Patent ID: 6914422

Claim:
A current monitoring and control circuit for monitoring current flow through a control winding, said monitoring and control circuit comprising: a magnetic amplifier, said magnetic amplifier including a first gate winding and a second gate winding electrically coupled in series and responsive to an AC drive voltage, said magnetic amplifier further including a bias winding responsive to a variable bias potential, said bias winding and said first and second gate windings being magnetically coupled to the control winding, said magnetic amplifier providing a gate voltage; and a feedback circuit, said feedback circuit being electrically coupled to the bias winding, said feedback circuit being responsive to a reference voltage and the gate voltage, said control circuit changing the bias potential in response to changes in the control current so that the gate voltage remains substantially constant at a fixed operating point, said bias voltage providing a bias current through the feedback circuit that provides an output voltage indicative of the direction and magnitude of the current flow through the control winding.