A Novel FB ZVS PWM DC-DC Converter Based on Digital Control

Conventional full-bridge (FB) zero-voltage-switching (ZVS) PWM DC-DC converter has several disadvantages, such as serious loss of duty cycle, narrow range of ZVS of the lagging leg, and voltage overshoot in the secondary etc. This paper presents a novel FB ZVS PWM DC-DC converter, which adds two passive circuits based on the conventional FB DC-DC converter. One is paralleled in the primary to widen the ZVS range of the lagging leg; the other is in series to the secondary to reduce the voltage overshoot and oscillation of the secondary voltage, so the voltage stress of rectified diodes has greatly reduced. The proposed circuit topology has several advantages, such as easily controlled, wide load ZVS range, and small loss of the duty cycle etc. so it can increase the efficiency of the converter. This paper analyses the operating principle of the converter and the ZVS qualifications. A digital control system with double-loop is also designed using TMS320F2812 DSP. A 48V/480W, 100 kHz prototype which based on digital control verified the validity the relative theory