In-situ magnetization of permanent magnet machines considering magnetizer capacity and connection types

There are frequent complaints from the local industry who produces rare-earth PM machines and is troubled by assembly problem. The high magnetic intensity of pre-magnetized rare-earth magnets slows down the production. The in-situ magnetization is considered to be a useful solution, which employs the own stator of the PM machine to magnetize its rotor after complete assembly. During the development of this technique for industry, one of the major problems is that the industry does not realize the match between the magnetizer and the machine windings. Therefore, this digest presents the study on the effect of various types of connections between a magnetizer and electric machine windings such that rare-earth PM machines can be fully magnetized using in-situ magnetization. This would be helpful for the industry to identify suitable magnetizer capacity for magnetization of their electric machines if the in-situ magnetization (ISM) is used. In this study, the wye-connected windings of the target PM machine are used to magnetize the rotor. There are various ways to connect the stator windings to a magnetizer for ISM. The connections are required to produce the flux patterns that correctly magnetize the rotor. Also, different connections form different line impedances that consequently affect the total magnetizing current. Thus, the magnetizer capacity should be considered. There has been research about the ISM technique but little looked into this issue. In this digest, FEA is used to simulate the ISM and the machine performances. A PM generator prototype is in-situ magnetized and then loaded to the rated point so that the presented ISM magnetizing connections and the required magnetizer capacity can be validated.