Magnetic Field Analysis of Irreversible Demagnetization in Brushless DC Motor According to the Dynamic and Static Characteristic

This paper reports on the development of dynamic characteristic analysis algorithm for irreversible demagnetization in brushless dc motors. In general, in static characteristic analysis of irreversible demagnetization, only the d-axis magnetic flux components are considered. As a result, this type of analysis cannot be used to accurately analyze the characteristics of irreversible demagnetization while the motor is actually being driven. Thus, we developed a dynamic characteristic analysis algorithm that we utilize to compare the static and the dynamic characteristic analyses of irreversible demagnetization. Consequently, we propose a maximum current limit for motor designs that reduces the impact of irreversible demagnetization.