A Transformerless Bidirectional Charger for Light Electric Vehicles

Generally, light electric vehicles (LEVs) like erickshaws, e-carts, and e-bikes, have a low battery voltage ranging from 24 V to 72 V. Therefore, the transformers (either line frequency or high frequency) are utilized in the existing charging systems of such LEVs, to get desired voltage gain without exceeding its duty ratio limits. However, the utilization of a transformer compromises the charger's size, cost, and overall efficacy. Moreover, the conventional LEVs chargers do not have bidirectional capability. Therefore, a transformerless bidirectional charger configuration based on the high step-down gain converter is presented to implement a cost effective, reduced size, and sustainable charging solution for the LEVs. A combination of frontend active bridge rectifier and back-end bidirectional switched inductor (SI) Cuk converter, is enacted to implement various modes of battery charging profile during distinct operating states. The effectiveness of the presented topology is validated through the Simscape toolbox of the MATLAB/Simulink environment. The relevant outcomes are demonstrated to justify its performance. It is noteworthy that the charger's feasibility against various disturbances like supply voltage and load demand variations are also tested. The charger excellently rejects such disturbances and ensures uninterrupted charging/discharging of the battery.