In this article, a parallel-series magnetic circuit multi-permanent magnet (M-PM) motor is designed and optimized considering magnet characteristic variation effects, where two kinds of permanent magnets (PMs) are utilized as co-magnetic. Based on the equivalent magnetic circuit method, the detailed design method for the M-PM motor is illustrated. Considering the various operation conditions in potential electric vehicle applications, the B–H curves of two PMs of different typical operation conditions are obtained. Then, a multiobjective optimization method is newly proposed which not only focuses on the magnet characteristics variation effect but also considers output torque, torque ripple as well as antidemagnetization capability under three typical operation conditions. The performances of the initial motor and optimal motor are compared under typical operation conditions. Finally, a prototype machine is built and tested. Both theoretical analysis and experimental results verify the validity of the motor and the proposed design optimization method.

In this article, a new controllable leakage flux multilayer barrier permanent magnet (PM) motor is proposed by adopting a new design concept of controllable leakage flux, where the PMs are uniquely placed in the d -axis magnetic circuit of the synchronous reluctance motor (SynRM). Compared to the conventional q -axis PM placement SynRM, the higher PM utilization and better flux-weakening capability can be obtained. For further comparison and verification, both of the controllable leakage flux multilayer barrier PM motor and the motor with traditional q -axis PM setting are designed. In addition, a multiobjective optimization method based on the correlation analysis method is proposed to obtain the optimized output torque and flux-weakening performances. Then, the performances of the two optimal motors are analyzed and compared in detail. Finally, two prototype motors are manufactured and tested. Both the theoretical and experimental analyses verify the effectiveness of the flux-weakening enhancement design and the proposed motor.

This article reveals the flux leakage design and modeling principle of a flux leakage controllable permanent magnet (FLC-PM) machine by considering driving cycles. The key is to obtain the relationship between flux leakage characteristics and multiple operating conditions. Based on the flux leakage controllable concept, an FLC-PM machine with an artfully designed flux leakage region is proposed. The design principle of the machine is investigated by analyzing the magnetic circuit of the machine in multiple operating conditions. The flux leakage factor is introduced to characterize the variable magnetic field in multiple operating conditions. On this basis, the mathematical model of the FLC-PM machine is deduced, and the driving characteristics of the machine are studied in detail. In order to evaluate the presented principle of the FLC-PM machine, a prototype is manufactured for experiments. Through the theoretical analysis and experimental testing, it is verified that the proposed principle is feasible and effective.

A comparative study of new partitioned stator hybrid excitation axial flux switching permanent magnet (HEAFSPM) motors with different partitioned excitation stator topologies for in-wheel traction applications is presented in this paper. The realization approaches of the partitioned stator HEAFSPM motor are discussed, and the motor topology with windings and permanent magnets (PMs) separately setting on different stators is selected in view of the advantageous structure for thermal management. On this basis, two partitioned excitation stator topologies including C-type tooth core and T-type tooth core stator configuration are proposed, and the air-gap flux modulation and flux regulation principle of the motors are analyzed. In addition, the design method of the partitioned stator HEAFSPM motor considering the effect of hybrid excitation sources is provided, and the two motors with different tooth cores are designed respectively. Meanwhile, for a fair comparison, the multiple objectives optimization method coupled with the sensitivity analysis is employed to optimize the two motors. The electromagnetic performances, anti-demagnetization capability, and flux regulation performance of the two motors are all investigated in detail. Finally, two prototype motors are fabricated and tested. Both the theoretical analysis and experimental results verify the effectiveness and reasonability of the motor.

This article proposes a novel pole-changing (PC) permanent magnet (PM) Vernier machine (PC-PMVM), in which an unevenly distributed modulation tooth structure is adopted in the stator, and a set of three-phase PC-winding is installed in the stator slots. On the rotor, surface-mounted PMs are adopted to generate PM excitation field. First, the topology design principle of PC-PMVM is discussed for the purpose of PC, based on which a 12/34-pole PC-PMVM is proposed. The analytical analysis shows that there are a series of working harmonics in the air-gap and can be grouped into two different types with different phasor diagrams for realizing PC operation. Thus, the speed range can be widened greatly because of the different PM flux linkage and inductances before and after PC. Next, the electromagnetic performance of PC-PMVM is investigated by finite element analysis and compared with an interior PM motor and a PC induction motor. Finally, a prototype is manufactured and tested. The results verify the correctness of theoretical analysis, and show that the proposed motor owns both high torque density and excellent speed-widening capability benefiting from the PC design and PC operation.

This paper presents a new asymmetrical-rotor hybrid permanent magnet (AR-HPM) motor with good torque performances. Different from the traditional symmetrical rotor structure, the asymmetrical rotor structure is employed to improve the torque production. This makes the reluctance torque and the magnetic torque reach the maximum at the same current phase angle. Based on the concepts, the motor is investigated by the finite element method (FEM). The frozen permeability method (FPM) is applied to divide the torque into the reluctance torque and the magnetic torque. The electromagnetic characteristics and torque performances of the motor are compared with a conventional motor. The results show that the proposed design is efficacious in boosting output torque at the same operating conditions. Moreover, the results also demonstrate that the topology of the proposed AR-HPM motor exhibits the advantage of avoiding the risk of demagnetization.