Smart power devices in soft switching applications

A smart power device, having a monolithic cascode structure with a high-voltage bipolar junction transistor and a low voltage power MOSFET, is presented and investigated in soft switching applications. The basic characteristics of this device are described both in terms of its structure and electrical performances. In particular, the device behavior is investigated in a zero-voltage quasi-resonant boost converter switching at a frequency of 100 kHz in order to show the high performances of this switch in the field of high voltage, and high-frequency applications. The experimental tests are carried out in several working conditions, and emphasis is given to a comparison with alternative switches as power MOSFETs, and IGBTs in order to understand better the main advantages and drawbacks of this switch. Finally, some figures relative to the power losses versus the switching frequency and the limit on the working frequency of the devices are given with reference to the actual converter used as a benchmark. The experimental results show the superiority of the cascode in the field of the considered switching frequency.