The design of frequency tracking control circuit in induction heating power supply based on SG3525

Because the load parameter in the induction heating power supply system is varying according to the temperature, the frequency tracking to the load is necessary for keeping the load as series resonance and improving energy transmission efficiency. The zero voltage switching can be realized and the switching loss reduction of the power switching device can be received by the frequency tracking to the load. In this paper, the main circuit of the series resonance induction heating power supply is introduced first, secondly introduce the structure and principle of the PLL, at last the frequency tracking circuit based on SG3525 is provided. The experimental results show it works stably and reliably.