Affiliations: [a] College of Energy and Electrical Engineering, Hohai University, Nanjing, Jiangsu, China | [b] Research Center for Renewable Energy Generation Engineering, Ministry of Education, Nanjing, Jiangsu, China | [c] Electric Power Science Research Institute, Jiangsu Electric Power Company, Nanjing, Jiangsu, China
Correspondence:
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Corresponding author: Zhenfei Chen, College of Energy and Electrical Engineering, Hohai University, No. 8 Focheng west Road, Jiangning District, Nanjing 211100, Jiangsu, China. Tel.: +86 025 58099080; E-mail:chenzhenfei@hhu.edu.cn
Abstract: Two kind of nonuniform slot distribution models, the unit
machine shift model (Model 1) and the single slot shift model (Model 2), are
proposed for reducing cogging torque of surface-mounted permanent magnet
(SPM) machines. Further, based on exact subdomain model and Maxwell stress
tensor, an analytical model is further built for calculating cogging torque
in SPM machines with nonuniformly distributed stator slots. Its accuracy and
feasibility have been validated by finite element (FE) method. With the
analytical model, effects of slot shift angle on cogging torque are
investigated for an 8-pole/12-slot SPM machine. Meanwhile, coupling
relationships between shift angle and other design parameters (slot/pole
number, pole arc coefficient and slot opening) are analyzed. In addition,
influences of slot shift on back-EMF and electromagnetic torque are also
studied. Conclusions are drawn from the analysis and indicate that Model 1
is much better than Model 2 in improving the performances of SPM machine.
