Research on Frequency Tracking Capacitive PWM of Induction Heating Power Supply

The principle of capacitive PWM control circuit was analyzed in this paper, the soft-switching solution was applied in the switching devices, and the practical main circuit topology was given. On the load current to achieve a frequency tracking, To make the power factor of the inverter close to or equal to a quasi-resonant state, the Frequency of the load current was tracked. The phase compensation and start-up of the circuit were analyzed also. The application of the capacitive PWM control in the induction heating power supply composed with series IGBT inverter was correctly verified by the test.