GB190823396A - Improvements in the Generation of Electrical Power, and Means of Speed Regulation in Electrical Propulsion of Ships, Railway, Tramway, or other Road or similar Vehicles, Locomotives, Trains, and the like. - Google Patents

Abstract

23,396. Durtnall, W. P. Nov. 2. Motor road vehicles; locomotives.-Consists in arrangements for generating polyphase currents of varying frequency by a prime mover running at constant speed, whereby variable speed may be given to motors for propelling road or rail vehicles or locomotives &c. The armature B, Fig. 2, of the alternator C is keyed to the constant-speed driving-shaft A, which also carries the rotor H of a frequency transformer and generator I, the stator of which supplies the working induction motor K. The stator and rotor windings C, H may be connected so that the field of the transformer rotates either in the same or in the opposite direction to that of the rotor H so that the current taken from the stator I will have a frequency either greater or less than that of the generator C by an amount depending on the number of poles in the transformer. The rotation of the field is reversed by changing over two of the phases between the generator and transformer, as by means of a throw-over switch 2, Fig. 4. This Figure, which shows the application to a vehicle having a motor on each axle V, also shows a switch 1 whereby the motors K may be directly coupled to the generator. The generator is preferably excited by a series machine E, the field E<1> of which is short-circuited in order to reduce the generator voltage to zero when the connexions are being changed. In addition to the frequency corresponding to the direct connexion and the two in which the transformer is used, a fourth may be obtained by taking direct current from the generator, as by means of a commutator, and leading it to two of the transformer slip-rings. Intermediate frequencies may be obtained by rotatably mounting the armature C, as shown in Fig. 4, and providing a band-brake T, whereby its speed relatively to the rotating magnet may be controlled and the speed of the motors K thus continuously varied. The armature C may also be separately driven in the opposite direction to that of the poles B, for raising its frequency and voltage. By employing motors with stators wound for two speeds, the number of available set speeds may be doubled. Several transformergenerators may be used, each with its own prime mover, as shown in Fig. 6, in which the alternator B, C and two transformer-generators I', H' and I<2>, H<2> are connected in cascade, the stator I<2> being connected either directly to the mains W by a switch X or through a step-down transformer Z, through which energy may be tiken to cause the machines to start their prime movers.