Speed assist system for electric vehicles: Manual speed assist system and fail-safe torque strategies

This paper presents the Manual Speed Assist System (MSAS) and implemented in Electric Vehicles to regulate vehicle actual speed as the driver wishes. One of the important safety related concerns is the proper torque coordination while exiting from MSAS function due to failure modes in the Electric Vehicles. This paper talks about different failure cases that can generate an uncertain torque command to motor and results in poor dynamics, and discussed its associated fail-safe strategies and the importance of torque coordination in Electric Vehicles. The vehicle behaviour during failure conditions have been thoroughly analysed and fail-safe strategies are implemented in Traction Control Unit application software of the vehicle. The MSAS function is experimentally validated, and results are presented.