Patent ID: 7026776

Claim:
A method for controlling current in a direct current motor having a back emf constant (k e ) and motor resistance (R s ) comprising the steps of: rotating a motor shaft of the direct current motor with a controller by applying a first voltage across the direct current motor corresponding to a first current value passing through armature windings of the direct current motor; determining a maximum value of current to pass through the armature windings of the direct current motor; receiving a signal corresponding to a desired motor speed (ω) with the controller during said rotating step; first computing a second voltage with the controller to replace the first voltage after said receiving and determining steps and in view of the back emf constant (k e ) and motor resistance (R s ) of the direct current motor; and limiting the second voltage before replacing the first voltage based at least in part on a difference between the maximum value of current and the first value of current to dynamically control current during said operating step.