Novel Dual-Layer and Triple-Layer Permanent-Magnet-Excited Synchronous Motors

This paper first presents a novel dual-layer permanent-magnet (PM)-excited (DPME) synchronous motor in which an extra set of iron teeth is employed in an inner stator between the PM rotor and the shaft. It can provide additional variation of magnetic reluctance along the circumferential direction of the air gap, and the strength of the flux modulation among the magnetic fields produced by the armature windings and the PMs is improved. The proposed motor has tactfully integrated the two pairs of flux-modulated motors inside one frame with one shared set of armature windings. The advantage of the proposed DPME motor is that it offers much higher torque capability than its conventional counterparts, making it more competitive for low-speed high-torque applications. In this paper, a novel triple-layer PM-excited (TPME) synchronous motor is further presented with the similar operating principle of the DPME, and it has three PM layers inside the frame. Finite-element method of magnetic field with mechanical motion coupled computation is employed to evaluate the electromagnetic torque precisely, showcasing that the proposed DPME motor can output an extra 37.5% more torque compared with a conventional synchronous motor, and the proposed TPME motor can output an additional 70% more torque with a similar power efficiency compared with the conventional PM synchronous motor.