Patent GB-642447-A (GB)
Title: A circuit connection for the compensation of shunt multiphase commutator machines
IPC: H02K27/16
Filed: 1947-12-30
Abstract: 642,447. Automatic speed control systems. MORAVIAN ELECTRICAL ENGINEERING WORKS, and KLIMA, V. Dec. 30, 1947, No. 34657. Convention date, Sept. 20, 1946. [Class 38 (iv)] [Also in Group XXXVII] In order to obtain speed control and phase compensation of a polyphase shunt commutator motor a voltage having the following components is introduced in its rotor: (A) Voltage component produced by the secondary winding 6. This component is constant but has such a magnitude and phase as to cause the no-load current to flow in the rotor 2 at synchronous speed. (B) Voltage component produced by the tapped secondary winding 10. This component is regulated automatically, e.g. by means of a tachometer dynamo driven by the rotor 2, a relay and a servomotor, in order to maintain normal rotor current according to the load at synchronous. speed. (C) Voltage component produced by the tapped secondary winding 4. This component is adjusted to obtain different no-load speeds with unchanged rotor current. (D) Voltage component produced by the tapped secondary winding 8. This component is also regulated according to the load. The brushes 13, 15 of the secondaries 4, 8 of the transformers 3/4, 7/8 respectively are linked and move together, and the brushes 14, 16 of the corresponding secondaries 4, 8 are also linked, but the movement of the latter is in opposite direction to that of the brushes 13, 15. Also the brushes 17, 19 of the secondaries 10, 12 of the transformers 9/10, 11/12 respectively are linked, and the brushes 18, 20 of the corresponding secondaries 10, 12 are also linked and move simultaneously in opposite direction. The primaries 5, 9, 11 of the transformers 5/6, 9/10, 11/12 respectively are divided and arranged on two cores in order to attain in the respective secondaries 6, 10, 12 induced voltages having a phase displacement with respect to the main voltages. The winding 12 supplies the primary 7 of the transformer 7/8. The windings 6, 10, 8, 4 producing the four components A, B, D, C of the voltage introduced in the rotor 2 are connected in series with the rotor 2. Fig. 2 shows a modification in which a double-wound induction regulator 3/4 is used instead 'of the regulating transformer 3/4 used in Fig. 1. Two transformers are used, one having a primary 5 with two secondaries 6, 12. The latter is variable and supplies the primary of the second transformer. One secondary 10 of the second transformer produces said voltage component B and a second secondary produces said voltage component D and is in series with a winding of the induction regulation 3/4. The secondary winding 6 of the first transformer, the winding 4 of the induction regulation 3/4 and the winding 10 of the second transformer are in series with the rotor 2. In a further modification, automatic regulation is obtained in dependence on constant wattless current, by using a small 1-phase commutator motor, the rotor of which is fed from a current transformer having a large air gap with its primary carrying a current proportionate to the stator current of the 3-phase shunt commutator motor. The rotor of the 1-phase commutator motor is adapted to adjust the number of turns of the winding 4 of the regulating transformer 3/4.