Electromagnetic and Thermal Analysis of Permanent-Magnet Synchronous Motors for Cooperative Robot Applications

Smaller and lighter motors are needed to be used for cooperative robots, which are becoming a recent issue among articulated robots. In order to make the motor small, the axial length must be reduced within a limited diameter, so a reduction in the length of the core lamination and the winding end length must be considered. However, loss and thermal analysis are essential in the design process, as loss increases to meet output with excessive volume reduction and may consequently increase temperature severely. In this article, the magnetic performance for various analytical models studied to reduce the axial length is invested, and the thermal behavior is predicted by the analytical lumped-circuit method. A model with the tradeoff between the low temperature rise and high magnetic performance among several analytical models is selected. The magnetic characteristics and predicted temperature rise are compared to the measured results and found to be quite consistent.