Analysis and design of a 500 kHz series resonant inverter for induction heating applications

Abstract

The steady state model and analysis of a phase-shift controlled series resonant inverter (PSC-SRl) is presented. This steady state model includes the evaluation of the zero-voltage switching (ZVS) condition and the determination of the ZVS operating region. Based upon this analysis a frequency control strategy that minimizes circulating energies is proposed. Also, a methodology to design the power stage components, and to predict the duty ratio and the operating frequency range is presented using a PSC-SRl design example operating at 500 kHz and 10 kW. In addition, a novel and simple frequency control circuit that implements the proposed frequency control strategy is provided. Besides, the analysis of the PSC-SRl complete power stage and two control-loop system (frequency control and duty ratio control) is given. Furthermore, the small-signal model and the compensation schemes for each of the control loops is presented. The analytical predictions are compared with experimental data measured from a 500 kHz, 10 kW laboratory prototype and conclusions are drawn.