An improved Current-Doubler-Rectifier ZVS PWM Full-Bridge converter

Current-Doubler-Rectifier Zero-Voltage-Switching PWM Full-Bridge converter (CDR ZVS PWM FB converter) ([10]) achieves ZVS for the switches In a wide load range with the use of the energy stored in the output filter inductances, and the rectifier diodes commute naturally, therefore no oscillation occurs. However the leakage inductance of the transformer should be very small, which needs special manufacture method to produce the transformer. To overcome this drawback, this paper proposes an improved CDR ZVS PWM FB converter, in which a blocking capacitor is introduced in series with the primary winding. The operation principle of the improved converter is analyzed, the ZVS achievement and the design of the output filter inductance and the blocking capacitor are discussed. A 540W prototype converter is built in the lab to verify the operation principle of the improved converter, the experimental results are also included in this paper.