Low impedance gate drive for full control of voltage controlled power devices

In order to have full control of voltage controlled, power devices gate voltages must be under control. This requires low impedance (R_G and L_G) in gate drive circuits. A prototype of a gate drive circuits applied to an IGBT half-bridge module, results in L_G of 2.5nH and gate resistance R_G of 0.54 Ohm for a 400A/1200V IGBT module. Test results demonstrate the controllability of the gate voltage during switching, as well as during short circuit conditions. Due to improved control of gate voltage, short circuit current becomes lower by 30%. In order to allow low impedance in the gate drive circuit, switching slopes are adjusted by shaping the input signals to the gate drivers.