Optimization of Minimum Negative Current BCM Synchronous Buck Converter

Abstract

Non-isolated DC-DC converters are widely used in renewable energy applications, such as the hybrid energy storage system (HESS), charging and discharging system of batteries and supercapacitors and the photovoltaic power generation. With the advantages of achieving zero-voltage-switching (ZVS), high efficiency and power density, low cost, and fast dynamic response, the converters operating in boundary current mode (BCM) have caught researchers' eyes recently. Taking the synchronous buck converters as an example, this paper briefly introduces the working principle and advantages of BCM converter realize soft switching. Firstly, it is pointed out that the phenomenon of circulating energy exists in the BCM converter. Then, the relationship between circulating energy and negative current is analyzed, and an optimal control strategy of negative current minimization is proposed to reduce the circulating energy. In the condition of realizing ZVS, negative current minimization not only improves the efficiency of the converter, but also reduces the ripple of inductor current to a certain extent. Finally, the experimental platform of 100 W synchronous buck converter is built. Experimental results validate that the optimal control of minimum negative current has good effect on improving efficiency of converter and reducing the ripple of inductor current.