Single-switch coupled-inductors-based high step-up converter with reduced voltage stress

This paper proposes a non-isolated DC-DC high step-up converter. To achieve a high voltage conversion ratio and overcome the problems related to near unity duty-cycle of the conventional boost converter in high step-up applications, coupled-inductors along with switch-capacitor techniques are merged in this topology. The proposed converter provides continuous input current with low ripple without using any current ripple cancellation method and the voltage across the switch is limited inherently. In order to reduce the control circuit complexity, the proposed converter uses only one switch. These features decrease the complexity of the proposed converter structure. The voltage stress of the semiconductor components is reduced significantly; thus, high-quality elements (fast power MOSFET switches with low on-state resistance and Schottky diodes with low forward voltage drop along with low power losses) can be used, which minimizes the switching and conduction losses and improves the converter efficiency. To confirm the converter operation and theoretical analysis, a 200-W prototype converter with 24-to-200-V input and output voltages operating at 100-kHz is implemented in the laboratory.