A Novel Control System for a Direct Drive Linear Permanent Magnet Actuator with Intrinsic Position Hold

Abstract

A novel control and mechanical system design of a linear direct drive permanent magnet actuator is presented. The actuator consists of a Halbach permanent magnet array for the moving part and a two-phase air core stator winding. The magnet assembly is clamped to the stator with springs that maintain the actuator in a fixed position when no power is applied. By applying a sequence of controlled current pulses both separating and propelling forces are generated. A prototype of the actuator was built. The control system was developed and tested with the actuator prototype. The proposed control algorithms require neither high computational capacity of the hardware nor high resolution velocity information. A model was developed to assess the control system performance. The control system design and associated test results are discussed.