Combined Experimental and Numerical Method for Loss Separation in Permanent-Magnet Brushless Machines

Permanent-magnet synchronous machines are a high-efficiency motion solution. As the efficiency bar is raised, it is no longer adequate to consider only the dominant core, dc conduction, and friction losses. The challenge for motor developers experiencing additional losses is determining which of the previously neglected losses is significant for their motor. This research presents a best-fit least-squares approach to loss separation that can be applied to experimental data to highlight the source of additional losses. This is a powerful tool for practical motor designers looking to meet challenging specifications. The proposed technique has been applied to the experimental data from three different prototype motors. Although a simple core model of core loss is used, in each case the losses were classified with a residual of less than 2%. Each loss type (defined by proportionality to speed and current) showed good agreement with the corresponding loss type calculated from finite-element analysis (FEA).