High-Efficiency Coupled-Inductor-Based Step-Down Converter

This study mainly investigates a high-efficiency single-input multiple-output (SIMO) step-down converter. The proposed converter can step down the voltage of a high-voltage dc bus generated by the rectifier of an ac utility power to a controllable low-voltage output terminal and middle-voltage output terminals. In this study, a coupled-inductor-based SIMO step-down converter utilizes two power switches with the properties of voltage clamping for the middle-voltage switch, and soft switching for all power switches due to the appropriate choice of the corresponding device specifications. As a result, the leakage inductor energy of the coupled inductor can be recycled, and the voltage spikes on power switches can be alleviated. Moreover, the switching losses can be significantly decreased because of all power switches with zero-voltage-switching features. Therefore, the objectives of high-efficiency power conversion, high step-down ratio, and various output voltage with different levels can be obtained. The effectiveness of the proposed SIMO step-down converter is verified by experimental results of a converter prototype in practical applications.