Advanced Longitudinal and Lateral Stability Control System for a Four-Wheel-Independent-Drive Electric Vehicle Using a New Power Converter Topology

This work develops an advanced control system to improve the handling, comfort, and longitudinal and lateral stability of a four-wheel-independent-drive electric vehicle, based on the combination of longitudinal and lateral control. Firstly, to avoid the wheels from slipping or locking when accelerating or braking a longitudinal control combining traction and braking control is proposed. The coordinated ASR/ABS control can operate as an acceleration slip regulation (ASR) by preventing the wheels from slipping during acceleration and as an antilock braking system (ABS) by preventing the wheels from locking during braking by adjusting the electric motor torques dynamically. Secondly, to stabilize the lateral movement of the vehicle in severe turns, a lateral vehicle dynamic control combining direct yaw control and active front steering is designed. The advanced control system uses the fast and precise torque of the electric motors transmitted directly to the wheels. The originality of the present work is the use of a new power converter topology to simultaneously supply the four in-wheel motors, simplifying the architecture of the electric vehicle design and control laws. The configuration of the electric vehicle studied allows the in-wheel motors to turn at identical or different speeds by imposing an independent control on each drive wheel. Finally, and in order to diminish the torque ripple, provide better speed tracking performance, and achieve a high-performance torque control for the electric vehicle with interior permanent magnet synchronous in-wheel motors, the fuzzy SVM-DTC strategy is proposed to be utilized. Numerical simulations using Matlab/Simulink software were carried out under diverse driving situations of a four-wheel-independent-drive electric vehicle, highlighting the robustness of the control techniques developed by means of the new topology of the power converter.