Influence of wall insulation material in BPM synchronous servomotor

This paper provides a study of the main stator thermal barrier of an inner-rotor cylindrical brushless permanent magnet (BPM) synchronous servomotor with a concentrated winding configuration. Operating synchronous servomotors over continuous periods requires efficient thermal distribution of heat within the motor and also efficient dissipation of heat away from the motor. This is necessary to ensure that motors are running at cooler temperatures and hence provide optimum overall performance and better operating characteristics. Problems which may result if this is not achieved include demagnetising of the permanent magnets, burn-out of the windings, localised hot-spots and a consequent reduction in the operating life of the motor. Optimum performance and high efficiency requires investigation of the numerous machine parameters which necessitates a model that can be used to interpret how the characteristics interact and affect the output performance. The two motors used for this investigation were 12/10 slot/pole servomotors with concentrated winding configurations. Each servomotor was loaded and run up to the winding reference temperature at different speeds. The temperatures of the motor body parts for different wall insulation papers were recorded and compared with predicted values obtained from data using Motor-CAD software and an analytical model. Analysis and test results have been provided of the servomotor performance and thermal conductivity for two different main wall insulation materials.