Research On The Driving Circuit And Overvoltage Suppression For High Power IGBT

The driving and protecting circuit for IGBT serves as a bridge between the power electronic main circuit and the control circuit,and its performance directly determines the working state of the IGBT.In the high-frequency and large-capacity working environment,when the IGBT is turned off,an overvoltage is induced at the collector-emitter ends of the IGBT.If it is not restricted,it may even exceed the maximum collector-emitter voltage that the IGBT can withstand and directly break down IGBT.If the fault is not detected in time when the IGBT is short-circuited or overloaded,the current will continue to increase,which will cause irreversible thermal breakdown of the IGBT.Therefore,it is of great significance to study the drive protection circuit of IGBT.This paper analyzes in detail the structure,working principle,working characteristics of the IGBT and the causes of overvoltage generated by the IGBT,and simulates and analyzes the existing IGBT overvoltage protection technology through SABER software,and compares and summarizes their advantages and disadvantages.The working principle and time sequence of the traditional dynamic voltage rise control circuit are analyzed in detail,and the influence of key parameters on the traditional dynamic voltage rise control circuit is analyzed through simulation.Established the IGBT small signal model and transfer function,and proposed a current amplifier circuit based on the composite tube structure that can change the gain,replacing the current amplifier circuit of the original circuit,making up for the original circuit gain which is not adjustable,and is easy saturated,using the MOS tube as the signal amplifier circuit.The program proposed in this paper is simulated and verified,and various relevant parameters are continuously adjusted through simulation to achieve the desired effect.The simulation results show that the new dynamic voltage rise control circuit can control the IGBT microswitching voltage to suppress the IGBT turn-off overvoltage by changing the rising slope of the collector U_CE at the turn-off time of the IGBT.Based on its principles and simulation results,a new dynamic voltage rise control hardware circuit is designed and developed,and a single pulse experimental platform is built,and continuous debugging in the experiment finally achieves the desired effect.The simulation and experimental results show that the new dynamic voltage rise control circuit can change the U_CErise slope and reduce the collector current I_C fall rate when IGBT is turned off,so as to ensure the safe operation of IGBT.Moreover,the voltage peak overshoot is increased by about 30%compared with the traditional dynamic voltage rise circuit,and the operation stability of the circuit is improved;at the same time,it can effectively suppress the shock at the moment of turning off and improve the reliability of the circuit.