US3564292A

US3564292A - Electrical interstage control

Info

Publication number: US3564292A
Application number: US608865A
Authority: US
Inventors: Arthur K Littwin
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-01-12
Filing date: 1967-01-12
Publication date: 1971-02-16
Anticipated expiration: 1988-02-16
Also published as: GB1224005A; LU55241A1

Abstract

Auxiliary SCR''s of low current carrying capacity utilized for controlling main SCR''s of high current carrying capacity, to compensate for internal heating of the main SCR''s, and physically and spatially separated to compensate for ambient heating.

Description

United States Patent Arthur K. Littwin Lincolnwood, Ill.

[21] App]. No. 608,865

[22] Filed Jan. 12, 1967 [45] Patented Feb. 16, 1971 [73] Assignees Arthur K. Littwin;

Robert L. Littwin; Donald F. Littwin; Horace A. Young, Chicago, Ill. as trustees under trust dated 1/2/51 known as Littwin Family Trust No. l

[72] Inventor [54] ELECTRICAL INTERSTAGE CONTROL 6 Claims, 2 Drawing Figs.

[52] US. Cl 307,252; 307/305 [51] Int. H03k 17/00 [50] Field of Search 307/252, 237; 315/251, 192; 328/81; 323/22 (CR), 24

[56] References Cited UNITED STATES PATENTS 3,204,113 8/1965 Snygg 315/251 3,299,334 1/ 1967 Ramadah 307/252X 2,666,887 I/ l 954 Rockafellow... 315/251 3,181,071 4/1965 Smith et a1 307/252 3,129,341 4/1964 Rockafellow 315/251X 3,229,161 l/l966 Anger 315/251X 3,249,801 5/1966 Kirk et a1. 3 l 5/251X OTHER REFERENCES G.E. SCR Manual TK2798G49 1961 Second Edition page 65 Primary Examiner Donald D. Forrer Assistant Examiner-B. P. Davis Attorney-Paul HjGallagher ABSTRACT: Auxiliary SCRs of low current carrying capacity utilized for controlling main SCRs of high current carrying capacity, to compensate for internal heating of the main SCRs, and physically and spatially separated to compensate for ambient heating.

MAIN CIRCUIT BTI sec- 3g. CONTROL cIRcun' ELECTRICAL INTERSTAGE CONTROL BACKGROUND OF THE INVENTION many installations become heated due to the ambient temperatures and for this reason also lose their accuracy of control.

2. Description of the Prior Art There is no known prior art'relating to the present invention.

SUMMARY OF THE INVENTION A broad object of the invention is to provide a control circuit separate from a main circuit, the control circuit including auxiliary SCRs for controlling main SCRs in the main circuit but arranged to avoid the disadvantageous effects due to heat- Ing.

Another and more specific object is to provide a main circuit and a separate controlcircuit which is adapted for connection with a relatively low voltage source and not subject to objectionable internal heating, and is out of the effects of the internal heating of the main circuit, the auxiliary SCRs being utilized to control the main SCRs and to do so without the dis advantages caused by heating of the main SCR's.

I Another and more specific object is to provide a control arrangement of the character just referred to in which the auxiliary SCRs transistors are devoid of the effects of the internal heating of the main SCRs. I

Still another and more specific object is to provide a control arrangement of the character just referred to in which the auxiliary SCRs are devoid of the effects of ambient heating of the main SCR's.

BRIEF DESCRIPTION OF Tl-IE DRAWING DESCRIPTION OF A PREFERRED EMBODIMENT In the diagram of FIG. I a main circuit is shown at and a control circuit at 12. The main circuit 10 is adapted for connection with a relatively high voltage AC source, and includes line conductors l4, l6 and a load 18. The load may be of any of a wide variety of devices, including for example a motor as well as others. In the main circuit also is a control means indicated generally at 22 in seriestherein, this control means including a pair of back-to-back

main SCRs

24, 26 of relatively high current carrying capacity and adapted for accommodating the relatively high voltage in the main circuit 10, such as 460 volts, as indicated. Associated with the SCRs are the secondaries 288, 308 of

transformers

28, 30, the primaries of which will be referred to hereinbelow. The secondaries 285, 308 have one terminal connected with the SCRs and the other with a conductor thereof, forming a circuit through the SCR's for performing a gating control thereon, when they are energized by their primaries as referred to hereinbelow.

The control circuit 12 includes a pair of

conductors

32, 34 adapted for connection with a relatively low voltage AC source, such as l 10 volts, as indicated. Connected across these lines are

conductors

36, 38 having auxiliary SCR's 40, 42 therein, of relatively low current carrying capacity. These conductors include the primaries 28P, of the

transformers

28, 30, the secondaries I of which are in the circuit 10 as referred to above. These transformers are of step-up type for providing higher voltage in the secondaries. The

conductors

36, 38 are connected to a common conductor 44 which is also connected with

conductors

46, 48 leading from the

lines

32, 34 and which have

rectifiers

50, 52 therein. The present circuit utilizes back-to-back SCRs and rectifiers, but the invention is not limited thereto, and may include other arrangements such as center tap and bridge networks, etc.

The common conductor 44 leads to a potentiometer 54 from the opposite side of which leads a conductor 56 having

branches

58, 60 leading to the gates of the auxiliary SCR's 40, 42 and, when energized, effective for producing a gating control on those SCR's. Connected across the potentiometer 54 is a DC source 62 which may be a battery as indicated, or other instrumentality deriving its energization from the

lines

32, 34 for example. Connected across the

conductors

58, 60 on the one hand and the common conductor 44 on the other hand, are capacitors 63 and coils 648 in series therewith, the coils center tapped to the conductor 44, and forming secondaries of a primary MP of a transformer 64 deriving its energization from a suitable source such as

conductors

32, 34 as shown at bottom right of FIG. 1.

Upon energizing the circuit 10, and performing a control operation on the load 18 (or motor 20), it is desired that the power not be applied at full force constantly, but at varied and cyclically controlled values. This is accomplished through the control of the

main SCRs

24, 26 and specifically by controlling the energization and current carrying capacity thereof at each cycle of the AC. These SCRs become heated due to the internal heating effect and also from the ambient temperature in the instrument in which the load is contained, such for example as in a cabinet. The SCR's lose their accuracy in con- 'trol upon becoming heated and the arrangement of the present invention compensates for that increase in heat and maintains accuracy of control. The auxiliary SCR's 40, 42 are electrically separated from the main SCR's 24, 26 and have indirect connection therewith through the

transformers

28, 30. The relatively low current carrying capacity auxiliary SCR's 40, 42 do not become heated readily, being of little tendency to internal heating and being provided with effective heat dissipating means so that their accuracy is maintained throughout a wide range of variation in surrounding circumstances. Accordingly, when the

auxiliary SCRs

40, 42 are energized, they perform a corresponding'energization on the

main SCRs

24, 26 in the manner desired, such for example as either increasing or decreasing the capacity thereof, depending upon the intended arrangement in their installation. Specifically, in the present instance upon energization of the

auxiliary SCRs

40, 42 the

primaries

28P, 30P are energized which in turn energize the-secondaries 288, 308 in a step-up arrangement, providing greater, voltage and current in the secondaries with corresponding control functions performed on the

main SCRs

24, 26.

The potentiometer 54 is operative for adjustably setting the SCR's 40, 42 so as to control the

main SCRs

24, 26 at the desired intervals or portions of the AC cycles. The

auxiliary SCRs

40, 42 are gate-controlled from the source 62 and when so controlled pass current therethrough, correspondingly energizing the

transformers

28, 30. The arrangement of DC bias provided by the source 62, and the counteracting AC bias provided by the secondaries 64 produce an unusually accurate control. The DC bias is constantly positive and the AC bias is cyclical and negative, providing phase angle shift, and by adjusting the potentiometer, the control of the capacity of the

SCRs

40, 42 is infinitely variable throughout full range. It is desirable that the SCR's not be shut off, but gradually varied, for infinitely varying the average gating current in the SCR's 40, 42 and correspondingly varying the average current through the SCR's 24, 26. However, the

SCRs

40, 42 can be completely shut off, or arranged for completely shutting off the

SCRs

24, 26, if desired. The arrangement accommodates or compensates. for variations from desired and perfect capacitances, impedances, andrelations therebetween.

FIG. 2 illustrates a physical and spatial separation of the

secondary SCRs

40, 42 from the

main SCRs

24, 26. In this figure a cabinet or enclosure is indicated diagrammatically at 65 having a pair of separate'compartments 66, 68 formed by a central divider 70. These two compartments are entirely spatially separated from one another by the divider so that the heat from the

SCRs

24, 26, or the transformers, whether from internal heating or from heating through ambient temperature, is not transmitted to the

auxiliary SCRs

40, 42. The enclosure or cabinet 65 may for example represent a practical structure used in a plant and as such the enclosure tends to confine the heat generated. However in the arrangement as represented in FIG. 2, the auxiliary SCRs being in a separate compartment which may be independently ventilated, are out of the effects of the heat referred to.

While I have herein shown a preferred embodiment of the invention it will be understood that changes may be made therein within the spirit and scope of the appended claims.

lclaim:

1. Electrical control apparatus for use with an AC source, comprising a main circuit including a load, back-to-back solid state main valve means in the main circuit, transformers having secondaries controlling the valve means, a control circuit, back-to-back solid state auxiliary valve means in the control circuit, said transformers having primaries controlled by the auxiliary valve means, the main and auxiliary valve means being arranged for mutually counteracting effect responsive to respective phases of the AC, rectifiers respectively associated with the auxiliary valve means and operative for passing current at the respective half cycles of the AC to the associated auxiliary valve means, and further including independent variable control means for performing a gating function on the auxiliary valve means including conductors to the auxiliary valve means and a common conductor, the last means including a potentiometer connected between the gating conductors and the common conductor, and further including a supplemental DC source across the potentiometer for controlling the gating of the auxiliary valve means.

2. Electrical control apparatus according to claim 1 wherein the means for producing the gating current is operative for infinitely varying the current throughout full range, and adapted for adjustment for varying without shutting off the auxiliary control means, or for shutting it off, selectively.

3. Electrical control apparatus for use with an AC source, a main circuit including a load, and including main back-toback SCR's and secondaries of main transformers controlling the gates of those SCRs, a control circuit, auxiliary (and) back-to-back SCRs in the control circuit in series with the primaries of said transformers, the auxiliary SCR's, through the current passing therethrough and through said primaries, controlling the gates in the main SCR's and thereby the current through those SCRs and thus through the load, (second) additional transformers in the control circuit in series with the gates of the auxiliary SCRs arranged in counteraction to the main transformers, capacitors in series with the additional transformers, and potentiometer means operative for controlling the auxiliary SCRs independently of the (second) additional transformers.

4. Electrical control apparatus according to claim 3 and including a DC source and the potentiometer means is operative through the DC source for controlling the auxiliary SCR's.

5. Electrical control apparatus for use with an AC source, and including a pair of conductors including a load, a main control component in one of the conductors and including back-to-back SCRs, and secondaries of transformers controlling the gates of those SCR's, a control circuit including a pair of conductors adapted for connection with an AC source, the main circuit and control circuit being connected with AC sources of relatively greater and lesser voltage, the control circuit including a pair of back-to-back auxiliary SCRs connected with the conductors of the control circuit and the primaries of said transformers in series with respective ones of the auxiliary SCRs, the main and auxiliary SCRs being arranged for mutual counteraction m respec the we phases 0 AC a common conductor interconnecting the bases of the auxiliary SCRs, branch conductors connecting the gates of the auxiliary SCRs, additional transformers interconnecting said branches and said common conductor, and capacitors in series with respective additional transformers, a potentiometer interconnected between said common conductor and said branch conductors and a DC source connected across the potentiometer, the potentiometer being operative for directly controlling the auxiliary SCRs according to the potential output DC independently of the AC, and acting through the gates of the auxiliary SCRs controlling the primaries of said transformers and thereby through the secondaries of those same transformers controlling the gates of the main SCRs and in turn controlling the current through the main circuit to the load.

6. Electrical control apparatus according to claim 5 and including cabinet means having a plurality of compartments heat insulated from each other, the main SCR's and said main transformers being in one of the compartments, and the auxiliary SCRs being in the other of the compartments.

Claims

1. Electrical control apparatus for use with an AC source, comprising a main circuit including a load, back-to-back solid state main valve means in the main circuit, transformers having secondaries controlling the valve means, a control circuit, backto-back solid state auxiliary valve means in the control circuit, said transformers having primaries controlled by the auxiliary valve means, the main and auxiliary valve means being arranged for mutually counteracting effect responsive to respective phases of the AC, rectifiers respectively associated with the auxiliary valve means and operative for passing current at the respective half cycles of the AC to the associated auxiliary valve means, and further including independent variable control means for performing a gating function on the auxiliary valve means including conductors to the auxiliary valve means and a common conductor, the last means including a potentiometer connected between the gating conductors and the common conductor, and further including a supplemental DC source across the potentiometer for controlling the gating of the auxiliary valve means.

3. Electrical control apparatus for use with an AC source, a main circuit including a load, and including main back-to-back SCR''s and secondaries of main transfoRmers controlling the gates of those SCR''s, a control circuit, auxiliary (and) back-to-back SCR''s in the control circuit in series with the primaries of said transformers, the auxiliary SCR''s, through the current passing therethrough and through said primaries, controlling the gates in the main SCR''s and thereby the current through those SCR''s and thus through the load, (second) additional transformers in the control circuit in series with the gates of the auxiliary SCR''s arranged in counteraction to the main transformers, capacitors in series with the additional transformers, and potentiometer means operative for controlling the auxiliary SCR''s independently of the (second) additional transformers.

4. Electrical control apparatus according to claim 3 and including a DC source and the potentiometer means is operative through the DC source for controlling the auxiliary SCR''s.

5. Electrical control apparatus for use with an AC source, and including a pair of conductors including a load, a main control component in one of the conductors and including back-to-back SCR''s, and secondaries of transformers controlling the gates of those SCR''s, a control circuit including a pair of conductors adapted for connection with an AC source, the main circuit and control circuit being connected with AC sources of relatively greater and lesser voltage, the control circuit including a pair of back-to-back auxiliary SCR''s connected with the conductors of the control circuit and the primaries of said transformers in series with respective ones of the auxiliary SCR''s, the main and auxiliary SCR''s being arranged for mutual counteraction in respective phases of the AC a common conductor interconnecting the bases of the auxiliary SCR''s, branch conductors connecting the gates of the auxiliary SCR''s, additional transformers interconnecting said branches and said common conductor, and capacitors in series with respective additional transformers, a potentiometer interconnected between said common conductor and said branch conductors and a DC source connected across the potentiometer, the potentiometer being operative for directly controlling the auxiliary SCR''s according to the potential output DC independently of the AC, and acting through the gates of the auxiliary SCR''s controlling the primaries of said transformers and thereby through the secondaries of those same transformers controlling the gates of the main SCR''s and in turn controlling the current through the main circuit to the load.

6. Electrical control apparatus according to claim 5 and including cabinet means having a plurality of compartments heat insulated from each other, the main SCR''s and said main transformers being in one of the compartments, and the auxiliary SCR''s being in the other of the compartments.