Accurate wheel speed measurement for sensorless ABS in electric vehicle

The In-Wheel technology is emerging as the dominant drive system for electric vehicles. The existence of an electric motor at each wheel provides opportunities for development of efficient intelligent brakes for In-Wheel cars. This paper considers the practical realization of a sensorless ABS for In-Wheel Electric Vehicles. In the proposed braking system, the wheel speed is estimated from the back EMF of the In-Wheel motor, which makes the conventional wheel speed sensor redundant. The paper also introduces an effective denoising method using the wavelet packet technique, to increase the accuracy of the wheel speed measurement by the back EMF signal of the In-Wheel motor. The proposed strategy has also been implanted on a conventional ABS braking test rig. The experimental results showed that the proposed system can adequately replace the conventional ABS wheel speed sensor.