Abstract
This paper addresses novel control strategy for 6 salient-pole active magnetic bearings (AMBs). An AMB is not widely used because of its high cost and dimensions are significantly larger than those of mechanical bearings. Since 6 salient-pole type AMB has less number of poles as compared with usual 8 salient-pole type AMB, it becomes advantageous to a miniaturization and a low cost. However, since the magnetic circuit has not been independent in x and y direction, bearing forces for coil currents become complicated. To solve this problem, two control methods have been proposed; one is a minimum energy control method, which minimizes copper loss in coils, another is a maximum bearing force control method, which generates larger bearing force than that of the minimum energy control method. The minimum energy control method provides low loss and better control performance, but the control program is complex and requires high computing power. On the other hand, the maximum bearing force control method is simple and easy for implementation. In this paper, two control methods are introduced and rotational tests were carried out for comparison. The rotor could rotate up to 17,000 rpm with both controllers. Experimental results shows that the minimum energy control method provides better control performance and less power consumption than those of the maximum bearing force control method.
