Feedforward compensation of back electromotive force for suppressing rotational motion errors in a magnetically levitated system

摘要

AbstractThe magnetically levitated system, so called maglev system, has been researched and developed with the purpose of vacuum compatibility in the semiconductor industry. In the maglev system, the back electromotive force is inevitably generated when the system moves. The back electromotive force causes force/moment disturbances. Especially, the moment disturbances have negative effect on controlling the rotational motions (θx,θy,θz) whose control bandwidth is low. Therefore, the back electromotive force causes rotational motion errors. The rotational motion errors should be suppressed since they prevent high speed motion of the maglev system due to the rotational motion allowance of sensors. The rotational motion errors are suppressed by compensating the back electromotive force. In this paper, the back electromotive force, the cause of the rotational motion errors, is mathematically found in terms of the mover velocity and element of force-current matrix. A maglev system without the compensation was simulated and the rotational motion errors due to back electromotive force were found. Then, a feedforward compensated system using a mathematically modeled back electromotive force was simulated. It was verified that the feedforward compensation method with the modeled equation could be useful for suppressing rotational motion errors.]]>