Abstract: An electromechanical dynamic model of the urban light rail vehicle with independently rotating wheels (IRW) is developed so as to study the steering performance of the independently rotating wheel. In the model, the urban light rail vehicle is modelled as a multi-body dynamic model, while the independently rotating wheels are modelled as the electrical coupled wheelset (ECW) incorporating with a speed-differential-based sliding mode control system to consider the coupling effects between the IRW and the motor. Using the proposed electromechanical dynamic model, the effects of the speed-differential control parameters on the hunting stability and curving performance of the ECW are investigated, and the enhancement of curving performance of ECW is further demonstrated through comparing with the IRW in absence of the control system, in terms of the wheelset attack angle, the wheel lateral force, the derailment coefficient, and the wear index. The results show that a critical value is identified in the control parameter ranging from 10⁴ to 7.5×10⁵. The steering performance of ECW more like a typical IRW as the control parameter below that critical value, while the ECW show the characteristic of the traditional rigid wheelset when the control parameter is greater than the critical value. The ECW with a control parameter close to the critical value, however, could be subjected to the hunting motion. With a rational control parameter, the wheelset attack angle, lateral force, derailment coefficient and wear index of the ECW decrease by 23%, 16%, 16% and 35%, respectively, comparing with those of IRW in absence of the control system.

Key words: ECW, IRW, motor characteristics, sliding mode control, speed-differential control parameters, steering performance