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 25 58099080; E-mail:chenzhenfei@hhu.edu.cn
Abstract: Electromagnetic torque model is built in this paper for
permanent-magnet synchronous machine (PMSM) with non-sinusoidal back
electromotive force (back-EMF) and current. Electromagnetic torque is
divided into four parts depending on the different combinations of
fundamental and harmonic component. Effects of current harmonic order,
amplitude and initial angle on average torque and torque ripple are
investigated based on the mathematic model. Desired harmonic parameters are
obtained from the analysis, in order to suppress the torque ripple as much
as possible. Further, a method for reducing the 5th and 7th
harmonic components of torque ripple is proposed, according to the
characteristics of back-EMF harmonic distribution. The proposed method is
greatly simplified and more feasible by only injecting 5th and 7th
harmonic currents. The theoretical analysis validity has been proved by
finite element (FE) simulation, and the FE results show that torque ripple
would be more effectively reduced by injecting proper harmonic current than
weakening it merely.
