A New Approach Of DC-Link Capacitor Design For 6.6kw E-Cap less Single-Phase On-Board EV charger

This article presents an innovative approach for substituting electrolytic capacitors with film capacitors in on-board electric vehicle ($\mathbf{E V}$) chargers. In contrast to conventional methods that employ active power decoupling to reduce the DC-link capacitor size or use quasi-sinusoidal current for battery charging without any de link capacitor, this study demonstrates the feasibility of achieving constant current battery charging without the need for additional circuitry. This is accomplished by mitigating the effect of DC-link voltage ripple on the battery side with using the regulation capability of DC-DC stage without any additional circuit. The traditional practice of over-designing the DC-link capacitor value is replaced with a new method aiming for optimal selection. This novel capacitor selection method considers the constraints of both the rectifier and DC-DC stage of the charger. Moreover, a feed-forward has been introduced to prevent high fluctuations and instability. The effectiveness of the proposed approach is validated through simulation and compared with the conventional method in terms of switch voltages, capacitor values, total harmonic distortion (THD), and power factor.