FPGA-Based All Digital Phase-Locked Loop Controlled Induction Heating Power Supply Operating at Optimized ZVS Mode

This paper introduces a new induction heating power supply, whose rectifier is a three-phase buck-type rectifier modulated with space vector PWM method (SVPWM) and the full-bridge series-resonant inverter is controlled by an all digital phase-locked loop operating at optimized ZVS mode. All the control circuits including SVPWM generator for rectifier, all digital phase-locked loop for resonant inverter and other functions are realized on one chip field programmable gate array (FPGA). The advantages of the developed system are nearly unity power factor in AC supply currents, accurate phase locking at high resonant frequency and low power losses of switching IGBTs. The theory analysis and modeling method about the system are introduced as well as the control scheme and implementation based on FPGA. It is proved from experiments that the developed power supply, using all digital technique, has very high reliability, good dynamic and static performances