Effect of design parameters on electromagnetic torque of PM machines with concentrated windings using nonlinear dynamic FEM

This paper focuses on influence of design parameters of permanent magnet machines with concentrated windings on cogging torque, torque ripple and mean torque. An efficient approach is presented to estimate the magnet width and slot opening width for minimizing cogging torque and/or maximizing mean torque. Two-dimension nonlinear finite element analysis including rotor motion is used for the calculation. The torque is calculated using different methods: Maxwell's stress tensor and Virtual work method. Comparison of results between linear and nonlinear magnetic circuit show that the torque is sensitive with magnetic saturation. The maximum torque of the linear case is about 15% higher than for the magnetic saturation case. Linkage flux, internal voltage and mean electromagnetic torque calculation are verified by experiments with error margin smaller than 1%, 2% and 3% respectively.

[1]  J. A. Guemes,et al.  Analysis of torque in permanent magnet synchronous motors with fractional slot windings , 2008, 2008 18th International Conference on Electrical Machines.

[2]  T.J.E. Miller,et al.  Assessment of torque components in brushless permanent magnet machines through numerical analysis of the electromagnetic field , 2004, Conference Record of the 2004 IEEE Industry Applications Conference, 2004. 39th IAS Annual Meeting..

[3]  D. Lahaye,et al.  Modeling magnetic saturation for the design of exterior rotor permanent magnet machines , 2010, The 2010 International Power Electronics Conference - ECCE ASIA -.

[4]  D. Lahaye,et al.  Studying rotor eddy current loss of PM machines using nonlinear FEM including rotor motion , 2010, The XIX International Conference on Electrical Machines - ICEM 2010.

[5]  T. Sebastian,et al.  Issues in reducing the cogging torque of mass-produced permanent-magnet brushless DC motor , 2004 .

[6]  D. Howe,et al.  Influence of design parameters on cogging torque in permanent magnet machines , 1997, 1997 IEEE International Electric Machines and Drives Conference Record.

[7]  Nicola Bianchi,et al.  Design techniques for reducing the cogging torque in surface-mounted PM motors , 2000, Conference Record of the 2000 IEEE Industry Applications Conference. Thirty-Fifth IAS Annual Meeting and World Conference on Industrial Applications of Electrical Energy (Cat. No.00CH37129).

[8]  Valéria Hrabovcová,et al.  Design of Rotating Electrical Machines , 2009 .

[9]  Ayman M. El-Refaie,et al.  Fractional-Slot Concentrated-Windings Synchronous Permanent Magnet Machines: Opportunities and Challenges , 2010, IEEE Transactions on Industrial Electronics.

[10]  I. Husain,et al.  Permanent Magnet Synchronous Motor Magnet Designs with Skewing for Torque Ripple and Cogging Torque Reduction , 2007 .

[11]  D. Lahaye,et al.  Validation of non-linear dynamic FEM model for design of PM machines with concentrated windings in ship application , 2011, Proceedings of the 2011 14th European Conference on Power Electronics and Applications.

[12]  P. Pillay,et al.  Cogging Torque Reduction in Permanent Magnet Machines , 2006, IEEE Transactions on Industry Applications.

[13]  M. Aydin,et al.  Magnet skew in cogging torque minimization of axial gap permanent magnet motors , 2008, 2008 18th International Conference on Electrical Machines.