An extendable soft-switched high step-up converter with near zero-ripple input current suitable for fuel cell-powered applications

In this paper, an extendable high step-up topology is presented for the low input voltage applications, that is, fuel cell (FC) source. The proposed converter eliminates the pulsating input current and reduces the high input current ripple. Thus, the lifetime of this non-linear source and energy flow is significantly improved. The high output voltage is achieved by using voltage multiplier cells (VMC) and a coupled inductor (CI) with reduced elements. Moreover, an auxiliary circuit is applied due to restoring the energy of leakage inductance in the CI. Therefore, not only all power switching devices are turned on under zero voltage switching (ZVS) but also the input current ripple is remarkably reduced to zero. Furthermore, normalized semiconductors' voltage stresses are diminished. The reverse recovery problem of diodes and their turn-off power losses at high frequencies are alleviated owing to their zero current switching (ZCS) turn-off. In this paper, the performance of the proposed structure is investigated and compared with the traditional converters considering their voltage gain and voltage stress. Eventually, a 500-W prototype of the proposed converter is built and tested to validate mathematical analyses.