A MOSFET-GTO cascode-connected power switch for high efficiency

Considerable research has been undertaken so as to obtain as near as possible the no loss ideal gate-controlled electrical power switch. In general, two approaches have been followed: one to optimize the structure of the device in order to improve the device parameters, the other to find the optimum gate drive conditions. The authors examine the performance of the cascode connection of semiconductor devices with the aim of increasing the switching performance without incurring too large an increase in on-state losses. The type of connection differs from the series connection of semiconductor switches whose purpose is to share equally the blocking voltage. The power range considered is 100 W to about 10 kW. The authors concentrate on the efficiency levels of the switching circuitry and on the switching waveforms at different frequencies, with particular interest in high frequency chopper operation up to 1 kHz. The application of the cascode connection to a DC drive system is briefly considered