Design and analysis of a new high-torque-density three-dimensional magnetic circuit permanent magnet motor in aircraft electrical propulsion applications

To improve the torque density, a new Three-Dimensional Magnetic Circuit Permanent Magnet Motor (3DMCM) is proposed for the electric propulsion aircraft, which innovatively makes use of both the radial and axial magnetic circuits to increase the electromagnetic torque performance per unit weight. The topological structure of the 3DMCM is firstly proposed, which consists of the three-sided rotor, three-dimensional magnetic circuit stator and the toroidal winding. The cobalt–iron (Co-Fe) alloy stator with three-dimensional stacking design is proposed to guarantee the high saturation magnetic performance in both radial and axial directions, which can avoid the use of the Soft Magnetic Composite (SMC) material and the associated low saturation magnetization issue. Furthermore, the three-dimensional equivalent magnetic circuit model of the 3DMCM is proposed, while the analytic expression between the output power and the main dimensions is derived. The electromagnetic torque and the torque density behaviors are systematically analyzed via the parameter sensitivity analysis, which can provide a guideline for the 3DMCM design. The Cooling Support Plate (CSP) cooling structure is proposed to guarantee the stable operation of the motor. Finally, a 630 N · m 3DMCM is designed and developed, which has the outstanding output torque performance per unit weight with the torque density for 25.65 N·m/kg.