Regenerative active suspension system with residual energy for in-wheel motor driven electric vehicle

The active suspension system is a practical solution to improve vehicle comfort and safety by applying controlled forces to the vehicle body and wheels. However, the widespread application of the system is significantly inhibited by their large power demands. This paper proposes a new regenerative active suspension system for the in-wheel motor driven electric vehicles. In this system, a new advance dynamic-damper mechanism with a suspended driving motor is designed. Two electromagnetic actuators are controlled to imitate the behaviors of skyhook damper and conventional shock absorber for better ride comfort and harvesting energy from the vibration of suspended driven motor, respectively. An improved boost-buck converter is employed to regulate the damping force only utilizing the feedback of current of actuators. To further improve the regenerative efficiency, a variable threshold strategy is designed for the hybrid energy storage system to keep its terminal voltage locating in high-efficiency regions, which are identified through analyzing system performance. The results indicate that the desired damping forces of actuators are precisely tracked regardless of the voltage conditions. The vehicle ride comfort and comprehensive performance are improved by 52% and 14%, respectively. In addition, the variable thresholds strategy shows higher regenerative efficiency than the fixed one. After offsetting the energy consumed by active control, the average regenerated power is 4.9, 17.7, 49.2 and 45.0 W on A, B, C and D class roads, respectively. The proposed system is verified as a practical solution to simultaneously improve the dynamic and energy conservation performances of vehicles.