Effect of angle displacements on electromagnetic performance of dual three-phase consequent-pole permanent magnet machine

The machine with consequent pole (CP) rotor can improve the utilisation ratio of permanent magnet (PM). However, all the N poles or S poles are replaced by salient rotor iron, leading to the asymmetric air-gap flux density. It potentially results in even-order back electromotive force (back-EMF) harmonics and unbalanced magnetic force. This study aims to investigate the influence of various angle displacements (i.e. 0°, 15°, 30° and 60°) on the electromagnetic performance of the dual three-phase PM machine with CP rotor. The electromagnetic characteristics, including air-gap flux density, back-EMF, torque performance, short circuit current, braking torque and PM demagnetisation under both healthy and fault conditions are compared comprehensively. Finally, the 24-slot/22-pole prototype machine is manufactured. The back-EMF waveforms and static torque are measured and compared to the finite-element predicted results to validate the theoretical analysis.