Patent GB-680289-A (GB)
Title: Improvements relating to control systems for electrically propelled vehicles
Inventor: ABBINK-SPAINK JOHANN HERMANN
IPC: H02P5/68
Filed: 1949-08-26
Abstract: 680,289. Control of D.C. motors. ENGLISH ELECTRIC CO., Ltd. Aug. 28, 1950 [Aug. 26. 1949], No. 22235/49. Class 38 (iii) [Also in Group XXXV] In an engine-electric power transmission system for a vehicle wherein constant engine speed and loading is maintained by a generator field regulator controlled through a servo-motor by an engine-driven governor, and wherein the regulator also initiates field weakening of the traction motors when load conditions permit, the regulator is arranged for complete rotational movement, part of which movement is effective to control generator excitation, the remainder of the movement effecting first a reduction of generator excitation and then field weakening of the traction motors, provided a predetermined motor current is not exceeded at the reduced generator excitation. In the arrangement shown, traction motors 2, 3, having diverter resistances 28 to 31 for their fields 2a, 3a, are supplied from a generator 1, the field 1a of which is manually controlled when a controller 6 is in any of its first three notches, but which in its fourth position closes a switch 6h to energise a relay 24 which, through a contractor 21, puts the generator field under automatic control of a regulator 7 driven by a reversible servomotor 19, 19a, 19b controlled by a governor 22. Assuming switch 5 to be in the upper (or "running"), position and the engine to be underloaded the governor will close contact 22a to energise relay 23 which causes the servomotor to start up and rotate in an anticlockwise direction the arm 7t of the regulator. Resistance is progressively cut out of the generator field circuit by the sequentially operated contacts 7k to 7s as the arm rotates, the arm stopping when contact 22a opens upon sufficient resistance being cut out for the generator to become normally loaded. If the engine now becomes overloaded the governor operates contact 22b and relay 20 starts up motor 19 in the reverse direction to increase resistance in the generator field circuit. If the engine is underloaded with all generator field resistance cut out, arm 7t moves past contacts 7s and opens limit switches 7a, 7b to break the energising cirucit of relay 21. Relay 23 is now energised over contacts 21e, 21g, so that the servomotor continues to drive the arm 7t in an anti-clockwise direction, thereby effecting the following operations:-firstly, opening of contacts 7s to reduce generator excitation; secondly, actuation of relay 26 (over contacts 7d) to connect diverters 28, 29 across the traction motor fields-subject to non operation of a current overload relay 27 in series with the field 2a; and thirdly, actuation of relay 25 (over contacts 7e), if so allowed by current overload contacts 129a to introduce the other motor field diverters 30, 31. The governor regains control of the servo-motor when arm 7t reaches the position shown and re-energises relay 21 over contacts 7g. Switch 5 is moved into its lower position for rheostatic braking of the traction motors by fan-cooled resistors 17, 18, the regulator 7 then being controlled by a manual switch 11 (over relays 20, 23) to determine the amount of braking.