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

Abstract

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.