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Use of compensating magnets to reduce thrust imbalance in cylindrical linear pulse motors
Author(s) -
Sanada Masayuki,
Takeda Yoji,
Ishikawa Sadao,
Hirasa Takao
Publication year - 1993
Publication title -
electrical engineering in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.136
H-Index - 28
eISSN - 1520-6416
pISSN - 0424-7760
DOI - 10.1002/eej.4391130413
Subject(s) - thrust , magnet , stator , linear motor , control theory (sociology) , mechanism (biology) , point (geometry) , electromagnetic coil , physics , mechanical engineering , engineering , mechanics , electrical engineering , computer science , mathematics , geometry , control (management) , quantum mechanics , artificial intelligence
A linear pulse motor (LPM) has many advantages for a high‐accuracy positioning actuator because it has linear motion without any mechanical link. The flat‐type LPM generally is used in many industrial applications. However, it has a disadvantage in that the mover support mechanism becomes complex and heavy because the attraction force between the stator and the mover is very large. As the attraction force is balanced in the cylindrical structure, the cylindrical LPM is allowed to have a simple and lightweight support mechanism. The inset magnet‐type cylindrical LPM, which has a permanent magnet between the A‐phase and B‐phase stator, has such merits as a magnet of simple shape and a reduction of the motor diameter. Its weak point is that thrust unbalance occurs because the magnetic flux pass of the outer poles is longer than that of the inner poles. The thrust unbalance decreases the pull‐in thrust force and increases the positioning error. This paper proposes two practical methods to improve the thrust unbalance: 1) the exciting current adjustment; and 2) the method with compensation permanent magnet. These effects are examined with theoretical and experimental results.