Towards an Energy Efficient Series Production of High Performance Permanent Magnet Synchronous Motors by Selective Magnet Assembly


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When installing magnets on synchronous rotors, the target values of energy efficiency, vibration, noise emissions, power density and synchronism are decisively influenced by the quality of the rotor magnetic field. This depends on the real position of the magnets after mounting, on the polarization of the magnet and on the direction of magnetisation. However, large component tolerances in the magnet bodies also require tolerances in the rotor magnetic field. The quality assurance in the field of rotor production, which is largely lacking in the current state of the art, is compensated for by robust motor designs in order to keep the rejects low. Unconventional machine designs, such as the Halbach arrangement of the magnets, exploit optimization potential in terms of power density by eliminating the ferromagnetic component in the rotor and reduce harmonics due to the almost sinusoidal field shape, so that more efficient winding processes, such as linear winding in the stator with a constant low torque ripple compared to distributed winding, are used. At the same time, however, the requirement for homogeneity of the magnetic field increases due to the matching pairing of the magnets and the correct magnetic position when using sintered, isotropic rare earth magnets. By 100 % testing of magnets and rotors, it is possible on the one hand to exploit these design potentials and on the other hand to estimate the performance data of the motor before the final assembly test by means of data mining. In the framework of the E|MagTol project, the process feasibility of a logistics solution for storing magnetized goods has already been successfully investigated. In order to extend the potential uncovered in the previous project, it is necessary to record all process data of the rotor assembly process such as magnet geometry, magnet position, polarization and magnetization direction. The aim of E|S2MART is on the one hand to increase machine efficiency by compensating for component deviations by adapting or matching the magnetic position and magnetic parameters in a closed-loop control loop in the assembly process and on the other hand to significantly increase the energy efficiency of the assembly process. This is done by optimizing the magnetization process and coupling with inductive heating to replace the furnace process during the bonding process and to reduce the energy consumption during magnetization. On the basis of the existing process experience, the savings potential in the assembly process is estimated to be at least 70 % compared to conventional processes.



Edited by:

Jörg Franke, Michael Scholz and Annika Höft




A. Meyer and J. Franke, "Towards an Energy Efficient Series Production of High Performance Permanent Magnet Synchronous Motors by Selective Magnet Assembly", Applied Mechanics and Materials, Vol. 882, pp. 111-118, 2018

Online since:

July 2018




* - Corresponding Author

[1] N.N.: Selten-Erd-Dauermagnete. Vacuumschmelze GmbH & Co. KG, company document, 2013, Hanau, Germany.

[2] Rodewald, W.: Fortschritte bei pulvermetallurgisch hergestellten Neodym-Eisen-Bor Magneten. Vacuumschmelze GmbH & Co. KG, company document, 2013, Hanau, Germany.

[3] Weickhmann, M.: Nd-Fe-B Magnets, Properties and Applications. Vacuumschmelze GmbH & Co. KG, Company document, 2009, Hanau, Germany.

[4] Gasparin, L. Additional Cogging Torque Components in Permanent-Magnet Motors Due to Manufacturing Imperfections. In: IEEE Transactions on Magnetics, Vol. 45, No. 3. March (2009).


[5] Klausnitzer, M.; Moeckel, A.: Quick cogging torque calculation for electronically commutated motors considering combinations of deviant and flawless magnets, International Symposium on Power Electronics, Electrical Drives, Automation and Motion, 2012, Sorrent, Italy.


[6] Gracia, M. H.; Hameyer, K.: Effect of non-sinusoidal currents on the acoustic noise excitation of induction motors, In: the 13th International Symposiumon Numerical Field Calculation in Electrical Engineering, IGTE, (2008).

[7] Coenen, I.; van der Giet, M.; Hameyer, K.: Manufacturing tolerances: Estimation and prediction of cogging torque influenced by magnetization faults. Proceedings of the 2011-14th European Conference on Power Electronics and Applications (EPE), 2011, Birmingham, United Kingdom.


[8] Guo, H. Statistical analysis on the additional torque ripple caused by magnet tolerances in surface-mounted permanent magnet synchronous motors. In: Electric Power Applications, IET, (2015).


[9] Hofmann, B. Automated Magnet Assembly for Large Synchronous Rotors with Integrated Permanent Magnets. 2nd International Conference on Electric Drives Production E|DPC, 2013, Nuremberg, Germany.


[10] Franke, J.; Kreitlein, S.; Risch, F.; Guenther, S.: Energy-Efficient Production Strategies and Technologies for Electric Drives, International Conference on Industrial Technology 2013, Capetown, South Africa.


[11] Franke, J.; Tremel, J.; Kühl, A.: Innovative Developments for Automated Magnet Handling and Bonding of Rare Earth Magnets, International Symposium on Assembly and Manufacturing, 2011, Tampere, Finnland.


[12] Brela, M.; Michalski, M.; Gebhardt, H.-J.; Franke, J.: Hall Measurement Method for the Detection of Material Defects in Plastic-Embedded Permanent Magnets of Rotors, Industrial Electronics Society, IECON 2013 – 39th Annual Conference of the IEEE, Vienna, Austria.


[13] Brela, M.; Meyer, A.; Selective Assembly of Permanent Magnets for the Optimization of Operating Characteristics of PMSM. 4th International Conference on Electric Drives Production E|DPC, 2015, Nuremberg, Germany.

[14] Z. Q. Zhu and D. Howe, Halbach permanent magnet machines and applications: a review,, in IEE Proceedings - Electric Power Applications, vol. 148, no. 4, pp.299-308, Jul (2001).


[15] R. P. Praveen, M. H. Ravichandran, V. T. Sadasivan Achari, V. P. Jagathy Raj, G. Madhu and G. R. Bindu, Design and analysis of Enclosed Rotor Halbach array Brushless DC Motor for spacecraft applications,, The XIX International Conference on Electrical Machines - ICEM 2010, 2010, pp.1-6.


[16] Alexander Meyer, Jörg Franke, et. al.: Concept for Magnet Intra Logistics and Assembly Supporting the Improvement of Running Characteristics of Permanent Magnet Synchronous Motors, Procedia CIRP, Volume 43, 2016, Pages 356-361.


[17] Matthias Burchert; Andreas Manhart; Jürgen Sutter: Untersuchung zu Seltenen Erden: Permanentmagneten im industriellen Einsatz,. Study, Öko-Institut e.V., 2014, Germany.

[18] J. Ou, Y. Liu, R. Qu and M. Doppelbauer, Experimental and Theoretical Research on Cogging Torque of PM Synchronous Motors Considering Manufacturing Tolerances,, in IEEE Transactions on Industrial Electronics, vol. 65, no. 5, pp.3772-3783, May (2018).


[19] A. Meyer, C. Nolte, C. Fischer, A. Sauerhöfer and J. Franke, Increasing the energy efficiency of the impulse magnetizing process,, 2016 6th International Electric Drives Production Conference (EDPC), Nuremberg, 2016, pp.22-26.


[20] A. Meyer et al., Energy Efficient Strategies for Processing Rare Earth Permanent Magnets,, Applied Mechanics and Materials, Vol. 856, pp.195-200, (2017).


[21] Schneider, M., Urban, N., Meyer, A., Franke, J. A new approach for flexible production of loss-optimized stator core packages [Neuartiger Ansatz zur flexiblen Fertigung verlustoptimierter Statorblechpakete] (2017).


[22] Meyer, A., Heyder, A., Brela, M., Urban, N., Sparrer, J., Franke, J. Fully automated rotor inspection apparatus with high flexibility for permanent magnet synchronous motors using an improved hall sensor line array (2015).


[23] Meyer, A., Abersfelder, S., Urban, N., Schneider, M., Franke, J. Quality control during production in the manufacture of electric motors: By magnetic field test of permanent magnet synchronous rotors [Fertigungsbegleitende Qualitätskontrolle in der Elektromotorenfertigung: Durch Magnetfeldprüfung von permanenterregten Synchronrotoren] (2017).