Experimental Self-Sensing Results for a Magnetic Bearing

Experimental results are presented for a self-sensing magnetic bearing system operated in both the linear and saturation regions. When the magnetic actuator operates exclusively in the linear region, a simple, inexpensive analog estimation technique is implemented. When operating conditions are expected to drive the bearing into magnetic saturation, a digital-analog hybrid estimator is introduced. It follows that expected operating conditions of the magnetic bearing system determine the necessary complexity of the position estimator. Further, the performance of the analog hardware plays a critical role in the operation of the estimator from the perspective of signal gain and phase. Such hardware issues, as they relate to estimator performance, are discussed. Recommendations for improved estimator performance in conjunction with reduced estimator cost and complexity follow.