This paper investigates a novel 3-phase doubly salient permanent magnet (DSPM) motor. Because of the adoption of ⊓-shaped stator iron core segments, the asymmetrical magnetic circuit among different phases occurring in conventional DSPM motors with E-shaped stator iron core segments can be avoided, so that balanced and sinusoidal 3-phase PM flux linkage and no-load EMF can be achieved. Firstly, based on a 12/7 stator/rotor pole combination, the operation principle of ⊓-core DSPM motor is discussed using the least magnetic reluctance principle. Then the general airgap field modulation theory (AFMT) is extended to the ⊓-core DSPM motor for explaining its operation principle further and armature winding connection. The finite element analysis is used to validate theoretical analysis, as well as to calculate its electromagnetic performances. The results show that the 12/7-pole ⊓-core DSPM motor possesses higher average torque output capability and lower torque ripple compared with the 12/8-pole E-core counterpart. Finally, a 12/7-pole ⊓-core DSPM motor is built and tested so as to experimentally verify the theoretical analysis.

This article proposes a new partitioned stator hybrid excited (PS-HE) machine with dc-biased sinusoidal current. On the inner stator, the consequent pole permanent magnets (PMs) are employed as the PM excitation. On the outer stator, a set of integrated dual three-phase winding is adopted to produce the wound and armature fields at the same time by injecting the sinusoidal current with dc bias. So, the flexible flux regulation can be realized by controlling the dc bias component. The rotor composed of segmented iron cores is sandwiched between two stators. By employing the air-gap field modulation theory, the air-gap magnetic field harmonics are analyzed to explain the operating and flux regulation principle. Furthermore, a design optimization and the electromagnetic performances of the proposed machine are investigated by finite element analysis. When compared with the existing series and parallel PS-HE machines, the proposed machine can avoid the disadvantage of low torque density of PARALLEL HE machine, and it can solve the problem of the poor flux regulation ability of series HE machine as well, which is mainly contributed by the reasonable space allocation of PMs and field winding excitations. Finally, a prototype is built and tested to verify the theoretical analyses.

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 article presents a new pole-changing (PC) doubly salient permanent magnet (DSPM) motor. According to the general air-gap field modulation theory (GAFMT), the permanent magnet excitation field can be modulated by the stator and rotor teeth to a series of harmonics with different pole-pair numbers and different slot pitch angles. Thus, when the armature winding is connected and reconnected according to the different excitation field harmonics, the PC operation can be realized to obtain a high torque density at the low-speed region and a widened speed regulation range with a simple motor structure. According to the GAFMT, the operating principle of the proposed motor is introduced, and the winding connection is discussed. Then, to verify the validity, the electromagnetic performance of the proposed motor is analyzed by the finite element analysis. Finally, a prototype is built and tested.

A flux switching permanent magnet (FSPM) motor is designed and optimized in this article to achieve high torque density and expanded speed regulation range from a design viewpoint of pole-changing (PC). Based on the field modulation theory, the PM field in the FSPM motor is modulated by the stator and rotor teeth, generating rich harmonics with different pole-pair numbers in the air-gap flux density. By adopting an appropriate slot pole combination, working harmonics with different slot pitch angles are obtained to establish a basis for the PC-FSPM motor. Then, different working harmonics can be used to achieve different energy conversions with different winding configurations, so the PC operation can be performed to realize the high torque and wide speed regulation range by switching the working modes. Based on the field modulation theory, the operation principle of conventional and PC-FSPM motors is analyzed and compared. Then, according to the design principle of the PC-FSPM motor, a 24/22-pole PC-FSPM motor with the E-core is designed and optimized by a multilevel optimization method. Finally, the electromagnetic performances are analyzed by finite-element analysis and the test results of the prototype have verified the feasibility of the motor.

A new partitioned stator (PS) hybrid excitation (HE) machine with slot Halbach permanent magnet (PM) arrays is proposed in this paper. Due to the adoption of PS structure, its armature winding (AW) is located in the outer stator, and the PMs and the field winding (FW) are housed in the inner stator, thus the space utilization is significantly enhanced. The key difference of proposed machine is that Halbach PM arrays are employed in the inner stator slot openings, so that the parallel magnetic circuit between PM field and wound field is performed and the ratio of PM field short-circuited in the inner stator is effectively reduced. Thus a wider speed regulation region and a higher torque/power density can be achieved. Firstly, the configuration of proposed machine is described, based on which its operating principle is discussed. Then the electromagnetic performances are calculated and compared based on 2-dimensional finite element analysis (FEA). The results show that the torque can be improved by 76% with a similar magnetic field regulation ratio compared with an existing PS-HE machine with slot PMs. Finally, a prototype machine is built and tested to verify the analysis and FEA results.