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This article investigates novel fractional slot nonoverlapping winding hybrid excited (HE) machines with consequent-pole permanent magnet (PM) rotors. The proposed machines accommodate the rotor PM and stator field winding separately, which has solved the spatial confliction of double excitations. Different consequent-pole interior PM rotor configurations are extended to retain the PMs and utilize the flux-concentrating effect. Then, the relationship of field and armature current ratio with the PM and wound field fluxes is identified theoretically, which provides design and optimization guidelines for the HE machines. Furthermore, the HE machines are optimized and compared with conventional PM machines. It is revealed that the HE machines exhibit enhanced torque density with flux-enhancing field excitation, and extended operation range with flux-weakening field excitation. Besides, the HE machine utilizing flux-concentrating effect exhibits the highest PM torque but sacrificed flux regulation capability due to magnetic saturation. Finally, the HE prototypes with different rotor configurations are fabricated and tested to validate the analyses. [ABSTRACT FROM AUTHOR]

Switched-flux permanent magnet (PM) (SFPM) machines have attracted considerable interest in recent years, since the flux focusing can be utilized, both armature windings and PM excitation sources are on the stator, while the salient pole rotor is very simple and robust. In SFPM machines, the high variable flux densities throughout the stator core result in iron loss being a significant proportion of the total losses. This paper presents a novel modular-rotor SFPM machine that facilitates a reduction in iron loss for a marginal reduction in output torque. The modular rotor also offers a reduction in rotor mass over the conventional-rotor topology. The electromagnetic performance of both conventional- and modular-rotor SFPM machines is analyzed by 2-D finite element analyses and is verified by measurements on small-scaled prototype SFPM machines. [ABSTRACT FROM AUTHOR]

This paper proposes a novel permanent-magnet (PM) flux switching (PMFS) machine with an outer-rotor configuration for in-wheel light traction applications. The geometric topology of the outer-rotor PMFS machine is introduced, and the analytical sizing equations are derived to determine the main design parameters of the machine. Two-dimensional finite-element analysis (FEA) models are developed to investigate and optimize the machine performance. Furthermore, the flux-weakening capability of the machine is analyzed and further improved by segmental PMs with iron bridges. The machine performance predictions by 2-D FEA models are validated by experimental tests on the prototype machine. The suitability of the proposed outer-rotor PMFS machine for in-wheel light traction application is demonstrated. [ABSTRACT FROM PUBLISHER]

This paper presents a comparative study of torque–speed characteristics and cogging torque of the fractional-slot interior permanent magnet brushless ac machines having different slot openings, viz. open slot, closed slot, and hybrid slot (sandwiched open and closed slots), and unskewed and step skewed rotors. The influence of such alternate slot openings on the magnetic cross-coupling and cogging torque is particularly emphasized. Furthermore, the repercussion of the manufacturing limitations and tolerances on the cogging torque of machines having these alternate slot openings is also investigated. The magnetic cross-coupling level and the sensitivity of cogging torque to manufacturing limitations and tolerances strongly depend on the slot opening materials. The finite-element analyses are experimentally validated. [ABSTRACT FROM PUBLISHER]

A novel E-core switched-flux permanent-magnet (SFPM) brushless machine is proposed, and its electromagnetic performance is compared with that of the conventional SFPM brushless machine. The operation principle of the E-core SFPM machine will be first described, and the influence of stator and rotor pole number combinations is investigated, while the electromagnetic performance of the optimized E-core SFPM machine is predicted by finite-element analyses and validated by experiment. It is shown that the number and volume of magnets in the E-core SFPM machine is significantly reduced, only half of that in the conventional machine, while the phase back electromotive force and torque of the E-core machine are \sim 15% larger than those of the conventional machine. [ABSTRACT FROM AUTHOR]