A Novel Dual-Asymmetrical Permanent Magnet Machine for Single Rotor Compressors in Vehicles

To improve the ripple in resultant torque or rotating speed of a single-rotor permanent magnet compressor, a Dual-Asymmetrical Permanent Magnet Machine (DAPMSM) is proposed in this paper. The designs of the rotor and stator are both asymmetrical; hence, the DAPMSM could generate fluctuating torque with respect to mechanical position under a simple control strategy, without a special prediction algorithm or harmonic injection. This paper proposed a 24-slot and 8-pole DAPMSM. Considering 8 special positions and their generating torques when fully aligned, a fluctuating torque is generated when the machine is excited by a standard sinusoidal current source. To start with, the principle of fluctuation torque generation is introduced. After that, a machine topology with pole-based magnet amount and magnetisation direction, rotor design, and coil-based number of turns and reversed-coiling winding armature design is proposed. Moreover, the finite element analysis (FEA) method is used to evaluate the machine’s performance. Lastly, a prototype DAPMSM is manufactured, and an experimental test is reported. The results show that DAPMSM can generate fluctuation torque to track the aim load torque waveform.