US2546039A

US2546039A - Regulating system

Info

Publication number: US2546039A
Application number: US660032A
Authority: US
Inventors: Moir James; William S Graff-Baker
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1945-08-21
Filing date: 1946-04-06
Publication date: 1951-03-20
Anticipated expiration: 1968-03-20

Description

March 2o, 1951` A J. Mom mL 2,546,039

REGULATING SYSTEM Filed April e, 194e mgl.

Inverjtors James Mof, Wiliam SGVaFFBakeV;

bym The r-Attorn @y Patented Mar. 20, 1951 'Y REGULATING SYSTEM v James/Muir and 'Wiliiam S. Graff Bakerg Rugby,

*"England, assignors, to General EiectricigCompany, a corporation of New York Application April r6, 1946, Serial No. 660,032

InGi-eat Britain August v21, 1945 6 Claims. 1

Ourinvention relates to 'regulating systems .and more-particularly to electron tube regulators utilizingv a source of :referencepotential which varies in voltage'in accordance with ambient temperature.

In a common system for regulating a load characteristicv as, for example,v load voltage, a `series 'connected electron discharge device is placed between aV unidirectional voltage source and a load fc'ircuit and the grid bias controlledin accordance With output voltage. This is accomplished by providing .a current. path across the supply .voltage source comprisinga resistance, anV electron dischargedevice;` ande a source of reference voltage in seriesrelation. The grid' ofthe .latter device is connected toa potentiometer ,connected across `the load-circuit. so `that theV total effective grid bias applied thereto is determine-d bythe difier- 'ence` between the selected portionofload voltage andthe constant reference voltage.

ATheabove' mentioned voltage regulator constitutesia .negative feedback system wherein the 'difference lbetween outputvoltage andthe desired regulated value'is fed back to the control circuit lin Adegenerative phase. Inasmuch as the system always tends to cause the value of this difference'voltage to approach a specic value, the 'system outputis influenced 'byany changes' in VtheY voltage of the reference source. Since the reference voltage sourcesnormally used' have some' variationY in l voltage `with temperature, temperature changes produce a variation in regulating :output voltage. In particular, in the .case ofgas discharge devices ordinarily used as a sourcev of reference voltagel a voltage' variation Withftemperature of the order of ".0005 per Y"C. takes pla-ce -Whereas batteries used for this purpose have a' voltage variation with tem erature ofthe order of '.000l5rper C.

It is theobject .of our invention -to provide regulator-Which operates substantially independently ottempera-ture variations at thesource of reference potential.

It is a further object of our invention to provide .and improved regulator wherein thel .effects of temperature variationsat :the gas discharge tube or battery used as a source of reference potential are compensated by other circuit changes.

l In general,V our invention resides in providing a temperature sensitive-resistance physically disposed tovpartake-of the-,temperatureof the source of :reference voltage andy electrical-ly- .connected .to-introduce a compensating voltage 'sufficient-to .balance .thefchanges in reference voltage With temperature. In thefspecic embodiments of our Vinvention disclosed herein thisis accomplished .by providing'. a :resistance in vthe ypotentiometer;'connected across Vthe output circuit :of a voltage regulator, thereby altering 'the effective electrical :position of the 'r'oving'terminal of the potentiometer in `accordance Withfthe temperature condi- Itio'ns at the 'source vof referencevoltage.

H The 'novelfeatures which we believe to be characteristic of our invention are 'setforth -Withparticularity in the appended claims. .'Our invention itself, however, fboth vas'- to its organization andmethod of operation; together :with kfurther :objects 'and advantages thereofymay 'bestfbe 'understood by `reference .to the kfollowingdisclosure taken nconnectionvvith the accompanying .drawings'in'vvhich: Fig. 1 is a yschematic diagram of .a regulator circuitiiembodying the invention. in 'which a resistance having a negative temperature coefiicientxs utilized; and Fig.;2:is a schematic diagram .of an. alternative `regulatorcircuit kin which a resistance having a positiyeftemperature coeiiicient is utilized.

"Fig: 1 lsliovvs an electron tube voltage regulator or" 'the above described type. In this regulator, input terminals I and 2 are connected-'tocasource of unidirectional electromotive force, terminal' l boeing connected tothe positive side of thesource and fterminal 2 tothe negative` side. Theanode of electron Ydischarge devicer 3 'isf connected to terminal vrand the cathode connected to positive output terminal .4. Negative'. output terminal 5 connects directly to negative input terminal 2. Resistance 6, electrondischarge.device 1:, andgas dischargedevice 8 comprise a circuit across-output terminals 4 and 5 in'which current flow biases the grid of device 3 to alterthe effective resistance thereof. Potentiometer 9 provides a. means for applying a'preselected portion of `output voltage to the' grid 'of einplierdevice l.

VTheicircuitof Fig; l comprises a feedbackv systemin Which'device 'l receives gridbias in vaccordance with the dierence -betvveenfthe` vselected portion of output voltage across terminals 4 and 5 and the relatively constant voltage acrossjgas discharge device t. Thisbias voltageis amplified in device 'i and applied tobias the gridA oi' device 3. Byzchoosing device 'I and device 3, together with resistance' 5, to `have values g-iving'a high degree.v of amplification in thefeedback path, rthe dierence -betWeen -output- `voltage across terminals 4 and 5 and the desired output voltagefis caused to'be verysmall. despite variations'in the impedanceacrossterminals 4. and Sand the value of input voltage across terminals; |andv .2.

.inasmuch as the regulator ofi Eig. 1 acts to maintain the selected portion of output voltage at a predetermined value with respect to the value of reference voltage at gas discharge device 8, any

changes in the reference voltage are reiiected as corresponding changes in output voltage. Actually, gas discharge tube 8 provides constant reference voltage only at a particular temperature, and if lits temperature is changed, a corresponding voltage change appears at terminals d and 5. For this reason, the circuit of Fig. 1 does not provide exactly constant voltage but instead provides a voltage varying in accordance with the ambient temperature at gas discharge tube 8.

In accordance with the embodiment of our invention shown in Fig. 1, auxiliary resistance l is provided between the negative side of potentiometer 9 and the negative load terminal 5. This ,resistance is physically mounted close to gas discharge device 8 so that its temperature corresponds with the temperature of that tube. In addition, this resistor has a negative coefcient of resistance change with temperature so that as device 3 heats or cools in accordance with ambient temperature the value of resistance ill decreases or increases accordingly. Since the total effective grid bias at amplifier device 'l is equal to the diierence between the voltage of gas discharge device S and the combined voltage across resistance lil and the preselected portion of the voltage across potentiometer 9, the decreased voltage at tube 8 associated with a temperature increase is compensated by a corresponding decrease in resistance it and the voltage thereacross accordingly reduced. Conversely, if the temperature of gas discharge device 8 decreases, thereby increasing the value of reference voltage, the value of resistance lli increases and the voltage drop thereacross is correspondingly raised. In either event, the total effective grid bias at device l for a particular output voltage remains constant.

A further modification of our invention is shown in Fig. 2. In this modiiication, resistance l l is provided between the positive terminal of potentiometer 9 and the positive load terminal 4. By physically locating this resistance to partake of the temperature of gas discharge device 8, and utilizing a resistance material having a positive resistance change with temperature, a compensating voltage is provided which maintains constant grid bias of tube i despite temperature changes at device 8. In this circuit, an increase in temperature at gas discharge device 8 causes the Voltage thereacross to decrease while at the same time the increased value of resistance Il produces a corresponding decrease in voltage across the preselected portion of the voltage drop across potentiometer 9. Hence the eiective grid bias at tube 'l remains unchanged. Operation of the regulator is, therefore, independent of temperature changes at gas discharge device 8.

It will be evident to those skilled in the art that if the source of reference potential is a battery or other source wherein output voltage increases with rising temperature, the above described circuits may be applied except that resistance i9, Fig. l, should have a positive coefficient of resistance change with temperature, and resistance i I, Fig. 2, should have a negative coeilicient of resistance change with temperature.

While We have described our invention with reference to a particular voltage regulating circuit, it will be understood that it may be readily applied to other types of regulating circuits whether adapted to maintain constant voltage across load terminals or to maintain some other characteristic such as motor speed, load current, temperature, etc., constant inasmuch as our invention in its broadest aspect contemplates the use of a resistance physically located to partake of the temperature of the reference voltage source and adapted to provide a compensating voltage which balances the change in reference voltage ssociated with temperature variations.

While we have illustrated particular embodiments of our invention, it will of course be understood that we do not wish to be limited thereto since various modications, both in the circuit management and in the instrumentalities employed, may be made, and we contemplate by the appended claims to cover any such modiiications as fall within the true spirit and scope of our invention.

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

l. A voltage regulator comprising in combination, a source of unidirectional electromotive force, a load connected thereto, a source of substantially constant reference voltage having decreasing voltage with increasing temperature, a temperature sensitive resistance mechanically disposed adjacent said source so as to be maintained at substantially the same temperature as said source or" reference voltage, said resistance having a temperature coeicient producing decreasing resistance with increasing temperature, a second resistance, means connecting said iirst and second resistances in series relation across said load, and means to control the voltage .of said first mentioned source in accordance with the difference between the voltage of said source of reference voltage and the total voltage across said first resistance and at least a portion of said second resistance, thereby to maintain constant the electromotive force at said load, said rst resistance having a resistance change with temperature such that temperature changes at said source of reference voltage are substantially prevented from influencing the voltage output of said regulator.

2. A voltage regulator comprising in combination, a source of unidirectional electromotive force, a load connected thereto, a source of substantially constant reference voltage having decreasing voltage with increasing temperature, a temperature sensitive resistance mechanically disposed adjacent said source so as to be maintained at substantially the same temperature as said source of reference voltage, said resistance having a temperature coeiiicient producing increasing i'esistance with increasing temperature, a second resistance, means connecting said first and second resistances in series relation across said load, and means to control the voltage of said iirst mentioned source in accordance with the dilerence between the voltage of said source of reference voltage and the voltage across at least a portion of said second resistance, thereby to maintain constant the electromotive force at said load, said first resistance having a resistance change with temperature such that temperature changes at said source of reference voltage are substantially prevented from innuencing the voltage output of said regulator.

3. A voltage regulator comprising in combination, a source of unidirectional electrornotive force a load connected thereto, a source of substantially constant reference voltage having increasing voltage with increasing temperature, a

temperature sensitive resistance mechanically disposed adjacent said source so as to be maintained at substantially the same temperature as said source of reference voltage, said resistance having a temperature coecient producing decreasing resistance With increasing temperature, a second resistance, means connecting said rst and second resistances in series relation across said load, and means to control the voltage of said first mentioned source in accordance with the difference between the voltage of said source of reference voltage and the voltage across at least a portion of said second resistance, thereby to maintain constant the electromotive force at said load, said rst resistance having a resistance change with temperature such that temperature changes at said source of reference voltage are substantially prevented from iniiuencing the volt- 'age output of said regulator.

4. A voltage regulator comprising in combination, a source of unidirection electromotive force, a load connected thereto, a source of substantially constant reference voltage having increasing voltage with increasing temperature, a temperature sensitive resistance mechanically disposed adjacent said source so as to be maintained at substantially the same temperature as said source of reference voltage, said resistance having a temperature coefficient producing increasing resistance with increasing temperature, a second resistance, means connecting said rst and second resistances in series relation across said load, and means to control the voltage of said first mentioned source in accordance With the difference between the Voltage of said source of reference voltage and the total voltage across said rst resistance and at least a portion of said second resistance, thereby to maintain constant the electromotive force at said load, said rst resistance having a resistance change with temperature such that temperature changes at said source of reference voltage are substantially prevented from inuencing the voltage output of said regulator.

5. The combination, in a voltage regulator, of a voltage source, a load connected across said source through an impedance, tWo paths across said load, one including a constant voltage gaseous discharge device and the other including resistance, means responsive to the difference in 5 voltages across said gaseous discharge device and a part of said resistance to vary said impedance thereby to maintain the voltage across said load substantially constant, and means to prevent said voltage across said load from being aiected by variations in voltage across said gaseous discharge device produced by ambient temperature variations, said means comprising a resistance element included in one of said paths and positioned closely adjacent said discharge device so as to be subject to the same ambient temperature variations as said gaseous discharge device, said element having a resistance coeicient varying therewith in a direction tending to maintain said difference in voltage independent of said ambient temperature.

6. A voltage regulator comprising in combination, a source of unidirectional electromotive force, a load connected thereto, a source of substantially constant reference voltage having voltage variations with temperature changes, a temperature sensitive resistance mechanically disposed adjacent said source so as to be maintained at substantially the same temperature as said source of reference voltage, said resistance having a temperature coeflicient producing a resistance change with temperature change, a second resistance, means connecting said first and second resistances in series relation across said load, and means to control the voltage of said rst mentioned source in accordance with the difference between the voltage of said source of reference voltage and the voltage across at least a portion of said second resistance, thereby to maintain constant the electromotive force at said load, said rst resistance having a resistance change with temperature such that temperature changes at said source of reference voltages are substantially prevented from influencing the voltage output of said regulator.

JAMES MOIR. WILLIAM S. GEHT-BAKER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,875,043 Leece et al Aug. 30, 1932 2,093,626 Ward Sept. 2l, 1937 2,219,195 Norgaard Oct. 22, 1940 2,362,562 Kelly Nov. 14, 1944