Single-Stage Single-Phase High-Step-Up ZVT Boost Converter for Fuel-Cell Microgrid System

In this paper, a voltage multiplier cell is inserted in the conventional boost converter operated in continuous conduction mode (CCM) to provide another design freedom for the voltage-gain extension. Thus, the voltage conversion ratio is enlarged and the narrow turn-OFF period is avoided in the high step-up applications. Furthermore, the voltage multiplier cell makes the voltage stress of all the power devices lower than the high output voltage. As a result, the low-voltage-rated power devices can be employed to reduce the conduction losses and to improve the power device reliability. Moreover, zero-voltage switching soft-switching operation is achieved for the power MOSFETs in the whole-switching transition. Zero-current switching turn-OFF condition is provided for the diodes. Therefore, the power device switching losses and the diode reverse-recovery losses are minimized greatly. In addition, the input current ripple is reduced due to the CCM operation compared with most of the published single-stage single-phase high step-up converters, which makes it more advantageous in the hybrid electric vehicles and the fuel-cell power conversion systems. Finally, the experimental results from a 500-W, 36-380-V prototype are provided to validate the effectiveness of the proposed converter.