Soft Switching fast charger for batteries used in Renewable Energy applications and electric vehicles

Abstract

High Capacity Li-ion and Pb-acid batteries are widely used in present Renewable Energy and EV applications. Consequently, charging these batteries in a minimum amount of time whilst maintaining efficiency is crucial. The need for fast charging has brought up the method of Pulse Charging. However, present pulse charging methods which involve hard-switching, pose problems due to switching losses in the semiconductor devices. This paper presents a Fast Pulse Charging mechanism for High Capacity Pb-acid and Li-ion Batteries which minimizes switching losses by Soft Switching. The operation of the methodology is centered on the Fully Clamped Quasi-resonant DC Link Converter which strategically generates current pulses to charge the battery in both Constant Current (CC) and Constant Voltage (CV) phases. Switching losses are minimized by exploiting Zero Current Switching (ZCS), and the simulated results show that this can be achieved for higher switching frequencies further reducing the circuit size. Experiments were carried out by the research group for both conventional CC-CV method and for current pulse charging method. The results professed that proposed methodology reduces the charging time of Pb-acid batteries by 14.01% in comparison to the conventional CC-CV charging method.