Analysis of Air-Gap Field Modulation and Magnetic Gearing Effect in Fractional-Slot Concentrated-Winding Permanent-Magnet Synchronous Machines

In this paper, the torque production of fractional-slot concentrated-winding (FSCW) permanent-magnet synchronous machines (PMSMs) is analyzed from the perspective of the air-gap field harmonics modulation accounting for slotting effect. It is found that the average torque of FSCW PMSM is produced by...

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Bibliographic Details
Published inIEEE transactions on industrial electronics (1982) Vol. 65; no. 5; pp. 3688 - 3698
Main Authors Zhu, Z. Q., Liu, Yue
Format Journal Article
LanguageEnglish
Published New York IEEE 01.05.2018
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects
Air gaps
Cogging
Concentrated winding
Finite element method
fractional slot
Gears
Harmonic analysis
Magnetic effects
Magnetic fields
Magnetic flux
magnetic gear
magnetic gearing effect
magnetically geared machine
Modulation
Permanent magnets
permanent-magnet (PM) machines
Power capacitors
Product design
Restoration
Synchronous machines
Torque
Winding
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Summary:In this paper, the torque production of fractional-slot concentrated-winding (FSCW) permanent-magnet synchronous machines (PMSMs) is analyzed from the perspective of the air-gap field harmonics modulation accounting for slotting effect. It is found that the average torque of FSCW PMSM is produced by both the principle of conventional PMSM and the magnetic gearing effect. A finite-element analysis (FEA) based equivalent current sheet model and harmonic restoration method is first used in FSCW PM machines with different slot-pole number combinations to quantify the respective contribution of the conventional PMSM and the magnetic gearing effect to the average torque. The influence of slot opening on the magnetic gearing effect, cogging torque, and torque ripple is analyzed. The results show that the magnetic gearing effect makes a nonignorable contribution to the average torque when a large slot opening stator is used. The expression of the gear ratio in FSCW PMSMs is derived. The influence of gear ratio on the contribution of the magnetic gearing effect to the total torque is investigated by FEA. The FEA-predicted torques are validated by experiments on the prototypes.
ISSN:0278-0046
1557-9948
DOI:10.1109/TIE.2017.2758747