Current-vector controlled high-frequency resonant inverter with zero-current soft switching sub-circuits for induction heating

This paper describes a voltage-clamped resonant high-frequency inverter with quasi-resonant switches and load-dependent resonant tank, which can operate at a zero-current soft-switching (ZCS) mode over a wide load range as well as in power regulation process. The operating principle of this inverter is presented and its instantaneous current vector controlled power regulation scheme is proposed. The steady-state operating characteristics of this inverter are illustrated by using computer-aided analytical results and the open-loop steady-state operating characteristics of the proposed inverter are presented graphically with a normalized expression useful for circuit design purposes. The trially-produced new resonant inverter using B-SITs is demonstrated for the induction-heating power supply and its performance is discussed from a practical point of view as compared with the conventional resonant inverters