LVIII. Permanent magnets.—III. On magnetic decay (continued)

Permanent Magnetic Synchronous Motor Control System based on ADRC

Permanent magnetic synchronous motor (PMSM) is a strong coupling and non-linear system. In the PMSM speed-regulation system, PID controller is the conventional one, it is difficult to decide the parameters of PID. Moreover, the performance of PID controller is not very well in large disturbance. In the paper, the Active Disturbance Rejection Controller (ADRC) is applied to the PMSM speed-regula...

Permanent magnets and hard magnetic materials

This review deals with the definition and development of hard magnetic materials with special emphasis on more recent developments in this field. After discussing the fundamental properties of all hard magnetic materials, based on the intrinsic and extrinsic properties, some remarks on the history of hard magnetic materials and permanent magnets are given. The important hard ferrites are only b...

A Novel Permanent Magnetic Angular Acceleration Sensor

Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating s...

Magnetic reversal in Sm2Fe17Ny permanent magnets

Reversal mechanism in permanent magnetic materials

The phenomenon of magnetization reversal in a hard magnet is studied analytically within a framework of a simplified energy minimization model for a two grain system. The transition region ~a domain wall-like moment structure! is found to play a crucial role in nucleating a reversed domain and in the subsequent formation of a domain wall near the grain boundary. This is shown to result in a con...