US3012187A

US3012187A - Voltage regulating system

Info

Publication number: US3012187A
Application number: US839983A
Authority: US
Inventors: Robert R Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-09-14
Filing date: 1959-09-14
Publication date: 1961-12-05
Anticipated expiration: 1978-12-05

Description

R. R. JOHNSON VOLTAGE REGULATING SYSTEM Filed Sept. 14, 1959 Dec. 5, 1961 Smwm oom+ l 1. NN

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UnitedStates Patent O 3,012,187 VOLTAGE REGULATING SYSTEM Robert R. Johnson, Menlo Park, Calif., assigner, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Sept. 14, 1959, Ser. No. 839,983 2 Claims. (Cl. 323-56) The present invention relates in general to voltage regulators, and more particularly .to a regulating device, incorporating a magnetic amplifier, which is effective to develop an essentially constant output potential regardless of random iluctuations in supply line voltage.

In some types of electronic equipment, it is highly desirable to have available -an unv-arying voltage which can be applied, for example, to a vacuum tube heater circuit in cases where signal ouput from the apparatus is critically dependent upon the avoidance of variations in cathode emission resulting from random heater voltage liuctuations. Such heater voltage irregularities can change the gain of the tubes, or bring about a shift in the point at which they operate on their characteristic curves. Although equipment of the nature referred to is frequently provided with a regulated power supply for the tube plates or anodes, it is not usually practicable to bleed energy from this source -for heater purposes since the complexity and/ or weight of such an anode power supply is markedly increasedk by lthe heavy current drain thus imposed thereon.

The present invention yovercomes this difficulty by utilizing energy direct from the power line, and then provides means to compensate for `any fluctuations in Iline supply. This means includes a magnetic amplifier controlled from a pair of balanced vacuum tubes, the latter being biased in accordance with the algebraic sum of the voltages respectively derived from the regulated power supplyand from the power yline input. Any change in the value of this bias, resulting from a power line Variation, unbalances the vacuum tubes, and results in the development of an electromagnetic flux to partially saturate the core of the magnetic amplifier. This has the effect of altering the value of the amplifiers output as compared to the input thereto, and such output, in proper polarity and phase, is fed back to the heater trans-former to neutralize the power line fluctuations.

' One object of the present invention, therefore, is to provide 4an improved form of electronic voltage regulator actingto compensate for random irregularities in energy received from a supply line.

- lAnother object ofthe invention is to provide a voltage regulator, of the type described, incorporating a magnetic amplifier which acts to develop a control variation of such polarity and phase as to neutralize input fiuctuations which would otherwise appear in the output of the apparatus.

Other objects and many of the attendantadvantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed .description when considered in connection with the accompanying drawing, the singlegure of which is a schematic representation of a voltage regulating circuit embodying a preferred form of the present invention.

Referring now to the drawing, there is illustrated a transformer, generally identified by the reference numeral 10, which acts in 4the example chosen to step down a standard A.C. line input of llO-lZO kvolts to approximately 6 volts for utilization by some such equipment as the heaters of a series of vacuum tube amplifiers in a radar detection system or other similar receiver of radiant energy. The transformer 10 has two primary windings `12 and 14 between which a connection is made at 16 for 3,012,187 Patented Dec. 5, 1961 ice purposes -to be later described. The line input, a-t approximately volts, is applied to winding 12, this input wave having a frequency which may, for example, be in the neighborhood of 400 cycles per second. As is often the case with energy taken directly from a general supply source, random fiuctuations may be ypresent which normally are passed into the transformer output circuit and are thus received by the utilization apparatus.

In the system of the drawing, such a utilization apparatus (not shown) is connected to one secondary tr-ansformer winding 18. The latter is magnetically coupled, as illustrated, to the primary winding 14. The relative number of turns of each of these windings is so chosen that the value of the output energy is approximately 5.8 volts, although this figure is obviously predetermined in accordance with the particular operating requirements of the utilization equipment. Another secondary transformer winding 20 is lcoupled to the primary winding 12. From winding 20 energy is supplied to the series-connected primary windings 22 of a saturable-core transformer acting as a magnetic amplifier. This latter is generally identified in the `drawings by the reference numeral 24.

The saturable-core transformer 24 includes, in addition to the previously-mentioned primary windings 22, a pair of series-connected second-ary windings 26 and a further pair of series-connected control windings 28. All three

windings

22, 26, and 28 of transformer 24 are disposed in inductive relationship to one another, and, in accordance with the well-known operating characteristics of such devices, the transfer of energy between the primary -and secondary windings 22 and 26, respectively, is a function of the degree of saturation of the transformer core, and the latter in turn is `dependent upon the density of the magnetic flux developed by current diow in the control windings 28. Such flux tends to saturate the transformer core and reduce the output of the transformer. Expressed differently, the output of the unit 24, as derived from windings 26, is a function both of the energy supplied to the primary windings 22 and the flux developed by current flow in the control windings 28, these two factors being broadly effective in an opposite sense in lthat an increase in the latter tends to reduce the electromagnetic coupling between the primary and secondary windings 22 and 26, respectively, and hence precludes an increase in input energy to windings 22 from being proportionally transferred to the transformer output.

The voltage appearing at point 16 is rectified by a crystal diode 30. This diode is electrically connected so that the yoltage developed on its associated storage capacitor 32 1s of negative polarity, with the circuit constants being so chosen that fluctuations in line voltage appearing at point 16 develop corresponding changes in the value of the energy stored by the capacitor. Such energy is applied to one terminal of a series-connected voltage divider network consisting of two

resistors

34 and 36 and a potentiometer 38. The remaining terminal of the voltage divider is connected to a stable source of energy such as that which supplies operating potential to the anodes of the electron discharge tubes of the receiver. It is essential thatsuch source be regulated, or otherwise `free from liuctuations, throughout the interval during which described system is to be effective. The value of this potential source connected to resistor 36 (approximately300 volts in the example given) is such that the movable Contact of potentiometer `38'can be manually adjusted close to a point of nominally zero voltage, based upon the magnitude of the energy stored in capacitor 30 under normal line input conditions. This is accomplished when the positive potential from the regulated sourceapproximately equals (at the location of the movable potentiometer terminal) A pair of vacuum tube triodes V1 and V2 are arranged y in Abalanced relationship, with the cathodes of the tubes being directly connected together and thence to ground through a common resistor 40. The anode of triode V1 is supplied with energy from the regulated operating po4 tential source through one of the control windings 28 ofv the magnetic amplifier 24, While the anode of triode V2 is similarly supplied through the remaining control winding, as illustrated in the drawing. The control electrode of triode V2 is grounded directly, while that of triode V1 is connected to the movable contact of potentiometer 38.

In describing the operation of the illustrated circuit, it will rst be assumed that the line input is of normal value, thus yielding a desired constant voltage output from the transformer secondary winding 1S. Under such conditions, the cylically varying voltage appearing at point 16 is rectied lby the diode 30 to develop on capacitor 32 a negative voltage of such magnitude as to lapproximately balance, at the movable contact of potentiometer 218, the positive potential obtained from the regulated source 'connected to resistor 36. This is equivalent to stating that the potential on the control electrode of triode V1 approxi-V mates zero volts. Since the potential on the control electrode of triode V2 is always at zero volts (ground), the two tubes are close to being in balance, and conduct almost equally to cause nearly equal currents to flow through the two control windings 28 of the magnetic amplifier 24.` These two currents are in such directions as to oppose one another, however, and hence'little resultant electromagnetic flux is produced in the transformer y The core` and only slight saturation of the latter occurs. input energy, -as it appears across the secondary winding Ztl of the heater transformer V1t); is electromagnetically transferred between the primary and secondary windings 22 and 26 of the magnetic amplifier 24 and fed back to the point 16 so as to maintainr a predetermined voltage drop across Winding 14.

Now, however, assume that an undesired fluctuation occurs in the line supply, and that the voltage appearing at point 16 rises momentarily as a result thereof. Nominally this Would cause a corresponding increase in the output energy derived from the transformer secondary winding 18. However, when such a rise occurs, the unidirectional voltage developed on capacitor 32 also arises,

Vand hence the potentiometer voltage at its movable con- 4 It is desirable to have the voltage on the control electrode of triode V1 only approximate zero in order to allow for uctuations of the line voltage in a negative `as well as in a positive direction. Otherwise tube V1 would be in complete balance with triode V2 under normal voltage conditions, and momentary drops; in line voltage would place a positive potential on the control electrode of the tube. Its conductive status at such times would therefore not be such as to yield the desired compensating action.

Obviously many modifications and variations of the present invention are possible in the light 'of the above teachings. It is therefore'to be understood that within the scope y of the appended claims the invention may be practiced partially saturate the core thereof and thereby modify the y y energy transfer from primary windings 22 `to. secondary windings 26. The latter are sowound Ythat the phase vof `the energy fed back to pointj16 neutralizes, or compensates for, the yincrease -in line'voltage, tand hence the drop across transformer winding 1 4 remains constant reglardlessrof the input fluctuation from which the regulatory elect was derived. f

otherwise than as specifically described.

I claim:

1. In a regulatory circuit for developing a substantially constant output voltage of relatively low amplitude from a cyclically varying higher-amplitude bidirectional line input which is subject to randomrfluctuations from a nominal value: the combination of :a transformer having at least one primary winding to which input energy from said line is applied, a secondary winding for developing a regulatory control voltage, and a step down secondary winding for deriving said relatively low-amplitude output voltage; a saturable-core magnetic amplier having primary, secondary, and control windings; a connection between the regulatory control winding of said transformer and the primary winding of said magnetic amplifier; a feedback connection from the secondary winding of said magnetic amplifier to a point on the yprimary winding of said magnetic amplifier; a feedback connection from the -said transformer; means for rectifying at least a portion of the `cyclically-varying input energy; a source of constant potential of opposite polarity to that developed by said rectifying means; a voltage divider connected betweenV ythe constant potential source and the output of said rectifying means; circuit means responsive to changes yin the voltage appearing at a nominally balanced point onsaid voltage divider to correspondingly vary the vamountof current flowing throughout the control windings of .said magnetic amplifier and thereby alter the degree of saturation of said core andfhence the transfer of .energy between the pirmary and secondary windings of said amplifier; and means for applying the energy so transferred between .the primaryand secondary windings of said magnetic ampliiier to'stabilize the amountV of inductive coupling between theprimary and step down secondary windings of said. transformer.

2. A regulatory circuit accordingto `claim l in'whicih Vthe circuit means responsive to .changes in thevoltage References Cited in the file of this patent UNITED STATES PATENTS 1,894,133 ThompsQn Jan. 10, 193.3 1,997,657 `561mm f Apr. 16, 1955 2,743,785 L66 u May 1, 1956 ,2,883,608 v smith 'Apr. 21, 195,9 2,920,264