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CN-122001200-A - SiC MOSFET over-voltage clamping grid driver, control method thereof and power module

CN122001200ACN 122001200 ACN122001200 ACN 122001200ACN-122001200-A

Abstract

The invention discloses an over-voltage clamping grid driver of a SiC MOSFET, a control method thereof and a power module, wherein the over-voltage clamping grid driver comprises a drain clamping unit, a grid amplifier and a logic control unit, the drain clamping unit is electrically connected with the SiC MOSFET and is used for clamping an over-voltage peak of a drain and a source of the SiC MOSFET at a safety threshold V dth and outputting an over-voltage fault signal V fal , the grid amplifier is electrically connected with the SiC MOSFET and is used for switching on and off the SiC MOSFET and blocking clamping current to be shunted to the grid amplifier through switching off an internal switching tube when the over-voltage fault happens, and the logic control unit is electrically connected with the drain clamping unit and the grid amplifier and is used for controlling logic of the grid amplifier according to the over-voltage fault signal V fal and the switching signal V PWM . The invention can fundamentally eliminate the problem of shunt of the clamping current, solves the problem of efficiency reduction caused by shunt of the clamping current in the traditional circuit, and greatly improves the current utilization rate and the inhibition efficiency of the clamping circuit.

Inventors

  • ZHANG JINGWEI
  • TAN GUOJUN
  • Qiu Qiaolong
  • YANG BO

Assignees

  • 江苏国传电气有限公司

Dates

Publication Date
20260508
Application Date
20251231

Claims (11)

  1. 1. A SiC MOSFET over-voltage clamped gate driver, comprising: The drain clamping unit is connected with the drain of the SiC MOSFET, and is used for monitoring the drain-source voltage of the SiC MOSFET, clamping the overvoltage peak of the drain-source of the SiC MOSFET at a safety threshold V dth and synchronously outputting an overvoltage fault signal V fal ; the grid amplifier is connected with the grid of the SiC MOSFET, and is used for receiving a switching signal V PWM to realize the on-off control of the SiC MOSFET, and blocking the clamping current to shunt to the grid amplifier by switching off an internal switching tube when an off overvoltage fault occurs; And the logic control unit is respectively and electrically connected with the drain clamping unit and the gate amplifier and is used for performing turn-off control on the gate amplifier according to the overvoltage fault signal V fal and the switch signal V PWM to ensure that clamping current is fully injected into the gate of the SiC MOSFET, so that the drain voltage of the SiC MOSFET is clamped at a safety threshold V dth .
  2. 2. The SiC MOSFET over-voltage clamp gate driver of claim 1, wherein the drain clamp cell comprises a TVS diode VD 1 , a TVS diode VD 2 , a TVS diode VD 3 , a diode D, a resistor R 1 , a resistor R 2 ; the cathode of the TVS diode VD 1 is connected with the drain electrode of the SiC MOSFET; The anode of the TVS diode VD 1 is connected with one end of the resistor R 2 , the anode of the diode D and the cathode of the TVS diode VD 2 ; The anode of the TVS diode VD 2 is connected with the cathode of the TVS diode VD 3 and is used as the output end of the overvoltage fault signal V fal ; the anode of the TVS diode VD 3 is grounded; the cathode of the diode D is connected to the grid electrode of the SiC MOSFET through the resistor R 1 ; the breakdown voltage of the TVS diode VD1 is matched with a safety threshold V dth ; The other end of the resistor R 2 is connected to a negative driving voltage V EE .
  3. 3. The over-voltage clamped gate driver of a SiC MOSFET of claim 2, wherein the clamping current flows through a diode D and a resistor R 1 in the drain clamping unit to be injected into the gate of the SiC MOSFET, the resistance range of the resistor R 1 is below 10Ω, the resistance range of the resistor R 2 is above 100deg.OMEGA, and the maximum value of the clamping current is determined according to the breakdown peak current of VD 1.
  4. 4. The SiC MOSFET over-voltage clamped gate driver of claim 1, wherein said gate amplifier comprises an N-type transistor Q 1 , a P-type transistor Q 2 , a switching transistor M 1 , a gate resistor R g ; The collector of the N-type triode Q 1 is connected with positive driving voltage V CC ; the emitter of the N-type triode Q 1 is connected with the emitter of the P-type triode Q 2 and one end of a grid resistor R g to form an output node of the grid amplifier; The base electrode of the N-type triode Q 1 is connected with the base electrode of the P-type triode Q 2 to form a common node of a control signal; the other end of the grid resistor R g is connected with the other end of the resistor R 1 and the grid of the SiC MOSFET; the collector of the P-type triode Q 2 is connected with the drain of the switch tube M 1 ; An emitter of the switching tube M 1 is connected with a negative driving voltage V EE ; The switching-on and switching-off of the switching tube M 1 is controlled by the logic control unit and is used for blocking the clamping current to shunt to the grid amplifier by switching off the internal switching tube when the switching-off overvoltage fault occurs.
  5. 5. The SiC MOSFET over-voltage clamp gate driver of claim 1, wherein said logic control unit comprises an not gate G a1 , an or gate G a2 ; The base electrode of the N-type triode Q 1 is connected with the base electrode of the P-type triode Q 2 or the first input end of the OR gate G a2 , and receives a control signal V PWM of the gate driver; the second input end of the OR gate G a2 is connected with the output end of the NAND gate G a1 ; The output end of the OR gate G a2 is connected with the grid electrode of the switch tube M 1 ; The input of the NOT gate G a1 receives an overvoltage fault signal V fal output by the drain clamp unit.
  6. 6. The SiC MOSFET over-voltage clamped gate driver of claim 5, wherein the logic control unit is configured to output a high level from the or gate G a2 to turn on the switching tube M 1 when the switch control signal V PWM is high or the over-voltage fault signal V fal is inactive, and to output a low level from the or gate G a2 to turn off the switching tube M 1 when the switch control signal V PWM is low and the over-voltage fault signal V fal is active high.
  7. 7. The SiC MOSFET over-voltage clamp gate driver of claim 1, wherein: the SiC MOSFET over-voltage clamp gate driver further includes: The fault indication unit is electrically connected with the output end of the overvoltage fault signal V fal of the drain clamp unit and is used for emitting an optical signal or an electric signal alarm when the overvoltage fault signal V fal is detected to be at an effective level, and the fault indication unit comprises a comparator CP and a resistor R 3 、R 4 , The overvoltage fault signal V fal is connected with the positive input end of the comparator CP; The negative input end of the comparator CP is connected with one end of the resistor R 3 and one end of the resistor R 4 , and the output end of the comparator CP sends an alarm signal V sig outwards; The other end of the resistor R 3 is connected with positive driving voltage VCC; the other end of the resistor R 4 is grounded.
  8. 8. The SiC MOSFET over-voltage clamp gate driver of any one of claims 1 to 7, further adapted to an IGBT, wherein when used in an IGBT, the drain clamp unit is connected to a collector of the IGBT, the gate amplifier is connected to a gate of the IGBT, the over-voltage fault signal V fal corresponds to a collector-emitter over-voltage fault of the IGBT, and the safety threshold V fal matches a collector-emitter rated withstand voltage of the IGBT.
  9. 9. A SiC MOSFET over-voltage clamping method performed with the SiC MOSFET over-voltage clamping gate driver of any one of claims 1 to 7, the method comprising: During turn-off of the SiC MOSFET, monitoring its drain voltage by the drain clamp unit; When the drain voltage exceeds a safety threshold V dth , the TVS diode VD 1 breaks down and conducts, and the drain clamping unit generates an overvoltage fault signal V fal ; When the overvoltage fault signal V fal is detected to be in an effective level and the switching signal V PWM is detected to be in an off level, the logic control unit outputs a control signal to turn off the switching tube M 1 in the gate amplifier, so that clamping current is fully injected into the gate of the SiC MOSFET through the diode D and the resistor R 1 , the potential of the gate is raised to inhibit the drain voltage from continuously rising, the SiC MOSFET is enabled to enter a weak conduction state, the drain voltage is lowered, and the drain voltage clamp is located at a safety threshold V dth .
  10. 10. A power module comprising the SiC MOSFET over-voltage clamp gate driver of any one of claims 1-7.
  11. 11. A power conversion device comprising the SiC MOSFET over-voltage clamp gate driver as claimed in any one of claims 1 to 7.

Description

SiC MOSFET over-voltage clamping grid driver, control method thereof and power module Technical Field The invention belongs to the technical field of power electronics, and particularly relates to a SiC MOSFET overvoltage clamping grid driver, a control method thereof and a power module. Background Silicon carbide (SiC) MOSFETs have become a core power switching device for new generation high-efficiency, high-power density power electronics (e.g., new energy automobile electric drive systems, photovoltaic inverters, industrial frequency converters, etc.) because of their excellent characteristics such as high switching frequency, high temperature resistance, and low conduction loss. However, siC MOSFETs typically operate at higher switching frequencies and faster switching speeds, and their switching process is susceptible to line parasitic inductance, inducing higher voltage spikes and oscillations in the gate loop. The gate overvoltage phenomenon not only threatens the reliability of the gate oxide layer, leads to the degradation of the device performance and even permanent damage, but also can cause the false turn-on of a circuit, and severely restricts the full play of the performance of the SiC MOSFET and the improvement of the system reliability. To suppress gate overvoltage, conventional solutions typically employ passive clamping circuits (e.g., a zener diode or a TVS connected in parallel between the gate and source) or active clamping circuits (e.g., active regulation of the gate potential by detecting the drain voltage). However, the passive clamping mode has relatively slow response speed, limited clamping precision and influence effect due to parasitic parameters under high-frequency application, while the conventional active clamping technology has the problem of clamping current shunt in the typical structure, namely, part of clamping current which is injected into a grid electrode to offset overvoltage is shunted by other paths (such as a driving resistor or related branches) in a driving circuit, and cannot be completely used for rapidly pulling down or stabilizing the grid voltage, so that the clamping response delay and efficiency are reduced, and rapid and accurate suppression of the grid overvoltage cannot be realized. Therefore, a novel grid driving scheme is urgently needed, the current diversion problem in the existing clamping technology can be effectively solved, clamping current is ensured to act on a grid electrode efficiently and completely, the inhibiting effect and response speed to the grid overvoltage of the SiC MOSFET are remarkably improved, and the devices and systems are ensured to run safely, stably and efficiently under the working condition of high frequency and high voltage. Disclosure of Invention The invention aims to provide an over-voltage clamping grid driver of a SiC MOSFET, a control method thereof and a power module. Aiming at the core defect of the prior clamping technology, the invention can fundamentally eliminate the problem of shunt of the clamping current, actively block the clamping current from flowing to parallel branches such as a driving resistor and the like through the turn-off action of a switching tube M 1, solve the problem of reduced efficiency caused by shunt of the clamping current in the traditional circuit, and greatly improve the current utilization rate and the inhibition efficiency of the clamping circuit. In order to achieve the above object, the technical scheme of the present invention is as follows: in a first aspect, the present invention provides a SiC MOSFET over-voltage clamp gate driver comprising: The drain clamping unit is electrically connected with the drain of the SiC MOSFET, and is used for monitoring the drain-source voltage of the SiC MOSFET in real time, clamping the overvoltage peak of the drain-source of the SiC MOSFET at a safety threshold V dth and synchronously outputting an overvoltage fault signal V fal; The grid amplifier is electrically connected with the grid of the SiC MOSFET, and is used for receiving a switching signal V PWM to realize the on-off control of the SiC MOSFET, and blocking the clamping current to shunt to the grid amplifier by switching off an internal switching tube when an off overvoltage fault occurs; The logic control unit is respectively and electrically connected with the drain clamping unit and the gate amplifier and is used for performing turn-off control on the gate amplifier according to an overvoltage fault signal V fal and a switch signal V PWM to ensure that clamping current is fully injected into the grid of the SiC MOSFET so as to clamp the drain voltage of the SiC MOSFET at a safety threshold V dth. In some embodiments, the drain clamp unit includes TVS diode VD 1, TVS diode VD 2, TVS diode VD 3, diode D, resistor R 1, resistor R 2; the cathode of the TVS diode VD 1 is connected with the drain electrode of the SiC MOSFET; The anode of the TVS diode VD 1 is connected with one e