BEMF characteristic analysis of IPM type motor according to demagnetization pattern of permanent magnet

This paper is analyzed on back electromotive force harmonic characteristic in interior permanent magnet type brushless DC motors according to demagnetization patterns. Demagnetization patterns consist of equality, inequality, and weighted demagnetization. In addition, we used the same pole-slot ratio with different pole-slot numbers models and different pole-slot ratio with different pole-slot numbers model. Furthermore, we performed analysis of flux linkage, back electromotive force, and harmonics of back electromotive force according to demagnetization patterns. In conclusion, we propose detection technique of irreversible demagnetization condition using back electromotive force harmonics characteristic of an interior permanent magnet type brushless DC motors.