Digital Control of Magnetic Bearing with Rotationally Synchronized Interruption

For the purpose of clean and high speed rotation, an actively controlled magnetic bearing has been developed. Recently, a digital control system has been used to get high performance by using the state variable feedback. However, the gyroscopic or inductive mutual effect of a rotating disc sometimes makes the high speed rotor unstable. This paper introduces a new digital control scheme which utilizes the rotational interruption. The standard PID control is carried out with the constant time interval interruption, while the rotational interruption subroutine carries the static error cancellation and the cross coupling feedback to compensate for the undesirable mutual effect. This scheme is applied to a single rotor bearing system, and its capability is tested.