| abstract |
Servo control using ferromagnetic core material and electrical windings is based on monitoring of winding currents and voltages and inference of: magnetic flux, a force indication; and a magnetic gap, a position indication. The third order nonlinear servo control is split into nested control loops: a fast non-linear first order inner loop (1636) causing flux to track a target by varying a voltage output; and a slower almost linear second-order outer loop (1650, 1670, 1680) causing magnetic gap to track a target by controlling the flux target of the inner loop. |