Fixed Frequency Highly Efficient Resonant Converter With Low Component Count for CC and CV Charges of Electric Vehicles Batteries

This paper presents a novel approach for implementing constant-current (CC) and constant-voltage (CV) battery charges for electric vehicles using a reconfigurable resonant converter with a low component count. In the proposed approach, the CC and CV charging methods are implemented using the inherent characteristic of an LCC converter as a current source and an LC converter as a voltage source, when operating at the resonant frequency without any need for wide frequency variation. The proposed simple battery charging structure is based on a dual resonant network and the transition from CC to CV charge occurs by reconfiguring from LCC to LC resonant network. Moreover, the resonant inductance is reduced so that the transformer leakage inductance can be utilized. The proposed battery charger operates at a fixed resonant frequency and zero voltage switching (ZVS) for input switches while zero current switching (ZCS) for output diodes is provided in the entire operation range. The proposed topology is analyzed comprehensively and a 180 W laboratory prototype is implemented to justify the converter performance, which converts 340 V input voltage to 50–90 V output voltage and 0.2–2 A output current is realized. The maximum efficiency of 97.9% is achieved in the experimental results.