1756-L73 B is a schematic diagram of a phase-shift controlled full-bridge zero-voltage switching PWM converter circuit. Where Vin is the input DC voltage, D1-D4 are the internal parasitic diodes of Q1-Q4, C1-C4 are the parasitic capacitors or external capacitors of Q1-Q4, and Lr is the resonant inductance, which consists of the leakage inductance of the transformer.The bridge arms composed of Q1 and Q2 are the overrun bridge arms, and those composed of Q3 and Q4 are the lagging bridge arms. The switching frequency is 100KHZ.

In order to be able to output the required voltage within the specified input voltage range, 1756-L73 B transformer ratio should be selected according to the minimum input voltage Vin. Taking into account the existence of phase-shift control of the vice duty cycle loss phenomenon, the choice of the vice duty cycle of 0.85, boost circuit power switching tube selection FAIRCHILD company’s FQA160N08, its drain-source voltage of 80V, the normal drain current of 160A. its channel resistance Rds (on) = 0.0056Ω.

1756-L73 B is the output DC voltage, VD is the output rectifier diode pass-state voltage drop, VL is the output filter inductor on the DC voltage drop. Therefore, the transformer primary and secondary ratios are: and the selected ratio is K=1/10. MOSFETs are selected as the power switching tubes to form the full-bridge circuit for this DC boost link. Since the maximum input DC voltage is 48V