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Патент USA US2114856

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April 19, 1938.
H. NE/IDHARDT
2,114,856
ELECTRIC VALVE CONVERTING‘ SYSTEM
Filed ‘Sept. 20, 1937
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Inventor‘:
Hans Neidhék‘dh,
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His Attorn-e‘y: _
- April 19,- 1938.
H. 'NEYIDHARDT
2,114,856
ELECTRIC VALVE CONVERTING SYSTEM
Filed _Sept. 20, 1937
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April 19, 1938.
H. NEIDHARDT I
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2,114,856
ELECTRIC VALVE CONVERTING SYSTEM
Filéd Sept. 20, 1937
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April 19,1938.
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ELECTRIC VALVE CONVERTING SYSTEM
Filed Sept. 20, 1937
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2,114,856
Patented Apr. 19, v1938
UNITED STATES PATENT OFFICE
2,114,856
ELECTRIC‘ VALVE CONVERTING SYSTEM
Hans Neidhardt, Berlin, Germany, assignor to
General Electric Company, a corporation of‘
New York
Application September 20, 1937, Serial No. 164,811
In Germany October 9, 1936
5 Claims.
(01. 172-481)
My invention relates to electric valve convert
ing systems for transmitting energy between al
ternating current circuits of different frequencies
and more particularly to improved excitation ap
5 paratus for such converting systems.
Heretofore in frequency changers it has been
proposed to control the control electrode or grid
of the electric valve of such a system by impress
ing thereon voltage components obtained from
10 each of the alternating current circuits. In some
instances this has been accomplished by distrib
utors coupled to synchronous motors and in other
arrangements one or more control transformers
were supplied for each of the valves or discharge
l5 paths. Such arrangements often havethe dis-~
advantage that the control equipment is neither
simple nor economical to produce. It further
more has been suggested that these voltage com
ponents from the different circuits which are sup
20 plied to the control electrodes b of substantially
rectangular wave shape. Where?3such rectangular
impulses have been utilized 1 has often been
found difficult to prevent undesired gaps between
the various impulses, and the abnormal operation
25 of the system resulting from such‘ gaps in the
control potentials. In some instances where the
output voltage was decreasing in magnitude it is
found that the rectangular voltage component
increased in time duration so that it was not at all
30 certain that proper commutation would occur at
all times. In some arrangements it has been
found that the output characteristics and the
frequency thereof were varied due to the fact that
when the output voltage began to drop, the
35 rectangular voltage component obtained from
proper voltage component for both recti?er and I
inverter operation.
'
In accordance with the preferred embodiment
of my invention the disadvantages of the prior art
have been obviated by the use of a grid excitation 5
circuit which uses a minimum of apparatus. In
a system utilizing two polyphase networks with
zero anodes or electric valves for the neutral
points thereof two transformers are common to
all of the control circuits and one transformer 10
supplies control energy to two discharge paths
corresponding to phase opposed windings in the
two networks.
The one transformer supplies
voltage components which insure proper commu
tation between the zero anode and the anode con- 15
nected to the various terminals of the phase net
work and the second common transformer sup
plies negative voltage components which insure
that an anode will not become conductive during
its normal nonconductive periods. By means of 20
a plurality of windings and unilaterally conduc
tive devices such as contact recti?ers the remain
ing transformers supply control components to
the anodes of one of the phase networks so that
this network will operate as an inverter and si- 25
multaneously the transformer operates at the
proper time intervals to supply voltage compo
nents having the proper relation to the other
anodes on the other network so that this network
will operate as a rectifier. Since this latter trans- 30
former is effectively in series with the trans
formers deriving voltage components from the
output source, it operates to reverse the operation
of the various networks whenever the direction
of the flow of the energy between the two cir- 35
cuits is reversed. This occurs automatically with
out the use of auxiliary windings or auxiliary ap
the output circuit would increase thereby caus
ing such undesired changes in the characteristics
paratus.
and frequency of the system. In still other ar
My invention itself, however, both as to its
rangements it has been found that a change in the organization and method of operation, together 40
40 phase of the voltage components supplied to the' with‘ further objects and advantages thereof, will
control electrode produced an undesired change be better understood by reference to the follow
in the phase of the voltage output of the system ing description taken 'in connection with the ac
without changing appreciably the output voltage. companying drawings in which Fig. 1 shows one
It is an object of my invention, therefore, to
embodiment of my invention; Fig. 2 is an explan- 45
4 GI provide a new and improved electric valve con
atory ?gure; Fig. 3 shows the detail of one of the
vertlngsystem and an improved grid excitation transformers utilized therein; Fig‘. 4 shows a
apparatus therefor which will simplify the sys
modi?cation which may be utilized in the embod
tems of the prior art ‘and which will solve the iment shown in Fig. 1; Fig. 5 shows a preferred
embodiment of my invention, and Fig. 6 shows 50
above mentioned difficulties.
_
.
50
It is another object of my invention to provide curves explanatory of the?operation of the em.
a new 'and improved electric valve converting bodiment shown in Fig. 5.
Referring now to Fig. 1 of the drawings, I
system and an excitation apparatus therefor
wherein the apparatus is greatly simpli?ed and have illustrated an electric ‘valve converting sys
55 a single apparatus supplies automatically the tern for 'ransferring energy between two alter- 55,
72
2,114,856
nating current circuits of different frequencies
such as the circuit indicated as h and the circuit
indicated as f2. This electric valve converting
system includes a transformer having its primary
'io
winding connected to the circuit f1 and having
two groups of secondary windings I’, 3’, 5’ and
I”, 3", 5", the neutral points of which are
connected through the primary winding of the
transformer connected to the circuit f2 and the
reactor D to the cathode K of a multi-anode
single-cathode controlled electric valve. The
various extremities of the groups of secondary
windings A’ and A” are each connected to anodes
of the recti?er which are controlled by starting
15 electrodes or grids. The neutral points of each
of‘ these secondary windings are each connected‘
to a grid controlled anode. The various grids
of the anodes which are connected to the ex
tremities of the secondary windings A’ and A"
20 are controlled by means of a control circuit in
dicated by the rectangle St. which comprises a
plurality of transformers arranged ‘to be ener
- gized from the circuits f1 and f2. For the pur
poses of explanation it will be assumed that the
25 transformer T2 is connected to the circuit f2
which is of a lower frequency than the circuit f1.
The grid control circuit utilizes only one such
transformer, but three transformers similar to
T1 which are each connected to the high fre
30 quency circuit ii are utilized. For the purpose
of simplifying the disclosure the grid circuit for
only one of the grids of the secondary network
A’ and A" is shown. The transformers T1 and
T2 are so designed as to supply rectangular volt
35 age impulses such as illustrated in Fig. 2. In
Fig. 2 the line Uz indicates the critical voltage
which must be exceeded in order to initiate the
flow of current between one of the anodes and
the cathode. The curve UTl represents a volt
age impulse applied by the transformer T1 and
the curve UT2 represents the voltage impulses
supplied by the transformer T2. As is apparent
from Fig. 2, the duration of the positive impulse
of the transformer T2 as‘ shown by curve UTZ is
45
somewhat shorter than the time interval of the
positive impulse supplied by the transformer T1
as shown by curve UT‘; The critical voltage U2
is only exceeded when thevoltage impulse of
50 UT, and U122 are cumulative.
one of the secondary windings of the transformer
T2 and the biasing battery Uv to the cathode K
of the electric valve. A pair 'of resistors I5 are
each connected between the current limiting re
sistors I and an intermediate point on the bias
battery Uv so as to prevent retardation of de 10
ionization of the discharge paths between the
various anodes and the cathode of the electric
valve. If very high potentials are utilized in
the grid circuit it mayv occur that the control
voltages would deviate from the rectangular
shape, and in order to avoid such deviation a
voltage and limiting device may be connected
across each of the secondary windings of the
transformer T2.v A transformer T0 is connected
to the circuit 12 through a pair of contact recti 20
?ers to energize the grids of the anode connected
to the neutral points of the networks A’ and A”.
The midpoint of the secondary winding of the
transformer To is connected through a portion
of the bias battery Uv to the cathode of the
electric valve.
In operation the various anodes become con
ductive only when there is applied to the grids
thereof the accumulative effect of the two rec
30
tangular voltages Url and Ur2 shown in Fig. 2
so that they exceed the negative bias Ut thereby
intersecting the critical voltage line Uz. The I
contact recti?ers 6 operate to prevent the sec
ondary windings of the transformer T1 from. be
coming short circuited and furthermore permit
only the positive voltage impulses to be applied
to the control grid. If it is assumed at a given
instant that the left side of the transformer T2
is positive the transformer produces the' positive 40
voltage impulse UT2 of Fig. 2. At the same in
stant the transformer T1 will supply the positive
voltage impulse Ur1 so that the anode connected
to the winding I’ becomes conductive. The
45
curves shown in ‘Fig. 2 show that the voltage
waves Ur1 and UT2 coincide substantially be
cause there‘ has been no direct current magnet
ization of the transformer T1 by the winding I2
which is energized from a suitable source of
'
The transformer T1 is provided with a primary
winding which is connected to the circuit f1 and
a plurality of secondary windings 8, 9, I0 and II
and an auxiliary winding I2 which is connected
55 to a variable source of direct current Ug.
ti?er 6, the current limiting resistor ‘I to the
grid of the anode of the phasewinding I’. The
remaining extremities of the secondary wind
ings 8i] and II are connected together through
One
of the secondary windings 8 of the transformer
T1 is connected through the conductor IT, a
unilateral conducting device or contact recti?er
6, a current limiting resistor ‘I, to.the grid of
80 the anode which is connected to the phase wind
ing I’. The secondary winding 9 is connected
through the conductor I8 through a contact rec
tifler 6 and a current limiting resistor ‘I ‘to the
grid of the anode which is connected to the
66 phase winding I".
The remaining connections
vof the secondary windings 8 and 9 are connected
through oneJof the secondary windings of the
transformer T2 through the source of biasing
voltage Uv to the cathode K of the-electric valve.
70 Similarly, the secondary winding III of the trans
former T1 is connected through the conductor
I9,‘ the contact recti?er 6, the current limiting
resistor ‘I. to the. grid of the anode of the phase
winding I”; and the secondary winding. II is.
75 connected through conductor I6, the contactrec
current Ug. If now the winding I2 is supplying
direct current magnetization to the transformer
T2 the impulses supplied to the anode connected '
to the phase winding I’ vwill be shifted in a lag
ging sense, and the impulses transmitted to the 55
grid of the anode connected to the phase wind
ing I" will be shifted in a leading sense. This
phase relation will be maintained in the same
direction as long as the flow of power between
the two circuits remains the same, but ifthe 60
power ?ow reverses, this direction of phase dif
ference will also be reversed. The connections
3 and 5 shown adjacent to the secondary wind
ing T2 indicate the points at which the other
two transformers similar to T1 are to be con
nected in order to provide the necessary control
circuits for the grids of the anodes 3', 5', 3", 5"
Fig. 3- illustrates the magnetic core structure
of one of the grid transformers T1, the primary
winding of which is energized from the circuit ii. 70
The terminals indicated bythe reference char
acter I are connected to opposite terminals of
the secondary winding of the transformer T2
whereas the remaining terminals of the windings
8, 9, I0 and II are connected respectively to the 75
3
2,114,856
conductors I‘l, I8, l9 and Hi. The magnetiza
tion of the core is controlled by energization
of the winding l2 from a suitable source of di
rect current such as U2. This change in the
Ci magnetization of the core shifts the phase of
the control impulses.
-
_
In accordance with further modi?cations of
my invention, the arrangement shown in Fig. 4
illustrates how the transformer T1 may be con
structed with only two secondary windings in
stead of four secondary windings. For the sake
of clarity the primary and magnetizing wind
ings of the transformers ,T1 and T2 have been
omitted._ The transformer T1 is therefore pro
15 vided with two secondary windings l3 and M
which are each connected between two groups
of contact recti?ers, 6 and 6'. The series opera
.. tion is the same as that shown in connection
passed by one of the recti?ers 24 are connected
between the source of biasing voltage Uv and
the current limiting resistor ‘I of the control
circuits of the grids of the anodes of the neutral
points of the networks A’ and A". Thus the
control grids or electrodes of the zero anodes
receive only the positive half wave impulses ap
pearing across the secondary winding of the
transformer T3.
1
The operation of the grid control circuits may 10
be best understood by referring to Fig. 6 in con
nection with Fig. 5 from which it will be ob
served that the transformer T1 supplies a volt
age impulse UT., and shown in the ?rst curve
of Fig. 6 ma manner similar to the arrange 15
ment shown in connection with Fig. l. The
voltage UTl must have a phase shift in a direction
dependent on whether the network is operating
with Fig. 1.
Of course, it will be understood by those skilled
in the art that while the operation has been
is indicated by the angle 25. Thus in certain 20
instances the component supplied by this trans
described as occurring between two alternating
former will appear as shown in the second curve
current circuits having a frequency f1 and f2
that the ratio between these two frequencies
25 need not be constant, but may vary during the
operation of the system.’ It furthermore will be
apparent that for optimum operation the zero
of Fig. 6. The degree of'this phase shift is con
trolled by the magnitude of the current ?owing
through the winding l2 and which is supplied
anodes or the anodes connected to the neutral
ondary winding portions of the transformer T2,
this transformer supplies to the grid control
circuit negative half wave components illustrat
20
points of the networks A’ and A” should not be
30 rendered conductive until such time, in the in
stants of recti?er operation, that the rectangular
as an inverter or a rectifier and this phase shift
from a suitable source of current Ug. Due to
the use of a contact recti?er 6’ across the sec
ed in the third curve of Fig. 6. The transformer
voltage impulse supplied by the transformer T2
T2 supplies negative voltage ‘components which
has reached a zero value.
appear in the fourth curve of Fig. 6. This volt
age obtained from the transformer T3 is about
It furthermore will
be apparent that between the positive impulses
35 supplied to the various grids there always is a
time interval between each sufficient to permit
the zero anodes to become conductive.
In Fig. 5 there is shown a preferred embodi
ment of my invention in which the power cir
40 cuit and certain portions of the grid circuit are
identical to the arrangement shown in Fig. l
and hence these parts have been given similar
reference characters. The control circuits for
the grids of the anodes of the windings I’ and
45 I" include a transformer T1 which is identical
to the transformer T1 of Fig. 1. The arrange
ment of the transformer T2 has been modi?ed
by the addition of the contact recti?er 6' across
each of the secondary windings thereof 26, 21,
50 so that the transformer T2 now supplies to the
grid control circuit only the negative half wave
component appearing across the secondary wind
ing.‘ A transformer T1 is connected between the
source of biasing voltage Uv and the transformer
55 T2 so as to supply negative half wave components
to the grid circuits at the same time that positive
half wave components arebeing supplied to the
grid circuits of the anodes connected to the neu
tral points ofthe networks A’ .and A”. The
transformer T3 therefore comprises a primary
winding connected to the circuit f2 and two sec
ondary windings comprising respectively the in
ductive portions 20, 2| and 22, 23. A pair of
contact recti?ers 25 are ,connected across the.
65 inductive portions 20, 2| ‘of one of the second
ary windings, which inductive portions are con
nected in series between the biasing source Uv
and the transformers T2 and T1 of the grid cir
cuits of the. networks A’ and A". The trans
70 formers T1 and T3 are common to all of the
grid controlled circuits of the anodes of the
networks A’ and A”, but three transformers
similar to T1 -are utilized, one for each of the
groups of the anodes I’, I": 3’, 3"; and 5', 5".
The inductive windings 22 and 23 each by
75
90 degrees out of phase with respect to the volt
age obtained from transformer T2 since the pri
mary winding of the transformer T2 is so ar
ranged that a voltage supplied thereby is ap
proximately 90 degrees out of phase with respect 40
to the voltage suppliedby the primary winding
of the transformer T2. These three components
combine so as to produce the control represented
by the sixth curve of Fig. 6.
- ~
_
In the sixth curve of Fig. 6 the dotted line
which is separated from the center line by an
interval of Uv represents the critical voltage which
must be exceeded and which critical voltage has
45
been obtained by proper adjustment of the source '
of biasing voltage Uv. Thus, during the first time
interval 1, the high frequency impulses obtained 50
from the transformer T1 operate to render con
ductive the anode controlled by this transformer.
During the time interval II'the voltage impulses
supplied by the transformer T2 prevent these 55
anodes from becoming conductive and during the
time interval III the negative voltage impulse
supplied by the transformerT2 continues to pre
vent these anodes from becoming conductive and
still further during the interval II’ these anodes 60
still remain non~conductive due to the voltage
supplied by transformer T3. During the time
intervals II and II’ a voltage wave corresponding
to the ?fth curve and indicated as Ur30 operates
to exceed the biasing‘ voltage Uv thereby render
ing conductive the zero anode or the anode con
nected to the neutral point of the networks A’ and
A”.
From the last curve of Fig. 6 it is quite ap
parent that the voltage component supplied by
the transformer T2 operates as .a rough control
of the times at which certain anodes are not to
be conductive and that the voltage component
supplied by the transformer T3 operates as a
?ner control to determine with accuracy the time
during which the anodes are not to be conduc
2,114,856
The curve shown in Fig. 6 at the bottom
tangula‘r positive potential components from'said
of the page of course is a representation of the
high frequency circuits, means for controlling the
phase of said latter components with respect to
said high frequency potential, and means for sup
tive.
control supplied when the particular network
is operating as an inverter.
7
While the control voltages U'r3 and Ursa have
5
been obtained by the use of a saturable trans
former together with contact recti?ers 254 and 25
across the secondary windings of the transformer
T3 it will of course become apparent to those
skilled in the art that any other means may be
utilized in order to produce a similar wave shape.
Furthermore it will be apparent_to those skilled
in the art that the voltage component obtained
plying said control electrodes with said alternat
ing potential of rectangular wave form together
with said rectangular, positive potential compo
nent.
-
2. An electric valve converting system for
transferring energy between high frequency and 10
low frequency alternating current circuits com
prising two groups of_ inductive windings each
provided with an electrical neutral, an electric
from the transformer T2 by means of the contact valve for each of said inductive windings and
15 recti?er 6' may also be obtained by means of the said neutrals, each of said valves being pro
vided with a control electrode, a control circuit
well known full wave recti?er connection.
If during the time for commutation a change for said valves comprising means for deriving
of direction of energy occurs there has been the from said low frequency circuit alternating po~
tentials of rectangular wave form, means for de
possibility in prior arrangements that short cir
riving from said high frequency circuit rectangu
20 cuit currents would arise. This would happen,
for instance, when there is a short circuit current _ larpositive potential components, means for con
trolling the phase of said latter components with
?owing between the different windings of the net
work A’ or between the two windings A’ and A". respect to said high frequency potential, means
The initial magnetization of the transformer T1 ' for supplying the. control electrodes of the valves
associated with said inductive windings with said
25 by the winding I2 causes this current to be sup
pressed. The transformer Tl furthermore may alternating potentials of rectangular wave form
be provided with such a winding which receives together with said rectangular positive potential
its energy from that portion of the circuit which components, and means for supplying to the con
trol electrodes of said valves associated with said
includes the inductive choke D.
30
30
It of course. will be understood that if desired neutral point rectangular positive potential com
the arrangement in Fig. 5 can be made to supply ponents derived from said low frequency circuit.
any predetermined load characteristic by provid
ing the transformer T1_ with a magnetizing wind~
ing similar to winding l2 which is energized from
35 the direct current flowing to~the cathodes of the
multi-anode single cathode valve. If the trans
former T1 is thus energized the voltage wave sup
3. An electric valve converting system for
transferring energy between high frequency and
low frequency alternating current circuits com
prising two groups of inductive windings each
provided with an electrical neutral, an electric
valve for each of said inductive windings and said
' plied thereby for both recti?er and inverter op
neutrals, each of said valves being provided with
eration will be shifted in phase so that the sys
40 tem will have a predetermined operating char
acteristic. If with such an arrangement the rec
ti?er should supply an excess current, the phase
shift may be so great as to render all the valve
a control electrode, a control circuit for said valve
comprising means for deriving from said low fre
oaths nonconductive thereby protecting the oper
ation of the system. It of course will be appar
ent to those skilled in the art that regulation of
the power output of the system can also be ob
tained by variation of the voltage components
UT, and U'r's supplied by the transformer T2 and
50
Ta. A variation in the duration of these voltage
impulses may be obtained by supplying each of
the transformers T2 and T3 with auxiliary wind
ings energized from a suitable source of direct
current which source may be proportional to the
current ?owing to the cathode K.
While I have described what I at present con
sider the preferred embodiment of my invention,
it will be obvious to those skilled in the art that
various changes and modi?cations may be made
without departing from my invention, 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:
1. An electric valve convertingsystem for trans
mitting energy in either directionbetween a high
frequency alternating current circuit and a low
quency circuit rectangular negative potential
components, means for deriving‘ from said high
frequency circuit rectangular positive potential
components, means for controlling the phase of
said latter components with respect to the po
tential of said high frequency circuit, means for
deriving from said low frequency circuit simul
taneously positive and negative rectangular po
tential components displaced in phase with re
spect to the potential of said low frequency cir
cuit, a common source of negative biasing poten
tialfor all of said valves, means for supplying
to the control electrodes of said inductive wind
ings said high frequency positive potential com
ponents, said low frequency negative potential
components and said phase displaced low fre
quency negative potential components, and
means for supplying said phase displaced posi
tive potential components to the control elec
trodes of the valves associated with said neutral‘
points.
4. An electric valve converting systemv for
transferring energy between two alternating cur
rent circuits of different frequency comprising
two groups of inductive windings each provided
with an electrical neutral, an electric valve for
two groups of inductive windings, an electric valve
for each of said windings, each of said valves hav
ing a control electrode, a control circuit for said
valves comprising means for deriving an alter
each of said windings and said neutrals, each of
said valves being provided with a control elec
trode, a control circuit for said control electrodes
comprising means for supplying to the control
electrodes of the valves of said inductive windings
voltage components derived from one of said al
ternating current circuits, means for supplying
nating potential of rectangular wave form from
said low frequency circuit, means for deriving rec
said alternating current circuits to the control
frequency alternating current circuit comprising
voltage components derived from the other of
5
2,114,856
electrodes of the valves of one of said inductive
windings for recti?er operation and to the control
electrodes of the valves of the other of said in
ductive windings for inverter operation, and
means for supplying simultaneously to the con
trol electrodes of said valves of said inductive
windings negative voltage components and to
the control electrodes of the valves of said neu
tral points positive voltage components.
5. An electric valve converting‘ system for
transferring energy between a high frequency al
ternating current circuit and a low frequency
alternating current circuit comprising two groups
of inductive windings each provided with an elec
trical neutral, an electric valve_ for each of said
inductive windings and said neutrals, each of
said valves being provided with a control elec
trode, a control circuit for said valves compris
ing means for supplying to the control electrodes
of the valves of both-of said inductive windings
voltage components derived from said low ,fre
quency circuit, means for simultaneously supply
ing to the control electrodes of the valves of one
of said inductive windings voltage components
derived from said high frequency circuit and re
tarded in phase relative thereto and to the con
trol electrodes of the valves of the other of said
inductive windings voltage components advanced
in'phase relative to said high frequency circuit,
and means for supplying simultaneously to the
control electrodes of the valves of said inductive
windings negative voltage components derived
from said low frequency circuit and to the con
trol electrodes of the valves of said neutral point
positive voltage components.
HANS NEIDHARDT.
-
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