Implementation of a PLL-based high frequency resonant ac power supply

A growing demand for size reduction of power systems has stimulated substantial development and research efforts in high power density power supplies. To achieve high power density converters, it is required that they operate at high switching frequencies. This paper presents a high frequency resonant AC power supply with frequency tracking control by using phase-locked loop (PLL) techniques. Based on the PLL control method, the resonant inverter can be guaranteed to provide a stable operation characteristic in spite of sensitive load parameters variation as well as power regulation. The detailed control circuit and the operation principle of resonant AC power supply are analyzed and verified experimentally.