Servovalve drive electronics improvements

Abstract

The present invention provides a circuit for obtaining higher accuracy and total system response for complex mechanical impedance loads, such as earthquake simulators, and in particular to compensate for limitations in controlling the actual valve spool displacement and adequately stabilizing and controlling it at high frequencies. The improvement circuit includes a state variable filter to extend the band width of servovalve actuation frequencies by adding a lead compensation signal compensating for servovalve hydraulic responses. The output of the first filter circuit then in turn feeds a summing junction where the spool displacement feedback is provided, and the output of the summing junction or circuit is provided with the output from an additional filter which cleans up the signal by filtering out noise and insures that the phase of stabilizing signals is proper. The final input signal that is then fed into a unique drive system utlizing two amplifiers connected as current pumps to independently drive the electrical motor coils that in turn drive the valve spool to insure adequate current for driving the spool in opposite directions at high frequencies.

Dependencies are inferred from the claim text.