US2907921A - Voltage regulators - Google Patents

Description

Oct. 6, 1959 F. M. CAMERON, JR., ET AL 2,9 1

7 VOLTAGE REGULATORS Filed Sept. 25, 1957 7% fA/l/ENTOQS M CZMe'eo/v, J12. 655 566 A4 A04 ro/v United States Patent O VOLTAGE REGULATORS Application September 25, 1957, Serial No. 686,060 3 Claims. (Cl. 315-205) This invention relates generally to regulators and more particularly to voltage or current regulators supplying non-linear loads, such as magnetrons. In supplying magnetron loads, under some conditions, the magnetron may have an undesirable tendency to run away; that is, the magnetron plate current may tend to change at a very rapid rate. This rapid change in plate current may be due to a small change in magnetron voltage which occurs because of a small change in line voltage at the power supply. Because of the highly non-linear characteristics of the magnetron, a small change in magnetron voltage causes a large and rapid change in plate current. If the magnetron voltage remains constant and the magnetron load characteristics change, a large change in plate current may also result. The purpose of the invention is to prevent the magnetron from running away in operation when line voltage or load conditions change. The regulation of such a non-linear device as a magnetron is accomplished in the invention by utilizing the non-linear characteristics of the non-linear load itself to bring about such regulation.

:The invention utilizes a saturable reactor in series with the line voltage. In addition to the variable impedance windings of the saturable reactor, a bias winding and a control Winding are provided on the core of the reactor. Because the magnetron load is connected essentially in series with the control winding, a large and rapid change in current in the load provides a large and rapid change in current through the control winding. The control winding current change causes the impedance of the variable impedance windings to vary in such a direction as to compensate for changes in line voltage or load characteristics. Thus, a constant load voltage may be maintained if the line voltage changes and load characteristics remain constant and a constant load current may be maintained when load characteristics change and line voltage remains constant.

The operation of the invention can be described best with reference to the accompanying drawing wherein the figure shows a particular embodiment of this invention.

The figure shows a power supply which uses an alternating input voltage. In the figure, terminal 1 of a source of alternating line voltage 2 is connected to the variable impedance windings 3 of a saturable reactor 4 and, thence, to one terminal of the primary side 5 of a power transformer 6. Terminal 7 of the line voltage source 2 is connected to the other terminal of primary 5. The terminals of the secondary side 8 of transformer 6 are tied to terminals 9 ad 10 of a bridge rectifier 11. Terminal 12 of the bridge rectifier is connected to one side of the control winding 13 of saturable reactor 4. The other side of control winding 13 is connected to ground. Terminal 14 of the bridge rectifier is tied to the cathode of magnetron 16. The anode of magnetron 16 is connected to ground. Terminal 10 of bridge rectifier 11 is also connected to cathode 18 of diode 19. The plate 20 of diode 19 is connected to an R-C filter 21 made up of condenser 24 and variable resistor 25 and,

thence, to one side of bias winding 22 of saturable reactor 4.

The variable resistor 25 permits adjustment of the bias level, which in turn ultimately adjusts the output voltage level of the magnetron within the necessary of operation. The condenser 24 acts as a clamping device for the bias circuit by holding the average bias voltage level at its desired value and, thus, acts as a stabilizing factor in the bias circuit. In addition, condenser 24 serves as a filter for the ripple that may be present at the output of the rectifier that supplies the bias winding. The other side of bias winding 22 is connected to tap 23 on the secondary side of power transformer 6. The bias winding is, thus, supplied with a D.-C. voltage that provides a high biasing magnetizing force. The D.-C. voltage that supplies the bias winding can be obtained in a manner other than that shown in the figure. Any suitable source of direct voltage may be used toprovide a large magnetizing force for the bias winding for the purpose of operating the reactor in its saturable region. The bias Winding 22 and the control winding 13 are arranged in such a manner that their polarities are opposing. Thus, the operation of the reactor depends on the ampere-turn difierential between the bias winding and the control winding. It has been found that such operation substantially reduces the quantity of core material required from that needed for the single control winding operation that is generally prevalent in circuits of this nature.

' At nominal line voltage input, the currents through the bias winding 22 and the control winding are at particular values such that the reactor operates in a saturated region. When the core of the reactor is saturated, the windings 3 present little or no impedance and the voltage drop across these windings is essentially small. The current through control winding 13 of the saturable reactor is derived from the current system of magnetron 16. The plate resistance of the magnetron has a nonlinear characteristic such that a small change in magnetron voltage results in a large change in current through the magnetron. Therefore, an increase in the input line voltage 2 results in an ultimate increase in voltage at the magnetron and, hence, a large increase in current through the magnetron. Because the control winding derives its signal from the current system of the magnetron, this increase in magnetron current results in a large increase in the current through control winding 13.

An increase in line voltage also results in a small change in D.-C. voltage across bias winding 22 of the saturable reactor and, hence, only a small change in the bias current. Because the bias and control windings are in opposition, a large increase in control current opposes a small change in bias current. The net result is a decrease in D.-C. magnetizing force and the reactor core then operates in an unsaturated region and thereby results in an increase in the impedance of the variable impedance windings 3 and, hence, a greater voltage drop across the reactor impedance windings.

Because of the increase in voltage drop across impedance windings 3, the voltage at the transformer is decreased so as to compensate for the original increase in line voltage and, hence, a constant voltage is maintained at the transformer. The entire operation results, therefore, in a constant output voltage supply at the load.

If the line voltage originally decreases, similar effects, though opposite in sign, are produced in the system, and a decrease in voltage drop across impedance windings 3 compensates for the decrease in line voltage and a constant voltage is maintained at the transformer. Because of the non-linear characteristics of the magnetron, the large current change results in a rapidly varying current in the control winding that provides excellent regulation.

line variations isobtained.

'fIhus,the-voltageregulator describedwill supply a constant output voltage regardless of variations in line voltage. Because the; current system of the control winding of the circuit shown. Means of rectifying the voltage otherthan a bridge-type rectifier may .be used. Accordingly, it is desired .that the invention not be limited by the details of the particular embodiments described herein except as defined by the appended claims.- What is claimed'i's: a 1

1. A voltage and current regulator comprising, in combination, source means for generating an alternating voltage, variable impedance means connected to said source means, rectifier means, transformer means for coupling said variable impedance means to said rectifier means whereby a rectified voltage ,is produced, nonlinear load means connected to said rectifier means for producing a predetermined current output, said nonlinear loadmeans responsive to small variations in said rectified voltage whereby large changes in said predetermined current output are produced; and feedback control means in series with said non-linear load means responsive to said large changes in current output for rapidlycontrolling the impedance value of said variable impedance means. a

2; A voltage and current regulator comprising, in combination, source means for generating an alternating voltage, variable impedance means connected to said source means, rectifier means, transformer ,means for coupling-said variable impedance means to said rectifier means whereby a rectified voltage is produced, magnetron load meansjconnected to said rectifier means for producing a predetermined current output, said magnetron load means responsive to small variations in said rectified voltage whereby large changes in said predetermined current output are produced, and feedback control means in series with said magnetron load means responsive to said large changes in current output for rapidly controlling tlre impedance value of said variable impedance means. I

3. A voltage and current-regulator comprising, in combination, a first source means for generating an alternating voltage, saturable reactor means comprising variable impedance windings, a bias Winding, and a feedback control winding, said variable impedance windings connected to said first source means, rectifier means, transformer means for couplingsaid variable impedance Windings to said rectifier means whereby a rectified voltage is produced, a second source means connected to said bias Winding for producing a direct voltage for said bias winding, non-linear load means-connected to said rectifier means for producing apredetermined current output,

said non-linear load means responsive to small variations in said rectified voltage whereby large changes in said predetermined current output are produced, and vsaid feedback control winding of said saturable reactor means connected in series with said non-linear load meansvresponsive to said large changes in current output for rapidly controlling the'impedance value of said variable impedance windings of said saturable reactor-means.

References Citediin the file of this patent UNITED STATES PATENTS Smith Qct. 22, 1957

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