Analysis of Temperature Rise in Short-Term High Overload Torque Motor With LPTN Considering Demagnetization and Saturation

Abstract

Periodic short-term high overload operation of robot joint motors can significantly influence the temperature rise of the motors. To accurately analyze the temperature rise of the joint motor under periodic overload conditions, this paper develops a Lumped Parameter Thermal Network (LPTN) model that considers permanent magnet demagnetization, saturation, cross saturation, and temperature effects. First, the impact of temperature rise on permanent magnet demagnetization is considered, and its effect on the ultimate output torque of the motor is analyzed. Subsequently, an electromagnetic torque model accounting for thermal effects and magnetic circuit nonlinearity is established. Based on this model, an LPTN that considers temperature and permanent magnet demagnetization is developed. The accuracy of the thermal network model is validated through finite-element analysis. Finally, an experimental platform for motor temperature rise is constructed, and experiments are conducted. Experimental results indicate that the temperature estimation errors of both methods are within 5% under both single working conditions and periodic overload conditions, meeting practical engineering requirements. It provides a crucial reference for the temperature field analysis of motors under periodic short-term high overload conditions.