US2693571A - Voltage regulator - Google Patents

Description

Nov. 2, 1954 E. R. HIGGINS, JR

VOLTAGE REGULATOR Filed Dec. 22, 1953 INVEN TOR.

EDWARD R. Hleamsp.

l$l10 44W ATTYS.

United States Patent VOLTAGE REGULATOR Edward R. Higgins, Jr., Acton, Ind.

Application December 22, 1953, Serial No. 399,846

4 Claims. (Cl. 323-19) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

My invention relates to voltage regulators and is particularly directed to regulators of the type having a gaseous discharge tube connected in parallel with the power source and with the load to be regulated.

In voltage regulators of the type employing a gaseous discharge tube, the tube is connected directly across the voltage source. Because of the peculiar property of ionized gas between an anode and a cathode to maintain a constant voltage drop independently of the amplitude of current flowing through the space, the gas tube is commonly used for voltage regulation. Unfortunately the minimum voltage necessary to start ionization varies considerably and is dependent upon such factors as light intensity, temperature, presence of nuclear radiation and the time the voltage is applied. For example, the commercial gas tube 5651, which under normal light would readily ionize at 108 volts, may in the absence of light, require 160 volts. Variations in starting voltage are also quite sensitive to temperature. The 0A2 and 0B2 commercial gas tubes are observed to exhibit similar tendencies.

For certain circuit applications it is undesirable for reasons of efiiciency that the starting voltage be supplied to the gas tube from the power source through a large voltage dropping impedance. In the practical system the voltage of the power source is only slightly above the minimum potential required to maintain ionization and discharge. Power sources having voltages higher than any expected starting voltage is inherently inefiicient.

An object of my invention is an improved voltage regulator of the gaseous tube type.

A more specific object of my invention is an improved voltage regulator of the gas tube type with a source voltage efiiciently selected near the actual operating voltage.

Other objects and features of my invention will become apparent in the following description of a preferred embodiment of my invention. My invention is defined with particularity in the appended claims and said embodiment is illustrated in the accompanying drawing in which:

Figure l is a circuit diagram of the voltage regulator of my invention, and

Figure 2 is a circuit diagram of a regulator of my invention with specific circuit parameters.

The direct current power source 1 is connected to the load 2, the load being resistive or reactive in nature. Connected across the power transmission line between the power source and the load is the gaseous type tube 3. When ionization exists in the gas tube the potential across the terminals of the tube and across the load remain substantially constant. Impedance Z1 at 6 is included in the power circuit and may comprise the internal impedance of the source 1 as well as any external resistance that may be required. The voltages and impedances of the source and the load may, following the teachings of my invention, be designed for more efficient use of power without regard to the problem of the starting potential of the discharge in gas tube 3.

According to my invention a rectifier 4 is connected in series with the gas tube 3. The rectifier 4 may be of any unidirectional current conducting device with relatively high back resistance and relatively low forward resistance. An ideal rectifier, of course, is one in which the forward resistance is zero and the back resistance is infinite in value. A voltage source 5 is connected across the rectifier, with the negative terminal of the voltage source connected to the junction of the gas tube and the rectifier. Impedance Z2 at 7, which may be the internal impedance of the source 5 and any desired external impedance, is preferably of relatively high value compared to the impedance Z1 of the power circuit. It will now be noted that the polarity of the power source 1 and the voltage source 5 are in series aiding relation between the anode and cathode of the gas tube. It follows that the only requirement of voltage source 5 is that its potential be high enough, when added to the potential of source 1, to initiate gaseous discharge under any conditions, when we neglect leakage currents through gas tube 3 and rectifier 4.

In operation, when gas is ionized current flows from the positive terminal of the power source 1 through the anode-cathode path of gas tube 3 and through the nearzero forward resistance of rectifier 4 and hence to the negative terminal of the power source 1. As the forward resistance of the rectifier 4 is but a small fraction of the forward resistance of the gas tube 3 the effect of the rectifier upon the regulating capabilities of the gas tube 3 may be neglected. The impedance of the voltage source 5 is high compared to the forward impedance of the rectifier and will shunt negligible amounts of the current from the rectifier. With both supply voltages fixed the maximum value of impedance Z2 will depend on the ionization characteristics of the gas tube and the back resistance of the rectifier.

Once gas tube 3 has ionized the current through the rectifier is large compared to the current through the impedance Z2 and the voltage across the rectifier is small, as the rectifier is conducting in the forward direction.

Quite a number of circuit variations are possible in my novel voltage regulator depending upon circuit requirements. For example, direct current, alternating current or pulse voltage can be utilized at source 5 to initiate the ionization of the gas tube. It is to be remembered that only an instantaneous application of igniting potential is required to start ionization. Further, the voltages can be of either polarity depending upon the location of the rectifier, that is, in either the plate or the cathode side of the gas tube.

An interesting feature of this circuit in ionizing gas diodes is that a voltage from a high impedance source can initiate the discharge in much the same manner as an initiating voltage applied to the grid of a gas triode. A switch 8, for example, may be inserted in series with the high voltage source 5 of Figure 1. A certain amount of energy is required to initiate the discharge, however, this is a small fraction of the controlled energy.

Good results have been obtained with the specific voltage regulator of Figure 2 for regulating power to airborne electronic equipment. The airborne power source was lirnited to 150 volts direct current and the load 2 was 9,000 ohms. The gas tube used was the commercial 5651 while the rectifier was the commercial bimetallic rectifier known as the General Electric 1N93. The starting voltage source 5 was volts 400 cycle A. C. available on the aircraft and was coupled across the rectifier through a .001 microfarad condenser. In this circuit it is desirable that the forward resistance of the rectifier be kept at a minimum. Although selenium, or point contact germanium will give good results, diffused junction germanium diodes appear to be superior because of their low forward resistance together with their relatively high back resistance.

Many modifications may be made in the circuitry of my novel voltage rectifier without departure from the scope of the invention defined in the following claims.

I claim:

1. In combination, a power source, a gas tube with a relative stable forward voltage drop connected across said source to regulate the voltage of said source, means to initiate discharge of said tube when the voltage of the source is lower than the initiating voltage, said means comprising a rectifier with a relatively low forward resistance and a relatively high back resistance connected in series with source connected across said rectifier, said voltage source being polarized to add to the power source voltage to initiate discharge.

2. In combination in a voltage regulator, a powersource with relatively low impedance, low. terminal voltage, and high current capacity; a gas tube with relatively high forward resistance, a rectifier with relative low forward resistance, said tubeand rectifier being connected in series across the terminals of said power source; and means to initiate a discharge in said tube comprising a voltage source of relatively high impedance connected acrosssaid rectifier and in series aiding relation with said power source.

3; In combination in a voltage regulator comprising a tube having constant voltage-variable current characteristics, said tube being coupled across a power source to be. regulated, a rectifier with a forward resistance, relatively lower than the efiective forward resistance of said tube connected in series with said tube across said power source, a voltage source with impedance relativelyhigh compared to the impedance of said power source connected in series with said power source across the terminals of said tube.

4. A voltage regulator circuit comprising a source of power of predetermined terminal voltage, a load connected to said terminals and a gaseous discharge device, a semi-conductor type rectifier, said discharge device and said rectifier being connected in series across said terminals, said discharge device having a discharge initiating potential higher than said terminal voltage; a second high-impedance voltage source connected across said rectifier, the voltage of said second source being greater than the difference between said terminal voltage and said initiating potential.

No references cited.

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