Gate-Controlled dv/dt- and di/dt-Limitation in High Power IGBT Converters

Abstract

A central issue in reducing the size and cost of IGBT power converters is to control or limit dv/dt and di/dt during the switching process. Load side snubbers and clamp circuits are bulky and expensive. Increasing the gate resistors values is cheap and simple but switching times as well as power losses are increased.In this article the authors suggest to use a gate-side control loop to limit the switching transients. No extra Components are needed on the load side since the internal stray inductance of the power module is used to sense the current. The only extra component is a high voltage capacitor of some picoforads to sense the voltage transients. The overall losses are reduced compared to the traditional method, where the gate resistor value is increased to limit the switching speed. The proposed method can easily be integrated in an intelligent gate-drive circuit.