A chopper soft-switching igct power module and a method of operating the same

Abstract

The application discloses a chopper type soft switching IGCT power module and an operation method thereof, and relates to the technical field of direct current power transmission. The chopper type soft switching IGCT power module comprises a switching circuit, a first half-bridge switching device and a second half-bridge switching device. The first half-bridge switching device and the second half-bridge switching device are connected in series, and the switching circuit is connected in parallel with a branch formed by the first half-bridge switching device and the second half-bridge switching device in series. The two ends of the second half-bridge switching device are used as an input end and an output end of the chopper type soft switching IGCT power module respectively. The application solves the technical problem that, in the prior art, when devices are in a hard switching state for a long time, the loss increases rapidly under an overload working condition, heat collapse is easily caused, and there are obvious defects in loss control and overload tolerance.

Description

Technical Field

[0001] This invention relates to the field of DC power transmission technology, and in particular to a chopper-type soft-switching IGCT power module and its operation method. Background Technology

[0002] Flexible DC-DC converter technology is a core support for my country's transformation to a new power system. Modular multilevel converters (MMCs) have become the mainstream technology due to their strong voltage scalability, good output waveform quality, and outstanding power output capability. MMCs consist of a large number of power modules connected in series to form bridge arms. The near-power frequency switching characteristics of these modules result in high on-state losses, which are a key factor limiting converter efficiency. Integrated gate commutator thyristors (IGCTs) possess high blocking voltage, strong current-carrying capacity, and low on-state voltage drop, offering significant advantages in flexible DC-DC converters.

[0003] Currently, most flexible DC-DC converter power modules adopt hard-switching operation, resulting in high switching losses and high electrical stress on the devices. Under long-term operation, the hard-switching IGCT is constantly in a hard-on-off state, and switching losses accumulate continuously. The matching anode reactor and RCD snubber circuit will continuously generate additional losses, which will reduce the power conversion efficiency in the long run. When the load current fluctuates and the device operates at high current for a long time, the device turn-off losses steadily increase, the junction temperature remains high and is difficult to dissipate, and the long-term high temperature will accelerate the aging of the device. At the same time, frequent voltage and current peak stresses will continuously wear down the device itself, significantly reduce its service life, and result in insufficient long-term operational stability and overload durability of the equipment. Summary of the Invention

[0004] This invention provides a chopper-type soft-switching IGCT power module and its operation method to solve the technical problem in the prior art where the device is in a hard-switching state for a long time, and the surge in loss under overload conditions can easily lead to thermal collapse, resulting in obvious defects in loss control and overload tolerance.

[0005] To address the aforementioned technical problems, this invention provides a chopper-type soft-switching IGCT power module, comprising: a switching circuit, a first half-bridge switching device, and a second half-bridge switching device. The first half-bridge switching device and the second half-bridge switching device are connected in series, and the switching circuit is connected in parallel with the branch formed by the series connection of the first half-bridge switching device and the second half-bridge switching device. The two ends of the second half-bridge switching device serve as the input and output terminals of the chopper-type soft-switching IGCT power module, respectively.

[0006] As a preferred embodiment, the switching circuit includes: a first auxiliary switch, a second auxiliary switch, and a switched capacitor; The emitter of the first auxiliary switch is connected to the positive terminal of the switched capacitor, the emitter of the second auxiliary switch is connected to the negative terminal of the switched capacitor, and the collectors of both the first and second auxiliary switches are connected to the first half-bridge switching device. The emitter of the second auxiliary switch is also connected to the second half-bridge switching device.

[0007] As a preferred option, it also includes: anodic reactance; The anode reactance is connected to the collector of the first half-bridge switching device and the first auxiliary switch.

[0008] As a preferred embodiment, the first half-bridge switching device includes: a first commutation thyristor and a first freewheeling diode; The anode of the first commutator thyristor is connected to the cathode of the first freewheeling diode, and the cathode of the first commutator thyristor is connected to the anode of the first freewheeling diode. The anode of the first commutator thyristor and the cathode of the first freewheeling diode are both connected to the anode reactance; The cathode of the first commutator thyristor and the anode of the first freewheeling diode are both connected to the second half-bridge switching device.

[0009] As a preferred embodiment, the second half-bridge switching device includes: a second commutation thyristor and a second freewheeling diode; The anode of the second commutation thyristor is connected to the cathode of the second freewheeling diode, and the cathode of the second commutation thyristor is connected to the anode of the second freewheeling diode. The anode of the second commutation thyristor and the cathode of the second freewheeling diode are both connected to the first half-bridge switching device; The cathode of the second commutation thyristor and the anode of the second freewheeling diode are both connected to the emitter of the second auxiliary switch.

[0010] As a preferred embodiment, it also includes: a first buffer branch and a second buffer branch; One end of the first buffer branch is connected to the anode of the first commutator thyristor and the cathode of the first freewheeling diode, and the other end of the first buffer branch is connected to the cathode of the first commutator thyristor and the anode of the first freewheeling diode. One end of the second buffer branch is connected to the anode of the second commutator thyristor and the cathode of the second freewheeling diode, and the other end of the second buffer branch is connected to the cathode of the second commutator thyristor and the anode of the second freewheeling diode.

[0011] As a preferred embodiment, the first buffer branch includes: a first buffer resistor and a first buffer capacitor; the first buffer resistor and the first buffer capacitor are connected in series. One end of the first buffer resistor is connected to the anode of the first commutation thyristor and the cathode of the first freewheeling diode; One end of the first buffer capacitor is connected to the cathode of the first commutation thyristor and the anode of the first freewheeling diode.

[0012] As a preferred embodiment, the second buffer branch includes: a second buffer resistor and a second buffer capacitor; the second buffer resistor and the second buffer capacitor are connected in series. One end of the second buffer resistor is connected to the anode of the second commutation thyristor and the cathode of the second freewheeling diode; One end of the second buffer capacitor is connected to the cathode of the second commutation thyristor and the anode of the second freewheeling diode.

[0013] Accordingly, the present invention also provides an operation method for a chopper-type soft-switching IGCT power module, implemented by any one of the chopper-type soft-switching IGCT power modules described above, comprising: During steady-state operation, the first auxiliary switch is kept on and the second auxiliary switch is closed. When a commutation occurs, the first auxiliary switch and the second auxiliary switch of the control circuit are alternately turned on and off according to a preset frequency, and the duty cycle of the first auxiliary switch and the first auxiliary switch is adjusted to reduce the equivalent output voltage. During the commutation process, the first auxiliary switch is controlled to turn off and the second auxiliary switch is controlled to turn on until the first half-bridge switching device or the second half-bridge switching device is turned off to reduce the blocking output voltage and peak current.

[0014] As a preferred embodiment, the present invention further includes: After the first half-bridge switching device or the second half-bridge switching device is turned off, the second auxiliary switch is controlled to remain on to construct the zero-point voltage stage of the chopper-type soft-switching IGCT power module.

[0015] As a preferred embodiment, before the first auxiliary switch and the second auxiliary switch controlling the switching circuit alternately turn on and off according to a preset frequency, the circuit further includes: The first auxiliary switch of the switching circuit is turned off, and the second auxiliary switch is turned on to start the equivalent bidirectional BUCK circuit of the chopper-type soft-switching IGCT power module.

[0016] As a preferred embodiment, the present invention further includes: After the commutation is completed, both the first auxiliary switch and the first auxiliary switch controlling the switching circuit remain in the off state, so that the equivalent bidirectional BUCK circuit of the chopper-type soft-switching IGCT power module stops working.

[0017] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: The technical solution of this invention uses a first half-bridge switch and a second half-bridge switch connected in series. The switching circuit is connected in parallel with the branch formed by the series connection of the first half-bridge switch and the second half-bridge switch. The two ends of the second half-bridge switch are respectively used as the input and output terminals of the chopper-type soft-switching IGCT power module. This constitutes a low-loss IGCT power module with DC fault clearing capability, realizing near-zero voltage switching of the IGCT device, reducing the switching losses of the main circuit devices, improving overload capacity, and by controlling the switching circuit, an equivalent BUCK circuit can be formed. The duty cycle can be adjusted to lower the device blocking voltage in advance, controllably constrain the rate of change of commutation current, realize low-stress soft turn-off of IGCT and diode, effectively reduce long-term accumulated switching losses, avoid the additional power consumption brought by the traditional hard-switching reactor and absorption circuit, and at the same time weaken the repeated impact of voltage and current spikes, slow down the aging speed of devices, suppress the problem of abnormal junction temperature rise under high current conditions, and comprehensively improve the efficiency and overload stability of the equipment during long-term operation. Attached Figure Description

[0018] Figure 1 : This is a structural diagram of a chopper-type soft-switching IGCT power module provided in an embodiment of the present invention; Figure 2 : This is a specific circuit diagram of the chopper-type soft-switching IGCT power module provided in an embodiment of the present invention; Figure 3 : A flowchart illustrating the steps of an operation method for a chopper-type soft-switching IGCT power module provided in an embodiment of the present invention; Figure 4 : A schematic diagram of the flow path under steady state provided in an embodiment of the present invention; Figure 5 : A schematic diagram of the flow path under another steady state provided in an embodiment of the present invention; Figure 6 : A schematic diagram of the equivalent bidirectional buck structure formed when the first half-bridge switch is turned off during the commutation process, provided by an embodiment of the present invention; Figure 7 : A schematic diagram of the equivalent bidirectional buck structure formed when the second half-bridge switch is turned off during the commutation process, provided by an embodiment of the present invention; Figure 8 : A schematic diagram of the transient zero-level state of the switch constructed by the normally-on second auxiliary switch provided in an embodiment of the present invention; The reference numerals for the accompanying drawings in the specification are as follows: Switching circuit 01, first half-bridge switching device; 02, second half-bridge switching device; 03, first auxiliary switch Sa1, second auxiliary switch Sa2, switched capacitor C D Anode reactance L A First commutator thyristor T1, first freewheeling diode D1, first buffer resistor R1, first buffer capacitor C1, second commutator thyristor T2, second freewheeling diode D2, second buffer resistor R2, second buffer capacitor C2. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In existing power modules using IGCT modular multilevel converters (i.e., IGCT power modules), the IGCT rapidly loses its voltage-bearing capacity upon turn-on. Therefore, a corresponding anode reactor must be configured in the module to passively limit di / dt, thereby protecting the diodes. However, configuring the anode reactor significantly increases the inductance of the commutation path, resulting in severe overvoltage during IGCT hard turn-off and diode reverse recovery. Therefore, an RCD (Resistor-Capacitor-Diode, overvoltage absorption circuit) is also required. As the anode reactor inductance and load current increase, the additional losses caused by the clamping circuit also increase, degrading the operating efficiency of the converter valve. On the other hand, since the IGCT module is entirely in a hard-switching state, the turn-off losses of the IGCT devices and diodes increase proportionally with the external current under overload conditions. This leads to a rapid rise in junction temperature after repeated high-current turn-offs, ultimately causing thermal breakdown and loss of turn-off capability. Therefore, existing IGCT power modules still have certain shortcomings in terms of losses and overload capacity.

[0021] This invention utilizes soft-switching technology, enabling the IGCT power module to achieve zero voltage or current during current transfer, thereby significantly reducing switching losses and electrical stress on the devices during transient switching behavior. Furthermore, the switching circuit operates under zero voltage or zero current conditions, creating a soft-switching window through a resonant network. This results in no voltage / current overlap, controlled peak voltage / current, substantial reduction in switching losses and electromagnetic interference, enabling high-frequency operation with low device stress and eliminating the need for high-power RCD absorption.

[0022] Example 1 Please see Figure 1 The present invention provides a chopper-type soft-switching IGCT power module, comprising: a switching circuit 01, a first half-bridge switching device 02, and a second half-bridge switching device 03. The first half-bridge switching device 02 and the second half-bridge switching device 03 are connected in series, and the branch formed by the switching circuit 01 and the series connection of the first half-bridge switching device 02 and the second half-bridge switching device 03 is connected in parallel; the two ends of the second half-bridge switching device 03 serve as the input and output terminals of the chopper-type soft-switching IGCT power module, respectively.

[0023] In this embodiment, the switching circuit 01 works in conjunction with the first half-bridge switching device 02 and the second half-bridge switching device 03 to effectively regulate voltage and control commutation. This reduces the blocking voltage experienced by the devices during turn-off, smoothly constrains the rate of current change, and significantly reduces switching losses and voltage / current spikes. Simultaneously, this structure reduces the need for an RCD snubber circuit, decreases additional power losses, slows down device aging and temperature rise, and effectively improves the long-term operating efficiency, overload capacity, and reliability of the power module.

[0024] As a preferred embodiment, the switching circuit 01 includes: a first auxiliary switch Sa1, a second auxiliary switch Sa2, and a switched capacitor C. D .

[0025] The emitter of the first auxiliary switch Sa1 and the switched capacitor C D The positive terminal of the second auxiliary switch Sa2 is connected to the positive terminal of the switched capacitor C. D The negative terminal is connected, and the collectors of the first auxiliary switch Sa1 and the second auxiliary switch Sa2 are both connected to the first half-bridge switching device 02; the emitter of the second auxiliary switch Sa2 is also connected to the second half-bridge switching device 03.

[0026] As a preferred embodiment, the chopper-type soft-switching IGCT power module further includes: an anode reactance L. A The anode reactance L A It is connected to the collector of the first half-bridge switch 02 and the first auxiliary switch Sa1.

[0027] In this embodiment, the anode reactance L A It can effectively constrain the rate of change of current through the first auxiliary switch Sa1, the second auxiliary switch Sa2, and the switched capacitor C. D The synergistic effect of these technologies can smoothly adjust the terminal voltage during device commutation, reduce the voltage stress at the moment of IGCT half-bridge device turn-off, and suppress the current spikes generated by reverse recovery.

[0028] In this embodiment, as Figure 2 As shown, the first auxiliary switch Sa1 and the second auxiliary switch Sa2 are auxiliary switching devices in the chopper-type soft-switching IGCT power module. The emitter of the first auxiliary switch Sa1 is connected to the switched capacitor C. D The positive terminal of the second auxiliary switch Sa2 is connected to the DC support switching capacitor C. D The negative terminals are connected, and the collectors of the first auxiliary switch Sa1 and the second auxiliary switch Sa2 are connected; wherein, the anode reactance L A The right end is connected to the first half-bridge switching device 02, and the left end is connected to the common collector node of the first auxiliary switch Sa1 and the second auxiliary switch Sa2.

[0029] In a preferred embodiment, the first half-bridge switching device 02 includes: a first commutation thyristor T1 and a first freewheeling diode D1; the anode of the first commutation thyristor T1 is connected to the cathode of the first freewheeling diode D1, and the cathode of the first commutation thyristor T1 is connected to the anode of the first freewheeling diode D1; both the anode of the first commutation thyristor T1 and the cathode of the first freewheeling diode D1 are connected to the anode reactance L. A Connection; the cathode of the first commutator thyristor T1 and the anode of the first freewheeling diode D1 are both connected to the second half-bridge switching device 03.

[0030] In a preferred embodiment, the second half-bridge switching device 03 includes: a second commutation thyristor T2 and a second freewheeling diode D2; the anode of the second commutation thyristor T2 is connected to the cathode of the second freewheeling diode D2, and the cathode of the second commutation thyristor T2 is connected to the anode of the second freewheeling diode D2; both the anode of the second commutation thyristor T2 and the cathode of the second freewheeling diode D2 are connected to the first half-bridge switching device 02; both the cathode of the second commutation thyristor T2 and the anode of the second freewheeling diode D2 are connected to the emitter of the second auxiliary switch Sa2.

[0031] As a preferred embodiment, the chopper-type soft-switching IGCT power module further includes: a first buffer branch and a second buffer branch; one end of the first buffer branch is connected to the anode of the first commutator thyristor T1 and the cathode of the first freewheeling diode D1, and the other end of the first buffer branch is connected to the cathode of the first commutator thyristor T1 and the anode of the first freewheeling diode D1; one end of the second buffer branch is connected to the anode of the second commutator thyristor T2 and the cathode of the second freewheeling diode D2, and the other end of the second buffer branch is connected to the cathode of the second commutator thyristor T2 and the anode of the second freewheeling diode D2.

[0032] In this embodiment, the commutation thyristors and freewheeling diodes corresponding to the first half-bridge switching device 02 and the second half-bridge switching device 03 are connected in reverse parallel to form a half-bridge switching unit. The first half-bridge switching device 02 and the second half-bridge switching device 03 are connected in series to form the main power circuit, which is matched with the first auxiliary switch Sa1, the second auxiliary switch Sa2, and the switched capacitor C. D and anode reactance L A A coordinated control circuit is formed, and independent buffer branches are added at both ends of the first half-bridge switching device 02 and the second half-bridge switching device 03. A controllable commutation architecture is constructed based on the device topology.

[0033] It should be noted that during operation, the anti-parallel thyristors and diodes can adapt to bidirectional current flow requirements, satisfying the commutation and transmission of electrical energy under different operating conditions; anode reactance L A Real-time suppression of current change rate during commutation, auxiliary switch and switched capacitor C D By coordinating with the voltage amplitude of the regulating circuit, the device turn-off blocking voltage is reduced in advance to achieve a soft-switching commutation effect. The first and second buffer branches can absorb residual voltage spikes to a small extent, avoiding damage to the devices from instantaneous overvoltage surges.

[0034] In this embodiment, by setting the first half-bridge switching device 02 and the second half-bridge switching device 03, the switching loss is reduced from the source, the power consumption burden of the traditional RCD absorption circuit is greatly reduced, the operating temperature rise of the device is effectively controlled, the aging process of the component is delayed, and the long-term operating stability, overload capacity and power conversion efficiency of the power module are significantly improved.

[0035] As a preferred embodiment, the first buffer branch includes: a first buffer resistor R1 and a first buffer capacitor C1; the first buffer resistor R1 and the first buffer capacitor C1 are connected in series; one end of the first buffer resistor R1 is connected to the anode of the first commutator thyristor T1 and the cathode of the first freewheeling diode D1; one end of the first buffer capacitor C1 is connected to the cathode of the first commutator thyristor T1 and the anode of the first freewheeling diode D1.

[0036] As a preferred embodiment, the second buffer branch includes: a second buffer resistor R2 and a second buffer capacitor C2; the second buffer resistor R2 and the second buffer capacitor C2 are connected in series; one end of the second buffer resistor R2 is connected to the anode of the second commutator thyristor T2 and the cathode of the second freewheeling diode D2; one end of the second buffer capacitor C2 is connected to the cathode of the second commutator thyristor T2 and the anode of the second freewheeling diode D2.

[0037] In this embodiment, series-connected RC buffer branches are respectively configured at both ends of the first half-bridge switching device 02 and the second half-bridge switching device 03. Relying on the energy storage and energy dissipation characteristics of resistors and capacitors, a voltage buffer structure for the half-bridge switching device is formed, which can be specifically adapted to the working conditions of thyristors and freewheeling diodes.

[0038] It should be noted that during the switching of the first half-bridge switching device 02 and the second half-bridge switching device 03, the buffer capacitor can quickly absorb instantaneous voltage spikes, and the buffer resistor synchronously consumes the circuit oscillation energy, effectively clamping the voltage amplitude across the device, suppressing sudden changes in peak current / voltage, and mitigating the voltage surge caused by reverse recovery. Simultaneously, it can share overvoltage stress, reduce the voltage loss of the device body, and prevent voltage fluctuations from damaging the semiconductor chip.

[0039] Understandably, the structure of the first and second buffer branches with RC buffers, working in conjunction with the overall soft-switching topology, further optimizes the commutation conditions, reduces device heat loss, slows down component aging, improves the reliability of the power module, and allows the module to maintain stable power conversion performance under long-term load fluctuation conditions.

[0040] Implementing the above embodiments has the following effects: The technical solution of this invention uses a first half-bridge switch and a second half-bridge switch connected in series. The switching circuit is connected in parallel with the branch formed by the series connection of the first half-bridge switch and the second half-bridge switch. The two ends of the second half-bridge switch are respectively used as the input and output terminals of the chopper-type soft-switching IGCT power module. This constitutes a low-loss IGCT power module with DC fault clearing capability, realizing near-zero voltage switching of the IGCT device, reducing the switching losses of the main circuit devices, improving overload capacity, and by controlling the switching circuit, an equivalent BUCK circuit can be formed. The duty cycle can be adjusted to lower the device blocking voltage in advance, controllably constrain the rate of change of commutation current, realize low-stress soft turn-off of IGCT and diode, effectively reduce long-term accumulated switching losses, avoid the additional power consumption brought by the traditional hard-switching reactor and absorption circuit, and at the same time weaken the repeated impact of voltage and current spikes, slow down the aging speed of devices, suppress the problem of abnormal junction temperature rise under high current conditions, and comprehensively improve the efficiency and overload stability of the equipment during long-term operation.

[0041] Example 2 Please see Figure 3 This invention provides a method for operating a chopper-type soft-switching IGCT power module, implemented by any of the above-mentioned chopper-type soft-switching IGCT power modules, including the following steps S101-S103: S101: During steady-state operation, control the first auxiliary switch to remain on and control the second auxiliary switch to be off.

[0042] In this embodiment, during steady-state operation, the first auxiliary switch remains in the on state because the first commutation thyristor is an IGCT and the first freewheeling diode is a PiN diode, both of which are current-controlled devices. When on, they exhibit significant conductance modulation effects and extremely low on-state voltage drop. Furthermore, since the first auxiliary switch is only connected to the main circuit when current flows through the first commutation thyristor or the first freewheeling diode, the additional on-state losses caused by the series-connected first auxiliary switch do not significantly affect the module's operating efficiency. Specifically, as follows... Figure 4 and 5 It is the flow path under steady state.

[0043] S102: When a commutation occurs, the first auxiliary switch and the second auxiliary switch of the control circuit are alternately turned on and off according to a preset frequency, and the duty cycle of the first auxiliary switch and the second auxiliary switch is adjusted to reduce the equivalent output voltage.

[0044] In this embodiment, when a commutation behavior is about to occur, the first auxiliary switch and the second auxiliary switch are controlled to switch alternately and complementaryly. This reduces the equivalent output voltage by adjusting the duty cycle between the first and second auxiliary switches. As a result, the switching capacitor of the switching circuit, based on the periodic switching of the switches, can lower the blocking voltage that the device is to withstand in advance, thereby changing the on / off boundary conditions of the device from the operating conditions.

[0045] In this embodiment, after the voltage pre-drop, both the thyristors and freewheeling diodes in the first and second auxiliary switches can complete the turn-off operation at a low voltage level, effectively weakening the voltage-current superposition effect at the moment of switching and significantly reducing inherent switching losses. Simultaneously, it smooths the current change rate, suppressing electromagnetic oscillations and spikes generated by commutation.

[0046] It is understood that the control method of the present invention, combined with the soft switching working mechanism, reduces the energy dissipation burden of the buffer branch and controls the temperature rise of the junction of the control device, which can not only improve the overall efficiency of power conversion, but also enhance the module's ability to withstand large currents and long-term operation.

[0047] As a preferred embodiment, before the first auxiliary switch and the second auxiliary switch of the control circuit alternately turn on and off according to a preset frequency, the following method is further included: The first auxiliary switch of the switching circuit is turned off, and the second auxiliary switch is turned on to start the equivalent bidirectional BUCK circuit of the chopper-type soft-switching IGCT power module.

[0048] In this embodiment, when a commutation event occurs, the first auxiliary switch, the second auxiliary switch, the anode reactor, and the first or second buffer branch together form an equivalent bidirectional BUCK circuit, such as... Figure 6 and Figure 7 As shown. Wherein, when the second buffer branch is closed, as... Figure 6 As shown, the first auxiliary switch, the second auxiliary switch, the anode reactor, and the first buffer branch constitute an equivalent bidirectional BUCK circuit structure; and when the first buffer branch is closed, as... Figure 7 As shown, the first auxiliary switch, the second auxiliary switch, the anode reactor, and the second buffer branch constitute a bidirectional equivalent BUCK circuit structure.

[0049] S103: During the commutation process, the first auxiliary switch is controlled to turn off and the second auxiliary switch is controlled to turn on until the first half-bridge switching device or the second half-bridge switching device is turned off to reduce the blocking output voltage and peak current.

[0050] In this embodiment, during the commutation stage, the on / off state of the auxiliary switches is controlled, causing the first auxiliary switch to turn off and the second auxiliary switch to turn on. This reconstructs the circuit electrical parameters based on the switch state switching, actively lowers the blocking output voltage across the half-bridge switching devices, thereby changing the circuit's operating conditions and weakening the pressure foundation when the devices are turned off from an electrical perspective.

[0051] Understandably, the control method in this embodiment can effectively clamp the circuit potential, suppress the surge current that appears at the moment of turn-off, smooth the current change trend, and avoid the impact stress caused by drastic changes in voltage and current. It also avoids the problem of concentrated energy release under hard turn-off, reducing internal device losses. Furthermore, it can significantly reduce the switching losses of the thyristor and freewheeling diode, slow down the device temperature rise rate, reduce energy consumption in the buffer branch, effectively improve device lifespan, and ensure stable and reliable operation of the power module during commutation.

[0052] As a preferred embodiment of this invention, the present invention further includes: After the first half-bridge switching device or the second half-bridge switching device is turned off, the second auxiliary switch is controlled to remain on to construct the zero-point voltage stage of the chopper-type soft-switching IGCT power module.

[0053] In this embodiment, after the first and second half-bridge switching devices complete their turn-off actions, the second auxiliary switch remains continuously on, and the loop potential distribution is reconstructed based on the on-state of the second auxiliary switch to construct a stable zero-voltage operating range, such as... Figure 8 As shown. Based on the potential clamping effect, the voltage across the second auxiliary switch drops back to the zero potential range, forming the zero-voltage switching condition necessary for soft switching.

[0054] In this embodiment, the zero-voltage stage completely eliminates the overlap region between voltage and current during switching, fundamentally avoiding hard switching losses. It also significantly reduces the impact stress caused by voltage surges and suppresses electromagnetic oscillations in the circuit. Furthermore, this transition mode optimizes the switching environment, effectively reducing heat loss from semiconductor devices, slowing down component aging, and further improving the commutation stability and long-term reliability of the power module.

[0055] As a preferred embodiment of this invention, the present invention further includes: After the commutation is completed, both the first auxiliary switch and the first auxiliary switch controlling the switching circuit remain in the off state, so that the equivalent bidirectional BUCK circuit of the chopper-type soft-switching IGCT power module stops working.

[0056] In this embodiment, after the commutation process is completed, the first auxiliary switch and the second auxiliary switch are kept open to cut off the auxiliary control loop path, so that the equivalent bidirectional Buck circuit terminates operation and the circuit returns to the normal power transmission state, ending the soft-switching control mode. This avoids the chopper circuit from running continuously under no-load and generating additional power consumption, reduces unnecessary energy loss, and allows the circuit electrical parameters to return to steady-state values, eliminating potential shifts and current disturbances during the control phase.

[0057] Furthermore, after the circuit operating conditions are smoothly reset, the stress on the first half-bridge switching device and the second half-bridge switching device returns to the normal and reasonable range. This not only ensures stable output under the current operating conditions, but also reserves the conditions for regular circuit operation for the next commutation operation, thereby improving the overall operating economy and operating condition switching reliability of the module.

[0058] Implementing the above embodiments has the following effects: The technical solution of this invention uses a first half-bridge switch and a second half-bridge switch connected in series. The switching circuit is connected in parallel with the branch formed by the series connection of the first half-bridge switch and the second half-bridge switch. The two ends of the second half-bridge switch are respectively used as the input and output terminals of the chopper-type soft-switching IGCT power module. This constitutes a low-loss IGCT power module with DC fault clearing capability, realizing near-zero voltage switching of the IGCT device, reducing the switching losses of the main circuit devices, improving overload capacity, and by controlling the switching circuit, an equivalent BUCK circuit can be formed. The duty cycle can be adjusted to lower the device blocking voltage in advance, controllably constrain the rate of change of commutation current, realize low-stress soft turn-off of IGCT and diode, effectively reduce long-term accumulated switching losses, avoid the additional power consumption brought by the traditional hard-switching reactor and absorption circuit, and at the same time weaken the repeated impact of voltage and current spikes, slow down the aging speed of devices, suppress the problem of abnormal junction temperature rise under high current conditions, and comprehensively improve the efficiency and overload stability of the equipment during long-term operation.

[0059] Example 3 This embodiment provides a low-loss operation mode for bidirectional Buck soft switching under normal operating conditions. Specifically, it provides a low-loss operation mode for the chopper-type soft-switching IGCT power module under normal steady-state and frequent commutation conditions. The core of the chopper-type soft-switching IGCT power module consists of a first half-bridge switching device, a second half-bridge switching device, a first buffer branch, a second buffer branch, a switched capacitor, a first auxiliary switch, a second auxiliary switch, and an anode reactance, forming an equivalent bidirectional Buck circuit structure. The first auxiliary switch S... a1 Emitter connected to switched capacitor C D Positive terminal, second auxiliary switch S a2 Emitter connection switch C D The negative electrode is formed by interconnecting the collectors of the first auxiliary switch and the second auxiliary switch to form a common node. The left end of the anode reactor is connected to this common collector node, and the right end of the anode reactor is connected to the anode of the first commutation thyristor and the cathode of the first freewheeling diode of the first half-bridge switching device, thereby realizing the deep integration of the bidirectional Buck circuit and the first half-bridge switching device.

[0060] During normal system operation and frequent commutation of the power module, the controller, based on a preset modulation strategy, drives the first and second auxiliary switches to conduct alternately at high frequencies, activating the integrated bidirectional Buck circuit. By dynamically adjusting the duty cycle of the first and second auxiliary switches, the equivalent blocking voltage during the commutation process of the first commutation thyristor and the first freewheeling diode can be actively reduced. Combined with the anode reactance constraining the commutation spike current, soft-switching commutation of the IGCT device and the freewheeling diode is achieved. This structure completely changes the overlapping voltage and current characteristics of traditional hard-switching IGCTs during switching, significantly reducing switching losses and reverse recovery losses. At the same time, it suppresses commutation spike voltage and current surges, reduces the workload of the buffer branch, and fundamentally solves the problems of high long-term operating losses and high temperature rise of traditional modules, significantly improving the normal operating efficiency and stability of the power module.

[0061] After a single commutation process is completed, the first and second auxiliary switches are turned off, the bidirectional Buck circuit stops working, and the module returns to the normal power transmission state. This avoids additional losses caused by long-term no-load operation of the auxiliary circuit, and realizes the adaptive working mode of active buck soft switching and steady-state low-loss operation.

[0062] Example 4 This embodiment addresses the adaptive stress suppression mechanism of a soft-switching IGCT power module under transient impact conditions such as grid voltage fluctuations and load surges. Under load surges and instantaneous power fluctuations, the first and second half-bridge switching devices are prone to severe voltage surges and current oscillations. Traditional hard-switching IGCT modules are susceptible to overvoltage breakdown and excessive reverse recovery spikes. The bidirectional Buck circuit integrated in this embodiment can respond quickly to transient disturbances, rapidly switching the circuit's operating state via an auxiliary switch, in conjunction with the switched capacitor C. D Voltage regulation characteristics and anode reactance L A Its current-limiting characteristics buffer and absorb transient energy from the first or second half-bridge switching device.

[0063] When the first and second half-bridge switching devices are about to turn off, a zero-voltage buffer zone is quickly established through the control logic of turning on the second auxiliary switch and turning off the first auxiliary switch. This reduces the voltage amplitude at the moment of commutation turn-off of the first commutation thyristor and the first freewheeling diode, smooths the current surge rate under transient conditions, and effectively suppresses the problem of excessive peak voltage / current. Compared with the traditional solution that relies solely on the RC buffer branch to passively absorb peaks, this structure adopts an active chopping voltage reduction control method, which can adaptively adapt to transient impacts of different intensities. This avoids the problems of accelerated aging and parameter drift caused by long-term alternating stress impacts on devices, and significantly improves the operating condition adaptability and impact resistance of the power module.

[0064] Understandably, by integrating an equivalent bidirectional Buck circuit between the half-bridge power structure and the DC support capacitor, and relying on the topological coordination of the first auxiliary switch, the second auxiliary switch, the anode reactor, and the switched capacitor, soft-switching commutation of the devices under normal operating conditions is achieved, significantly reducing long-term operating losses of the module, suppressing device temperature rise and switching stress. It also adapts to transient impact conditions to achieve adaptive protection and possesses independent DC fault rapid clearance capabilities. Compared to traditional hard-switching IGCT power modules, this solution does not rely on large-capacity RCD absorption circuits and additional fault protection devices. It features high structural integration, low operating losses, and strong fault tolerance, effectively adapting to high-voltage, high-current, and long-term continuous operation power electronic conversion scenarios, and possesses extremely high engineering application value.

[0065] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A chopper-type soft-switching IGCT power module, characterized in that, include: Switching circuit, first half-bridge switching device, and second half-bridge switching device; The first half-bridge switching device and the second half-bridge switching device are connected in series, and the switching circuit is connected in parallel with the branch formed by the series connection of the first half-bridge switching device and the second half-bridge switching device. The two ends of the second half-bridge switching device serve as the input and output terminals of the chopper-type soft-switching IGCT power module, respectively.

2. The chopper-type soft-switching IGCT power module as described in claim 1, characterized in that, The switching circuit includes: a first auxiliary switch, a second auxiliary switch, and a switched capacitor; The emitter of the first auxiliary switch is connected to the positive terminal of the switched capacitor, the emitter of the second auxiliary switch is connected to the negative terminal of the switched capacitor, and the collectors of both the first and second auxiliary switches are connected to the first half-bridge switching device. The emitter of the second auxiliary switch is also connected to the second half-bridge switching device.

3. The chopper-type soft-switching IGCT power module as described in claim 2, characterized in that, Also includes: Anode reactance; The anode reactance is connected to the collector of the first half-bridge switching device and the first auxiliary switch.

4. The chopper-type soft-switching IGCT power module as described in claim 3, characterized in that, The first half-bridge switching device includes: a first commutation thyristor and a first freewheeling diode; The anode of the first commutator thyristor is connected to the cathode of the first freewheeling diode, and the cathode of the first commutator thyristor is connected to the anode of the first freewheeling diode. The anode of the first commutator thyristor and the cathode of the first freewheeling diode are both connected to the anode reactance; The cathode of the first commutator thyristor and the anode of the first freewheeling diode are both connected to the second half-bridge switching device.

5. The chopper-type soft-switching IGCT power module as described in claim 4, characterized in that, The second half-bridge switching device includes: a second commutation thyristor and a second freewheeling diode; The anode of the second commutation thyristor is connected to the cathode of the second freewheeling diode, and the cathode of the second commutation thyristor is connected to the anode of the second freewheeling diode. The anode of the second commutation thyristor and the cathode of the second freewheeling diode are both connected to the first half-bridge switching device; The cathode of the second commutation thyristor and the anode of the second freewheeling diode are both connected to the emitter of the second auxiliary switch.

6. The chopper-type soft-switching IGCT power module as described in claim 5, characterized in that, Also includes: First buffer branch and second buffer branch; One end of the first buffer branch is connected to the anode of the first commutator thyristor and the cathode of the first freewheeling diode, and the other end of the first buffer branch is connected to the cathode of the first commutator thyristor and the anode of the first freewheeling diode. One end of the second buffer branch is connected to the anode of the second commutator thyristor and the cathode of the second freewheeling diode, and the other end of the second buffer branch is connected to the cathode of the second commutator thyristor and the anode of the second freewheeling diode.

7. The chopper-type soft-switching IGCT power module as described in claim 6, characterized in that, The first buffer branch includes: a first buffer resistor and a first buffer capacitor; the first buffer resistor and the first buffer capacitor are connected in series. One end of the first buffer resistor is connected to the anode of the first commutation thyristor and the cathode of the first freewheeling diode; One end of the first buffer capacitor is connected to the cathode of the first commutation thyristor and the anode of the first freewheeling diode.

8. The chopper-type soft-switching IGCT power module as described in claim 6, characterized in that, The second buffer branch includes: a second buffer resistor and a second buffer capacitor; the second buffer resistor and the second buffer capacitor are connected in series; One end of the second buffer resistor is connected to the anode of the second commutation thyristor and the cathode of the second freewheeling diode; One end of the second buffer capacitor is connected to the cathode of the second commutation thyristor and the anode of the second freewheeling diode.

9. A method for operating a chopper-type soft-switching IGCT power module, characterized in that, Implemented by the chopper-type soft-switching IGCT power module according to any one of claims 1-8, comprising: During steady-state operation, the first auxiliary switch is kept on and the second auxiliary switch is closed. When a commutation occurs, the first auxiliary switch and the second auxiliary switch of the control circuit are alternately turned on and off according to a preset frequency, and the duty cycle of the first auxiliary switch and the first auxiliary switch is adjusted to reduce the equivalent output voltage. During the commutation process, the first auxiliary switch is controlled to turn off and the second auxiliary switch is controlled to turn on until the first half-bridge switching device or the second half-bridge switching device is turned off to reduce the blocking output voltage and peak current.

10. The operation method of the chopper-type soft-switching IGCT power module as described in claim 9, characterized in that, Also includes: After the first half-bridge switching device or the second half-bridge switching device is turned off, the second auxiliary switch is controlled to remain on to construct the zero-point voltage stage of the chopper-type soft-switching IGCT power module.

11. The method for operating the chopper-type soft-switching IGCT power module as described in claim 9, characterized in that, Before the first auxiliary switch and the second auxiliary switch controlling the switching circuit alternately turn on and off according to a preset frequency, the circuit further includes: The first auxiliary switch of the switching circuit is turned off, and the second auxiliary switch is turned on to start the equivalent bidirectional BUCK circuit of the chopper-type soft-switching IGCT power module.

12. The method for operating the chopper-type soft-switching IGCT power module as described in claim 11, characterized in that, Also includes: After the commutation is completed, both the first auxiliary switch and the first auxiliary switch controlling the switching circuit remain in the off state, so that the equivalent bidirectional BUCK circuit of the chopper-type soft-switching IGCT power module stops working.

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