Drivetrain design for an ultra light electric vehicle with high efficiency

The complete drivetrain for a single person ultra light electric vehicle (EV) is optimized towards a minimal total weight and a maximal average efficiency for different driving cycles. The EV is named ELBEV, which is an acronym for Ecologic Low Budget Electric Vehicle. The single person ultra light EV is a tricycle, with two driven and steering front wheels and one rear wheel. The drivetrain of each front wheel consists of an outer rotor permanent magnet synchronous motor (PMSM), a single-stage gearbox and the power electronics with converter and controller print. The drivetrain is optimized for the New European Driving Cycle, the New York City Cycle and the Federal Test Procedure. For the optimization of the drivetrain analytical models are used to calculate the losses and the efficiency. The optimized parameters of the motor are: the number of pole pairs, the number of stator slots and the outer rotor radius of the motor. Furthermore, an analytical model for the single-stage gearbox is implemented for different gear ratios (GRs). The optimized parameters for the gearbox are: the number of teeth and the module of each gear combination and the total mass of the gearbox for each GR. The analytical models are fast, and useful for designing a good PMSM in combination with a single-stage gearbox. The optimization of the complete drivetrain is always a compromise between total average efficiency over the drive cycle and the total mass of the drivetrain.