Compact Onboard Single-Phase EV Battery Charger With Novel Low-Frequency Ripple Compensator and Optimum Filter Design

TLDR: A novel double-grid-frequency-ripple-reducing technique for electric vehicle (EV) battery charger applications that can charge the battery with almost ripple-free current without using a bulky electrolytic capacitor and the battery life remains unaffected.

Abstract: This paper proposes a novel double-grid-frequency-ripple-reducing technique for electric vehicle (EV) battery charger applications. In 1- $\phi$ EV battery chargers, due to double-frequency ripple, it is not possible to control the current using a single-power-stage approach. Hence, a two-stage approach is used. However, a bulky inductor and a capacitor are required to control the current, which adds to the system's weight and cost. The single-stage charging system described in this paper can charge the battery with almost ripple-free current without using a bulky electrolytic capacitor. At the same time, it can maintain high power factor (PF) and low total harmonic distortion on the input ac side. The proposed ripple compensation solution is realized by an innovative combination of boost and zeta converters connected in series with the battery charger, which reduces the filter capacitor value considerably. This facilitates the use of a film capacitor, which has a much longer life compared with an electrolytic capacitor. Similarly, the value of the filter inductor used in series with the battery is reduced significantly. Battery ripple current is not increased in the process; therefore, the battery life remains unaffected. Representative analytical, simulation, and experimental results are presented.