Patent GB-190611298-A (GB)
Title: Improvements in Generators, Converters and Alternate Current Motors.
Inventor: FYNN VALERE ALFRED
Filed: 1906-05-14
Granted: 1907-04-11
Abstract: 11,298. Fynn, V. A. May 14. Armatures; dynamos and motors, alternating- current dynamos and motors combined as transformers ; dynamos, regulating field magnets.- Alternating-current generators and motors and rotary converters combine the features of synchronous and asynchronous machines, the object being, in the case of a motor, to provide high starting- torque and high power-factor when running, in the case of a generator to make the machine selfexciting and easily switched into parallel, and in the case of a rotary converter to provide a machine which will start from the alternating-current side with small current, be free from hunting and run with a high power-factor, and which will enable the voltage of the continuous current to be regulated independently of that of the alternating current. Fig. 4 shows the application to a singlephase shunt conduction motor. The stator, which is without defined poles, is provided with windings S1, S2, disposed, in a two-pole machine, at rightangles to one another, and also a winding F, disposed coaxially with the winding S2 and in transformer relation to it. The rotor winding W, of the continuous-current type, is connected to sliprings R1, R2 and to a commutator, on which rest brushes B1, B2, coaxial with the winding S1, adapted to be connected in series with part or the whole of the winding F by means of a switch K. At starting, the winding S2. is connected to the mains, the slip-rings being unconnected. A secondary electromotive force induced in the winding F is impressed on the rotor by means of the brushes B1, B2, starting the machine as a shunt conduction motor. The starting-current can be regulated by the switch K or by a regulating-resistance X, and the armature reaction may be neutralized by shortcircuiting the winding S1 by the switch K1. When full speed is nearly attained, the mains are disconnected from the winding S2 and connected to the slip-rings, the windings S1, S2 being short-circuited. At synchronous speed, the currant flowing from the rotor to the winding F is continuous and can be adjusted to give the best power-factor. The machine then runs as a synchronous motor, while the short-circuited windings S1, S2 enable it to run asynchronously if overloaded. To reduce the voltage at the brushes, the rotor may be wound as shown in Fig. 2, the continuous-current winding W being connected through windings W1, W1<0>, to the slip rings, R1, R2. The windings S2, F, Fig. 4, may be combined into one, as in an auto-transformer. Modifications are described in which the motor starts as a series induction or conduction motor, and in which a three-phase motor is started as an induction motor, the slip-rings being connected to the mains, and the stator winding being short-circuited. Fig. 12 shows the connections of a four-pole two-throw switch for starting a singlephase motor as a self-excited series induction motor and for running it as a synchronous motor. The stator is wound with a three - phase star winding S1, S2, S3, one phase of which is in transformer relation with a winding St, which is connected to the mains at starting and shortcircuited when running. The rotor is provided with a continuous-current winding Wand separate alternate-current windings W1, W1<0>, connected to slip-rings R1, R2. A modification, of the controller type, is also described in the Specification. Rotary converters may be started by any of the methods described, but it is preferable to derive the continuous-current excitation from a separate exciter E, Fig. 14, which may be compounded by a winding m in series with the brushes B1, B2. The rotor may be provided with two windings, wound for different numbers of poles. The winding W1, connected to the slip - rings, is wound for four poles, and the winding W, connected to the commutator, is wound for two poles. The stator is provided with a four-pole polyphase winding S1, S2, capable of being short-circuited, and with a twopole winding F, carrying the continuous-current excitation. By varying this excitation, the continuous-current voltage at the brushes may be regulated independently of the alternating-current voltage at the slip-rings. In a modification, the windings S1, S2, W1 are interchanged. A fourpole continuous-current winding may be added to the stator for adjusting the power-factor, and neutralizing and commutating-pole windings may be added. A further modification is described, in which the stator is wound like a gramme ring, two opposite points being adapted to be either connected to the mains or short-circuited, and two points midway between these being connected to the brushes.