A practical PWM inverter control circuitry for induction heating and studying of the performances under load variations

In induction heating applications, the heating coils may have different types for different loads. A suitable control method is often needed to let the power electronic circuit working in most fit condition to supply power to the load. In this paper, a simplified control strategy following the features of induction heating is described. The most outstanding advantage of this method is to allow a design of a simple PWM gate signal and Zero-Voltage-Switching (ZVS) operation. Another advantage of this technique is variable-frequency (VF) control. So that, switching loss is reduced under varying loads.