Improved sequential-switching high-power high-frequency inverters and their control techniques

This paper presents the state-of-the art developments in the sequential-switching high-power high-frequency inverter using reverse-blocking thyristors (SCRs) or GTOs. The newly-developed sequential inverters can produce economically large amount of power at the ultrasonic frequency range of lOkHz-about 100kHz. The control implementation of the inverters is demonstrated on the basis of the induction heating and melting applications in industry. The circuit analysis is described and the performance evaluations associated with voltage regulation characteristics and frequency control characteristics are generally examined in terms of the normalized variables and parameters.