Design Studies on Hybrid Excitation Motor for Main Spindle Drive in Machine Tools

This paper presents a hybrid excitation motor for a main spindle drive in end- and face-milling tools, which is operated with a high speed of 50 000 r/min. The proposed motor has not only a permanent magnet but also the field coil which makes field-weakening and field-strengthening controls possible with taking no notice of the permanent magnet demagnetization. In addition, the sum of iron and copper losses of the motor at the end-milling operation is significantly reduced by the field-weakening control. The 3-D finite-element-method-based design studies on the proposed motor for the target application are demonstrated.