US2140349A - Change-amplifying means - Google Patents

Description

Dec. 13, 1938. J w DAWSON 2,140,349

CHANGE-AMPLIFYING MEANS Filed Oct. 25, 1935 2 Sheets-Sheet l Fig-I l I I l I WITNESSES:

Patented Dec. 13,1938

UNITED STATES.

'CHANGE-AMPHFYING MEANS John W. Dawson, East McKeesport, Pa., assignmto Westinghouse Electric & Man

uhcturing Company, East Pittsburgh, Pa., a corporation vania of Pennsyl Application October 23, 1935, Serial No. 48,351

'iClaims.

My invention relates to voltage-change amplilying means and it has particular relation to change-amplifying means suitable for use in conjunction with alternating-current voltage adjusters and regulators and other comparable control systems.

Generally stated, the object of my invention is to simplify the circuits utilized by systems of the above-characterized class.

Another object is to provide a highly sensitive error-detecting circuit for electronic-tube and other regulating systems which does not require the heretofore necessary source of reference potential or other auxiliary apparatus requiring maintenance.

Another object is to provide an error-detecting circuit having the described high sensitivity which lends itself to ready adjustment in its degree of voltage-change amplification.

A further object is to achieve the above stated results through the use of non-moving part equipment of relatively inexpensive character.

My invention itself, together with additional objects and advantages, will best be understood through the following description of specific embodiments thereof. when taken in conjunction with the accompanying drawings, in which Figure 1 is a diagrammatic representation of apparatus and circuits comprised by a preferred form of the change-amplifying means of my invention,

Fig. 2 is a. diagram of curves illustrating the high sensitivity characteristics ofv the errordetecting equipment of Fig. l,

Fig. 3 is a diagrammatic representation of a generator voltage regulating system which incorporates the change amplifying means of Fig. 1,

Fig. 4 is a diagrammatic representation of a similar regulating system incorporating comparable means in a somewhat 'difierent manner,

Fig. 5 is a diagrammatic representation of apparatus and circuits showing the change-amplifying means of my invention incorporated in an electronic tube voltage regulator,

Fig. 6 is a reproduction of the basic change amplifying system of Fig. 1 showing how separate impedors may be utilized to supply the change-amplified output voltage and the saturating current to the reactor.

Referring to the drawings; I have represented in Fig. 1 one preferred arrangement of my improved voltage-change amplifying means. Basically, these means comprise a saturable core reactor,- Ill series connected with a resistor or other impedor l2 for energization by a. measure E1, of the alternating-current voltage the changes in which it is desired to amplify. This series connection includes the windings l4 carried by the two outer legs of the reactor core structure which preferably is of the well known threelegged construction illustrated.

The central leg of this structure carries a coresaturating winding it which is energized through a rectifier it by a uni-directional current determined by the'voltage EA appearing across the impedor l2. As is well known, the efiect of core saturation in a reactor of the type shown is to reduce the impedance presented by windings it to the flow of current therethrough. This same voltage EA follows in intensified degree changes in the magnitude of the input voltage EL. The uni-directional output voltage Ex of the rectifier i8 furthermore varies in exactly the same manner.

In operation of these change-amplifying means, the input voltage Ex. impressed thereon divides itself between the series-connected elements it and I2 in a manner determined by their relative impedances. When voltage E1. is of an intermediate value, the corresponding core saturating current supplied to the reactor winding 56, as a resultpf the impedor potential EA, causes the impedance presented by the reactor windings it also to be of an intermediate value.

As the magnitude of the total impressed voltage E1. is raised, this saturation determining potential EA is correspondingly increased with the result that the core of the reactor it is saturated to a greater degree. The resulting lowering of the impedance of the reactor windings it reduces the voltage drop appearing thereacross and causes a greater portion of the total voltage of E1. to appear across the resistor i2. Consequently, voltages EA and Ex are increased by an amount more than proportional to the increase in the total voltage EL.

Similarly, as voltage Er. decreases, the resulting lowering of voltage Es decreases the core saturation of reactor in and thereby raises the impedance of windings l4. As a result, a greater portion in the total voltage E1. appears across these windings, so that the resistor I2 has impressed across it a correspondingly lesser portion thereof. In consequence, the potential EA appearing across resistor i2 is decreased by an amount more than proportional to the decrease in the applied voltage EL.

The degree of this amplifying action obtainable in practice is depicted by the solid-line curve 20 of Fig. 2 which has been plotted from actual test data. It may be seen from it that as the total impressed voltage E1. is elevated from 100 to 110 volts, the voltage EA appearing across resistor i2 is elevated from 100 to 140 volts. A decrease from 100 to 90 volts in the voltage Er. likewise results in'a reduction of 40 volts in voltage EA. The equipment tested thus has, even throughout the wide range above specified, an eifective amplification factor of 4..

In certain applications, the modifications depicted in Fig. 7 may be useful. The system there represented is basically the equivalent of that 01' Fig. 1 except that a separate resistor 22 is included in the series-energizing circuit for supplying the change-amplified output voltage EA. In both combinations, the sensitivity or amplification factor may readily be changed by altering, as by meansof an aifiustable tap 25, the constants of the circuit through which the satuirating winding 16 of the reactor I is energized. Movement of this tap upwardly toward the end of the resistor raises this factor while a movement in the downward direction correspondingly lowers the sensitivity of the combination.

Considering now the several represented applications in which the above-described change amplifying means may be utilized with advantage, I have in Fig. 3 depicted these means as forming a part of a regulating system which is adapted to maintain constant the voltage of an alternating current generator 26, the armature windings of which are directly connected with the conductors 28 of an output circuit and the field winding 30 of which derives its energization from a separate exciting generator 32.

This exciter is shown as being provided with a pair of difierentially related field windings 34 and 36. Winding 34 is constantly energized from any suitable source such as a battery 38, while winding 36 derives its energization from the output terminals of the rectifier i8 of my changeamplifying means which is energized through reactor ID by a measure Er. of the voltage of regulated circuit 28 with which connections are established by means of a transformer 40.

In operation of the regulating system of Fig. 3, as long as the voltage of circuit 28 remains of the desired value, the rectifier l8 will supply to exciter field winding 35 an intermediate value of current which maintains the excitation of regulated generator 26 at the correspondingly proper value. When the regulated voltage falls, however, the output voltage Ex of rectifier i8 more than proportionately decreases with the result that the opposing efiect of winding 36 on the major field winding 34 of exciter 32 is correspondingly lessened and the excitation of machine 26 correctively raised. An increase above the desired value in the voltage of regulated circuit 28 by a more than proportionately raising the output voltage of rectifier I 8 similarly effects a corrective lowering of the excitation supplied to machine 26.

Should it be desired to further damp out tendencies of the regulating system to overshoot, the reactor ill may be provided with a second saturating winding 42 which derives energization from the voltage appearing across a resistor 44 which is serially connected with a capacitor 46 for energization by the voltage impressed upon the exciting winding 30 of the regulated machine 26. This anti-hunting connection functions to energize Winding 42 only when the machine excitation undergoes a change. At all other times the capacitor 46 is charged to a voltage which matches that of field winding 30. The direction of core saturating winding energization is such as to oppose the change which produced it to thereby so prematurely interrupt the corrective action as to eliminate all tendency of the regulating system to overshoot.

The regulating system of Fig. 4 is basically the same as that of Fig. 3 with the exception that the output connections of the change amplifying means forming a part thereof are modified in a manner to eliminate the need for the constantly energized exciter field winding 34 and to permit a single field winding 36 to alone be adequate. This modification consists in utilizing as a source of field winding energizing voltage that appeara ing across the reactor HI. This voltage is impressed upon the field winding 36' through a rectifier 50.

In operation of the system of Fig. 4 when the voltage of generator 26 rises, the potential drop across the reactor 10 is more than proportionately lowered. The resulting reduction in current supplied to the exciter field winding correctively lowers the excitation of machine 26. In a similar manner when the regulated voltage (of which Ex. is a measure) decreases, the potential appearing across reactor [0 more than proportionately increases to effect the necessary corrective raising of the machine excitation.

In both regulating systems the amplifying characteristics exemplified by curve 20 of Fig. 2 are directly made use of. Because of the fact that this curve crosses the line 52 determining a proportionate variation, the described regulating effects are readily obtained through the use of my improved voltage changing amplifying means.

In Fig. I have represented these means in combination with an electronic-tube type of voltage regulator. In the illustrated system, the field winding 36" of the machine exciter 32 is supplied from any suitable source such as a battery 54 with energizing current which is adjusted by suitable equipment generally indicated at 56 in accordance with the controlling influence, of an electronic tube 58.

The conductivity of this tube is determined by the magnitude of a control potential EG impressed between the cathode and grid elements 60 and 62 thereof. In the illustrated arrangement an increase in this potential causes equipment 56 to decrease the field current of exciter 32 and thereby lower the voltage of regulated machine 26 while a decrease in this control potential similarly functions to raise the machine voltage.

In operation of the system of Fig. 5, as the measure EL of the regulated voltage falls below its desired value, the change amplifying means of my invention decreases its output voltage Ex by a much larger amount and thereby correspondingly reduces the tube control potential Ea. This causes the before-explained equipment 56 to increase the excitation of regulated machine 26 to thereby correctively raise the voltage of circuit 28. An increase in the regulated voltage similarly acts to raise the magnitude of the control potential EG and thereby efiects a corrective lowering of the voltage of machine 26.

In the system of Fig. 5, the grid circuit of the electronic tube 58 is shown as including an antihunting resistor 12 connected in series with a capacitor 14 for energization by the voltage supplied to field winding 30 of the regulated machine 26.

Because of the described amplifying proportions of my error-detecting circuit, the sensitivity of the voltage regulating system is correspondingly enhanced to the extent in fact that the source of standard potential or other equivalent equipment heretofore required to obtain high sensitivity may be dispensed with.

A further advantage possessed by the illustrated arrangement is that by the addition of a second saturating winding 66 to the central leg of the core structure of reactor III the voltage calibration of the complete regulating system may be adjusted merely by altering, as by means of a rheostat 68, the magnitude of energizing current supplied, as from a battery 10, to this winding.

It will accordingly be apparent that the voltage change amplifying means of my invention are useful wherever it is desired to amplify magnitude variations in an alternating-current potential. The illustrated regenerative reactor connection is, therefore, adapted for wide variety of uses in control and regulating applications other than those specifically illustrated and described.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the scope of the appended claims,

I claim as my invention:

1. In a system comprising an alternating current circuit, voltage-adjusting means therefor and an electronic-tube adapted to control said adjusting means, the combination of a reactor having a core-saturating winding, a circuit for energizing the reactor by a measure of the voltage of said alternating current circuit, a rectifier included in said circuit for supplying to the saturating winding of the reactor a current determined by the flow of current in the reactor energizing circuit, and a circuit for impressing upon said electronic tube a control potential also determined by the flow of current in the reactor energizing circuit, said potential following in intensified degree changes in the magnitude of the said alternating-current circuit voltage.

2. In a system comprising an alternating-current circuit and voltage-adjusting means therefor in the form of an electrical winding, the combination of a reactor having a core-saturating winding, a rectifier, a circuit for connecting in series said rectifier and the reactor for energization by a measure of the voltage of the alternating-current, a circuit for impressing upon the adjusting-means winding the output voltage of said reactor, and a circuit for impressing upon the reactor saturating winding a measureof said output voltage.

3. Means for producing a unidirectional potential which follows in amplified magnitude variations in an alternating-current voltage comprising, in combination, an alternating current circuit, a reactor having a core-saturating winding and a pair of energizing windings, a circuit for supplying alternating current to said energizing windings at a voltage that is a measure of the voltage of the alternating current circuit, a rectifier for developing a unidirectional voltage that is determined by the voltage drop across said reactor energizing windings, and means for supplying current to the saturating winding of said reactor that is a measure of said developed unidirectional voltage for causing changes in the output unidirectional voltage corresponding in direction to changes in the value of said alternating current voltage.

4. In a regulator system, in combination, an alternating current circuit, means for controlling an electric quantity of said circuit comprising a reactor having a core saturating winding and a pair of controlled windings connected in a circuit supplied with alternating current at a voltage that is a measure of the voltage of said alternating current circuit, a rectifier for supplying a unidirectional current to the saturating winding of the reactor, means responsive to the voltage across the controlled windings of said reactor for causing the reactor to effect changes in the output voltage of the rectifier corresponding to changes in the value of the impressed alternating current circuit voltage, quantity adjusting means and means for supplying a unidirectional potential to said quantity adjusting means that is also determined by the voltage across the controlled windings of said reactor.

5. In a regulator system, in combination, an alternating current circuit, an electric generator for supplying power to said circuit, excitation means therefor, and means for governing said excitation means comprising an input circuit supplied with alternating current at a voltage that is a measure of the voltage of the alternating current circuit, an output circuit, and means for supplying a unidirectional current to the output circuit at a voltage that amplifies the voltage variations at which current is supplied to the input circuit, said means comprising a regulating reactor and an impedance device connected in series circuit relation in said input circuit, a rectifier for supplying said output circuit and connected to be supplied with current at a voltage that varies in the same direction as the voltage across said impedance device for determining the reactance of said reactor.

6. In a regulator system, in combination, an alternating-current circuit, an electric generator for supplying power to said circuit and having a field winding, excitation means for supplying current to said field winding, means for governing the excitation of said field winding including a reactor having a plurality of core saturating windings and a pair of energizing windings, a circuit for supplying alternating current to said energizing windings at a voltage that is a measure of the voltage of the alternating-current circuit, a rectifier for developing a unidirectional voltage that is determined by the voltage drop across said reactor energizing windings, means for supplying current to the saturating winding of said reactor that is a measure of said developed unidirectional voltage, and means responsive to variations of the voltage of said excitation means for controlling the energization of the other of said saturating windings.

7. In a regulator system, in combination, an alternating-current circuit, an electric generator for supplying power to said circuit and having a field winding, excitation means for supplying current to said field winding, means for governing the excitation of said field winding including a reactor having a core saturating winding and a pair of energizing windings, a circuit for supplying alternating current to said energizing windings at a voltage that is a measure of the voltage of the alternating-current circuit, a rectifier for developing a unidirectional voltage that is determined by the voltage drop across said reactor energizing windings, means for supplying current to the saturating winding of said reactor that is a measure of said developed unidirectional voltage, and anti-hunting means responsive to variations in the voltage of said excitation means for also controlling the excitation of said field winding.

JOHN W. DAWSON.

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