A Variable Frequency CC -CV Charging for Electric Vehicles with CLCL Resonant Converter

Abstract

The LLC resonant converter is commonly used in onboard charger applications because of its high efficiency and simple circuitry. However, the traditional LLC resonant converter with variable frequency control, possesses a wide switching frequency range between constant current (CC) and constant voltage (CV) charging mode and it also lacks zero voltage switching (ZVS) in constant current charging mode. As an alternative solution to this problem, a unique capacitor inductor capacitor inductor resonant converter (CLCL-RC) with built-in constant current (CC) and constant voltage (CV) output characteristics is provided. This converter uses the inherent properties of the CLCL resonant converter as a current source and a voltage source to achieve CC and CV charging. The paper also presents a design technique for the CLCL resonant converter to achieve the desired output voltage range in both CC and CV modes. The proposed converter can achieve ZVS for all primary -side inverter switches in both CC and CV charging modes, resulting in high efficiency. A 3.36 -kilowatt model, operating with a 250 -volt input and producing an output ranging from 126.3 to 168 volts, was designed and simulated. The simulated outcomes confirm the effectiveness of the proposed converter for CC -CV charging, particularly in the ZVS operating region.