Bidirectional power flow control for battery super capacitor hybrid energy system for electric vehicles with in-wheel motors

In order to improve the performance of electric vehicles (EV), in-wheel motors (IWM) system can be equipped to EV. Super capacitors (SC), and batteries are combined as hybrid energy storage system (HESS), aiming to realize both high energy density and high power density for the energy system. In this paper, bidirectional power flow control strategy for HESS to power the in-wheel motor system is presented. The aim of the energy sharing based on bidirectional power flow control of HESS is to satisfy the power requirement from high-performance in-wheel motor system, also for the energy recovery when motor brakes. The topologies of the converters, especially for different SC modules connection in different power classes, are analyzed in detail. The current control method for bidirectional non-isolated converters is applied to realize the power flow arrangement. Reduced-scale experiment platform test and experiment results show the effectiveness of the power control method.