Model-Based Commutation of a Long-Stroke Magnetically Levitated Linear Actuator

This paper concerns a commutation and switching algorithm for multi-degree-of-freedom (DOF) moving-magnet actuators with permanent magnets and integrated active magnetic bearing. Because of the integration of long-stroke actuation and an active magnetic bearing, DQ-decomposition cannot be applied. Therefore, these actuators are a special class of synchronous machines. A newly developed model-based commutation algorithm for linear and planar actuators enables long-stroke motion by switching between different sets of coils. Moreover, the ohmic losses in the coils are minimized. Three different versions of the algorithm are compared and successfully implemented on a three-DOF magnetically levitated linear actuator.