Abstract:

The real-time choice of an optimal slip rate control target for various road adhesion conditions is the key component in the traction control strategy for electric vehicle （EV）. In this paper, according to the traits of the four wheel-driven EV with bi-rotor motor, an adaptive Kalman filtering is adopted to estimate the information of vehicle velocity and traction forces on the four wheels. With the estimated information, the slope of the curves of the adhesion coefficient versus the slip rate is then calculated in real time, and, consequently, the road adhesion condition is accurately identified. Then, by taking the estimated road conditions and the pedal input as the controller inputs, a fuzzy control strategy with velocity correction factors is presented to control the output torque of the driving motor. It is demonstrated that the proposed strategy improves the capability of furthest utilizing the adhesion coefficient in various road conditions by the EV and result in an optimal anti-slip effect.

Key words: electric vehicle, slip rate, traction control, adaptive filtering, fuzzy control