In-Wheel-Motor-Driven Electric Vehicles Motion Control Methods Considering Motor Thermal Protection

Thermal protection strategies are employed to protect in-wheel-motors (IWM). Vehicle motions and stability can be affected by such motor thermal protections because they typically reduce the motor output torque to lower motor temperature and protect motor from thermal damage. This paper proposes a fault-tolerant control (FTC) method and a fault-prevention control (FPC) method for vehicle motion control considering motor thermal protection. The FTC method aims to stabilize vehicle motion when motor thermal protection is triggered. A control allocation (CA) algorithm using motor temperature measurement is developed for the FTC method. The output torque constraints can be actively adjusted with motor temperature to include thermal protection strategy in the controller design. When future vehicle trajectories are available, a model predictive control (MPC) FPC algorithm is created to regulate the control efforts in advance to avoid overheating the IWMs that triggers the thermal protection strategy. The proposed methods are validated in CarSim® simulations and the results show that both the FTC and FPC methods can reduce the vehicle yaw rate tracking errors when IWMs are subject to thermal protection strategy.