Permanent magnet flux-biased magnetic actuator with flux feedback

DETAILED DESCRIPTION An object of this invention is to avoid the limitations of the prior art by using permanent magnets to supply a reference bias flux to linearize the force characteristic of a magnetic actuator for a suspended element.
The magnetic actuator generally includes a pair of opposing electromagnets for providing a bi-directional force along a given axis, in combination with flux feedback means which automatically adjusts the opposing bias fields of the electromagnets when the suspended element is moved off the nominal operating point.
Permanent magnets in the electromagnets establish PM flux biasing which eliminates the need for continuous bias currents and thus reduces power dissipation by the actuator while extending the linear range and eliminating minimum bandwidth of the actuator.
The use of a current feedback loop results in even greater control of the resulting actuator force over the extended linear range.