High-voltage switch using series-connected IGBTs with simple auxiliary circuit

For high-voltage applications, the series operation of devices is necessary to handle high voltage with limited voltage rating devices. In the case of self turn-off devices, however, the series operation of devices is very difficult. The main problem associated with series-connected devices is how to guarantee the voltage balance among the devices both at the static and the dynamic transient states. This paper presents a simple and reliable voltage-balancing circuit for the series operation of devices to overcome the disadvantages of solutions presented so far, such as complex control or circuit, low reliability, and limited number of devices to be connected. The proposed balancing circuit realizes a complete voltage balancing at both static and dynamic states and allows series operation of an almost unlimited number of devices. The operation principle and analysis are presented and tested on 16 series-connected insulated gate bipolar transistors to handle 20-kV/400-A switching