Design and analysis of axial flux permanent magnet assisted synchronous reluctance motors for electric vehicle applications

Electric vehicles (EVs) emerge as an important solution for reducing emissions and dependence on fossil fuels in modern transportation. The traction motors at the hearth of EVs must deliver high performance, efficiency, and compactness under various driving conditions. This study presents the design and analysis of the Axial Flux Permanent Magnet-Assisted Synchronous Reluctance Motor (AF-PMa-SynRM) optimized for EV applications, with a focus on manufacturability, high performance, and mechanical and thermal stability. The AF double air gap motor design was chosen for its low volume, high torque, and high-power density. The AF-PMa-SynRM model is supported by a forced liquid cooling method with a cooling jacket and high current density. Through multi-objective optimization and multi-physics analyses conducted for EVs, the electromagnetic, mechanical, and thermal performance levels of the AF-PMa-SynRM model have been determined. The motor design achieved 96.1 Nm of torque, 30 kW of power, and 93.8% efficiency at a nominal speed of 3 000 rpm. The motor was found to reach a maximum speed of 10 000 rpm, 253.1 Nm of torque, and 65 kW of power. In this study, the rotor of the double-stator (DS) AF-PMa-SynRM model was designed with a barrier structure suitable for mass production. The conical structure of the magnets and barriers in AF motors, which decreases from the outer to the inner diameter, was replaced with a new barrier design to prevent volumetric changes. The new barriers were optimized using a multi-objective Genetic Algorithm (GA). In the final stage, the model was cooled using the cooling jacket method. The average temperature of the motor winding and the magnets was analyzed as 73.83 °C and 66.44 °C respectively at a nominal power value of 30 kW. An efficiency map of the AF-PMa-SynRM model was obtained, and the constant torque-power regions were determined.