The withstand voltage of a single IGBT can not keep up with the needs of practical application,the IGBT series connect is a simple and effective method to solve the problem,however,the gate drives can not ensure the balanced dynamic voltage sharing between switching devices.According to the characteristic that the IGBT gate drive resistance can change the switching speed,a kind of scheme to improve the IGBT series voltage balance by changing the gate drive resistance was designed.This scheme makes use of transistors,resistors and stabilivolt to form a circuit topology.When the IGBT is over or close to the overvoltage,the collector-emitter voltage is fed back to the gate drive resistance selection circuit through the detection circuit,and the drive resistance selection circuit increases the gate drive resistance to change the collector-emitter voltage,which makes the IGBT voltage equalized.