US2120884A - Regulator system - Google Patents

Description

June 14, 1938. BROWN JR 2,120,884

REGULATOR SYSTEM Filed Jan. 6, 1936 2 Sheets-Sheet l .3 UPPLY CONTEDL ol/TPUT VGLTHGE S UPPL Y J UPPLY OUTPUT L fru/enfor @rwlals Q firvwna/r by mgwdm s June 14, 1938. R. D. BROWN, JR

REGULATOR SYSTEM Filed Jan. 6, 1936 2 Sheets-Sheet 2 I/YPU T VOL THEE Patented June 14, 1938 UNITED STATES PATENT OFFICE REGULATOR SYSTEM Application January 6, 1936, Sa-lal No. 57,862 In Great Britain January 7, 1935 11 Claims.

This invention relates to control devices for electrical systems and has for its object the provision of a control device having a large power output, the voltage of which may be maintained constant or may be made to vary in accurate accordance with the voltage of a lower power input or control voltage regardless of variations in the load or in the power supply. If the input or control voltage is constant, the device will function as a regulator. Whenmeasured from the output side, it will appear to have a low internal resistance to unidirectional currents, but a high internal impedance with respect to even the lowest frequencies of alternating currents, and will maintain a constant output voltage in spite of variations in the load or in the power supply. Moreover, the output voltage may be accurately increased or decreased independently of the variations in the load or in the power supply by varying the input or control voltage. The device is also characterized by its instantaneous response, and its ability to function as a filter with respect to power supply variations.

If, however, the input voltage varies about some positive value, such that the input signal is maintained within the operable region of. the

system, the same voltage will appear in the output circuit and the device then acts as a power amplifier. It will be noted that the system is self-filtering as described in more detail hereinafter regardless of whether it is used as a regulator or amplifier. Further by so biasing the input signal that the instantaneous input voltage during at least a portion of each cycle extends below the control region of the system, the device may be used as a power detector having a high impedance input, low impedance output and a substantially ideal linear characteristic.

The invention may be clearly understood from the illustrated embodiments of the accompanying drawings, wherein Fig. 1 is a diagrammatic illustration of a simple embodiment;

Fig. 2 illustrates a modification;

Fig. 3 illustrates a further modification;

Fig. 4 illustrates a system embodying the invention;

Fig. 5 shows the characteristic curve of the device, enabling a clear understanding of the several adaptations of the invention;

Fig. 6 illustrates a modification of the invention embodying a push-pull arrangement.

In the simple embodiment of the invention shown in Fig. 1, the load is connected serially with one or more vacuum tubes across the supply line. Assuming, for example, that energy is supplied from a direct-current source, one side of the load may be connected to the negative side of the supply line and the other side of the load may be connected to the cathode or cathodes of the said tube or tubes. If there is to be more than one such tube, the additional tubes may be connected in parallel relation to the first. For simplicity of illustration, it may be assumed that there is a single tube A, which tube is preferably, but not necessarily, a power tube characterized by having a low amplification characteristic and high current-conducting ability. The anode of this tube may be connected to the positive side of the supply line.

A control circuit may also be connected across the supply line, which control circuit may comprise a source of input or control voltage, a vacuum tube B, and a resistor R, all connected in series. The resistor R may be of relatively high value and may have one side connected to the positive side of the supply line, while the other side of the resistor may be connected to the anode of the tube B. The control voltage may be applied between the cathode of tube B and the negative side of the supply line. The tube B is preferably one having a very high amplification factor and may be a pentode of well-known form. The control grid of tube B may be connected to the cathode of the tube A, while the control grid of tube A may be connected through a battery or other source of unidirectional potential to the anode of tube B. The battery or source of unidirectional potential supplies a suitable bias to the control grid of tube A and this bias is preferably of such magnitude and polarity as to make the control grid of tube A negative at all times with respect to its cathode.

As the load is connected in parallel with the control voltage and the cathode-to-control grid voltage of tube B, the latter two being series, it will be obvious that the load voltage must, at all times, be equal to the sum of these serially connected voltages. It has been found that the cathode-to-control grid voltage of tube Bis nearly constant for all operating conditions due to the high amplification of tube B and the high resistance R in series therewith and, therefore, the load voltage will always be equal to the control voltage plus a small constant.

In operation, if the supply line voltage suddenly increases, both of the above-described circuits will tend to draw more current. The increase in current through the load circuit will slightly increase the voltage across the load negative and thus further increase the current through tube B and the resistor R. The voltage across the resistor will, therefore, increase and by doing so will increase the voltage between the anode and control grid of tube A. Meanwhile, the voltage between the cathode and anode of tube A will have decreased due to the increase in the load voltage. Consequently, the grid of tube A will become much more negative and will, therefore, oppose the tendency of the current through the load to increase, to the extent that the load voltage is maintained at substantially the original value. If the supply line voltage were to decrease rather than increase, the opposite action would take place, thus maintaining the desired voltage across the load.

Assuming now that the resistance of the load were to increase, the load voltage would then tend to'increase, which would make the grid bias of tube B less negative and thus increase the current through tube B and the resistor R. This would cause a decrease in the load voltage to the desired value in the manner above explained. If the load resistance were to decrease rather than increase, the opposite action would take place, returning the load voltage to normal.

If both the supply line voltage and the load resistance were to change simultaneously, a combination of the two actions above described would take place and would maintain the load voltage at the desired value.

As stated above, the voltage between the oathode and control grid of the tube B is substantially constant and the control system maintains the load voltage at a value substantially equal to the control voltage plus the constant bias on the control grid of tube B. If desired, the constant portion of this grid bias may be counteracted by inserting a small battery of equal voltage but opposite polarity in the control circuit, as shown in tlfi: push-pull system of Fig. 6 described hereina er.

The negative bias on the tube A may be made sufllciently large so that when the control voltage is reduced to zero, tube A is biased to cut-off and the load voltage is reduced to zero. Thus, the operative range of the system may be extended to zero output. As the system will function properly as long as the grids of both tubes are negatively biased, this increase in operating range may be readily had.

The system may be used as a combination filter and regulator having a controllable voltage output. In such case, the control voltage may be supplied from a potentiometer, or voltage divider across an auxiliary source. The output or load voltage may then be adjusted from zero to its maximum value by manual adjustment of the potentiometer to give the desired control voltage. Such a system is shown in Fig. 4 and will be described hereinafter.

If the direct current power supply is taken from a rectifier or other non-constant unidirectional source, it is" only necessary to filter this supply sufficiently to obtain a voltage which at all times has a minimum instantaneous value somewhat greater than the desired load voltage. The system functions efliciently to filter out the residual ripple in the supply system, as described above with regard to variations in the supply voltage.

The operating characteristic in the form of a curve showing the relation of input voltage vs. output voltage is shown in Fig. 5. In the particuwhich will make the control grid of tube B less lar case the input voltage is so biased that for negative input signals the output tube is. cut-oi! and consequently the output voltage is zero. However for positive input voltages the output voltage will be directly proportional thereto, as indicated by the sloping straight line. The slope of this line is determined by the proportion of output voltage fed back to the control tube. When used as an amplifier it is simply necessary that the input voltage be maintained in the positive region which may be accomplished by proper circuit design and by use of proper biasing batteries. It will be noted that the amplifier may be used to amplify unidirectional as well as alternating voltages.

The device may be made to function as a de tector by biasing the input signal so that it fiuctuates about the zero point at which the output voltage becomes zero. Of particular importance is the fact that when the output voltage is positive it is directly proportional to the input voltage thus giving a linear detector characteristic.

Likewise by using two such systems in pushpull fashion back-to-back an amplifier of the class B type may be obtained and such an amplifier may be made substantially distortionless by so biasing the control voltages of each unit that when the input voltage is zero the output current of each unit is zero. Thus one unit will amplify one-half of each cycle of input voltage and the other unit will amplify the other half, as is characteristic of a class B system. Such a system is shown in Fig. 6 and will be described in detail later.

In a specific example of the use of the device as a regulator, six of the tubes A may be used, these tubes being type 42 pentodes connected as triodes and in parallel. The tube B may be a type 77 pentode. The resistor R may have a value of 2 megohms. The grid bias voltage applied to tubes A may be 144 volts with respect to the oathode and the bias on the screen grid of tube B may be 45 'volts with respect to its cathode. If the minimum instantaneous supply voltage is approximately 700 volts D. C. and if the control voltage be varied from zero to 600 volts, the output voltage will be varied from zero to 590 volts. The output current may be as high as 240 milliamperes, each of the type 42 tubes supplying about 40 milliamperes.

It is sometimes desirable to insert an additional tube C between the tubes A and B, as shown in Fig. 2, for the purpose of supplying current to the grid of tube A when its grid is positive with respect to its cathode, to thus increase the range over which regulation is effective. One effective manner of inserting the additional tube C is illustrated in Fig. 2. The anode of tube C should preferably be connected to the positive side of the power-supply line, while the cathode of this tube may be connected to the negative side of the power-supply line through a resistor R1 which may have a value approximating the rated internal anode impedance of tube C, or a higher value.

As the effective amplification due to the additional tube C in this circuit will be somewhat less than one, the insertion of the additional tube is solely for the purpose of increasing the range of regulation and not for the purpose of increasing the effectiveness of regulation within the range previously obtained.

In a further modification of. the system, as shown in Fig. 3, a glow-discharge tube C1, which may be a type 874 voltage regulator tube, may be used to supply a constant voltage in place of the 2,120,884 control voltage. In such case, the cathode of the tube B may be connected to the anode of the glow-discharge tube, while the cathode of this tube may be connected to the negative side of the supply line. A resistance R: of high value may be connected between the positive side of the supply line and the cathode of tube B. The screen grid of tube B may be connected to an appropriate point on this resistance; in which case, the screen grid is biased by the voltage drop across a portion of the said resistance. It will be noted that by so obtaining the screen voltage a certain portion of the voltage ripple of the supply voltage will appear thereon and be introduced in the system in the proper phase to balance out ripple in the output circuit. Thus the supply ripple may be further reduced by proper design of the circuit for obtaining the screen grid voltage. The control grid of tube A may be connected directly to the anode of tube B, if the grid bias voltage above mentioned for tube A be supplied in another part of its grid circuit. The control grid of tube B may be connected to the movable contact of a potentiometer P in the load circuit, the output being taken from across the potentiometer.

The principal feature of this modification is that it is self-biasing, due to the action of the constant voltage glow-discharge tube and this eliminates the auxiliary source of control voltage. This system is particularly adapted for use as a self-contained regulator. The output voltage may be controlled to a limited extent by varying the positionof the potentiometer contact, thus varying the voltage applied to the control-grid of tube B.

In a practical application of the above-described systems, these systems may be combined to provide a composite system, as shown in Fig. 4, characterized by its being divisible into units which can be placed wherever convenient and further characterized by having remote control means for adjusting the output voltage to the desired value and regulator means to maintain this desired voltage in spite of. variations in either or both the load and supply voltage. In the illustrated embodiment of this system, the supply current may be taken from an alternating current source and may be supplied to a rectifier D and also to an auxiliary rectifier F. These rectifiers may be of any well-known type. Preferably, the rectifier D is a full-wave gaseous rectifier and the output of this rectifier is partially filtered in a filter E. The essential function of this filter is to prevent the instantaneous value of this output voltage from becoming less than the desired voltage at any time. It is not necessary that this filter reduce the A. C. ripple superimposed on the D. C. output of the system, although it will, of course, do so to a limited extent. Both the rectifier D and the partial filter E are separate units and may be positioned in any convenient place. The output of the partial filter is supplied by a feed line to any desired location. This line may supply one or more regulator units I, each of which may take the form of the device of Fig. 1.

The rectifier F may be a half-wave or fullwave rectifier of any well-known type. The output of this rectifier is filtered in a filter G which may be a conventional filter such as is wellknown in the radio art. The output of this filter may be fed to a self-biasing regulator H which is preferably of the type illustrated in Fig. 3. The voltage output of this regulator will be constant and independent of the supply source voltage or load on the system. This constant voltage may be used as the control voltage for the regulator units I, above mentioned. To this end, the negative side of the auxiliary line from regulator H may be connected to the negative side of the main feed line. Each of the output units may comprise a remote control panel J and one of the above-mentioned regulator units I. The power supply -for each regulator unit I is taken from the main feed line, as above described, and the control voltage may be taken from a potent-iometer P1 at the corresponding remote control panel J. This potentiometer may be connected across the line of the auxiliary or control system which is regulated by the regulator H and the control voltage for the regulator I may be taken from the movable contact of the potentiometer and one side thereof. Preferably a condenser is connected to these two points in order to maintain the control voltage as the contact is moved along the wire-wound potentiometer. Otherwise, the violent voltage fluctuations which would occur as the potentiometer contact is moved might damage the external load in the output circuit.

It will be noted that a three-conductor supply line is provided for the regulator units I. The conductor I is a common conductor connected to the negative sides of the output circuits of devices E and H. Conductor 2 is connected'to the positive side of the output circuit of the self-biased regulator H, while conductor 3 is connected to the positive side of the output circuit of filter device F. It will be seen that a substantially constant potential is produced between conductors l and 2 or across potentiometer P1, while another potential is produced between conductors I and 3. This system lends itself very conveniently to the employment of a plurality of regulator units.

It is important to note that the control voltage source, as shown in Figs, 1 to 3, is preferably connected to the low voltage side of the supply line, thus maintaining the control voltage at a minimum value above the potential of the low voltage side of the line. This feature also lends itself to the three-conductor supply system of Fig. 4.

As will be readily apparent, each control panel may be combined with its outlet panel, while the corresponding regulator unit I may be separately located. However, due to the fact that the equivalent internal impedance of the regulator I is very small. it is desirable to keep the resistance of the leads from the regulator to the load as low as possible, so as not to impair the regulation.

In Fig. 6 there is illustrated a push-pull system such as above mentioned. The control voltage is supplied to two control tubes B1 and B: by means of a transformer T1 having a center tapped secondary. The load is connected across the secondary of an output transformer T2 having a center tapped primary. The output tubes are shown at A1 and A2. The circuit connections of the control tubes and the output tubes are the same as shown in Fig. .1, except for the input and output circuits. The control voltage for control tube B1 will be the voltage across one half of the secondary of the transformer T1 plus the voltage of the biasing battery, whereas the control voltage for control tube B2 will be the voltage across the other half of the secondary of transformer T1 plus the biasing voltage. The biasing battery is so arranged that when there is no voltage across the transformer T1, both tubes A1 and A: are biased to the point of cut off. Under these conditions, each unit A131 and A1131 will have an operating characteristic similar to that in Fig. 5. Thus, if the cathode of tube 131 is made positive with respect to the center tap of the transformer T1 while that of B2 is made negative, the tube A1 will transmit current in accordance with the input voltage supplied to B1, while tube A: will remain non-conductive. On the other hand, when the control voltage supplied to B2 is positive, then the tube A: will conduct and during this portion of the cycle, tube A1 will be non-conductive. Thus the tubes A1 and A: are alternately conductive during successive half cycles of the control voltage, the device functioning as a class B amplifier.

The effectiveness of any of the above-described regulators may be increased by increasing the amplification within the circuit in any wellknown manner. The sources of bias necessary for the operation of these devices may be inserted at any point in the circuit as various considerations may dictate.

Although the invention has been described with reference to certain specific embodiments, it will be understood that other forms are possible within the scope of the invention.

I claim:

1. In an electrical system, a control space discharge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, a source of electrical energy, a source of control voltage, said sources having one common connection, impedance means connecting said common connection to said cathode of said output device, a connection between said energy source and said anode of said output device, whereby the space current of said output device flows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element of said control device the potential diilerence between said control voltage and at least a portion of the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and a connection between said output circuit of said control device and said control element of said output device for controlling said potential across said impedance so as to minimize said potential difference.

2. In an electrical system, a control space discharge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, a source of electrical energy, a source of control voltage, impedance means connecting said cathode of said output device to said energy source, a connection between said energy source and said anode of said output device, whereby the space current of said output device fiows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element of said control device the potential difference between said control voltage and the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and a connection between said output circuit of said control device and said control element of said output device for controlling said potential across said impedance means so as to minimize said potential difierence when said control voltage has an instantaneous amplitude within a predetermined amplitude range.

3. In an electrical system, a control space discharge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, a source of electrical energy, a source of alternating current control voltage whose amplitude varies within a predetermined range, impedance means connecting said cathode of said output device to said energy source, a connection between said energy source and said anode of said output device, whereby the space current of said output device flows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element of said control device the potential difierence between said control voltage and the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and a connection between said output circuit of said control device and said control element of said output device for controlling said potential across said impedance means so as to minimize said potential difference for instantaneous amplitudes of said control voltage within said predetermined amplitude range, whereby said system operates as an amplifier.

4. In an electrical system, a control space discharge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, a source of electrical energy, a. source of alternating current control voltage whose amplitude varies with respect to a predetermined range, a portion of said control voltage extending outside said predetermined range, impedance means connecting said cathode of said output device to said energy source, a connection between said energy source and said anode of said output device, whereby the space current of said output device flows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element of said control device the potential difference between said control voltage and the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and a connection between said output circuit of said control device and said control element of said output device for controlling said potential across said impedance means so as to minimize said potential difierence for instantaneous amplitudes of said control voltage within said predetermined amplitude range, whereby said system operates as a detector.

5. In an electrical system, a control space discharge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, a source of electrical energy, a source oi control voltage, impedance means connecting said cathode of said output device to said energy source, a connection between said energy source and said anode of said output device, whereby the space current of said output device flows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element of said control device the potential diiference between said control voltage and the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and means for extending the range of operation of said output device.

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6. In an electrical system,,a control space discharge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, a source of electrical energy, a source ofcontrol voltage, impedance means connecting said cathode of said output device to said energy source, a connection between said energy source and said anode of said output device, whereby the space current of said output device fiows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element of said control device the potential diflerence between said control voltage and the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and means for extending the range or operation of said output device comprising a third space discharge device having an anode, a cathode and a control element, a connection between the output circuit of said control device and said control element of said third space discharge device, and a connection between said'cathode 01. said third space discharge device and the control element of said output device.

7. In an electrical system, a control space discharge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, a source of electrical energy, a source of substantially constant control voltage, said sources having one common connection, impedance means connecting said common connection to said cathode of said output device, a connection between said energy source and said anode of said output device, whereby te space current of said output device flows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element of said control device the potential difference between said control voltage and at least a portion 01' the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and a connection between said output circuit oi said control device and said control element oi said output device for controlling said potential across said impedance so as to minimize said potential difference.

8. In an electrical system, a control space dis charge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, a source of electrical energy, a control voltage-supplying device arranged to receive the space current of said control device and having a non-linear voltage-current characteristic wherein the voltage is generally independent of current variations over a predetermined range, said source and said voltage-supplying device having one common connection, impedance means connecting said common connection to said cathode of said output device, a connection between said energy source and said anode of said output device, whereby the space current of said output device flows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element 01' said control device the potential ditierence between said control voltage and at least a portion of the potential across said impedance means, an output aircuitior said control device, means for supplying electrical energy to said output circuit, and a connection between said output circuit of said control device and said control element 01 said output device for controlling said potential across said impedance so as to minimize said potential diflerence.

9. In an electrical system, a control space discharge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, a source of electrical energy. a source of control voltage comprising a voltage regulator device connected to the cathode of said control device and having a common connection with said first source, impedance means connecting said common connection to said cathode of said output device, a connection between said energy source and said anode of said output device, whereby the space current of said output device flows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element of said control device the potential difference between said control voltage and at least a portion 01 the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and a connection between said output circuit of said control device and said control element or said output device for controlling said potential across said impedance so as to minimize said potential difi'erence.

10. In an electrical system, a three-conductor supp y line. means for establishing a substantially constant potential between one of said conductors and a second of said conductors, means for producing a potential between said first conductor and the third conductor, an impedance connected between said first and said second conductors, and a regulator unit comprising a control space discharge device having an anode, a cathode and a control element, an output space discharge device having an anode, a cathode and a control element, impedance means connecting said cathode of said output device to said first conductor, a connection between said third conductorand said anode of said output device, whereby the space current of said output device flows through said impedance means and establishes a potential thereacross, means for supplying to said cathode and said control element of said control device the potential difference between at least a portion of the potential across said first impedance and the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and a connection between said output circuit of said control de vice and said control element of said output device for controlling said potential across said impedance means so as to minimize said potential difference.

11. In an electrical system, a three-conductor supply line, means for establishing a substantially constant potential between one of said conductors and a second of said conductors, means for producing a potential between said first conductor and the third conductor, a plurality of impedances each connected between said first and said second conductors, and a plurality of regulator units associated respectively withsaidimpedances, each of said units comprising a control space discharge device having an anode, a cathode and a control element, an output space discharge device having ananode, a cathode and a control element, impedance means connecting said cathode of first impedances and the potential across said impedance means, an output circuit for said control device, means for supplying electrical energy to said output circuit, and a connection between said output circuit of said control device and said control element of said output device for controlling said potential across said impedance means so as to minimize said potential diflerence.

REYNOLDS D. BROWN, JR.

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