Variable timing control for coupled-inductor feedback ZVT inverter

This paper presents a novel control scheme for the coupled-inductor feedback ZVT inverter with variable timing control. The previous proposed six switches coupled inductor scheme can only turn on the main switches at reduced bus voltage. With the proposed variable timing control, the true zero-voltage-switching for main switches ran be achieved by boosting current to a certain amount. Turn off loss of main switches is significantly reduced by adding snubber capacitors across the main PWM switches. Basic circuit operation and design consideration is presented. A design example for a 650 V 75 kW ZVT inverter for an induction motor is given with the verification of simulation results. Test results of the single-phase operation also show the effectiveness of the proposed ZVT scheme.