DAB-based WPT Charger with Integrated Battery Management System for Fast Charging of Mobility Devices

The wireless charging of electric mobility devices is a convenient charging method for people with physical disabilities and other potential users. Typically, a non-isolated converter is used at secondary of wireless chargers which lacks adequate protective features to keep the battery pack isolated from accidental fault conditions at the charger. Moreover, a CC-CV charge control method is generally used which does not take into account the cell-level imbalances in the battery, thereby is not ideal for ensuring battery longevity in a fast charging environment. In this paper, a solution to these issues is provided in the form of an isolated Dual Active Bridge (DAB)-based smart wireless charger design. The proposed Wireless Power Transfer (WPT) circuit employs smart battery charging features, including cell-level balancing and protection features. The designed WPT charger is implemented in an electric wheelchair system. The proposed charger is designed for about four times faster charging compared to conventional conductive wheelchair chargers. To accommodate the faster charging rate, a Li-ion replacement battery system having approximately the same volume but 66% more capacity compared to typical Sealed Lead-Acid (SLA) wheelchair batteries is deployed.