Modeling and simulation of an improved PLL-controlled circuit for series resonant inverter

This paper analyzes the necessity of PLL-controlled circuit for series resonant inverter in high frequency induction heating power supply and proposes an improved frequency tracking circuit. Model of series resonant inverter based on MATLAB/Simulink is established. The simulation results indicate that this circuit can keep the power-factor angle just changing within an acceptable range. It can guarantee the inverter operate in the small-inductive condition, reduce the switching losses of MOSFETs, and enhance the security of the power supply.