Evaluating the Electric Vehicle Traction Drive Effectiveness
The design of a powertrain system for an autonomous electric vehicle (AEV) with an on-board power source is presented. The AEV traction drive system uses electrical machines with permanent magnets. The front wheels are driven by individual traction motors without a gear. The rear wheels are driven by one traction motor, which transmits the torque through a reduction gearbox with a differential. Lithium-ion batteries are used as on-board energy sources owing to their high-energy intensity and a long lifetime. The main aim of this work is to investigate the possibilities of regulating the electric power consumption in the proposed electric traction drive system to ensure the highest efficiency when driving under the conditions specified by the Standard New European Driving Cycle (NEDC). The data of these studies will make it possible to compare the largest achievable mileages of electric and motor vehicles under the same conditions. To meet the performance requirements for the electric vehicle at the specified parameters, the required traction electric drive power capacity is calculated. To increase the mileage between the battery recharges, the rear wheel drive operates only in the low speed range (up to 40 km/h), and at a higher speed, only the front wheel drives remain in operation. To save energy, the traction drive control algorithm ensures a long duration of their operation with high rotation frequency. The traction characteristics of the front and rear wheel drives provide the required electric vehicle dynamics during its starting and braking. The traction drive operation was simulated using the AVL CRUISE software package. Control algorithms are proposed in traction and braking modes with a power flow distribution between the front and rear wheels for economically efficient use of the storage battery charge.