Concentrated winding axial flux permanent magnet motor with plastic bonded magnets and sintered segmented magnets

Direct drive axial flux permanent magnet (PM) motors are a cost effective and an energy saving choice for industrial use. Open slots make concentrated winding machines a favourable configuration with respect to manufacturing. However, open slots expose rotor surface magnets to large flux pulsations and the losses of sintered magnets may not be neglected. Plastic bonded magnets have very low eddy current losses but other magnetic properties of such magnet materials are not satisfactory at the moment. Divided sintered neodymium iron boron (NdFeB) may be used instead but the magnet configuration must be carefully analyzed to attain an acceptable eddy current losses level in the magnets. This paper addresses permanent magnet rotor constructions, which eliminate or remarkably reduce eddy-current losses in the magnets of a 2500 min-1 / 3000 min-1, 37 kW permanent magnet synchronous motor with concentrated windings. Different magnet materials, such as plastic-bonded Neo-magnets and sintered segmented NdFeB-magnets are evaluated. Also a prototype motor with plastic bonded magnets has been built. Analytical Matlabtrade- and finite-element-method-based (Flux2D/3Dtrade by Cedrat) programs are used in the calculations. The permanent magnets should be segmented into many small sections in the Machine which the flux pulsations in the magnets are high.

[1]  Asko Parviainen,et al.  Design of axial-flux permanent-magnet low-speed machines and performance comparison between radial-flux and axial-flux machines , 2005 .

[2]  D. Stone,et al.  Rotor loss in permanent magnet brushless AC machines , 1999, IEEE International Electric Machines and Drives Conference. IEMDC'99. Proceedings (Cat. No.99EX272).

[3]  D. Howe,et al.  Effect of Axial Segmentation of Permanent Magnets on Rotor Loss in Modular Permanent-Magnet Brushless Machines , 2007, IEEE Transactions on Industry Applications.

[4]  A.J.A. Vandenput,et al.  Design, development and testing of a high-speed axial-flux permanent-magnet machine , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[5]  Andreas Binder,et al.  Magnet Loss Analysis of Permanent-Magnet Synchronous Motors with Concentrated Windings , 2006 .

[6]  Jiabin Wang,et al.  Rotor eddy-current loss in permanent magnet brushless machines , 2004, IEEE transactions on magnetics.

[7]  A. Binder,et al.  Calculation of eddy current losses in permanent magnets of synchronous machines , 2008, 2008 International Symposium on Power Electronics, Electrical Drives, Automation and Motion.

[8]  D. Howe,et al.  ANALYTICAL PREDICTION OF THE AIRGAP FIELD DISTRIBUTION IN PERMANENT MAGNET MOTORS ACCOUNTING FOR THE EFFECT OF SLOTTING , 1992 .

[9]  Pia Salminen,et al.  Fractional slot permanent magnet synchronous motors for low speed applications , 2004 .

[10]  J. Partanen,et al.  FEM calculation of rotor losses in a medium speed direct torque controlled PM synchronous motor at different load conditions , 2002 .

[11]  Henk Polinder,et al.  Eddy-current losses in the segmented surface-mounted magnets of a PM machine , 1999 .

[12]  Eckart Nipp,et al.  Permanent magnet motor drives with switched stator windings , 1999 .

[13]  P. Campbell.  Permanent Magnet Materials and their Application: Applications , 1994 .

[14]  K. Atallah,et al.  Rotor Eddy-Current Loss in Permanent-Magnet Brushless AC Machines , 2004, IEEE Transactions on Magnetics.

[15]  Jacek F. Gieras,et al.  Axial Flux Permanent Magnet Brushless Machines , 2005 .

[16]  M. Kume,et al.  Heat resistant plastic magnets , 2005, INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005..