Analysis of a Half - Bridge Inverter for a Small-Size Induction Cooker Using Positive-Negative Phase-Shift Control under ZVS and NON-ZVS Operation

This paper presents a detailed analysis of circuit operation under ZVS and NON-ZVS conditions in a high-frequency half-bridge inverter for a small-size and low-voltage induction cooker, using the principle of positive- negative phase-shift control over a wide control range both in positive and negative directions. A variety of modes of circuit operation with the voltage and current equations during phase-shift power control under the operating conditions of ZVS and NON-ZVS are analyzed as a first step and the output voltage and current waveforms are obtained by MATLAB program. These waveforms will be analyzed by Fourier analysis which can lead further to the calculation of ac output power P_o, dc input power Pd , and hence the conversion efficiency Tj of the half-bridge inverter. The analysis results shows that the control ranges of ac output power P_o and dc input power Pd are limited by the occurrence of NON-ZVS operating condition, which changes according to the switching frequency f_s .