| This paper is mainly about permanent magnet ac servo motor for machine tool, The details are as follows:Firstly, the NdFeB permanent magnet material has relatively high conductivity and the relatively worse heatproof ability. The eddy current induced in permanent magnet often leads to heat when the quantity of harmonic magnetic field in the air-gap. So it is necessary to do rotor losses analysis and calculation and to find solutions. In this paper, eddy current loss in the permanent magnets of permanent magnet synchronous motor is analyzed, moreover, the mathematics model is created for eddy current and deduce the calculation formula of the eddy current loss in the permanent magnet. The physical model of the motor is established to solve the electromagnetic field by ANSOFT finite element software, finally the eddy current losses in the permanents is worked out.Secondly, traveling comfort is one of the important performance indexes of the servo motor, but it is influenced directly by torque ripple. In this paper, the reason of torque ripple of the permanent magnet AC servo motor is analyzed, moreover torque ripple of the motor has been calculated and compared when the power and the number of pole are the same, but the number of slot is different by the calculation formula of the torque ripple and ANSOFT finite element software. Through comparing the calculated values of the torque ripple percentage, the number of the pole and slot can be selected appropriately, so operation performance of the permanent magnet AC servo motor for machine tool can be improved.Finally, after selecting basic structure sizes and electromagnetism parameters of the permanent magnet AC servo motor, the influence of air-gap length to magnet consumption and pull-out torque multiple and the influence of magnet width to flux density waveform in the air-gap can be calculated and analyzed by finite element software, so the air-gap length and magnet width can be selected appropriately and the performance of the motor can be improved ,too. based on above studies, a prototype of the permanent magnet AC servo motor for machine tool with rated power 0.9kW and 8 poles 36 slots structure has been designed ,the tests have been finished. Experimental Measure results indicates the performance indexes of the electric machine have reached the prospective requirements and proves theoretical analysis and calculation are correct in motor design process. |
