Nonlinear Wheel Slip Control of Electric Vehicles with In-Wheel BLDC Motors

This paper introduces a vehicle wheel slip tracking using an in-wheel BLDC (brushless direct current) motor. The control objective is to track a reference input wheel slip. The control architecture consists of a two-layer structure. In the upper level of the control system, the controller design is based on a sliding mode control strategy and generates the required torque for each wheel as the wheel slip tracks the reference value. In the lower level, the torque controller is a current controller with the duty cycle of the PWM (pulse width modulation) pulses to achieve the desired torque demanded by the upper level. In torque controller, a BLDC motor controller with a three-phase inverter is designed using Hall Effect sensor feedback and current sensors. The design is performed so that the wheel slip tracks any reference input wheel slip. Simulations are performed to demonstrate the effectiveness of the proposed two-layer controller.