An improved current-fed ZVS isolated boost converter for fuel cell applications

This paper proposes an improved current-fed zero-voltage switching isolated boost converter suitable for fuel cell applications. Preserving the inherent advantages of the current-fed converter which include smaller input current ripple, lower diode voltage rating, and lower transformer turns ratio, the proposed converter does not require any clamping and start-up circuits unlike the conventional current-fed converters. The voltage ratings of the primary switches and secondary diodes of the proposed converter are significantly reduced. Some alternative schemes of the proposed converter without the voltagesecond unbalance are presented. These characteristics of the proposed converter lead to a high overall efficiency over wider load range. Experimental results on a 1kW prototype are provided to validate the proposed concept.