Design Reconsiderations of High Speed Permanent Magnet Hybrid Excitation Motor for Main Spindle Drive in Machine Tools Based on Experimental Results of Prototype Machine

This paper presents design reconsiderations of the proposed permanent magnet hybrid excitation motor (HEM) for high-speed main spindle drive in machine tools based on detailed analyses of experimental results obtained using prototype machine. The proposed HEM has been intentionally designed using 3D-finite-element analysis (FEA) for the target application. Although the basic working principle of HEM has been proven by the experimental results, the induced voltage waveforms measured have shown a large deviation from those computed by 3D-FEA. In particular, the induced voltage distortion due to fifth harmonics has been a primary factor which has degraded the drive performances of test machine. After checking the differences between the designed drawing and the real one being taken into account of real manufacturing, design reconsiderations are conducted to the tested HEM using 3D-FEA. As a result, it is demonstrated that 3D-FEA results reconsidering the differences of the design parameters, the stator pole shoe and the stator teeth, are relatively good agreement with the tested results.