Design and Analysis of LLC Resonant Converter and CCCV Topology for Battery Charging

The LLC resonant converters are widely used in various sectors of the electronics-based industries due to their advantages of high efficiency, high energy density, electrical isolation, low electromagnetic interference (EMI),wide output ranges and high operation frequency. A Good power factor for the LLC resonant tank is required to achieve high efficiency over a wide input voltage range. A unity voltage gain can be accomplished over the whole loading conditions by having switching frequency equal to resonant tank frequency in LLC converter, however it is not suited for constant current – constant voltage (CC-CV) battery applications. The use of a buck converter at the output of an LLC resonant converter to regulate the charging current and voltage for battery charging applications is proposed in this paper. The use of a buck converter allows the output voltage of the LLC converter to be varied, ensuring CCCV charging. The proposed system is analyzed and studied in MATLAB/Simulink.