Sensorless driving/braking control for electric vehicles

Abstract

A sensorless driving/braking control system for electric vehicles is explained in the present paper. In the proposed system, a field-oriented control (FOC) was used to integrate driving and braking controls in a unified module for reducing the cost of hardware and simultaneously incorporating functional flexibility. An antilock braking system can swiftly halt a vehicle during emergency braking. An electromagnetic reverse braking scheme that provided retarding torque to a running wheel was developed. The scheme could switch the state of the MOSFETs used in the system by alternating the duty cycle of pulse width modulation to adjust the braking current generated by the back electromotive force (EMF) of the motor. In addition, because the braking energy required for the electromagnetic braking scheme is related only to the back EMF, the vehicle operator can control the braking force and safely stop an electric vehicle at high speeds. The proposed integrated sensorless driving and electromagnetic braking system was verified experimentally.