in parallel with a diode instead of a diode in reverse parallel connection. Instead, a diode 111 is connected in parallel across the first resistor 214 of the dynamic voltage equalization unit 211. The anode of the diode 111 is connected to the first terminal of the first resistor 214, and the cathode of the diode 111 is connected to both the second terminal of the first resistor 214 and the first terminal of the capacitor 213. Furthermore, in the power clamping... When the circuit 300 includes an active clamping unit 312, the anode of the transition diode 313 is connected to the anode of the diode 111, the cathode of the diode 111 is connected to the first end of the gate resistor 314 and the gate of the thyristor 316, the cathode of the transition diode 313 is connected to the first end of the energy dissipation resistor 315 to form a first output port, the second end of the energy dissipation resistor 315 is connected to the anode of the thyristor 316, and the cathode of the thyristor 316 is connected to the second end of the gate resistor 314 to form a second output port, preventing the voltage equalization circuit 200 and the voltage clamping circuit 300 from conducting.

[0068] In one exemplary embodiment, optionally, based on the above embodiments, the series voltage equalization circuit of the power semiconductor devices may further include multiple branch voltage clamping circuits, each of which is connected in parallel with each power semiconductor device, and the number of branch voltage clamping circuits is the same as the number of power semiconductor devices connected in series.

[0069] Optionally, the structure of the branch voltage clamping circuit is the same as that of the voltage clamping circuit in the above embodiments, and will not be described again in this application embodiment.

[0070] Optionally, each power semiconductor device in the power semiconductor series circuit is connected in parallel with a branch voltage clamping circuit. The branch voltage clamping circuit may include at least one voltage clamping unit. Similarly, the voltage clamping unit may be a passive clamping unit or an active clamping unit. When the branch voltage clamping circuit includes multiple voltage clamping units, the voltage clamping units are connected in parallel. The structure of the branch voltage clamping circuits connected in parallel for each power semiconductor device may be the same or different, depending on the situation. This application embodiment does not limit this.

[0071] For example, such as Figure 8As shown, taking the parallel voltage clamping circuit 300 of the power semiconductor device series circuit 100, the parallel dynamic voltage equalization unit 211 of each power semiconductor device 110, the static voltage equalization unit 212, and the branch voltage clamping circuit 300' as an example, each branch voltage clamping circuit 300' is composed of a passive clamping unit 311, which can be a surge arrester. The equivalent impedance of each branch voltage clamping circuit 300' decreases as the voltage across the power semiconductor device increases, which is used to limit the further rise of the voltage across the overvoltage power semiconductor device during the turn-off transient, forcing other power semiconductor devices in the series branch to bear the voltage, thereby making the voltages across each power semiconductor device approach each other. The voltage clamping circuit 300 can clamp the voltage across the power semiconductor device during the turn-off transient by connecting multiple voltage clamping units in parallel, which can improve the voltage clamping effect of the voltage clamping circuit and further improve the problem of voltage imbalance during the series connection of power semiconductor devices.

[0072] In one exemplary embodiment, the power electronic converter includes the power semiconductor device series voltage equalization circuit described in any of the above-described power semiconductor device series voltage equalization circuit embodiments.

[0073] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0074] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A series voltage equalization circuit for power semiconductor devices, characterized in that, include: A series circuit of power semiconductor devices, wherein the series circuit of power semiconductor devices includes a plurality of power semiconductor devices connected in series; A voltage equalization circuit, comprising multiple voltage equalization units, each voltage equalization unit being connected in parallel with each power semiconductor device, for balancing the voltage across each power semiconductor device; A voltage clamping circuit is connected in parallel with the series circuit of the power semiconductor device. The voltage clamping circuit includes multiple parallel voltage clamping units, which are used to balance the voltage across each power semiconductor device during the power semiconductor device's turn-off transient. The plurality of parallel voltage clamping units include active clamping units; The active clamping unit includes a transition diode, a gate resistor, a power dissipation resistor, and a thyristor; the anode of the transition diode is connected to both the first terminal of the gate resistor and the gate of the thyristor, the cathode of the transition diode is connected to the first terminal of the power dissipation resistor to form a first output port, the second terminal of the power dissipation resistor is connected to the anode of the thyristor, and the cathode of the thyristor is connected to the second terminal of the gate resistor to form a second output port; When the voltage across the active clamping unit exceeds the operating voltage of the transition diode, the transition diode is reverse-broken down and generates a current injected into the gate of the thyristor, causing the active clamping unit to be in a low-impedance state. In a plurality of parallel voltage clamping units, at least two of the voltage clamping units have the same operating voltage, or, in a plurality of parallel voltage clamping units, at least two of the voltage clamping units have different operating voltages. When the operating voltages of the at least two active clamping units are different, the first active clamping unit is in a low-impedance state and the second active clamping unit is in a high-impedance state. The first active clamping unit absorbs energy to achieve voltage clamping. When the first active clamping unit cannot complete voltage clamping, the second active clamping unit is in a low-impedance state to reduce the equivalent parallel impedance of the voltage clamping circuit. The operating voltage of the transition diode in the first active clamping unit is lower than the operating voltage of the transition diode in the second active clamping unit.

2. The circuit according to claim 1, characterized in that, The voltage clamping unit is used to maintain a high impedance state when the voltage across the voltage clamping unit does not exceed a preset operating voltage. When the voltage across the voltage clamping unit exceeds the preset operating voltage, the voltage clamping unit is in a low-impedance state.

3. The circuit according to claim 1, characterized in that, The plurality of parallel voltage clamping units further include passive clamping units. If the plurality of parallel voltage clamping units include active clamping units and passive clamping units, the first output ports of each active clamping unit are interconnected and connected to the first terminal of the power semiconductor device series circuit and the first terminal of each passive clamping unit. The second output ports of each active clamping unit are interconnected and connected to the second terminal of the power semiconductor device series circuit and the second terminal of each passive clamping unit.

4. The circuit according to claim 1, characterized in that, Each of the aforementioned equalization units includes a dynamic equalization unit and a static equalization unit, wherein the dynamic equalization unit and the static equalization unit are connected in parallel; The dynamic voltage equalization unit is used to slow down the rate of change of voltage across the power semiconductor device during the power semiconductor device's turn-on and turn-off transients, so as to equalize the dynamic voltage across each power semiconductor device. The static voltage equalization unit is used to balance the leakage current of the power semiconductor device when the power semiconductor device is blocked, so as to equalize the static voltage across each power semiconductor device.

5. The circuit according to claim 4, characterized in that, The dynamic voltage equalization unit includes a capacitor and a first resistor, wherein the capacitor is connected in series with the first resistor; The static voltage equalization unit includes a second resistor, the resistance of which is less than the equivalent impedance of the power semiconductor device when it is blocked.

6. The circuit according to claim 1, characterized in that, In the series circuit of the power semiconductor devices, each power semiconductor device is connected in reverse parallel with a diode to block and control the forward current and forward voltage.

7. A power electronic converter, characterized in that, The power electronic converter includes a series voltage equalization circuit of power semiconductor devices as described in any one of claims 1 to 6.

Images