The Effect of Magnet Temperature on Speed, Current and Torque in PMSMs

In this study, the effect of magnet temperature on speed, current and torque in permanent magnet synchronous motor was investigated. First, the demagnetization curves of Neomag S 28VC class magnet related to different temperatures, which was used for MCS06C41 coded motor of Lenze Company, were approached. A mathematical expression was achieved to calculate the remanence value for any temperature using these curves and curve fitting method. Then, a simulation was made according to the field oriented vector control method in MATLAB/Simulink using real motor and driver parameters. The mathematical expression that gives the change of magnetic flux related to the temperature influence was included in the modelling. In this way, the change of the speed, current and torque for different magnet temperatures were made observable. Six simulations were made with 25 degrees C increase from 25 degrees C to 150 degrees C to observe the effect of the temperature on the motor much better. The simulation results have clearly demonstrated the effects of the increase of the magnet temperature especially on the current and torque.