Two-transformer current-fed converter with 0 to 100% switch duty range

Till now, various types of current fed converters utilizing multiple devices have been developed. These converters exhibit good performance in high power step-up applications. However, they have a common limitation that the duty cycle be larger than 0.5 to maintain a conducting path for the boost inductor current. Although an auxiliary circuit that is magnetically coupled to a boost inductor can be a solution for below 0.5 duty cycle, it increases size and complexity. To relieve this problem, a new two transformer current-fed (TTCF) converter, which can be operated along a wide duty cycle with a simple structure, is proposed in this paper. In the TTCF converter, the magnetizing inductor of the transformer acts as a boost inductor, thus no additional boost inductor is needed. Moreover, only one auxiliary diode is employed for below 0.5 duty cycle operation. Therefore, the proposed converter can be promising for high power step-up applications with a simple structure.