Improved Power Quality Charging System Based on High Step-Down Gain Bridgeless SEPIC APFC for Light Electric Vehicles

The limited voltage gain characteristic of the mainstream dc-dc converter restricts the application in single-stage light electric vehicles' (LEVs) chargers. Typically, the battery voltage of an LEV is in the range from 24 to 72 V. Thus, while implementing the single-stage LEVs' chargers, a line- or high-frequency transformer is essentially required. The utilization of transformer, however, compromises the overall cost, size, and efficiency of LEV chargers. Therefore, a transformerless single-stage bridgeless charger topology is presented in this article, aiming to realize a simple, reliable, efficient, and low-cost charger for the LEVs. The presented topology utilizes a switched inductor single ended primary inductance converter (SISEPIC) to achieve a high step-down dc voltage gain. Furthermore, the active power factor correction is incorporated to ensure enhanced power quality (low total harmonics distortion and unity power factor) at the ac supply side during constant current and constant voltage state charging. Additionally, this charger is controlled by employing reduced sensing devices and control complexities. Both simulation and experimental validations are provided to manifest the effectiveness of this SISEPIC charger topology for LEVs.