Design and Performance Analysis of Axial Flux Permanent Magnet Machines with Double-Stator Dislocation Using a Combined Wye-Delta Connection

Conventional fractional slot concentrated winding three-phase axial flux permanent magnet machines have an abundance of armature reaction magnetic field harmonics which deteriorate the torque performance of the machine. This paper presents a double-stator dislocated axial flux permanent magnet machine with combined wye-delta winding. A wye-delta (Y-△) winding connection method is designed to eliminate the 6th ripple torque generated by air gap magnetic field harmonics. Then, the accurate subdomain method is adopted to acquire the no-load and armature magnetic fields of the machine, respectively, and the magnetic field harmonics and torque performance of the designed machine are analyzed. Finally, a 6kW, 4000r/min, 18-slot/16-pole axial flux permanent magnet machine is designed. The finite element simulation results show that the proposed machine can effectively eliminate the 6th ripple torque and greatly reduce the torque ripple while the average torque is essentially identical to that of the conventional three-phase machines with wye-winding connection.