Contactless Energy Transfer to a Moving Actuator

Most high-precision machines are positioning stages with multiple degrees of freedom (DOF), which often consist of cascaded long- and short-stroke linear actuators that
are supported by mechanical or air bearings. Usually, the long stroke actuator has a micrometer accuracy, while the submicron accuracy is achieved by the short-stroke actuator. To build a high-precision machine, as much disturbances as possible should be eliminated. Common sources of disturbances are vibrations, Coulomb and viscous friction in bearings, crosstalk of multiple cascaded actuators and cable slabs.A possibility to increase throughput, while maintaining accuracy is to use parallel processing, i.e. movement and positioning in parallel with inspection, calibration, assembling, scanning, etc. To meet the design requirements of high accuracy while improving performance, a new design approach is necessary, especially if vacuum operation is considered, which will be required for the next generation of lithography
machines. A lot of disturbance sources can be eliminated by integrating the cascaded long- and short-stroke actuator into one actuator system.

Since most long-stroke movements are in a plane, this can be done by a contactless planar actuator. A contactless planar actuator or planar motor is supported by magnetic bearings that levitate the actuator platform, while controlling all six DOF of the platform. Long-stroke linear
movement in 2D is also provided by the magnetic bearing while small translations in height and small rotations remain possible. Magnetic bearings can also operate in vacuum. Parallel processing requires power on the platform to drive the actuators on the platform. In order to remove as much disturbances as possible, the power transfer needs to be contactless, i.e. without wires from the ground to the platform. A coil topology and geometry for a contactless
energy transfer system is proposed for energy transfer to a planar moving platform. The platform is equipped with permanent magnets and is levitated and propelled by a matrix of coils, which are fixed to the ground. Such a planar actuator is currently under investigation at Eindhoven University of Technology. The aim of this research project is to transfer energy to the moving platform continuously and at every position in order to enhance the functionality of the platform, while maintaining the advantages of operating without contact and cables slabs