Software-Reconfigurable Multistage Constant Current Wireless Battery Charging Based on Multiharmonic Power Transmission

Wireless power transfer technology (WPT) has been widely applied in electric vehicle (EV) battery chargers because of its convenience, reliability, and safety. A typical battery charging profile consists of a constant current (CC) charging process followed by a constant voltage (CV) charging process. Recently, a multi-stage constant current (MSCC) charging profile is proposed to increase the charging speed, flexibility, and other performances. MSCC charging profile consists of multiple CC charging processes, which are applied to the battery in turn. This paper proposes a low-cost software-reconfigurable MSCC charging technique for a typical single-stage DC-DC series-series (SS) compensated WPT converter using multiple high-order harmonics power transmission approach. Such technique does not require any additional component and it can achieve inherent load-independent CC output and zero phase angle (ZPA) input characteristics. Moreover, it provides a pre-charge process for deeply discharged batteries to increase their lifetime. A scaled-down design example and the corresponding laboratory prototype are implemented to verify the proposed method.