Performance Variation of Ferrite Magnet PMBLDC Motor With Temperature

The price fluctuations of rare-earth (RE) metals and the uncertainty in their availability have generated an increased interest in ferrite magnet machines. The influence of temperature on the B-H characteristics of the ferrite magnet differs considerably from that of the RE magnet, and hence, requires a different approach when deciding their operating point. In this paper, the laboratory measured B-H curves of a ferrite magnet are used for estimating the possibility of demagnetization in a segmented axial torus (SAT) permanent magnet brushless dc (PMBLDC) motor. The B-H characteristics for different temperatures have been used to study the performance variation of the ferrite magnet SAT PMBLDC motor with temperature. A detailed analysis is carried out to ensure that the designed ferrite magnet motor is capable of delivering the specified torque throughout the operating speed, without any irreversible demagnetization of magnets. It has been shown that the ferrite magnet PMBLDC motor operation is influenced by the magnet temperature, and the maximum motor speed for a given load torque decreases as the magnet temperature drops.