US2066943A - Regulating system - Google Patents

Description

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LA VERNE R. PHILF'OTT REGULAT ING SYSTEM a Ver/7e f? INVENTOR Ph//paff Jafh 5, 1937- L.A VERNE R. PHILPoTT 2,066,943

REGULATING SYSTEM Filed July 3l, 1935 2 Sheets-Sheet 2 WITNESSES: 54 INVENTOR Patented Jan. 5, 1937 UNITED STATES lPATENT OFFICE REGULATING SYSTEM Company, East Pitts of Pennsylvania Application July 31,

l 4 Claims.

My invention relates to electrical regulators of the electronic tube type and it has particular relation to means for improving electronic' of the above class which are suited for use with both alternating and direct current circuits the voltage or other characteristic of which is to be regulated.

A still further object is to provide an improved form of electronic tube regulator for dynamo'- electric machines which in operation simulates the ratio-regulated on and off the form of control provided by vibratory-contact regulating devices.

My invention itself, together with additional objects and advantages thereof, will best be understood by the following description of specic embodiments when taken in conjunction with the accompanying drawings, in which:

Figure l is a diagrammatic representation of an elementary form of the regulating system of my invention shown as being applied to control the voltage of an alternating-current feeder circuit;

Fig. 2 is a reproduction of the system of Fig. 1 showing how amplifying means may be utilized to increase the sensitivity thereof;

Fig. 3 is a partial reproduction of Fig. l illustrating one manner in which the direct-current voltages required to energize the electronic tube circuits may be supplied from a source of alternating-current power;

Fig, 4 is a diagrammatic representation of the regulating apparatus of Fig. 2 applied to control the voltage of a direct-current generator;I and Fig. 5 is a diagrammatic view of apparatus and circuits comprised by an `alternating-current generator voltage regulator arranged in accordance with my invention to provide a form of on and on" excitation adjustment control which simulates that afforded by a vibratory- Contact regulator.

Referring to the drawings, I have illustrated in Fig. 1 the improved system of my invention as being applied to maintain constant the voltage burgh, Pa., a corporation 1935, Serial No. 34,011

of an alternating-currentl circuit I0 which is energized from a suitable source of power through an adjusting device consisting of a saturable core reactor I2. This reactor is of a well-known construction comprising two outer core legs, upon which are positioned windings I4 connected intermediate the power source and the regulated circuit, and a central leg which carries a saturation control winding IB. The effective impedance of windings I4, and hence the voltage drop which the flow of current from the power source to the regulated circuit produces thereacross, is determined by the magnitude of a unidirectional current circulated through winding I6.

This current is supplied from a suitable source of power, indicated as a battery I8, through a circuit which includes one or more electronic tubes 2B of the grid-controlled variety. The current passed by each of these tubes is determined by the voltage impressed upon the grid element 22 thereof by a resistor 24, through which a second source of power 26 circulates a current determined by the conductivity characteristics of an error-detecting tube 28. This last-named tube is of the two-element type having a lamentary cathode 30 which is energized, through a connection which includes a transformer 32, by a measure of the voltage appearing between regulated circuit co-nductors H).

The illustrated use as a detector of the twoelement tube eliminates the necessity for the standard potential battery or other equivalent source of reference voltage which heretofore has been required in all high-sensitivity electronictube voltage-control applications. This tube is preferably operated with a voltage uponits anode 34 which is sufficiently high to saturate or place the tube in a condition in which all of the electrons emitted by the cathode are attracted to the anode. For such a condition, a change in the magnitude of the filament heating potential effects a highly amplified change in the magnitude of the current which the tube draws through the resistor 24. Essentially. such a filament controlled detector is a. temperature actuated device and functions to indicate the rootmean squared value, instead of the average as does a grid voltage control tube, of the alternating-current voltage which energizes its cathode. Thus in addition to being highly sensitive, such a tube provides a type of response which is especially desirable when the generator voltage wave is subject to deviation from the usual sinusoidal form.

In operation of the system of Fig. 1, as long as the voltage oi circuit I0 remains of the desired value, the illustrated electronic tube control maintains the voltage adjusting reactor I2 at that intermediate degree of saturation required to hold this desired voltage. The drop across windings Il then reduces the power source voltage appearing between conductors I6 by an intermediate amount necessary to properly supply circuit I0. If desired an auto-transformer may, as shown at 38 in Fig. 2, be utilized to boost the power supply voltage by an amount which compensates for the drop through the adjusting reactor I2.

Upon a decrease in this regulated voltage, however, the temperature of detector cathode 30 is lowered, its electronic emission reduced, and the current passed by tube 28 through resistor 24 correspondingly diminished. The lowered voltage drop across resistor 2l changes in the positive direction the potential applied to the grid 22 of tube 20, and correspondingly raises the conductivity of this tube. As a result, more current is passed to the saturation control winding I6. the degree of core saturation of device I2 raised, and the reactance of and hence the voltage appearing across windings I4 reduced. This correctively raises the voltage supplied to circuit III back to the desired value.

In a similar manner, when the regulated voltage rises, the electron emission and hence the conductivity of tube 28 is raised, the grid potential applied to grid 20 changed in the negative direction and the saturation of reactor i2 correspondingly lowered. In this manner. the voltage supplied to circuit Ill is correctively decreased back to the desired value.

Where unusually high precision of regulation is desired. an amplifying electronic tube, indicated at 40 in Fig. 2, may be interposed between the filament controlled detector 28 and the reactor saturation control tube 20. In the connection shown in Fig. 2, the current passed by detector tube 28 is circulated through a resistor I2 the voltage drop across which determines the potential impressed upon the grid u of the ampliiler tube I8. In addition to this grid and the usual anode and cathode elements 4l and Il, this tube is shown as being provided with a screen grid 5B.

A suitable source of unidirectional potential indicated as a battery 82 circulates through the grid-bias determining resistor 24, associated with the voltage-adjusting tube 20, a current determined by the impedance oi.' this amplifying tube 48. Small changes in the output of detector 28 are converted by means of the ampliner into considerably larger changes in the current supplied to resistor 24 which, through tube 28, functions in the manner already explained to adjust the voltage of circuit I0.

The operation of the system of Fig. 2 is thus essentially the same as that of Fig. l1, with the exception that greater sensitivity is afforded. In both systems, the magnitude oi' the regulated voltage may be adjusted by changing the setting of a rheostat 5l preferably connected in the manner shown in the energizing circuit of the detector lament.

Instead ofl utilizing batteries or other separate sources of unidirectional potential, the electronic-tube circuits comprised by my regulating system may, by the use of the rectifying equipment illustrated in` Fig. 3, 'be energized from a source of alternating-current power which, if

desired, may be the regulated circuit I0 of Figs. 1 and 2. The equipment of Fig. 3 comprises a transformer 56 energized by the alternatingcurrent power source and provided with a main secondary winding 58, the two ends of which are respectively connected with the anodes of a fullwave rectifying tube 60. The cathode of this rectifier may be supplied from another secondary winding 82, while still additional sections 64 and 66 may be utilized to energize the cath odes of the electronic tubes 2U and 28 comprised by the regulating system. Tube rectiiies both waves of the voltage impressed thereon by transformer winding 58, and causes to appear between the midtap connection 68 of this winding and the connection with cathode 1li a unidirectional voltage, the ripples in which are by means of equipment 12 filtered out before this voltage is impressed upon resistor sections I8 and 26', which respectively serve to supply the anode circuits of the tubes 20 and 28.

In'addition to the alternating-current feeder circuits represented in Figs. l and 2, my improved regulating system may also be utilized to control the voltage of a dynamo-electric machine, a direct-current generating type of which is indicated in Fig. 4 at ll. The armature winding of this machine is directly connected with the conductors Ill of a direct-current circuit the voltage of which is to be maintained constant, and the main field winding I6 is self-excited by the machine. An auxiliary or regulating field winding 18 is supplied from power source IS with an energizing current determined by tube 20 which, through amplifier l0, is controlled by detector 28, the cathode 30 of which is shown as being energized directly by the voltage of circuit I0'.

In operation of the system of Fig. 4, when the voltage of circuit I0 is of the desired value, the illustrated equipment functions to supply to eld winding 'I8 an intermediate value of exciting current which maintains the voltage of generator 14 at this desired value. When the circuit voltage falls, however, detector 28 responds in the manner explained in connection with Figs. 1 and 2 to cause amplifier 40 to increase the exciter current passed by voltage adjusting tube 20 and thereby correctively raise the generator voltage back to the desired value. In a similar manner, when the voltage rises, the electronic tube equipment correctively reduces the generator excitation.

In Fig. 5 I have illustrated a further extension of the basic regulating system of the preceding figures which in operation simulates a vibratory type of regulator in that adjustment in a quantity-determining current is, under certain circumstances, effected by rendering electronic tubes which control this current alternately fully conductive and fully non-conductive. The relative values or ratios of these conducting and non-conducting periods are varied in such manner as to maintain the regulated quantity at its desired value.

The system is shown as being adapted to maintain constant the voltage of an alternating-cur rent generator 80, the armature windings of which are connected with a three-phase circuit represented by conductors l0" and the field winding 8| of which is energized from a separate exciter 82. The exciter ileld winding 83 is supplied with a unidirectional energizing current derived from a source of alternating-cur- Lin , character to cause rent power, which, as shown, may be in the form of a separate circuit 84, or which may constitute the generator output circuit i8. The represented energizing connection includes a transformer 85 and a Lpair of rectifiers 85 and 81 which are connected in a well-known manner to effect full-wave rectification.

These rectifiers are of a well-known type having a make-alive element or firing rod 88 arranged in contact with the cathode, which comprises mercury or other vaporizable reconstructing material 88, in such manner that a current passage therethrough renders the rectifier conductive. Once instituted, this conduction persists during the remainder of the positive half cycle in which it was started. In the absence of make-alive element excitation, the device remains an insulator during both half cycles of voltage impressed upon its anode element 88.

In the system disclosed, I utilize for the purpose of exciting the make-alive element of each of these two rectiflers a capacitor with which there is associated a charging circuit. In the case of rectifier 88 this capacitor is shown at 88 and its charging circuit is energized by the voltage supplied to rectifier 81. This circuit is controllably completed through an electronic tube 82. When another electronic tube 83 is rendered conductive capacitor 88 is discharged through the make-alive element 88 of rectifier 86 to thereby render that rectifier conductive. In a similar manner, a charging circuit for capacitor 8i associated with rectifier 81 is energized by the voltage supplied to the anode of rectifier 88 and is controllably completed through an electronic tube 84. A circuit for discharging this capacitor through the make-alive element of rectifier 81 is completed when an additional electronic tube 85 is rendered conductive.

Tubes 82, 83, 84 and 85 are each of a threeelement type which may be maintained non-conductive by impressing thereon a grid bias in excess of a certain critical negative value. When this bias is reduced below this value, tube conductivity will result when a proper value of anode voltage is supplied to the tube. Tubes 83 and 85 are supplied with grid voltage of proper them to break down when the capacitors 8i and 88 are charged to a proper lvoltage by means of a from source 84 through a phase shifting device \81 the adjustment of which is initially fixed to obtain most satisfactory operation.

Tube 82 is so interconnected with tube 85 that whenever this last-named tube breaks down to discharge capacitor 8i through the make-alive element of rectifier 81, tube 82 will be rendered conductive to charge capacitor 88 during the same half cycle. Capacitor 88 then discharges during the succeeding half cycle to render rectifier 88 conductive.

Tube 84 is in turn controlled by the potential appearing across a resistor 24' connected in its grid circuit. This potential is determined by amplifier tube 48 controlled, as in the systems of the preceding figures, by a detector tube 28 upon the filamentary cathode 38 of which is impressed a measure of the voltage acting in regulated circuit i8.

In operation of the complete regulating system of Fig. 5, the control is such that the main rectifiers 86 and 81 are alternately conductive for a few cycles and non-conductive for the next succeeding few cycles, the ratio of these conducting tofnon-conducting periods being deteraoeaus transformer 88 energized mined by the voltage acting in regulated circuit i8". When this voltage is low, this ratio is caused to rise to thereby increase the excitation of generator 88, and when the voltage is high, the ratio is correspondingly reduced to lower the excitation and hence the voltage of machine 88.

At all times, therefore, it is necessary that the Voltage of circuit i8" very slightly fluctuate above and below the desired mean or average value. When below, the detector 28 adjusts in the negative direction the grid bias of amplifier 48. This lowers .the tube conductivity and, by decreasing the drop across the output resistor 24', lowers the grid bias supplied by this resistor, and the battery 88, t0 tube 84 to less than the aforementioned critical value.

This renders the tube conductive allowing it to pass to capacitor 8l a charging current during each of thelnegative half cycles of anode voltage supplied to rectifier 81. This current passage persists as long as tube 84 remains conductive. Duringy each succeeding positive half cycle of anode voltage, tube 85 discharges the capacitor 8i through the make-alive element 88 of rectifier 81, thereby rendering it conductive. With each passage of discharge current through tube 85, tube 82 is rendered conductive to pass .charging current to capacitor88 associated with rectifier 88, and tube 83 in turn discharges this capacitor through the make-alive element of rectifier 86 during each succeeding half cycle. As a result, for each half cycle that rectifier 81 is maintained conductive, rectifier 86 is also rendered in the same condition during the succeeding half cycle. Consequently, the rectifier conducting periods are always multiples of two half cycles.

When thus rendered conductive, rectifiers 86 and 81 supply the field winding 83 with an energizing current which boosts the voltage of exciter 82 and thereby raises the voltage supplied by machine 88 to circuit i8". When this rise has continued to slightly above the desired average or mean value, the detector 28 causes amplifier 48 to increase hits conductivity and thereby raise the grid bias applied to tube 84 to above the critical value required to maintain this' tube non-conductive. Charging current is then no longer supplied to capacitor 8i, the make-alive element 88 of rectifier 81 is no longer excited, and conductivity by the rectifiery is accordingly discontinued. Because of the before explained interconnection with rectifier 88, its conductivity is also discontinued.

As a result, energizing current is no longer supplied to field winding 83, the voltage of exciter 82 starts to drop causing machine 88 to lower the voltage supplied to regulated circuit I8". This lowering continues until tube 84 is again rendered conductive when the above described cycle is caused to repeat itself.

The circuit 'of field winding 83 supplied by the rectifiers is highly inductive, so that the current through it cannot be interrupted suddenly. Hence in thesupply circuit shown in Fig. 5 the normal tendency is to maintain conductive the rectifier 88 which last supplied current preceding a discontinuance by the control system of the rectifier conducting period. Such a condition is undesirable because it produces a high saturation in the main supply transformer 85, and to prevent this, I connect in shunt with the field winding 83 a bypass rectifier |82, which functions to complete a return circuit for the inductive voltage of winding 83 upon a discontinuance of current supply thereto through the rectiiiers I6 and 81.

The construction of this bypass rectifier may be similar to the before described tube rectifiers, and I have shown it as comprising a starting element 88 in circuit with which is connected an auxiliary rectifier |03 which insures that device |02 wil conduct current only in the proper direction. By means of this arrangement, tube |02 remains non-conductive as long as current is supplied through rectiers 86 and 81. as this supply is cut off, however, the bypass device becomes conductive, allowing rectiflers B6 and 81 immediately to revert to the non-conducting state when the control system so supervises.

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 for regulating the voltage of a dynamo-electric machine, the combination of a circuit for supplying exciting current to the machine, a rectifier tube for adjusting the magnitude of said current, means. comprising a twoelement tube having a lamentary cathode ener gized by a measure of the machine voltage, for supplying a control potential determined by said voltage, a triode electronic tube rendered conductive or non-conductive by ,changes in said potential, and means controlled by s'aid triode tube for rendering said rectifier tube fully conductive or fully non-conductive, regulation being eected through variation in the ratioof the conductive to non-conductive periods of said rectier tube.

2. In a system for regulating a characteristic of a dynamo-electric machine. the combination of a crcuit for supplying exciting current to the machine, a rectifier, having a conductivity instituting make-alive element, for adjust-ing the magnitude of said current, means for supplying a control potential determined by the said machine characteristic, a triode electronic tube rendered conductive or non-conductive by changea in said potential, a capacitor and a charging circuit therefor which includes said tube, and a circuit for discharging said capacitor through the make-alive element of said rectifier to there variation in the ratio o! the conductive to non-conductive periods of said rectifier.

3. In a system for regulating a characteristic of a dynamo-electric machine, the combination of an alternating-current source of power, a reccontrol potential determined by said machine characteristic, means responsive to changes in the magnitude of said potential for rendering said rectifier fully conductive or fully non-conductive, and a second rectifier connected in parallel-circuit relation with said machine-excitation determining circuit to bypass the cur rent of induction which results when the firstnamed rectier is rendered non-conductive.

4. In a system for regulating a characteristic of a dynamo-electric machine, the of an alternating-current power source, a pair of rectifiers, a machine-excitation determining circuit of inductive character supplied from said source through a full-wave rectifying eonnection of said rectiers, means for supplying a control potential determined by said machine characteristic, means responsive to changes in the magnitude of said potential for rendering one of said rectifiers fully conductive or fully nonconductive, means responsive to the conductivity of said initially controlled rectifier for controlling the conductivity of the other rectifier, and

a third rectier connected in parallel-circuit relation with said machine-excitation determining circuit to bypass the current of induction which results when said first-named rectiflers are rendered non-conductive.

LA VERNE R. PHILPOTT.

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