Dc motor drive system for winding reel

Claim 1

A DC motor drive system for driving at constant horsepower over an extended speed range a winding reel adapted to coil thereon strip material, said system comprising: a. a plurality of DC main drive motors each having an armature and an associated field, said main drive motors having a combined horsepower sufficient to drive the reel over their rated speed range with the required tension of the strip material coiled on said reel, b. auxiliary DC drive motor means comprising at least one motor having an armature and an associated field, c. coupling means mechanically coupling said main and auxiliary drive motors to rotate together and to drive the winding reel, d. an armature circuit electrically connecting all of the armatures of said main and auxiliary motors in series circuit relation to a source of DC power, e. a first excitation circuit for simultaneously varying the excitation current supplied to the fields of main drive motors, f. a second excitation circuit for separately varying the excitation current supplied to the field or fields of the auxiliary drive motor means, and g. excitation control means responsive to the flow of current in said armature circuit for controlling the relative magnitude of the excitation currents flowing in said first and second excitation circuits to vary the constant horsepower speed of the drive system over a speed range greater than the rated speed range of the drive motors.