US2513983A - Alternating voltage regulator - Google Patents

Description

July 4, 1950 O. H. WlNN ALTERNATING VOLTAGE REGULATOR Filed June 13, 194'? A.c. INPUT Fig.2. I22- 75, I F1 .5. I20 2 g A EH9 '2 n9 E, "a g 3- S J 1 0 n7 2 n1 R Sue l-!l6- 2 Bus ||5- o 9' QM 'ilm- I00 I05 no us :20 125 I250 '35 A.C.INPUT VOLTAGE (ans) 0 /.o 2.0 5.0

OUTPUT AHPERES (RMs) Inventor: Oliver H.\'Vi-nn,

His Attorney.

Patented July 4, 1950 2,513,983 anrnanarmc voLrAcn uncommon OIiVerH. Winn, Baldwinsville, N. Y.,

General Electric Com New York nsaignorto pany, a corporation of Application June 13, 1947, Serial No. 154.3

8 Claims. (01. 323-89) My invention relates to alternating voltage regulators and particularly'to an electronic voltage regulator for minimizing load voltage variations due either to input voltage variations or load current variations.

It is an object of my invention to provide an improved alternating voltage regulator which provides a regulated output voltage, the root-meansquare value of which is constant within very small limits. This is a particularly desirable type of regulating action for an electric heating load which is to be maintained at constant temperature, for example, since it is well known that the heating effect is dependent upon the root-meansquare (hereinafter abbreviated to R. M. S.) value of the applied voltage rather than the peak or average values of applied voltage.

It is a more specific object of my invention to provide an improved electronic alternating voltage regulator having no moving parts and which will maintain a substantially constant B. M. S. voltage output independent of changes in the wave form of the applied voltage.

Still another object of my invention is to provide an improved all-electronic alternating voltage regulator which is simple and energized entirely from the source of current to be regulated.

Still a further object of my invention is to provide an improved alternating voltage regulator which is particularly suitable for energizing an electric heatin loadand which tends to maintain constant absolute load temperature independent of ambient temperature changes. Although it is not limited thereto, my invention has particular utility in a regulated voltage supply for the tube filaments of a radio transmitter, receiver, or similar electronic apparatus. I

The features of my invention which I believe to be novel are set forth with particularity in the appended claims. My invention itself, however, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which Fig. 1 is a schematic circuit diagram of an alternating voltage regulator embodying the invention; and Figs. I

2 and 3 are curves illustrating the electrical per formance of a particular voltage regulator embodylng the invention. I

The regulator of Fig. 1 has a pair of input terminals l0, adapted to be connected to a suitable source of alternating current power, and a pair of output terminals l I adapted to be connected to an alternating current load. The lower terminals I0--ll may be grounded, as illustrated. The load voltage regulation is accomplished by means of a saturable reactor l2, which may be of conventional design, connected in series between the upper pair of terminals ll-H. The reactor I2 is conventionally represented as comprising a pair of reversely-connected windings [2a and I21) and a. direct current saturating winding l3. As is well known, the effective reactance between the terminals I4 and I! of the reactor I2 is readily varied by varying the direct current supplied through the saturating winding l 3.

In the illustrated embodiment of Fig. 1, it is desired to have the output voltage at terminals ll substantially the same as the input voltage at terminals l0. Since the reactor l2 introduces a certain voltage drop between the input and output terminals, this is compensated by means of a step-up voltage transformation in certain of the windings of a transformer I connected to the 'load side ii of the reactor l2. As illustrated, the transformer l6 includes a shunt primary winding section lBa connected from point [5 and through a tap I! to ground, and a series secondary winding llib connected between oint 15 and the upper output terminal II. The polarity of the voltage induced in the winding I Go is such as to oppose the voltage drop through the reactor l2. Transformer It also comprises an additional auto transformer section We and a further winding Hid, the functions of which will become apparent as the description proceeds. In some cases it may be desirable to omit the series winding |6b and to connect the upper output terminal H to a proper voltage point on the autotransformer secondary winding lie.

The regulating action is accomplished by varying the average value of direct current through the saturating winding I3 as a function of the R. M. S. value of voltage at the load side of the regulator. The circuits for accomplishing this in accordance with the invention comprise the electron discharge devices 2|, 2| and 22 and their interconnecting circuits, including a resistance bridge 23, now to be more particularly described.

The resistance bridge 23 comprises a pair of diagonally opposite resistance arms R1 and R: which have substantially constant resistances over the voltage control range. The other pair of diagonally opposite bridge arms Br: and Rm consist of non-linear resistances which vary substantially as a function of the R. M. S. value of applied voltage over the control range. This type of resistance characteristic may be provided by' various materials and resistor constructions.

known to the art, but it is very conveniently pro- 3 vided in this case by utilizing the cathode heating filaments 24 and 25 of the discharge devices 2| and 22, respectively. These filaments then perform the dual function of heating the cathodes of these discharge devices and providing the desired resistance arms for the control bridge. The bridge balance may be adjusted by moving contact l8 on resistor. R1 to short-circuit a selectable portion of R1. An alternating voltage E1, proportional to the output load voltage, is impressed across one diagonal 262'| of the bridge 23 from the transformer winding lid, and an alternating error voltage E0, utilized to efiect the regulating action, is derived from the other diagonal 28-29 of the bridge. Terminal 29 is grounded, as shown, and the alternating error voltages appearing between point 28 and ground are impressed upon the grid circuit of thetwo-stage voltage amplifier comprising the discharge device 2| and its associated circuits.

Discharge device 2| is represented as a dual triode having a first stage comprising the left-L hand triode section -2 la and a second stage com prising the right-hand triode section 2 |b.- These arecapacitance-resistance coupled in conventional manner and the. voltage output of the right-hand section Zlb is further coupled to the control grid of the discharge device 22, repre sented as a pentode amplifier. Suitable anode operating potentials *for device 2| and grid bias potentials for the devices 2| and 22 are supplied circuits. The device 20 is represented as a dual diode having a left-hand diode section 2012 connected in a conventional half-wave rectifier cirtapped portion of the transformer winding 16d.

as shown.

An alternating anode operating potential is supplied to the discharge device 22 from the autotransformer Ida-I60 through the saturating winding l3. The device 22 is biased. to operate as a grid-controlled, high-vacuum rectifier and the average value of direct current flowing in its anode circuit through the saturating winding l3 determinesthe alternating voltage drop.

* across the saturable reactor l2. The anode current is smoothed by means of the relatively large capacitor 33 in shunt to the saturating winding l3. 7

- In analyzing the operation of the system of Fig. I, assume for the moment that the instantaneous alternating potentials across the several transformer windings, and the instantaneous 1 values of the input and output bridge voltage El and E have the polarities with respect to groundindicated by the plus and minus signs and the voltage arrows.

Considering first the operation of the bridge network R1, R2, Rrn'Rm alone, the filament resistances Rm and Rm vary with voltage according v to the same function (i. e., they have the-same percent change in resistance for a given voltage change). Therefore:

from the discharge device 20 and its associated 60' will now be briefly traced,

where it is some constant. At time. bridge balance, the bridge is adjusted so the ar a?! and R2=Rm (2) 5 and under these conditions, lithe 7.1...- are of the same rating, one-half the input voltage.

El appears across each mament. For example, if the normal filament voltage is 6.3 volts, the transformer is designed to supply 12.6 volts at is rated output voltage or the regulating system:

At balance, then an t P: it)

15 and R1=FR2 and RF1=kRrz (4) The general bridge formula for output voltage En, using the indicated instantaneous polarities,

is: a

and E0 at balance is zero.

Since filament resistance increases as a'iunction of input voltage and temperature, if El now rises, Rm becomes greaterthan R1 and Rs:

greater than R2. From Eq. 6, it will be seen that.

E0 is negative, or out-of-phase with E1. If El decreases, the converse is true and E0 becomes positive, or in phase with El.

Since the change in filent resistance is a 4 function only of filament temperature, which in turn is a function of the R. M. S. value of input voltage, it will be apparent that the bridge can respond only to a change in the R. M. S. value game of the high voltage gain of the regulatin system which keeps the net change in El within very narrow limits.

The complete sequence of control operations 1. '1: for illustration that the regulator output voltage tendsto rise and that the instantaneous alternating current potentials have the polarities indicated by the arrows and the plus and minus signs of Fig.

1. As previously pointed out in the analysis of operation oi? bridge 22,- when the voltage E: (which is proportionalto the regulator output voltage) rises, a negative or o'ut-oi-phase voltage E0 alppears at point 28. This is applied to the 0 grid of amplifier section 2m. Since the grid and anode voltages of each of the amplifier sections Ma and 2lb are out-of-phase, the instantaneous voltage at the grid of 2": is represented by a plus sign and the voltage at the grid of pentode e5 22 by a minus sign. 7 Since the polarities of the transformer windings are such that the anode voltage of tube 22 is "plus at this instant, the grid -voltage is in phase opposition to the anode voltage and the. result is a decrease in the average value of the rectified anode current flowthe ambient temperature.

7 s oi the type illustrated test curves of Figs. 2 and 3. Fig. 2 shows the plotted against the R. M. S. value of output current. It will be observed that the voltage change was only about 0.2 volt at approximately 117 volts for a load change from 0.8 amp. to 2.70

in Fig. l'is shown'by the 'R. M. 8. value of alternating output voltage amp. Fig. 3 shows the R. M. S.-value of altervnating output voltage plotted against changes in the R. M. s. value of-the alternating input voltage. It will be seen from this curve that the output voltage change only about 0.1 volt from a value oi approximately 117 volts for an ments 24 and 25 regardless, of changes in -ambient temperature. Therefore,:the regulator will cause the output voltage to vary slightly with This is valuable when the alternating current load consists of the tube filaments of a transmitter, receiver, or similar electronic equipment, because the regulator will tend. to maintain a constant filament temperature at these tubes as well (assuming that they are subjected to the same ambient temperature as the filaments 24 and 25) .7 It would be possible to select materials of the proper temperature coefllcients for the bridgearms R1 and R2 so as to compensate for this effect and to provide constant output voltage independent of changes-in ambient temperature. However, the voltage variation with changes in ambient temperature is very small and this would generally be an unnecessar refinement even where substantially constant output voltage is desired.

While I have shown a particular embodiment of my invention, it will of course be understood that I do not wish to be limited thereto since various modifications may be made, and I con-' template by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A system for regulating the voltage supplied from an alternating current source to an alternating current load comprising a variable impedance element in series between said source and load, a' non-linear bridge network having an output impedance which varies as a function of the root-mean-square value of voltage applied to its input, means for energizing said input in response to the voltage'at the load side of said impedance, said network developin an alternating error voltage at said output having a magnitude dependent upon the extent of said variations from a predetermined value and being either in-phase or out-of-phase with the load voltage dependent upon the direction of said variation, and means responsive to said alternating error voltage for continuously varying the impedance of said element in a senseto reduce said variations.

2. A system for regulating the voltage supplied from an alternating current source to an alternating current load comprising a variable impedance in series between said source and load, means for deriving an alternating control potential proportional to the voltage supplied tosaid load, a bridge network havin one diagonal energized from said potential, one pair of diagonallyopposite bridge arms consisting of substantially asiacas linear resistances and the other pair consisting of nonlinear resistances whose resistance varies substantially as a iunction of the root-meansquarevalue of said potential, and means re- ,qsonsive to the alternating voltage across the other diagonal'of saidbridge for continuously varying said impedance in a sense to reduce said variations.

3. An alternating voltage regulator comprising a saturable series reactor adapted to be connected between an alternating voltage source and load and having a direct-current saturating winding, a resistance bridge having one diagonal energizedin proportion to the alternating load voltage, one pair of diagonally-opposite bridge arms having substantially constant resistances over a predetermined voltage control range and the other pair having non-linear resistances varying as a function of the root-mean-square value-oi voltage over said range, means for amplifying alternating potentials appearing across the other diagonal of said bridge, means responsive to said amplified potentials for developing a direct current, and means for continuously supplying said current to said saturating winding in polarity to reduce load voltage variations 4. An alternating voltage regulator comprising a variable impedance adapted to be connected in series between an alternating current source and load, means comprising a non-linear resistance bridge having one diagonal energized in response .to the voltage across said load for developing an alternating control voltage across the other diagonal which varies as a lfunction of variations in the root-mean-square value of load voltage over a predetermined control range, said control voltage having zero magnitude for a predetermined desired load voltage and increasing in inphase relation with said load voltage for variations in one direction and increasing in outof-phase relation for variations in the opposite direction, and means for continuously varying I the value of said impedance in response to said control voltage in a sense to reduce said variations.

5. In an alternating voltage regulator having input and output terminals for connection between an alternating current source and load, a saturable reactor in series circuit between said terminals having a. saturating winding, an electronic rectifying device having a control grid and an anode, an anode circuit for said device including said winding and energized in accordance with the alternating output voltage at said output terminals, means responsive to said voltage for developing an alternating control potential having relative phase and magnitude continuously determined by output voltage variations above and below a predetermined value, and

,means for impressing said alternating potential I on said control grid, thereby to control the aver- I nating errorv potential, said potential having either an iii-phase or an out d-phase relation means for impressing said alternating, P tential on said grid insuch phase relation as to cause compensatory load voltage variations due to change in anode current through said saturating 7. An alternating voltage regulator comprising a saturable series reactor adapted to be connected between an alternating voltage source and load and having a direct-current saturating winding, a resistance bridge having one diagonal energized in proportion to the alternating load voltage, one pair of diagonally-opgzslte bridge arms having substantially constan resistances over a predetermined voltage control range and the other pair comprising a pair of thermionic tube filaments having resistances varying substantially as a function of the root-mean-square value of voltage over said range, means responsive to alternating potentials appearing across the other diagonal of said bridge for developing a direct current which is a function of said potentials, and means for continuously supplying said current to said saturating winding in polarity to oppose load voltage variations.

8. An alternating voltage regulator comprising a saturable series-reactor adapted to be connected between an alternating voltage source and load and having a direct-current saturating vol age. one pair of diagonallypposite bridge arms having substantially constant resistances I over a predetermined voltage control range and the other pair comprising a pair of" thermionic tube filaments having resistances" varying substantially as a function or the root-mean-square value 01 voltage over said range, means for amplifying alternating potentials appearing across said other diagonal, an electronicv rectifying doan mations errnn The following references are or record in the file or this patent: I g I v a snares PA a? Date Number Name 1,847,893 I Palmer Mar. 1, 1932 1,917,146 Nixdoril et a]. July Q, 1933 1,972,696 :Suits Sept. 4, 1934 1,998,041 u w Mai. 26,- 1935 2,066,943 Jan. 5, 1937 2,276,822

' Mai. 17, 1942 vice having anode and control grid circuits, said anode circuit including said saturating winding and means for impressing said amplified

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