GB514789A - Improvements in electric motor control systems - Google Patents

Abstract

514,789. Field control of D.C. motors; varying E.M.F. ENGLISH ELECTRIC CO., Ltd., and CORNER, H. S. POUND-. May 16, 1938, No. 14552. [Class 38 (iii)] One or more compound-wound motors 1, 2, are connected to a source in series with a machine 3 which bucks or boosts the supply voltage and each motor has an additional field winding 1d, 2d, which is connected in series with at least one motor and in parallel with the booster. Thus with a decrease of motor speed the excitation increases, and vice versa. The field windings 1d, 2d, may be used only during regenerative braking of the motors. The machine 3, which is driven by a machine 4, may be excited as described in Specifications 509,041 and 509,884 so as to accelerate and regeneratively brake the motors with a predetermined armature current. When the motors have been accelerated up to the supply voltage they may be transferred to the supply and subsequently retransferred as described in Specification 509,138 and while they are connected only to the external source the machine 3 may supply the separately excited fields 1c and 2c, or the additional fields 1d and 2d, and a machine driven by the motors may control the excitation of the machine 3 to give a motor excitation which decreases with increase of speed as described in Specification 509,239. During regenerative braking switches 5 cut out sections 1b, 2b, of the motor series fields. The motors 1, 2, may be connected both on one side of the machine 3, and the fields ld, 2d, could be connected to the armature terminals of the machine 3.