Patent GB-190629482-A (GB)
Title: Improvements relating to Electrically Propelled Railway & Tramway Vehicles.
Inventor: COOPER WILLIAM
Filed: 1906-12-27
Granted: 1907-06-20
Abstract: 29,482. Cooper, W. Jan. 3, [date applied for under Patents Act, 1901]. Motor control systems.-Relates to electricallypropelled railway and tramway vehicles, and consists in means for preventing slipping of the forward wheels of reach truck while starting or accelerating in either direction, when the weights upon the forward and rear wheels are unevenly distributed owing to the tractive effort exerted by each truck tending to tilt,it. This is effected by reducing the strengths of the field magnets On the forward motors by means of shunt circuits, which are closed during the starting period when all the motors are in series, so as to reduce the torque exerted by the forward motors relatively to that exerted by the rear motors. The shunt circuits are afterwards automatically opened so as to re-establish equality between the torques exerted by the several motors when their circuits are connected in multiple rotation for running at higher speeds. Fig. 1 shows diagrammatically the arrangement of circuits and controller on the vehicle shown in Fig. 2, which has two trucks each carrying two motors of the, series type, the armatures 1, 2 driving the two axles of one truck, and the armatures 3, 4 the axles of the other truck. The circuit arrangement of these motors is dependent upon a controller 9, which regulates directly a number of electrically-operated switches through the connexions shown in thin lines, the connexions for the main current being shown in thick lines. The controller may occupy any of the positions a ...j for running in one direction, or k...t for running in the opposite direction. When the controller is in the first starting position a, current from the battery 10 is supplied from a contact 11 to contacts 13, 14, and 139, and also through the ring segments 138, 24, which are electrically. connected, to the contacts 25, 141 The contact 141 supplies curtent to operate switches 45, 46, which close the shunt circuits 53, 54 for the field magnets 6, 8 of the forward motors of each truck. The contacts 13, 14, 139 supply current to operate the switches 17, 20, 21, 23, the circuit being completed through the conductor 140. The contact 25 similarly supplies current to operate the switches 142, 39, 41, 43, 38, 40, 42, 44. Energy is thus supplied from a line conductor 47 through switches 17, 142, armature 1, switch 38, field magnet 5, and resistance 145, and similarly in series through the remaining three motors, excepting that the current also passes through the shunts 53, 54 of the field magnets 6, 8. connexion is made finally to the opposite line conductor 52. As the controller is moved through the remaining starting positions b c, d, e, the resistances 145, 49, 50, 51 are short-circuited in succession by the switches 55, 56, 57, 58. When the controller is moved to the position f, the contact 141 is disconnected from the ring segment 24, so that the shunts 53, 54 are cut out, and the several motors all exert equal torques. At the same time, some of the switches above referred to are opened and others closed, so that the motors 1, 2 are connected in series across the line conductors 47, 52, the other motors 3; 4 being similarly connected. For the remaining positions of the controller, g ... j, the resistances in the circuits are varied,.and in the position i the motors are all connected in parallel across the conductors. When the vehicle is running in the opposite direction, the controller is moved through the positions k ... t. The contact 81 is in this case energized instead of the contact 25, the direction of the current through all the armatures being thus reversed, When the controller is in the starting positions k ... o, the contact 82 is energized instead of the contact 141, so that current passes through the shunts 103, 104 of the field magnets 5, 7. A modification is described, applied to a single-truck vehicle having two motors, in which a separate reversing-switch is provided, and the supply of current to the motors is regulated directly by the controller. A single resistance is used for shunting either of the field magnets according to the direction of, travel.