US2400599A - Electronic energy conversion and control system - Google Patents

Description

y 1945. J. B. REEvEs 2,400,599

ELECTRONIC ENERGY CONVERSION AND CONTROL SYSTEM Filed April 17, 1944 {Sheets-Sheet 1 May 21, 1946.

J. B; REEvEs 2,400,599

ELECTRONIC ENERGY CONVERSION AND CONTROL SYSTEM Filed April 17, 1944 2 Sheets-Sheet 2 III II F F 6 F minal of which is connected to the center tap l4 of transformer 14. A variable resistor 22 has one of its end terminals connected to the center tap l4, while its other end terminal is connected in series with an inductance 23 to the cathode l5. Connected in parallel with the resistor 22 is a condenser 24. The variable resistor 22 is provided with a sliding contact 22 which is connected to the common point of the resistor 1 and the condenser 3. The resistor 22 is further provided with an intermediate tap 22 which is connected to the cathodes l9" and 20*. Connected between the center tap 14 and the anode 20, is a condenser 25, and a similar condenser 28 is connected between the center tap l4 and the anode IS". A resistor 21 has one terminal connected to the anode Iii and a similar resistor 28 has one terminal connected to the anode 20 The two other ends of the resistors 21 and 28 are jointly connected to the common point of the resistor 22 and the condenser 24. The anode 20 is further connected through a resistor 23, to the grid 4, while the anode is connected through a resistor 30 to the grid 3.

The field'winding 2 of the motor is supplied with energy through a pair of gaseous electron tubes 3| and 32, having cathodes 3i and 32, respectively, anodes 31 and 32 respectively, and grids 3 l and 32, respectively. The an de 31 is connected to the intermediate tap I, while the anode 32 is connected to the intermediate tap I The cathodes 3i and 32 are jointly connected to one terminal of the field winding 2, while the other terminal of said winding is connected to the center tap i.

A transformer 33 is provided with a primary winding 33, which receives energy from the same source as the winding l. The transformer 33 has also a center tapped secondary winding 33, the center tap being connected to the grid 31, while a center tapped resistor 34 is connected between the grid 31 and the grid 32. The center tap of said resistor is connected to the common terminal of the cathodes 3| and 32. One of the end terminals of the winding 33' is connected to one terminal of a condenser 35, the other terminal of said condenser being connected to the grid 32. A' variable resistor 35 is connected between the second end terminal of the winding 33', and the grid 32. Said resistor 36 is provided with a tap 36 and is also provided with a sliding contact 36' by means of which the value of part of the resistor nearest to the grid 32 may be varied.

Connected in parallel with the motor armature 2 is the winding 31 of a voltage responsive relay 31, which relay has normally closed contacts 31 connected between the intermediate tap 36 of the resistor 36 and the grid 32.

The system shown in Fig. 1 operates as follows: Be it assumed that the primary windings of the transformers I and 33 are connected to an alternating current source of supply, thereupon a voltage is then induced in the secondary winding I of transformer I, and in turn a voltage is impressed upon the primary winding ll of the transformer Ii. This induces a secondary voltage in the winding ll which impresses alternating voltages displaced by 180 degrees from each other between the cathode I 5 of the tube l5 and the anodes l5 and I5, respectively. These voltages appear as a rectified voltage between l5 and the tap 14 of transformer l4 which is smoothed out in the usual manner by the condensers l3 and 24 and the inductance 23,

and a direct current flows through the resistor 22.

The direct current voltage impressed upon the resistor 22 tends to charge the condenser 25, the current flowing from the positive terminal of resistor 22, through the resistor 28, condenser 25 and back to the negative terminal of resistor 22. A similar charging current will flow through the resistor 21 to the condenser 28, so that the two condensers 25 and 2B are charged.

The transformer I4 is also energized so that the terminals 14 and i4 become alternately positive with respect to the center tap 14. Assuming that the terminal l4 is positive with respect to the center tap i4, then the grid 20 of the tube 20 is positive with respect to the cathode 20, to render the tube 20 conducting, thereby substantially short circuiting the condenser 25 so that it cannot be charged. However, during the same half cycle the grid 19 is negative with respect to the cathode l9, so that the condenser 23 is being charged. The rates of charge of the condensers 25 and 28 are determined by the value of the resistors 28 and 21, respectively, and also by the positive grid bias resulting from the voltage difference between the lower end of the resistor 22 and the tap 22. As the charge of the condenser 26 increases, the anode l9 becomes increasingly negative with respect to its cathode l9. This also increases the negative potential of the grid 3, with respect to the cathode 3 and the tube 3 is rendered nonconducting. The potential of the grid 3 with respect to the cathode 3 is further modified by the voltage drop in the upper partition of the resistor it), which affords an adjustable positive biasing component. The condenser 25 and tube 20 function in a manner similar to that described to affect the grid 4. The potential of the grids 3 and 4 may be further modified by any voltage which is induced in the winding 5 as modified by the voltage drop through the resistor 1, and by the potential of the sliding contact 22 with respect to that of the cathode I5", as will be more fully explained hereinafter.

The armature 2 is supplied with alternate half waves of rectified current from the transformer winding lb, through the tubes 3 and 4. By varying the moment during the respective potential half cycle at which the tubes 3 and 4 become conducting, the effective current supplied to the motor armature 2 may be varied.

The way of changing the moment of starting the conduction of current through these tubes will now be explained. Referring to Fig. 2 the curve A is the voltage which is available between the cathode and anode of the tube 3 during a given half cycle or said voltage. This is substantially the voltage between the center tap l and the end tap i The tube 3 will be rendered conducting if the grid potential is at least as high as, or more positive than, the ignition potential indicated by the curve B. To attain this ignition grid potential at any given moment, the system is arranged to charge the condenser 24 to a gradually increasing potential indicated by the line C, and to discharge the condenser again substantially instantaneously approximately at the end of said half cycle represented by curve A, as indicated by the curve D. It will be obvious that when the potential C of the condenser equals the value B, the tube begins to conduct and it continues to conduct in a well known manner substantially to the end of the half cycle. To vary the point at which the line C intersects the curve B, a positive direct current potential bias E is added to the potential C resulting in a grid potential represented by line C and thereby shifting the moment during the half cycle when the grid potential equals the ignition potential B.

During the next half cycle of the available voltage the tub 4 is rendered conducting and the moment when it starts conducting is con- 180 degrees from each otherare impressed upon the grids l9 and 20, respectively. During the half cycle when the grid. l9 is negative with respect to its cathode IS, the tube I9 is nonconducting and the condenser 26 is gradually charged through the resistor 21, so that the Potential of the anode l9 becomes less positive with respect to the cathode l9. During the same half cycle the negative potential of the grid 20 with respect to the cathode 20*- decreases, so that the tube 20 is ultimately renderedcohducting thereby substantially short circuiting the condenser 25 through a circuit from the anode 20 to the cathode 20 to. tap 22*, through the lower part of resistor 22, to the condenser 25 and back to the anode 20". It will be apparent that as the condenser 25 becomes charged the negative potential between the slider 22 and grid 3 and therefore between the cathode 3 and the grid 3 decreases as indicated by line, C (Fig. 2). This negative potential is modified by a positive bias due to the voltage drop between the upper terminal of resistor 22 and the movable contact 22 as indicated by E in Fig. 2. At the end of the half cycle described, the voltages of the grids l9 and 20 become zero and then reverse so that the grid I9 becomes positive, thereby causing the condenser 25 to suddenly discharge as indicated by the line D, while the tube 20 is maintained nonconducting by thev negative potential of the grid 20, 50 that now the condenser 25 gradually charges in the manner aforedescribed for condenser 26. The primary and secondary voltages of the transformer H are displaced approximately 90" from the voltage impressed upon the tubes 3 and 4 by the phase-shifting network comprising the resistor l2 and condenser l3. This assures that the voltage of the grid l9 and 20 render the respective tubes conducting at themoments when the voltages of tubes 3 and 4 are substantially zero. 'It will be seen that the moment at which the line C intersects the curve l3 depends upon the value of the potential E, which is superimposed upon the potential of the corresponding condensers 25 and 26-, respectively, this value E depending upon the setting of the movable contact 22. With the contact 22* in its lowermost position the component E is a maximum so that the critical grid potential B will be attained during the earliest possible part of the half cycle, and the tubes 3 and 4, respe tively, will be conducting a maximum amount of current, while with the movable contact 229 in its uppermost position the biasing component E is zero and by properly selecting the tap 22*, the maximum value of the voltage C is just sufficient to intersect the curve B prior to reversal of the voltage A, so that the tubes 3 and 4, respectively, are nonconducting. By adjusting the position of the movable contact 22' it is therefore possible to vary the effective current which the armature 2! receives from the transiormer l.

A motor usually require a maximum torque for starting from standstill, whereas during acceleration the torque required is less than the maximum. Provision is therefore made to limit the rate of rise of the armaturecurrent during acceleration or changes in load. For this purpose the series transformer 5 is arranged to impress .upon the circuit of the grids 3 and 4, a subplemental potential which tends to increase the negative bias on the grids 3 and 4, respectively. As long as the current in the winding 5 remains constant, very little voltage is induced in the secondary winding 6 If, however, the current in 5 should suddenly change, it induces a corresponding electromotive force in the secondary winding 5, the polarity varying with the direc-. tion of change. In order to prevent a sudden de crease of the current through the primar winding 5 from increasing the grid potential of the tubes 3 and 4, the rectifiers 8 and 9 are provided to block flow of a, reverse current to the condenser 8. The potential derived fromthe secondary winding 5 is subtracted from the potential B so as to delay the moment of intersection of line C with the curb B'and thereby delay themoment of ignition of the tubes 3 and 4 during the respective half cycle.-

The system disclosed in Fig. 1 also provides compensation for variations in the terminal voltage impressed upon the armature 2 Thus the resistor 10 has impressed upon it the terminal voltage of the armature 2 A part of said resistor is connected by means of the movable contact l0 in series with the winding 5 and the voltage drop therein which is a function of the armature voltage is thus impressed upon the grids 3 and 4, the arrangements being such that for an abnormal armature voltage the additional bias is added to or subtracted from the voltage E so "as to advance or retard the moment of ignition for restoration of normal armature voltage.

The total potential impressed upon the grids 3 and 4 with respect to the cathodes 3 and 4 is therefore composed of the following: the voltage drop of the resistor l0 between the cathodes 3 and 4 and the movable contact 10, the voltage that may be induced in the winding 5 by a sudden increase of the armature current, the voltage drop between the movable contact .22 and the upper terminal of the resistor 22 and the charge of the condenser 25 or 26.

The field current of the motor 2 is controlled in the following manner:

As long as the armature voltage is below a certain value, that is, below that voltage which corresponds to the normal speed of the armature at full field excitation, the contact 31 of relay 31 is closed. As soon as the motor reaches normal speed, the winding 31 is suiiiciently ener- When the contacts 3'l open, the voltage which is impressed upon the grids 31 and 32 is reduced so that conduction of the tubes 3| and 32 is delayed after the passage of the voltage through zero iora time depending upon the phase displacement of the grid voltage with respect to the cathode voltage which depends upon the adjustment or the movable contact 36 Hence, after the contacts 31 have opened, the speed or the motor may be varied by varying the adjustment of the movable contact 36". It will be recognized that the voltage which is impressed upon the grids referred to is the resultant of the inductive voltage or the condenser 35 and the noninductive voltage drop through the resistor 36. As the efiective value of the resistor 36 is varied by adjustment of contact 36', the non-inductive component likewise varies, thus varying the phase displacement of the grid voltage with respect to the voltage of the tubes 3| and 32 in the usual manner.

Fig; 3 shows a modification of the system shown in Fig. 1, wherein an adjustable resistor 40 is interposed in the plate circuit of the tube 20 and ternating current supply system, it will be obvious that it is also applicable to a system supplied with energy from a polyphase source by interposing a suitable plurality of gaseous discharge tubes between the current supply source and the transtubes l9 and 20 may be replaced by high vacuum a similar resistor 4| is interposed in the plate circult of the tube l9. Thus the resistors 40 and ll increase the impedance of the discharge circuit of the condensers 25 and 26, respectively, when the latter are discharged, upon the respective tubes 20 and I9 becoming conducting, as has been described heretofore. It is obvious that instead of putting the resistors 40 and it into the plate circuit of the respective tubes they may also be put into the cathode circuits, that is, between the respective cathode and the tap 22 4 shows the operation of the system as modified in accordance with Fig. 3. It will be the condensers??? and 26 are charged in the same manner as 7 Therefore the is i. on upon tube i, rises in accordance with the line that is, it rises from a minimum to a maximum value during said half cycle. the moment when the voltage A passes through zero, the tube 20 becomes conducting, thereby discharging the condenser 25 through a circuit from one terminal of the condenser, through the lower part of the potentiometer 22, over tap 22*, through the tube 20, through the resistor 40, to the other terminal of condenser 25. denser 25 to discharge at a rate which is determined by the impedance of the tube 20 and the resistance of the resistor 40. The voltage of condenser 25 thus varies in accordance with the curve G, which is not necessarily a straight line. The resistor 40 is adjusted so that the condenser attains its minimum charge at the moment when the voltage impressed upon the tube 4 again passes through zero in the opposite direction to repeat another half cycle similar to the one just described. The voltage E is superimposed upon the voltages F and G in the same manner as has been described in connection with Figs. 1 and 2. The operation of the tube It and the condenser 28 is similar to that described in connection with tube 20 and condenser 26, as will be apparent from the foregoing description and the diagram Fig. 4. The operation during the next half cycle represented by the curve A will be apparent from the foregoing description in explanation of Fig. 2, as will also be the effect of changing the biasing voltage E, resulting in the resultant grid voltages FG' and F"'G"'.

While the invention has been illustrated and described in connection with a single phase altermined by the resistors This causes the contubes. Other modifications within the scope of this invention will be apparent to those skilled in the art.

I claim: a

1. In combination, an alternating current supply source, a translating device, a first gaseous discharge tube having a cathode, an anode and a control electrode and connected for conducting current from said source to said translating device during positive hali cycles oi. the alternating current voltage impressed upon said first tube by said source, a condenser, a resistor and a charging source providing a circuit for charging said condenser at a substantially constant rate, a second gaseous discharge tube having a cathode, an anode and a control electrode and connected to said charging circuit to be normally rendered nonconducting and to discharge said condenser upon being rendered conducting, a connection between the control electr de of said second tube and said alternating current source to initiate conduction of said second tube during alternate half cycles of the voltage impressed upon said first tube by said alternating current source, a connection between said condenser and the control electrode of said first tube to impress the voltage of the condenser thereupon, and means to superimpose an adjustable unidirectional potential upon the potential impressed by said condenser upon the control electrode of said first tube for varying the moment when said first tube becomes conducting during said positive half cycles.

2. In combination, an alternating current supply source, a translating device, a first gaseous discharge tube having a cathode, an anode and a control electrode and connected for conducting current from said source to said translating device during positive half cycles of the alternating current voltage impressed upon said first tube by said source, a condenser, a resistor and a charging source providing a circuit for charging said condenser at a substantially constant rate, a second gaseous discharge tube havinga cathode, an anode and a control electrode and connected to said charging circuit to be normally rendered nonconducting, and to discharge said condenser substantially instantaneously upon being rendered conducting, a connection between the control electrode of said second tube and said alternating current source to initiate conduction of said second tube during alternate halt cycles of the voltage impressed upon said first tube by said alternating current source,

a connection between said condenser and the control electrode of said first tube to impress the voltage of the condenser thereupon, and means to superimpose an adjustable unidirectional potential upon the potential impressed by said condenser upon the control electrode of said first tube for varying the moment when said first tube becomes conducting during said positive half cycles.

3. In combination, an alternating current supply source, a motor, a first gaseous discharge tube having a cathode, an anode and a control electrode and connected for conducting current from said source to said m tor during'positive half cycles of the alternating current voltage impressed upon said first tube by said source, a condenser, a resistor and a charging source providing a circuit for charging said condenser at a substantially constant rate, a second resistor, a, second gaseous dischargetube having a cathode, an anode and a control electrode, said second resistor and said second tube being connected to said charging circuit to normally render said second tube nonconducting and to discharge said condenser at a substantially constant rate when said second tube is rendered conducting, a connection between the control electrode of said second tube and said alternating current source to initiate conduction of said second tube during alternate half cycles of the voltage impressed upon said first tube by said alternating current source, a connection between said condenser and the control electrode of said first tube to impress the voltage of the condenser thereupon, and means to superimpose an adjustable unidirectional potential upon the potential impressed by said condenser upon the control electrode of said first tube for varying the moment when said first tube becomes conducting during said positive half cycles.

4. In combination, an alternating current supply source, a motor, a first gaseous discharge tube having a cathode, an anode and a control electrode and connected for conducting current from said source to said motor during positive half cycles of the alternating current voltage impressed upon said first tube by said source, a condenser, a resistor and a charging source providing a circuit for charging said condenser at a substantially constant rate, a second gaseous discharge tube having a cathode, an anode and a control electrode and connected to said charging circuit to be normally rendered nonconducting and to discharge said condenser upon being rendered conducting,'a connection between the control electrode of said second tube and said alternating current source to initiate conduction of said second tube during the negative half cycles of the voltage impressed upon said first tube by said alternating current source, a connection between said condenser and the control electrode of said first tube to impress the voltage of the condenser thereupon, and means to superimpose an adjustable unidirectional potential upon the potential impressed by said condenser upon the control electrode of said first tube for varying the moment. when said first tube becomes conducting during said positivehalf cycles.

5. In combination, an alternating current supply source, a motor, a first gaseous discharge tube having a cathode, an anode and a control electrode and connected for conducting current from said source to said motor during positive half cycles of the alternating current voltage impressed upon said first tube by said source, a condenser, a resistor, and a charging source providing a circuit for charging said condenser at a substantially constant rate, a second gaseous discharge tube having a cathode, an anode, and a control electrode and connected to said charging circuit to be normally rendered non-conducting, and to discharge said condenser upon being rendered conducting, a connection between the control electrode of said second tube and said a1- ternating current source to initiate conduction of impressed by said condenser upon the control said second tube at the moment when the voltage impressed upon said first tube by said alternating current source passes through zero from'a; positive to a negative value, a connection between said condenser and the control electrode of said first tube to impress the voltageof the condenser thereupon, and means to superimpose an adjustable unidiretctional potential upon the potential electrode or said first tube for varying the moment when said first tube becomes conductingduring said positive half cycles.

1 6. In combination, an alternating current supply source, a motor, a first gaseous discharge tube having a cathode, an anode and a control electrode and connected for conducting current from said source to said motor during positive half cycles of the alternating current voltage impressed upon said first tube by said source, a condenser, a resistor and a charging source providing a cirouitfor charging said condenser at a substantially constant rate, a second resistor, a second gaseous discharge tube having a cathode, an anode and a control electrode, said second resistor and said second tube being connected to said charging circuit to normally render said tube nonconducting and to discharge said condenser at a substantially constant rate when said second tube is rendered conducting, a connection -between the control electrode of said second tube and said alternating current sourcetto initiate conduction of said second tube during the negative half cycle of the alternating voltage impressed upon said first tube, a connection between said condenser and the control electrode or said first tube to impress the voltage of the condenser thereupon, and means to superimpose an adjustable unidirectional potential upon the potential impressed by said condenser upon the control electrode of said first tube for varyingthe moment when said first tube becomes conducting during said positive half cycles.

7., In combination, an alternating current supply source, a translating device, a first pair of gaseous discharge tubes each having a cathode. an anode, and a control electrode and connected for alternately conducting current from said said source to said translating device, a condenser and a resistor for each of said first pair of tubes, a charging-source providing with each resistor a circuit for charging the respective condenser-at a substantially constant rate, a second pair of gaseous discharge tubes one for each of said first pair of tubes and each having a cathode, an anode. and a control electrode and eachconnected to the corresponding charging circuit to be normally rendered nonconducting and to discharge the respective condenser upon being rendered conducting, a connection between the control electrode of each of said second tubes and said alternating current source to initiate conduction of the respective second tube during alternate half cycles of the voltage impressed by said supcurrent conduction by said tubes.

l pressed upon the tubes by said source initiates 8. In combination. an alternating current supply source, a translating device, a first pair of gaseous discharge tubes each having a cathode. an anode, and a control electrode and connected ior alternately conducting current from said source to said translatingdevice, a condenser and a resistor for each oi. said first pair of tubes. a charging source providing with each resistor a circuit for charging the respective condenser at a substantially constant rate and a second resistor and a second pair 0! gaseous discharge tubes one for each or said first pair 0! tubes and each or said second tubes having a cathode, an anode and a control electrode, each or said second resistors and said second tuberbelng connected to the corresponding charging circuit to normally render said second tubes nonconducting and to discharge the respective condenser at a substantially constant rate upon the tubes being rendered conducting, a connection between the control electrode of each 01' said second tubes and said alternating current source to initiate conduction of the respective second tube during alternate halt cycles of the voltage impressed by said supply source upon the respective first tube, a connection between each condenser and the control electrode 0! the corresponding first tube- JAMES B. REEVES.

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