高精度磁気軸受の研究 (第2報)

オブザーバの変位推定限界とセンサレス高精度位置決め

抄録

The positioning and rotational accuracies of ordinary magnetic bearings are not high enough because of low accuracies of displacement sensors. To improve their accuracies, there are two possible methods; use of expensive and precision sensors, or sensorless control by using an observer. In this report, first the mechanism which had electromagnetic characteristics suitable for sensorless displacement measurement by an observer was introduced. Then an observer was designed according to the dynamic model of the mechanism identified through measured frequency characteristics. In order to realize accurate displacement estimation, the dynamic model of the mechanisms was modified so that the estimated displacement coincided with the output of a precision sensor. The experimental results show that the resolution of estimated displacement and sensorless positioning were 150nm and 200nm respectively and the positioning range was above ±100μm by using the modified observer.