Abstract: A control system for one or more dc motors in which thyristor power modules selectively gate portions of half cycles of ac voltage to the motor field and armature windings, has digitally implemented parallel inner control loops for the armature which each generate an intermediate control signal to which proportional plus derivative control action has been applied. Logic selects the intermediate control signal which phases back firing pulses for the thyristor power modules the most for application to a common digital integrator which produces a control signal having proportional plus integral control action. The voltage across each of the thyristors is monitored and used to detect continuous and discontinuous current operation for adjusting integrator gain.