A Novel Control Method of Wheel Slip Phenomena in Electric Vehicles Based on the Number of Equilibrium Points

The quick and precise torque response of electric vehicles (EVs) will provide new advanced traction control systems (TCS). This paper presents an analytical result of the rapid variation of slip between wheel and road surface, and also proposes a novel TCS to suppress the phenomena. The analysis is carried out by means of focusing on the number and stability of equilibrium points. Then it is clarified the saddle-node bifurcation produces the phenomenon. In the discussion of the control method, it is proposed that a torque modifies the bifurcation structure to merge the multiple equilibrium points into one stable point to suppress the phenomenon. The effectiveness of the proposed method is illustrated by both a simulation and an experiment.