Single-Stage Bidirectional Isolated Charger With Reduced Output Capacitance for LEV Application

A single-stage bidirectional charger utilizing a SEPIC converter for light electric vehicles (LEVs) is presented in this work. Traditional unidirectional or bidirectional charger utilizes a bulky electrolytic capacitor to filter the double-line frequency component in battery current. Nonetheless, despite the reliability concerns linked to electrolytic capacitor, a significant ripple component is still observed in battery current of single-stage charger. Presented charger, along with its associated control, features an active power decoupling (APD) capability without any need for any extra passive or active components. It allows for a ripple-free battery current during both charging and discharging modes, resulting in an electrolytic-less topology. Thus, it lowers overall component count while incorporating supplementary APD capability. In addition, a simplified feed-forward-based control is designed for improved power quality in grid current. It also includes a detailed operating principle in each functional mode. Lastly, a 680 W laboratory prototype is developed to demonstrate bidirectional operational mode under various dynamic conditions.