Intelligent sensorless antilock braking system for brushless in-wheel electric vehicles

Brushless motors are increasingly used in different designs of in-wheel electric vehicles (EVs). In this paper, a sensorless antilock braking system (ABS) for brushless-motor in-wheel EVs is proposed. The proposed solution omits the need for installation of separate conventional ABS sensors at each corner of the vehicle. This paper also shows, both theoretically and experimentally, that the general form of a conventional ABS sensor output voltage is identical to a brushless dc (BLDC)-motor back electromotive force. The proposed sensorless system can reduce the costs of manufacturing and maintenance of the vehicle and significantly improves the performance of the ABS by accurate wheel speed estimation and road identification using wavelet signal processing methods. The sensorless system was extensively tested using actual ABS hardware. Those experiments showed that the accuracy of the proposed sensorless wheel speed estimation for BLDC propulsion was higher than that of commercial ABS sensors. In addition, sensorless ABS for brushless propulsion was compared with that of brushed dc motor, and the results showed that the brushless sensorless ABS achieved better accuracy, robustness, and reliability compared with the sensorless ABS for brushed dc motor.