AC voltage sensorless control of battery charger system in electric vehicle applications

This paper presents an effective control scheme for an electric vehicle battery charger where a symmetrical bridgeless power factor-corrected converter and a buck converter are cascaded. Both converters have been popular in industries because of their high efficiency, low cost, and compact size, hence combining these two converters makes the overall battery charging system strongly efficient. Moreover, this charger topology can operate under universal input voltage condition and attain a desired battery voltage and charging current without any ripple. In order to reduce the system cost, an estimating ac input voltage technique is introduced, which especially does not require the converter component information and therefore it is robust to the circuit parameters variation. Additionally, by adopting a duty ratio feed-forward path in current control loop, a unity input power factor and zero input current harmonic are achieved. The feasibility and practical value of the proposed approach are verified by simulation and experimental results.