Switching Frequency Control based on Phase-locked Loop for a Current-fed Parallel Resonant Inverter

This paper proposes a computer simulation in PSCAD program of a current-fed parallel resonant inverter. Even though the circuit parameters such as permeability and conductivity have changed regarding to the changing temperature during the heating period. The proposed idea is able to control the phase difference Deltathetas between the output voltage and output current to be constant at desired value. The principle of the proposed controller utilizes the phase-locked loop with a phase frequency detector. If the Deltathetas is constant without any effect from the temperature change, then the output power will be controlled precisely by adjusting only the DC-link current. The proposed idea is verified by the experimental results.