Cost effective phase shifted pulse modulation soft switching high frequency inverter for induction heating applications

A cost-effective high-efficiency high-frequency inverter with a PSM (phase-shifted pulse modulation) scheme is proposed for medium power (5-30 kW) induction heating applications. This inverter topology can achieve soft switching commutation in a wide range of power regulation, without an auxiliary active resonant snubber circuit. The high-frequency PSM control scheme presented can provide not only effective power regulation of the proposed inverter using IGBTs, but also soft switching commutation. Theoretical equations for the soft switching operation region are derived from the practical consideration of the gate pulse control strategy, in which the soft switching operation is limited only by the duration of dead time. Through experimental comparison of switching losses in the two-in-one IGBT power module, consideration is given to how much the effect of soft switching can improve actual efficiency. In this discussion, the cost effective high-efficiency inverter circuit topology is realised. The proposed inverter accomplishes soft switching operation over a wide power regulation range. The actual power conversion efficiency reached was 96.7%.