Harmonic current effect on torque density of a multiphase permanent magnet machine

Analytical calculation method of electromagnetic torque in time domain for multiphase permanent magnet machines is presented. And the accuracy of the proposed method is verified by FEM. The effectiveness of the harmonic current injection to boost torque density is confirmed by analytical results and also proven by FEM simulation. The torque characteristics of a nine-phase permanent magnet machine with various combinations of back-EMF and current waveforms are compared. It is shown that significant torque enhancement can be achieved by harmonic current injection if the phase back-EMF is designed appropriately. Further, the torque ripple is also affected by the back-EMF waveforms. Considerations on phase number choosing and the merits and demerits of multiphase permanent magnet machines with harmonic current injection are discussed.

[1]  Xavier Kestelyn,et al.  Right harmonic spectrum for the back-electromotive force of an n-phase synchronous motor , 2004, Conference Record of the 2004 IEEE Industry Applications Conference, 2004. 39th IAS Annual Meeting..

[2]  Emil Levi,et al.  Multiphase Electric Machines for Variable-Speed Applications , 2008, IEEE Transactions on Industrial Electronics.

[3]  Seung-Ki Sul,et al.  Synchronous frame current control of multi-phase synchronous motor. Part I. Modeling and current control based on multiple d-q spaces concept under balanced condition , 2004, Conference Record of the 2004 IEEE Industry Applications Conference, 2004. 39th IAS Annual Meeting..

[4]  K. T. Chau,et al.  A novel polyphase multipole square-wave permanent magnet motor drive for electric vehicles , 1994 .

[5]  S. Williamson,et al.  Pulsating torque and losses in multiphase induction machines , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[6]  Li Yong.  Torque Density Optimization for Five-phase PMSM With Third Harmonic Injection , 2010 .

[7]  Dong Liu,et al.  Multiphase machine theory and its applications , 2008, 2008 International Conference on Electrical Machines and Systems.

[8]  H. Toliyat,et al.  Five-phase permanent-magnet motor drives , 2005, IEEE Transactions on Industry Applications.

[9]  T.A. Lipo,et al.  Torque density improvement in a six-phase induction motor with third harmonic current injection , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[10]  Nicola Bianchi,et al.  Design and Tests of a Fault-Tolerant Five-phase Permanent Magnet Motor , 2006 .

[11]  P. Viarouge,et al.  Generalized transformations for polyphase phase-Modulation motors , 2006, IEEE Transactions on Energy Conversion.

[12]  M. Trlep,et al.  Increasing of output power capability in a six-phase flux-weakened permanent magnet synchronous motor with a third harmonic current injection , 2003, Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401).

[13]  A. Bouscayrol,et al.  Sensitivity of a 5-phase brushless DC machine to the 7th harmonic of the back-electromotive force , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[14]  Libing Zhou,et al.  Cogging torque reduction in interior permanent magnet brushless dc motor with flux-concentration type rotor , 2009, 2009 International Conference on Electrical Machines and Systems.