Designing, prototyping and testing of a ferrite permanent magnet assisted synchronous reluctance machine for hybrid and electric vehicles applications

Abstract

This paper aims at presenting the designing, prototyping and testing results of a permanent magnet assisted synchronous reluctance machine, suited for A/B-segment electric vehicles. The machine is designed to avoid the use of rare-earths materials in the magnets, compensating the loss of performance from adopting ferrite magnets with a novel hairpin winding for the stator and a lightweight modular design for the rotor. Beyond the motor itself, the paper presents the design of the full drive, with an integrated power-electronics and an air-cooled housing. The simulation results show that the drive provides a maximum torque performance of 133 Nm at 3,600 rpm and a maximum power of 52.9 kW at 4,300 rpm, with peak efficiency above 96% at 4,000 ± 500 rpm and 50 ± 20 Nm, decreasing to 93–94% by including the inverter. These performances are validated with Hardware-in-the-Loop measurements on the prototype, despite small deviations from the operation of the control algorithm, and from the slightly degraded material performance. The proposed drive is finally evaluated based on its machine constant of mechanical power and torque density values, bringing to an improvement of respectively +45% and +25% compared to the 2016 benchmark, thus resulting in the best-in-class ferrite-based PMaSYRM.