High-voltage, high-power, ZVS, full-bridge PWM converter employing an active snubber

The authors present the analysis, design, and applications of a high-voltage, high-power, zero-voltage switched (ZVS), full-bridge (FB) pulse-width-modulated (PWM) converter with an active snubber in the secondary circuit. The nondissipative snubber completely eliminates the voltage overshoot and ringing across the rectifiers. The ringing of the parasitic capacitance of the rectifiers and the leakage inductance of the transformer are eliminated in a nondissipative manner, thus increasing the overall efficiency of the circuit. The active snubber employs only a high-voltage low-power MOSFET and a high-voltage capacitor. The control of the snubber switch is simple and utilizes the PWM signal to control the primary switches with a time delay. The authors also present the complete steady-state analysis of the ZVS-FB-PWM converter employing the active snubber. The analysis shows that the transformer secondary voltage is a function of the steady-state duty cycle and gives the equation to calculate the steady-state secondary voltage. The results of the analysis are in good agreement with the experimental results.<
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