Interleaved current‐auto‐balance high step‐down converter with coupled inductors

Abstract

This study presents a current-auto-balance non-isolated interleaved high step-down converter with a coupled inductor. The proposed converter achieves low-voltage gain by the turns ratio of the coupled inductor and capacitive voltage division which avoids low duty cycles. The voltage stress across the power MOSFETs is decreased and the voltage stress across the diodes is controlled by the turns ratio of the coupled inductors. Therefore, low voltage semiconductors are adopted reducing the switching and conduction losses. Meanwhile, the zero current switching (ZCS) turn-ON for MOSFETs and ZCS for whole switching transitions of diodes are provided by the leakage inductances that reduces the switching losses and alleviates the reverse recovery problems. Besides, by replacing the inductors with the coupled ones, the power density is improved. Due to the interleaved structure, the output current ripple is minimised and the thermal stress is distributed between the phases. All of these factors improve the conversion efficiency and overall performance of the proposed converter. Moreover, the auto-current-sharing performance is realised due to the charge balance of the blocking capacitors. Finally, a 400 W prototype with 400–25 V voltage conversion is fabricated to demonstrate the performance of the proposed converter.