Effect of the Incomplete Magnetization of Permanent Magnet in the Characteristics of BLDC Motor

The incomplete magnetization is a frequently occurring phenomenon during the magnetizing process of magnets in precision motors because they use ring magnets which are not segmented. Even a small variance of the incomplete magnetization can make critical changes in the characteristics of motors like cogging torque profiles and the cogging torque profiles play an important part in reducing the noise and vibration of motors. So, the modeling of the incomplete magnetization area of magnets becomes a critical point in the analysis of the precision brushless dc motors. Conventionally, the modeling method of the area is to change the magnitude of the magnetization vector according to position angles in a magnet but the authors propose a novel method for modeling the incomplete magnetization area. This method is compared with the conventional method and verified by the measured cogging torque profile.