Closed loop power control of an induction furnace

In this paper, at first, an optimized resonant capacitor is designed for a practical induction furnace with parallel resonant inverter, by using Lagrange´s method. Then, rectifier and inverter snubber circuits are designed. To access a control system, a passive linear controller is also designed. Meanwhile the whole system is started and load is changing, the controller, by changing firing angle of the rectifier, provides proper DC current for inverter such that output power of inverter will be fixed at a favorite amount. Also, to protect resonant capacitor from over voltages that may happen in the system, sufficient margins for firing angle of rectifier are properly designed.