Improved Current-type LC Parallel Resonant Converter Based on Energy Storage Application and Frequency Regulation Characteristics

Abstract

This paper proposes an improved current type LC parallel resonant bi-directional isolated DC-DC converter with high efficiency and wide current regulation range for the application of interconnection of battery bank and DC bus in distributed energy storage as the interface between battery and DC bus. By establishing a simplified model of the converter and deriving the resonant inductor current, resonant capacitor voltage and output inductor current in the time domain, the resonant capacitor voltage gain curve and current transfer ratio curve are obtained in the average value, and the time domain analysis avoids the errors caused by the conventional fundamental analysis method when the switching frequency differs from the resonant frequency. The above derived current transfer ratio curves show that the proposed converter has a wide current regulation range for energy storage applications, and therefore, the converter can realize the control of energy storage charging and discharging with frequency modulation. Finally, a 7.5kW, 50V to 300V prototype with a power density of 1.15W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and a peak efficiency of 96.70% is built, and the validity of the previous analysis is experimentally verified.