Isabelle Hofman

Integrated Model of Power Electronics, Electric Motor, and Gearbox for a Light EV

This study presents a model of a drivetrain for an integrated design of a light electric vehicle (EV). For the drivetrain of each front wheel of the single-person, battery-powered EV tricycle consists of a battery, an inverter, and an outer rotor permanent magnet synchronous motor (PMSM), which is connected to an in-wheel gearbox. The efficiency of the inverter, motor, and gearbox is analyzed over the New European Driving Cycle. To calculate the losses and efficiency of the PMSM, the power electronics in the inverter and gearbox are used. The analytical models provide a fast, but less accurate result, useful for optimization purposes. To accurately predict the efficiency of the PMSM, a finite element model is used. The models are validated by test setups. Correspondingly, a good agreement between the measurements and the calculated results is achieved. A parameter study is performed to investigate the influence of the detailed component parameters (i.e., outer rotor radius, gear ratio, and number of pole pairs and stator slots) on the average efficiency of the drivetrain.

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.

Influence of Soft Magnetic Material in a Permanent Magnet Synchronous Machine With a Commercial Induction Machine Stator

This paper presents the efficiency study of a 6-pole and 2-pole induction motor (IM), converted into a 6-pole and 2-pole permanent magnet synchronous machine (PMSM). Firstly, the stator of the IM was kept unchanged and the rotor was converted into a permanent magnet (NdFeB magnets) rotor, resulting in higher average efficiency. Secondly, we investigated how much the efficiency can be increased by replacing the electrical steel in the stator by another material grade. The numerical approach is based on the finite element method (FEM), taking into account the rotor movement. Iron losses are computed according to the loss separation theory. From measurements and simulations, it is observed that the efficiency increases significantly compared to the original IM. The average efficiency of the orig inal 1.5 kW IM converted into the 1.5 kW PMSM led to a 14% higher efficiency in a speed range 0.5Ωnom - Ωnom and torque range 0.5Tnom - Tnom. When the stator iron is replaced by M235-35A laminations with the same geometry, the average efficiency increases by an additional 2% for the 1.5 kW PMSM with modified stator.

Optimal design and implementation of a drivetrain for an ultra-light electric vehicle

This paper presents an integrated design of a drivetrain for a single-person ultra-light electric vehicle (ULEV). To calculate losses and efficiency of the inverter, the permanent magnet synchronous machines (PMSMs) and the gearbox, parameterised analytical models are used. For the gearbox - which has a single gear ratio - the studied parameters are the gear ratio, the number of stages, the number of teeth and the module of each spur gear combination. The novelty of the paper is that it learns how the total average efficiency and the total mass of the drivetrain depend on the gear ratio, on the number of stages in the gearbox, on the motor parameters and on the chosen several driving cycles including the new European driving cycle (NEDC). On the basis of the presented results, it is possible to choose the right configuration of power electronics, PMSM and gearbox in order to have a good trade-off between high efficiency and low mass.