Fixed-Frequency LCC Resonant Battery Charger With Inherent CC-CV Operation for Electric Vehicles

This article proposes an isolated half-bridge LCC resonant battery charger with an inherent CC-CV charge profile and simple structure for lithium-ion battery charger in EVs application. The main advantages of the proposed battery charger are 1) simultaneous adoption of the CC and CV characteristics of the LCC and LC resonant converters when operating at the resonant frequency; 2) intrinsic CC-CV battery charging profile without using any mode-change switch or extra component; 3) appropriate zero voltage switching (ZVS) at turn-on for all inverter switches and zero current switching (ZCS) at turn-off for all rectifier diodes in the entire battery charging process; 4) fixed frequency operation due to operation at the LCC and LC resonant frequency and employing conventional PWM control for output voltage/current regulation; and 5) simple structure using lower components count than similar approaches. The analysis of proposed converter is discussed in detail and to validate its performance, a 100 W laboratory prototype with 340 V input voltage, 50–90 V output voltage and 0.2–2 A output current is realized. The maximum achieved efficiency is 98.3% based on the detailed loss-break down analysis.