A novel three-level ZVS PWM inverter topology for high-voltage DC/DC conversion systems with balanced voltage sharing and wider load range

As the three-level (TL) ZVS PWM DC/DC converter operates like a full-bridge (FB) ZVS PWM DC/DC converter and the blocking voltage of each switching device is a half of the DC-link voltage, it is suitable for high input voltage applications. However, it has some problems as follows; the blocking voltage of each device is unbalanced and it causes the power loss of the inner switching devices to be increased. Also, it has a narrow load range so that the switching losses and the efficiency are reduced as it goes to the light load. This paper presents a novel TL ZVS PWM DC/DC converter, which can reduce the overvoltage of the outer switches, eliminates the unbalance of the voltage sharing between the switches at turn-off due to the stray inductances, and operate from no load to full load. The characteristics and the performances of the proposed TL ZVS PWM DC/DC converter are verified by simulation and experimental results.