Power Processing Reduction in Energy Storage Systems by Using a Fractional Power Converter With Bipolar Output Voltage

Fractional power processing architectures can improve the efficiency of energy storage systems due to the reduced output power of the converter interfacing energy storage elements and the power system. This paper presents a fractional power converter, which provides a bipolar biasing voltage to regulate the system charging and discharging power. The energy storage system is composed of a main high-voltage battery, an auxiliary low-voltage battery, and the fractional power converter that is connected in series to the main battery and parallel to the auxiliary battery. Comparing with the existing fractional power converters with a unipolar biasing voltage, the proposed fractional power converter achieves much lower power processing. In this paper, the proposed method was verified by simulation results.