Reduction of Electromagnetic Vibration in Consequent-Pole Permanent Magnet Motors by Employing Harmonic Flux Barrier

Abstract This study employs a consequent-pole rotor in an 18-slot/6-pole motor to reduce the use of permanent magnets (PMs). However, the adoption of a consequent-pole rotor may increase the torque ripple. In addition, the vibration performance may deteriorate because lower-order radial forces arise compared with a surface-mounted permanent magnet synchronous motor. Because these low-order radial forces result in large electromagnetic vibrations, the main flux density sources of these forces are identified. A harmonic flux barrier (HFB) is employed to reduce the lower-order radial forces by increasing the specific harmonics of the air-gap flux density. Furthermore, the HFB decreases the torque harmonics, which mitigates the torque ripple. The proposed consequent-pole PM motor (CPMM) with HFB (HFB-CPMM), as well as the conventional CPMM, are optimized using finite element analysis (FEA) to improve the electromagnetic vibration performance. In addition, the performance of the optimized HFB-CPMM (O-HFB-CPMM) is compared with that of the optimized conventional CPMM (O-CPMM). Consequently, O-HFB-CPMM is found to exhibit considerably lower PM usage, torque ripple, and radial force harmonics than the O-CPMM. Finally, the electromagnetic vibrations of both the optimized models are calculated using multi-physics FEA to validate the theoretical analysis and the proposed vibration reduction design. Air-gap flux density harmonics consequent pole permanent magnet (PM) motors radial force vibration reduction design.