The Electronic Differential System For In-wheel Driven Electrical Vehicle

Since EV (Electrical Vehicle) is a vehicle with zero or nearly zero emission, and as the problem of environment protection and resource has been receiving more and more attention, there is a trend of EV's rapid development. It is possible to take resource, environment protection and transportation into consideration during the development of EV. The hub-motor has simple and compact structure, occupies small space and is easy to realize all-wheel drive, which has been used in many fields. Rear wheels driving EV and its power-train are studied in this thesis, respectively.The controller of the motor is the core technology of ED. The control principle and hardware design of the motor is explained. Two ways to control the motor are presents, one is single- polarity PWM, the other is double- polarity PWM. We compared the two ways in the area of the time of dead space, newborn energy, characteristic of power and control method. Furthermore, the speed of motor is calculated which is related to the duty cycle of PWM. The motor's dynamic equations and functions are analyzed and based on which the PID control method is presents.The EV in forward and four-degree-of-freedom steering operation is modeled. To improve the handling characteristics when turning, a control strategy, that controls the internal and external wheels to offer equal tractive force while turning is proposed. In the control strategy the slip ratio of driving wheel is limited to optimum value.Applying MATLAB/ Simulink software to model and simulation analysis, we can see thatβandρfrom novel electrical differential algorithm are better than traditional mechanical differential algorithm. With the control strategy on the basis of slip ratio limitation, handing characteristics of the hub-motor EV is improved.