Comparative Studies of Modular and Unequal Tooth PM Machines Either With or Without Tooth Tips

This paper presents four types of three-phase permanent magnet (PM) machines, that is, modular and unequal teeth (UNET) machines either with or without tooth tips. Two-dimensional finite element (FE) modeling has been carried out to analyze the influences of flux gaps (in alternate stator teeth) and UNET widths. These influences are mainly on winding factors, air-gap flux density due to PMs, flux linkage, back-electromotive force, and electromagnetic torques. For UNET machines without tooth tips, it has been found that the UNET widths affect both winding factor and air-gap flux density due to PMs. However, for UNET machines with tooth tips, the UNET widths have no effect on machines' electromagnetic performance. Nevertheless, for modular machines, the flux gaps influence three parameters: winding factor, air-gap flux density due to PMs, and flux focusing/defocusing. Meanwhile, for different slot/pole number combinations, the influences of flux gap and UNET widths are different. Several general rules concerning these influences have been established. These general rules can be extended to other single or dual three-phase modular or UNET machines with different slot/pole number combinations. Prototypes of modular machines have been built, and the predictions and conclusions have been validated.

[1]  N. Bianchi,et al.  Design considerations for fractional-slot winding configurations of synchronous machines , 2006, IEEE Transactions on Industry Applications.

[2]  Libert,et al.  Manufacturing methods of stator cores with concentrated windings , 1988 .

[3]  Bing Xia,et al.  A Modular Permanent-Magnet Flux-Switching Linear Machine With Fault-Tolerant Capability , 2009, IEEE Transactions on Magnetics.

[4]  Hamid Ben Ahmed,et al.  Switching flux permanent magnet polyphased synchronous machines , 1997 .

[5]  Z.Q. Zhu,et al.  Alternate Poles Wound Flux-Switching Permanent-Magnet Brushless AC Machines , 2010, IEEE Transactions on Industry Applications.

[6]  Yuji Enomoto,et al.  Cogging torque due to roundness errors of the inner stator core surface , 2003 .

[7]  Jiakuan Xia,et al.  Low speed high torque PMSM design based on unequal teeth structure , 2008, 2008 International Conference on Electrical Machines and Systems.

[8]  C. Hwang,et al.  Design of High-Performance Spindle Motors With Single-Layer Concentrated Windings and Unequal Tooth Widths , 2007, IEEE Transactions on Magnetics.

[9]  Mohamed Gabsi,et al.  Double and single layers flux-switching permanent magnet motors: Fault tolerant model for critical applications , 2011, 2011 International Conference on Electrical Machines and Systems.

[10]  E. Spooner,et al.  Modular design of permanent-magnet generators for wind turbines , 1996 .

[11]  D. Gerling,et al.  Different novel methods for reduction of low space harmonics for the fractional slot concentrated windings , 2012, 2012 15th International Conference on Electrical Machines and Systems (ICEMS).

[12]  Z.Q. Zhu,et al.  A simple method for measuring cogging torque in permanent magnet machines , 2009, 2009 IEEE Power & Energy Society General Meeting.

[13]  Z.Q. Zhu,et al.  Comparison of PM brushless motors, having either all teeth or alternate teeth wound , 2006, IEEE Transactions on Energy Conversion.

[14]  Ozgur Ustun,et al.  Design, analysis and implementation of a subfractional slot concentrated winding BLDCM with unequal tooth widths , 2011, IECON 2011 - 37th Annual Conference of the IEEE Industrial Electronics Society.

[15]  Z.Q. Zhu,et al.  Permanent magnet brushless machines with unequal tooth widths and similar slot and pole numbers , 2004, Conference Record of the 2004 IEEE Industry Applications Conference, 2004. 39th IAS Annual Meeting..

[16]  Nicola Bianchi,et al.  Use of the star of slots in designing fractional-slot single-layer synchronous motors , 2006 .

[17]  E. Spooner,et al.  Modular, permanent-magnet wind-turbine generators , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[18]  G. Ombach,et al.  Influence of Additional Air Gaps Between Stator Segments on Cogging Torque of Permanent-Magnet Machines Having Modular Stators , 2012, IEEE Transactions on Magnetics.

[19]  B. Bickel,et al.  Manufacturing cell for winding and assembling a segmented stator of PM-synchronous machines for hybrid vehicles , 2012, 2012 2nd International Electric Drives Production Conference (EDPC).

[20]  D. Gerling,et al.  Low costs and high-efficiency electric machines , 2012, 2012 2nd International Electric Drives Production Conference (EDPC).

[21]  J. Haylock,et al.  A comparative study of permanent magnet and switched reluctance motors for high performance fault tolerant applications , 1995, IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting.

[22]  Zhe Chen,et al.  A modular, permanent-magnet generator for variable speed wind turbines , 1995 .