GB845512A - System of supplying current to electric motor driving arrangements - Google Patents

Abstract

845,512. Control of several D.C. motors. RESEARCH INTEREST Ltd. (Montrose- Oster, L. E. W.). Feb. 26, 1957 [Feb.29, 1956], No. 6339/56. Addition to 723,678. Class 38 (3). Dynamo-electric machines M(I), M(II) are capable of operating both as motors and generators, and are mechanically coupled to the input shafts of a differential gear. The machines rotate in opposite directions and, when rotating at the same speed, the output member of the gear is stationary, the output member developing a high torque by increasing the speed of one machine and simultaneously braking the other. The machines are connected to a system comprising three generators, the generator DC having a constant voltage, and the generators DA, DB having voltages which are variable between maximum positive and negative values. Under idling conditions, the generators DA, DB are not excited, and the generator DC supplies equal currents to the two machines which turn at equal speeds in opposite directions. If the machine M (I) is to develop maximum torque to drive the cage of the differential in one direction, the voltages of the generators DA, DB are increased so that the voltages of generators DA, DC are added together to increase the terminal voltage of the machine M (I). At the same time, the voltage of generator DB is deducted from that of generator DC, so reducing the terminal voltage of the machine M (II). This causes the machine M (I) to operate as a motor supplied from the generators DA, DB, DC, as well as from the machine M (II) which now acts as a generator. To reverse the direction of rotation of the output member of the differential, the excitation of the generators DA, DB is reversed. The generators DA, DB may be replaced by a single generator having two separate armature windings, or a single winding associated with a voltage divider. The generators DA, DB, DC may be driven in common by a constant-speed motor, or the generator DC may be replaced by other sources of constant voltage. The field windings of the generators DA, DB may be supplied from the generator DC through current regulating and reversing means, the said means associated with the respective generators being coupled for simultaneous operation.