Coupled thermal and electromagnetic analysis of a permanent magnet brushless DC servo motor

This paper demonstrates, using a flange mounted brushless permanent magnet DC servomotor by way of an example, how an iterative solution of the equations governing the thermal, electrical and magnetic processes can be used to estimate the temperature distribution and hence the performance of a machine more accurately. Details of the test motor are given. Phase current waveforms and their RMS values are obtained from a dynamic simulation of the PWM controlled drive, which in turn enables the iron and copper losses to be calculated under any specified load condition, with due account of the effect of temperature on the winding resistance and the magnet demagnetization characteristic, and thus the induced EMF waveform. >