Optimal Slip Ratio Estimator for Traction Control System of Electric Vehicle Based on Fuzzy Inference

Abstract

In this paper, we propose the optimal slip ratio estimation method based on Fuzzy Inference. One of the remarkable advantages of electric vehicle (EV) is the quick and precise torque response of electric motor, which realizes a novel traction control system (TCS). To prevent wheel skid phenomena, the optimal slip ratio control has been successfully developed. It maintains the slip ratio to the optimal value which gives the maximum driving force. The remaining problem is how to generate the optimal slip ratio command to the controller. First, we indicate that the effective estimation of the optimal slip ratio is difficult for a simple gradient method, which is one of the well-known optimization methods. Various knowledge obtained by experiments can be easily installed into Fuzzy Inference. Therefore, its estimation performance can be easily improved by accumulation of human experiences. This is a remarkable advantage in nonlinear estimation of actual road-tire characteristics. The effectiveness of the proposed estimation and control methods is confirmed by numerical simulation. Copyright © 2000, The Institute of Electrical Engineers of Japan. All rights reserved.