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Патент USA US2126603

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Aug. 9, 1938.
B. D. BEDFORD
2,126,603
ELECTRIC VALVE CIRCUITS
Original Filed?Aug. 20, 1956
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Inventor‘:
Bumnice D. Bed-Ford ,
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Aug. 9,.11938-
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B. D. BEDFORD
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2,126,603
' _ .ELE'gTRIc VALVE CIRCUITS
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Original Filed Aug. 20, 1936
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' Inventor‘:
Bur'nioe D. Be for'ci,
by ?W/ai‘JMZM
His Attornekj.
Aug. 9, 1938.
B.‘ D.‘ BEDFORD
2,126,603
ELECTRIC ' VALVE CIRCUITS
?rigin'al Filed Aug. 20, 1936
5 Sheets-Sheet 3
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Bur‘nice D. Bed?ard
by
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2,126,603
Patented Aug. 9, 1938
UNITED STATES PATENT OFFICE
2,126,603
ELECTRIC- VALVE CIRCUITS ’
- Burnice D. Bedford, Schenectady, N. Y., assignor
to General Electric Company, a corporation of
' New York
Application August 20, 1936, Serial No. 97,010
Renewed January 29, 1938
(Cl. 175-363)
gizing the control winding to effect saturation
My invention relates to'electric valve trans
lating circuits and more particularly to control of the reactor by the control winding prior to
circuits for electric Valve translating apparatus. the beginning of the normal conduction period,
in this way providing arrangements for introduc
In electric translating circuits including elec
14 Claims.
5 tric valve means of the type using ionizable medi
ums such as gases or ‘vapors, there has been evi
denced a decided need for apparatus to eliminate
or reduce to a minimum the arc-back conditions
to which these electric'valves may be subjected.
10 It has been found that arc-backs may be elimi
nated or substantially reduced in number by pre
venting the establishment of high voltage gradi
ents within the electric valve means during the
commutation periods. It has also been found
15 that the establishment of these high voltage
gradients is in a large measure due to the increase
in ion concentration or storage of ions within the
electric valve means at the time the current is
commutated between the valves.
-'
It is an object of my invention to provide a
newv and improved control circuit for electric
valve means of the type employing ionizable me
diums.
‘
It is another object of my invention to provide a
25 new and improved electric valve circuit for pre
venting arc-back conditions within electric valves
of the type employing ionizable mediums.
In accordance with the illustrated embodi
ments of my invention,‘ I provide a control circuit
30 for electric valves of the type employing ionizable
mediums by which‘ arc-back conditions of the
electric valve means are substantially eliminated
or materially reduced in number. In particular,
I employ-a reactor, which may be of the saturable
type, having a winding connected in series rela
tion with the electric valve means for controlling
the rate of change of current through the elec
tric valve means at the end of the conducting
periods and during the commutation periods.
40 The reactor is also provided'with a control wind
ing whichcontrols the magnetic condition of the
reactor and hence e?ects control of the induct
ance of the winding, which is connected in series
relation with the associated electric valve means.
45 The reactor‘ is arranged or designed to become
substantially saturated at a relatively small per
centage of the normal full load current which
the series winding is designed to conduct. By
controlling the energization of the control wind
50 ing, I'pro-vide an arrangement whereby the reac
tor is saturated prior to and during the greater
part of the conducting period so that the reac
tor offers a relatively small inductive reactance
to. the flow of current. _ In several modi?cations
85 of. my invention I provide arrangements for ener
ing in the electric valve circuits only a relatively 5
small inductive reactance so that the power fac
tor of the circuit is not materially reduced. The
control winding eilects a substantial increase in
the inductance of the series winding near or
at the end of the conducting periods so that the 10
rate of change of current through the electric
valve means is reduced below the rate of change
of current, which for the particular electric valve
means employed, establishes dangerously high
voltage gradients within the electric valve means. 15
In other words, the rate of change of current is
maintained below a predetermined value so that
the positive ions associated with the ion plasma
within the electric valve are allowed a suf?cient
time to diffuse within the electric valve means 20
without establishing high ‘voltage gradients.
For a better understanding of my invention,
reference may be had to the following description
taken in connection with the accompanying
drawings and its scope will be pointed out in the 25
appended claims. '
Fig. 1 of the accompanying drawings diagram
matically illustrates an embodiment of my in
vention applied to a bi-phase recti?er in which
controlling reactors are connected in series re
lation with the electric valve means, and Figs. 2
and 3 represent certain operating characteristics
of vthe circuit shown in Fig. 1. Fig. 4 diagram—
matically shows another embodiment of my in
vention as applied to an electric valve translat
ing circuit for transmitting energy between a
three phase alternating current circuit and a di
rect current load circuit, and Fig. 5 represents
certain operating characteristics of the arrange
ment shown in Fig. 4. Fig. 6 diagrammatically
represents another embodiment of my invention
as applied to a quarter phase electric valve trans
lating system, and Fig. 7 diagrammatically shows
another embodiment of my invention as applied
to an arrangement for translating energy be
tween a three phase alternating current circuit
and a direct current circuit.
Referring vnow to Fig. 1 of the accompanying
drawings, my invention is diagrammatically
shown as applied to an electric valve translating
system for transmitting energy between an alter
nating current circuit I and a direct current cir
cuit 2 through a transformer 3 and electric valve
means 4 and 5 preferably of the type employing
an ionizable medium such as a gas or a vapor. 55
2
2,126,603
The conductivity of the electric valve means 4
and 5 may be controlled by means of any conven
tional excitation or control circuit such as the
excitation circuit 6 including a transformer ‘I, a
conventional phase shifting arrangement such
as a rotary phase shifter 8, current limiting re
sistances 9 and any suitable source of biasing
potential such as a battery I?.
'
In order to control the current through the
10 electric valve means 4 and 5 at the end of the
conduction period, I provide saturable reactors
II and I2 each including a core member I3, a
winding I4 connected in series relation with the
associated electric valve means, and a control
winding I5. The control windings I5 are ener
gized in accordance with the potential appearing
across the secondary winding of transformer 3
and are connected in series relation with an in
ductance I6 of relatively large magnitude.
The
saturable reactors II and I2 are designed so
that the core members I3 becom'e saturated by a
relatively small magnetomotive force as com
so that near the end of the conducting period
and during the commutating period the positive
ions within the electric valve means are aiforded
an opportunity to di?use without establishing
high voltage gradients within the electric valve
means. This decrease in the rate of decay of
current as represented by the portion of curve
A between the points b and c is e?'ected by the
increase in the inductance of the winding I 4. It
will be noted that during this interval the mag
netomotive force as represented by curve C has
reversed in direction and attained practically
maximum amplitude so that the core member I3
of reactor I I is not saturated during the interval
b——c and is operating in the vicinity of point e
along the linear portion of the magnetization
curve E. Curve D represents the voltage induced
in windings I4.
A particular feature to be noted in connection
with the embodiment of my invention diagram
matically shown in Fig. l is the characteristic
of operation by virtue of which the reactors II
and I2 offer a relatively small inductive reactance
to the flow of current at the beginning of the
pared to the magnetomotive force incident to the
?ow of the normal full load current through the
winding l4. In other words, the core members
I3 of saturable reactors II and I2 become satu
rated at relatively small values of magnetomotive
force and the windings I5 are provided with a
small number of turns, whereas the windings I4
are provided with a relatively greater number of
turns.
The operation of the electric valve translating
circuit diagrammatically shown in Fig. 1 may be
it is desirable that the current begin to flow prac
best explained by considering the operating char
valve means, as represented by curves A and B of
acteristics illustrated in Figs. 2 and 3. As will
be well understood by those skilled in the art,
the electric valve means 4 and 5 will be rendered
alternately conductive by the excitation circuit 6
so that each of these electric valve means con
40 ducts current for substantially 180 electrical de
grees. The current conducted by electric valve
means 4 may be represented by curve A of Fig.
2 and the current conducted by electric valve
means 5 may be represented by the curve B of
Fig. 2. By virtue of the presence of the large
inductance IB connected in series relation with
control windings I5 of saturable reactors II and
I2, the magnetomotive force established in the
core members I3 of these reactors may be made
to attain the position represented by curve C
of Fig. 2. Referring in particular to point a
of curve A, which represents the begininng of a
conducting period for electric valve means 4, it
will be noted that since the current through con
trol winding I5 is in a positive direction and of
substantially maximum magnitude, control wind
ing I5 will e?ect substantial saturation of the
core member I3 of reactor I I so that the inductive
reactance offered to the ?ow of current through
winding I4 will be relatively small and will per
mit the current to rise rapidly. It will be fur
ther noted that at the beginning of the conduc
tion interval the current through winding I5
establishes a ?ux in the core member I3 which
assists the flux established by the series winding
I4. Curve 'E of Fig. 3 represents the magnetiza
tion curve of the reactors II and I2. At the be~
ginning of the commutation period as represented
by the point a of curve A, the saturable reactor
70 II is substantially saturated and may be repre
sented as operating on the portion of curve E
lying beyond the point 11. On the other hand, it
will be noted that during the interval b—c of
curve A, the rate of decay of current through the
electric valve means 4 is substantially reduced
conducting periods. As will be appreciated by
those skilled in the art, in order to maintain a
relatively high power factor operating condition
tically coincidentally with the application of volt
age to the electric valve means.
Since the re 30
actors II and I2 are saturated by the control
windings I5 prior to the beginning of the con
ducting periods, the current through the electric
Fig. 2, may increase very rapidly. In addition, 35
the apparatus possesses the desirable character
istic of automatically increasing the inductance
of the windings I4 near the end of the conduct
ing periods so that the current decreases at a
slower rate to permit the positive ions within the 40
electric valve means 4 and 5 to diffuse. While
my invention as illustrated in Fig. 1 has been de
scribed in connection with an electric valve trans
lating system for transmitting energy between a
single alternating current circuit and a direct
current circuit, it should be understood that in 45
its broader aspects my invention may be applied
to electric valve translating circuits generally for
transmitting energy in either direction between
single phase or polyphase alternating current
circuits and direct current circuits, or between
alternating current circuits of the same or dif
ferent frequencies.
Fig. 4 of the accompanying drawings diagram
matically shows an embodiment of my invention
as applied to an electric valve translating sys
tem for transmitting energy between an alternat
ing current circuit I‘! and a direct current cir
cuit I 8 through electric valve means I9-24, in~
elusive. Electric valve means I9-24 are prefer
ably of the type employing an ionizable medium
such as a gas or a vapor.
The conductivity of
electric valves I9-24 is controlled by means of
an excitation circuit 25 including a transformer
26 having a primary winding 2'! and secondary
windings 2B. The excitation circuit 25 may be
energized from any suitable source of alternating
current, such as the alternating current circuit
I1, through any conventional phase shifting ar
70
rangement such as the rotary phase shifting de
vice 29. Current limiting resistances 30 are con
nected in series relation with control members
of each of the electric valve means I944, and
biasing potentials are impressed on the control
2,126,603
members of these valves by any suitable biasing
means such as batteries 3|. -
Connected in series relation with the alternat
ing current circuit I1 and the electric valve
means I9, 22; 20, 23 and 2|, 24, I employ sat
urable reactors 32, 33 and 34 each including a
core member 35, a winding 36 and a control.
winding 31. The windings 36 are employed to
control the rate of change of current through the
10 electric valves near the end of the conducting
periods, and the inductance of the windings 36
is controlled by the control windings 31. The
core members 35 of the saturable reactors 32,
33 and 34 are designed so that substantial satura
tion is effected by a small percentage of the nor
mal full load current which flows through the
windings 36. In other words, the core members
35 are designed to saturate at relatively small
values of magnetomotive force as compared with
the magnetomotive force impressed on the core
members when normal full load current is ?ow
ing through the windings 36. Control windings
31 are provided with smaller number of turns
than the inductively associated series windings
36 and are capable of independently effecting
substantial saturation of the core members 35 .
‘For the purpose of explaining the operation
of the embodiment of my invention diagram
matically illustrated in Fig. 4, let it be assumed
30 that the electric valve translating apparatus is
operating to transmit energy from the alternat
ing current circuit H to the direct current circuit
l8. As will be well understood by those skilled
in the art, the electric valve means Ill-24, inclu
35 sive, will be rendered alternately conductive and
non-conductive to effect full wave recti?cation of
the alternating current. It will also be noted that
the pairs of oppositely disposed electric valves,
such as valves l9 and 22, will be rendered conduc
40 tive substantially 180 electrical degrees out of
phase and will not be conductive during the same
intervals Furthermore, it will be noted that each
electric valve conducts current during two v120
electrical degree intervals during each cycle of
45 alternating potential, and that during each of
these intervals any one electric valve will con
duct only 60 electrical degrees with any one other
electric valve. For example, electric valves 20
and 24 will conduct current for substantially 60
50 electrical degrees and electric valves 20 and 22
will conduct current during the next succeeding
60 electrical degree interval, the current having
been commutated at the end of the ?rst 60 elec
trical degree interval from the electric valve 24
55 to the electric valve 22.
Considering the operating‘characteristics of the
electric valve translating system as shown in Fig.
5, curve F may be employed to represent the
current which is conducted through winding 36
of saturable reactor 32, and curve G may be
employed to represent the current which is con
ducted through winding 36 of saturable reactor
34 and control winding 31 of saturable reactor 32.
The phase relationship of these currents will
65 be apparent in view of the above discussed prin
ciples or operation. During the interval ;f—g,
there will be no current conducted through wind
ing 36 of saturable reactor 32, but the current
through control winding 31 of saturable reactor
70 32 will be of substantially full load value and the
magnetomotive force of this winding . will be
impressed on core member 35 of reactor 32. The
magnetomotive force impressed on the core mem
ber '35 of saturable reactor 32 may be represented
75 by curve H ‘of Fig. 5. Since the series winding
3
36 of reactor 34 is connected in series relation
with control winding 31 of reactor 32, the mag
netic condition of core member 35 of reactor 32
is controlled in accordance with the current of
this phase in the polyphase system. By virtue
of this current ?owing through the control wind
ing 31 of reactor 32, the core member 35 is sub
stantially saturated at the time represented by
the point g so that when electric valve 23 is ren
dered conductive to commutate current from £10
electric valve 22 the inductive reactance offered
by series winding 36 will be relatively small so
that the current may increase rapidly and will
not materially in?uence the power factor condi
tions imposed on the alternating current circuit 45
ll. During the interval g—h electric valves .23
and 2| will be conductive to transmit current from
the alternating current circuit l ‘I to the direct cur
rent circuit l8 through control winding 31 of reac
tor 34, series winding 36 of reactor 33, one phase
of the circuit I1, series winding 36 of reactor 32,
and control winding 31 of reactor 33. During the
interval h-—i, current will be supplied to the di
rect current circuit l8 from the alternating cur
rent circuit l1 through electric valves l9 and 23, 25
the current having been commutated from elec
tric valve 2| to electric valve I!) at the time cor
responding to point It. It will be noted that dur
ing the interval h—-i the direction of current
transfer through the control winding 31 of re- -‘~
actor 32 has been reversed relative to the direc
tion of current through this winding during the
interval f-Q. effecting thereby a reduction in
the net magnetomotive force impressed on core
member 35. At the time corresponding to point 1‘
current will be commutated from electric valve
23 to electric valve 24. During the commutation
period as represented by the portion of the curve
F lying within the interval 12-4‘, the current
through the electric valve means 23 decays at a
relatively slow rate by virtue of the increased
inductance effected by the oppositely directed
magnetomotive forces impressed on the core
member 35 of reactor 32 by means of control
winding 31. Curve J represents the voltage in- ;
duced in windings 31 of saturable reactor 32.
33 In
and
a similar
34 will manner,
control the
therate
saturable
of change
reactors
of cur~
rent to the electric valve means Iii-24 at the end
of the conducting periods or during the commu
tating periods to prevent the establishment of
high voltage gradients within the electric valve
means by allowing sufficient time for the positive
ions to diffuse.
A particular feature to be considered in con;
nection with the arrangement of Fig. 4 is that I
its
provide a means for e?ecting substantial satura
tion of the saturable reactors 32, 33 and 34 at the
beginning of the conducting periods so that the
current increases very rapidly, and it should be
further understood that I provide an arrange
ment whereby the saturation of the reactors is
automatically reduced prior to the commutation
periods so that the rate of change of current
through the electric valve means is decreased be
low a predetermined value to allow su?icient time
for the diffusion of positive ions within the elec
tric valve means and to prevent the establishment
of high voltage gradients within the electric valve
means. It should be further understood that this
control of the magnetic condition of the satura
ble reactors 32, 33 and 34 is effected by employing
the currents of associated phases in a polyp-base
alternating current system. In the arrangement
shown in Fig. 4, the same effect may be obtained
to
4
2,126,603
by reversing the direction of the control windings
31 of saturable reactors. 32, 33 and 34 and by
adopting the opposite phase rotation.
Fig. 6 of the accompanying drawings repre
sents another embodiment of my invention as
applied to an electric valve translating system for
transmitting energy between a three phase alter
nating current circuit 38 and a direct current cir
cuit 39 through electric valve means 49, 4|, 42 and
10 43 preferably of the type employing ionizable me~
diums such as gases or vapors.
Interposed be
tween the three phase alternating current circuit
38 and the electric valve means 46 to 43, inclusive,
I employ a transformer 44 of the type for effecting
15 three phase-quarter phase voltage transforma
tion having a primary winding 45 and secondary
windings 46, 41, 48 and 49. Connected in series
relation with the secondary windings of the trans
former 44 and the electric valve means 46 to 43,
I provide saturable reactors 50 and 5| having
windings 52, 53, 54 and 55, respectively. Wind
ings 52 and 53 are connected in series relation
with secondary windings 46 and 43, respectively,
of transformer 44, and windings 54 and 55 are
connected in series relation with‘ secondary wind~
ings 41 and 49, respectively, of transformer 64.
Reactors 56 and 5| are also provided with control
windings 56, 51 and 58, 59, respectively, which
control the magnetic condition of the core mem
bers of reactors 50 and 5 I, respectively, and which
thereby effect control of the inductance of series
windings 52 to 55, inclusive. Control windings 55
and 51 are energized in accordance with the cur
rent of secondary windings 41 and 45L respec
tively, of transformer 44, and control windings
58 and 59 are energized in accordance with the
current of secondary windings 46 and 46 of trans
former 44. The control windings 56 to 59, inclu
sive, are provided with relatively smaller number
of turns than the series windings 52 to 55, inclus
sive, but are designed to effect substantial satu
ration and desaturation of the respective core
61 are not shown but it will be understood that
any of the conventional arrangements shown in
the art may be applied to control the conductivity
of these electric valves. Interposed between the
secondary windings of transformer 66 and the
electric valves 62 to 61, inclusive, I provide satu
rable reactors 69, 16 and ‘H having core members
12, 13 and 14, respectively, and each having a
pair of similarly disposed series windings 15, 16
and each having a control winding 11. Windings 40
15 of reactors 69, 16 and 1| are connected in
series relation with electric valves 62, 63 and 64
respectively, and windings 16 of these reactors are
connected in series relation with electric valves
65, 66 and 61. The control windings ‘11 are ener .15
gized in accordance with the current of the direct
current circuit 6| and are connected in series
relation with the electric valves 65, 66 and 61.
The control windings 11 establish in the core
members 12, 13 and 14 a magnetomotive force
which opposes the magnetomotive forces estab
lished by the series windings 15 and 16.
The electric valve translating system of the
type shown in Fig. 7, and the associated reactors
69, 16 and 1| may be employed in those applica
tions where it is not objectionable to incur a
slight decrease in the power factor of the alter
nating current load imposed on the alternating
current supply circuit. Since the control wind~
lugs 11 at all times impress on the core members 30
12, 13 and 14 of saturable reactors 69, 16 and 1|
magnetomotive forces tending to oppose the mag
netomotive forces established by the series wind
ings 15 and 16, these control windings will tend
to effect an increase in the inductance of the
series windings 15 and 16 at both the beginning
and ‘the end of the conducting periods. Since
the rate of change of current near the end of the
conducting period will be decreased, the arrange
ment of Fig, 7 will also be effective to prevent 40
the establishment of high voltage gradients with
members during the predetermined desired start
ing and commutating intervals.
The operation of the electric valve translating
system diagrammatically shown in Fig. 6 is sub
in the electric valve means and will be effective
to prevent arc-back failures or reduce to a mini
mum the number of arc-back failures.
While I have shown and described my inven
tion as applied to a particular system of connec
stantially the same as that described above in
connection with the operation of the arrangement
shown in Fig. 4. As will be well understood by
tions and as embodying various devices diagram
matically shown, it will be obvious to those skilled
in the art that changes and modi?cations may
those skilled in the art, electric valves 4643, in
clusive, will be rendered conductive in a prede
termined order to transmit current from the three
phase alternating current circuit 38 to the direct
current circuit 39. Control windings 56 to 59, in
clusive, will effect substantial saturation of the
be made without departing from my invention. -
core members of reactors 56 and 5| so that the
inductive reactance offered to the flow of current
in series windings 52 to 54 will be relatively small
at the beginning of the conduction periods. Fur
thermore, control windings 56 to 59, inclusive, will
control the magnetic condition of the core mem
bers of reactors 56 and 5| to effect a substantial
increase in the inductance of series windings 52
to 55, inclusive, near the end of the conducting
65 periods and during the commutating periods so
that the rate of change of current is maintained
within a predetermined range.‘
Fig. 7 of the accompanying drawings diagram
matically shows another embodiment of my in
70 vention as applied to an electric valve translating
system for transmitting energy between an alter
nating current circuit 66 and a direct current
circuit 6| through electric valve means 62-61, in
elusive, and through a transformer 68. The con
75 trol or excitation circuits for electric valves 62 to
and I, therefore, aim in the appended claims to
cover all such changes and modi?cations as fall
within the true spirit and scope of my invention.
What I claim as new and desire to secure by
Letters Patent of the United States, is:
55
1. In combination, an electric translating sys
tem including an electric valve means connected
therein and arranged to conduct current during
predetermined intervals, and means for con
trolling the current conducted by said electric
valve means at the end of the conducting inter
vals comprising a saturable reactor having a
winding connected in series relation with said
electric valve means and a winding for increas
ing the inductance of said first mentioned wind 65
ing at the end of the conducting intervals.
2. In combination, an electric translating sys
tem including electric valvemeans connected there
in and arranged to conduct current during prede
termined intervals, and means connected in series .
relation with the electric valve means having a.
relatively small inductance at the beginning of
said conducting intervals and arranged to effect
a substantial increase in the inductance at the
end of the conducting intervals to control the 1
2,126,603
rate of change of current through the electric
valve
means.
'
-
'
'
"
3. In combination, an electric translating sys
tem including an electric valve means connected
therein and arranged to conduct ‘current during
predetermined intervals, and means comprising a
saturable reactor having a core member, a wind
ing connected in series relation with said electric
valve means and a control winding energized to
‘ e?ect substantial saturation of said core member
at the beginning of each conduction period and
to decrease the magnetization of said reactor to
effect an increase in the inductance of said ?rst
mentioned winding at the end of each conduction
1.’.
period.
-
1
‘
'
‘
4. In combination, an electric translatingv sys
tem comprising a plurality of electric circuits, a
plurality of electric valve means connected in
said circuits and arranged to conduct current
‘ during predetermined intervals, and‘ means for
controlling the rate of change of current through
said electric valve means at the’end of ‘the con
ducting intervals comprising a plurality of sat
urable reactors each associated with a di?erent
one of said electric circuits and each comprising
a winding connected in series relation with said
electric valve means and each comprising another
winding energized in accordance with the cur
rent of another of said electric circuits to increase
Hi) the inductance of said ?rst mentioned winding
at the end of the conducting intervals.
5. In combination, an electric translating sys
tem including a plurality of electric valve means
connected therein and arranged to conduct
current during predetermined intervals and in a
predetermined order, and means for controlling
the current conducted by said electric valve
means when the current is commutated from one
of said electric valve means to another of said
_, electric valve means comprising a plurality of sat
urable reactors each having a winding connected
in series relation with the associated electric valve
means .and each having another winding ener
gized in accordance with the current conducted
by another of said electric valve means to control
periodically the inductance of said ?rst men
60
5
each ‘comprising a winding inductively associated
with' said?rst mentioned winding for increasing
the inductance of ‘said ?rstfmentioned winding
to effect a decrease'in the rate of change of cur
rent at the ‘end of said’ conducting intervals.
8. In combination, a polyphase ‘alternating cur
rent circuit, a'direct current circuit, an electric
translating circuit interposed between said cir
cuits andincludinga plurality of electric valve
means arranged to ‘conduct current during pre 10
determined intervals and in a predetermined
order, and a pluralityof saturable reactors each
associated with? a di?erent one of said electric
valve means and each comprising a winding con
nected in series relation with the associated elec— ‘F
tric'valve means and‘each comprising a second
winding energized in accordance with the current
of another phase‘ of said alternating current cir
cuit to increase the inductance of said ?rst men—
tioned winding when current is commutated from
the associated electric valve means.
9. In combination, an electric translating sys
tem including a polyphase alternating current cir
cuit, a plurality of electric valve means connect
ed in said alternating current circuit and arrang
ed to conduct current during predetermined in
tervals and in a predetermined order, and means
associated with each of said electric valve means
comprising a plurality of saturable reactors each
including a core member, a winding connected in .
series relation with the associated electric valve
means and a second winding energized in accord
ance with the current of a different phase of said
polyphase circuit for increasing the inductance
of said ?rst mentioned winding to control the
rate of change of current through the associated
electric valve means when the current is com
mutated therefrom.
10. In combination, an electric translating sys
tem including an electric valve means connected
therein and arranged to conduct current during
predetermined intervals, and means for control—
ling the rate of change of current through said
electric valve means at the end of the conducting
intervals comprising a saturable reactor includ 45
ing a core member, a winding connected in series
tioned associated winding.
relation with said electric valve means and a con
6. In combination, an electric translating sys
tem comprising a plurality of alternating current
circuits, a plurality of electric valve means con
nected in said circuits and arranged to conduct
trol winding for controlling the magnetic condi
tion of said core member, said control winding
being energized to establish in said core member
at the beginning of each conducting interval a
current during predetermined intervals, and
?ux in the same direction as that establish-ed by
means for controlling the current through said
electric valve means at the end of the conducting
intervals comprising a plurality of saturable
the ?rst mentioned winding and tending to estab
reactors each associated with a different one of
said electric valve means and each having a wind
ing connected in series relation with the associ
ated electric valve means and a winding induc
established by said ?rst mentioned winding.
11. In combination, a polyphase alternating
current circuit, a direct current circuit, and
tively associated with said ?rst mentioned wind
ing and energized in accordance with the current
said circuits including a plurality of electric valve 60
means and a plurality of saturable reactors each
having a core member, a winding connected in
of another of said electric valve means to increase
periodically the inductance of said ?rst mentioned
associated winding.
'7. In combination, an electric translating sys
tem comprising a plurality of electric conductors,
said conductors being arranged to conduct poly
phase alternating current, a plurality of electric
valve means each associated with a different one
of said conductors and arranged to conduct cur
rent during predetermined intervals, a plurality
of saturable reactors each associated with a dif
ferent one of said electric valve means and each
comprising a winding connected in series rela
75 tion with the associated electric valve means and
lish in said core member at the end of each con
ducting interval a ?ux which opposes the ?ux
electric translating apparatus interposed between
series relation with a predetermined different one
of said electric valve means for controlling the
rate of change of current at the end of the con
ducting intervals and a control winding energized
in accordance with the current conducted by a
different electric valve means for establishing a
flux in said core member at the beginning of the
conducting intervals in the same direction as the
flux established by said ?rst mentioned winding
and tending to establish a flux in the opposite
direction. at the end of the conducting intervals.
12. In combination, a polyphase alternating
current circuit, a direct current circuit, and elec 75
6
2,128,608
tric translating apparatus interposed between said
circuits including a plurality of pairs of electric
valve means serially connected relative to said
direct current circuit and a plurality of saturable
reactors interposed between said alternating cur
rent circuit and said electric valve means, each
of said reactors including a winding connected in
series relation with a predetermined pair of seri
ally-connected electric valve means and a control
winding energized in accordance with the cur
rent conducted by a different pair of serially
connected electric valve means for increasing the
inductance of said ?rst mentioned winding at the
end of the conduction intervals.
13. In combination, an alternating current cir
15
cuit, a direct current circuit, electric translating
apparatus interposed between said circuits in
cluding a plurality of electric valve means, and
means comprising a plurality of saturable re
20 actors each associated with a different electric
valve means and each including a core member,
a winding connected in series relation with the
associated electric valve means and a winding for
establishing a unidirectional ?uX in said core
member to decrease the rate of change of cur
rent through said associated electric valve means
at the end of the conducting intervals.
14. In combination, a three phase alternating
current circuit, a direct current circuit, and elec
tric translating apparatus interposed between said
circuits including a transformer for obtaining
three phase-quarter phase voltage transforma
tion, a plurality of electric valve means each 10
associated with a different secondary phase wind
ing of said transformer and two saturable re
actors interposed between said transformer and
said electric valve means, each of said reactors
including two- windings each connected in series 15
relation with a predetermined different one of
said electric valve means and two control wind
ings each energized in accordance with the cur
rent conducted by a different electric valve means
for increasing the‘inductance of said ?rst men 20
tioned windings at the end of the conduction in
tervals of the associated electric valve means.
BURNICE D. BEDFORD.
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