Design and analysis of a less-magnets consequent-pole line-start permanent magnet motor with low cogging torque

The paper suggests a design and optimisation approach for a consequent-pole line-start permanent magnet motor (CPLSPM) with flexible pole arc coefficients and high utilisation of rare-earth (RE) materials, without the need for a variable frequency drive. The presence of dual-sided slots and adjustable pole arc coefficient sets CPLSPM apart from other types of motors, making the analysis of its cogging torque more complex. Taking into account the double-sided slotted and flexible adjustable pole arc coefficient, a cogging torque and airgap flux density model was established, and the influence of the pole arc coefficient on the characteristics of the cogging torque and airgap flux density of CPLSPM was analysed. The authors conduct multidimensional optimisation considering the coupling of multiple parameters to obtain a CPLSPM with minimal RE material usage, low cogging torque and excellent start-up and steady-state performance. Finite element simulation data are presented to validate the factors affecting the cogging torque and the feasibility of the proposed less-magnetic CPLSPM design. Finally, a prototype of a 750 rpm/2.2 kW CPLSPM is built, and performance testing is carried out for comparison, and applied to submersible mixers.