US2085940A

US2085940A - Phase control system

Info

Publication number: US2085940A
Application number: US40546A
Authority: US
Inventors: Edwin H Armstrong
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-09-14
Filing date: 1935-09-14
Publication date: 1937-07-06
Anticipated expiration: 1954-07-06

Description

July 6, 1937. E. H. ARMSTRONG. 2,085,940

PHASE CONTROL SYSTEM Filed Sept. 14, 1955 I N VENTOR.

Edw/h H. Armsfronq.

ATTORNEYS.

Patented July 6, 1937 UNITED STATES PATENT OFFICE 2,085,940 PHASE CONTROL SYSTEM Edwin H. Armstrong, New York, N. Y.

Application September 14, 1935, Serial No. 40,546

2 Claims.

may be readily obtained. The general arrangel figure of the accompanying drawing. figure, l represents the input current whose phase it is desired to alter. 2, 3, 4, 5, and 6, i represent three branch circuits each consisting of equal 20 high resistances, 2, 4, and 6. In series with resistance 2 is a capacity 3, in series with resistance e is a resistance 5, and in series with resistance 6 is an inductance I. The impedances of the capacity 3, resistance 5 and inductance l. are all adjusted to be equal in the frequency to be employed. Three vacuum tubes 8, 9, and I have applied to their grids, respectively, the voltages existing across the capacity-3, the resistance and the inductance 1. Three equal 0 resistances H, l2, and I3 are inserted in the plate circuits'of these tubes. Connecting the points A with B and B with C are equal high resistances forming a potentiometer arrangement between these three plates. Connected be- 5 tween the midpoint of the resistance connecting points A and B and the junction point of the three resistances ll, l2, and I3 is a high resistance l6. Similarly connected to the midpoint of the resistance connecting points B and C is 40 a high resistance whose other terminal goes to the junction point of the resistances H, l2, and I3. The output circuit is taken between the junction points of the resistances II, I2 and I3 and point P on the potentiometer. The operation of 45 the system is as follows:

The voltages at the three points A, B, and C taken across the resistances ll, l2, and I3, respectively, are 90 apart from each other, C lead- 50 ing point B by 90 and A lagging behind point B by 90. Since the resistances are all equal and the impedances of 3, 5, and I are equal, the voltages at the points A, B, and C are equal to each other. The resistances l4, l6 and I5, I! are made 55 sufiiciently high with respect to the resistances ment of the system is illustrated in the single In this H, l2 and l3 that their effect on the impedances in the plate circuit is negligible.

By proportioning resistance l6 with respect to the value of resistance l4 it is possible to bring point D midway in phase between points A and B, 5 that is, 45 from either of them and equal in amplitude to either of these voltages. Similarly, it is possible by adjustment of resistance I1 with respect to resistance l5 to produce the same phase and amplitude relations at point'E. These five points on the potentiometer are therefore definitely fixed 45 apart and all of equal amplitude. As potentiometer point P travels along the potentiometer it will pass gradually through any degree of phase relationship which may be desired. The variation in amplitude at those points on the potentiometer which are not definitely fixed will be very slight from the average value, but if it is desired more points on the potentiometer may have their amplitudes definitely fixed and the degree of variation reduced thereby below any desired limits. It will be observed that in eiiect this arrangement corresponds to a tapered potentiometer, the variations in the resistance of the potentiometer compensating for the changes in amplitude which would occur as the pointer is moved around the potentiometer.

. While I have illustrated three voltages spaced 90 apart it will of course be understood that other values of spacing may be used and that where an adjustment of phase of less than 180 is required two voltages may be all that is required. Various other modifications and combinations may be employed without departing from the spirit of the invention. I

I claim:

1. A system for adjusting the phase of an alternating current without simultaneously producing a change in its amplitude, comprising a series of vacuum tubes, means for dividing an 40 alternating current into a series of currents successively difiering in phase by the same amount, means for each of said currents for equalizing the voltages derived therefrom and for selectively impressing them on the input of, a vacuum tube, a tapered potentiometer-and means for connecting the output sides of said tubes to points on said potentiometer diiiering from each other in phase by the same amount, the amount of impedance introduced into the output circuit of each tube by the potentiometer being substantially equal, said potentiometer having means for selectively deriving current therefrom.

2. Apparatus for adjusting the phase of an alternating current without simultaneously profor combining the output voltages of the vacuum tubes; the amount of impedance introduced into the output circuit of each tube by the potentlometer being substantially equal, and means for selecting voltage from said resistance network.

EDWIN H. ARMSTRONG.