Modeling and Control of a New Horizontal-Shaft Hybrid-Type Magnetic Bearing

This paper reports on the development of a new horizontal-shaft hybrid-type magnetic bearing system. The bearing system will be used for a horizontal-shaft machine. The rotor is levitated due to the repulsive force between a stator and a rotor permanent magnet (PM). A lower cost and higher radial stiffness have been achieved by using a strontium-ferrite magnet on the rotor and an Nd-Fe-B PM above and below the rotor magnet. A finite-element analysis was performed to calculate the levitation force and radial stiffness. An upper stator magnet subtending an angle of 45° provides the best compromise between a large levitation force and radial stiffness. A model for the horizontal-shaft hybrid magnetic bearing system has been developed and includes the effect of the rotordynamics and the electromagnetic forces. An integral servocontroller was designed to stabilize the axial position. The controller has been implemented in a digital signal processor. Experimental results performed on a prototype system are in agreement with the theoretical results.Third IEEE International Workshop on Electronic Design, Test and Applications, DELTA 2006; Kuala Lumpur; Malaysia; 17 January 2006 through 19 January 2006; Category numberP2500; Code 6920

Application of the Repulsive-Type Magnetic Bearing for Manufacturing Micromass Measurement Balance Equipment

Many applications of the single-axis controlled repulsive-type magnetic bearing have been proposed earlier. However, both passive and active magnetic bearings are employed in most of such systems. In this paper, a new permanent magnet (PM) repulsive-type micromass measurement system is developed. The repulsive forces of the PM section are used effectively to keep the radial direction stable where the electromagnets, control circuits, and peripheral devices needed for controlling the unstable direction are simplified. The configuration, control design, and operating characteristics of the proposed system have been presented

Application of the Repulsive-Type Magnetic Bearing for Manufacturing Micromass Measurement Balance Equipment

金沢大学環日本海域環境研究センター生体機能計測研究部

Sub-Optimal Control Law for Active Magnetic Bearings Suspension

This paper deals with the comparison of three types of sub-optimal control law for the stable levitation of a turbojet shaft, sustained by two radial active magnetic bearings (AMBs). Shaft is considered rigid for the procedure simplification. The utilized approach leads to development of different sub-optimal control laws to use in speed-varying simulations in the angular speed of the shaft. The first control matrix is obtained by explicit relationships of the parameters of the control law vs. speed, obtained using a curve-fitting procedure neglecting the speed-varying elements out of the main diagonal of each single block constituting the entire control matrix. The second control law is obtained by control matrix set to zero angular speed during speed-varying simulations. The third control matrix is obtained by the second neglecting the elements out of main diagonal. Time response to the step input shows difference in performance of the AMBs when varying the control law. All control laws are tested by means of simulation. The study allows showing like a polynomial representation of the control matrix, developed to the variation of angular speed, is able to maintain stable the magnetic levitation