close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2406143

код для вставки
Aug. 20, 1946'.
s, GODET
2,406,143.
FOLLOW-UP CONTROL SYSTEM
Filed June 5, 1942
£7 ZZZ
=%.?
a
223
mil ~20“
‘@773
v
o
\\\\
g440d
\_
\
.
“ii a?‘
I
?h‘E! o
m1
J
Inventor‘:
Sidney Godet,
H is Attorney.
Patented Aug. 20, 1946
2,406,143
UNITED STATES PATENT OFFICE
2,406,143
FOLLOW-UP CONTROL SYSTEM
Sidney Godet, Schenectady, N. Y., assignor to
General Electric Company, a, corporation of
New York
Application June 5, 1942, Serial No. 445,949
3 Claims.
1
(Cl. 172-239)
This invention relates to control systems, more
2
to be driven into positional agreement with a
particularly to follow-up control systems for driv
pilot device or director H by suitable driving
ing an object into positional agreement with a
means such, for example, as represented by the
pilot device, and it has for an object the provision
direct current motor [2 to the drive shaft of
of a simple, reliable and improved control system
which the object H1 is connected by means of
of this character.
suitable reduction gearing (not shown). Direct
A further and more speci?c object of the in
current is supplied to the armature of the motor
vention is the provision of improved means for
I2 by means of a special generator l3 having a
preventing hunting or oscillation of the driven
pair of short-circuited armature brushes l3a and
object about the position of correspondence with 10 a'pair of load brushes | 3b to which the armature
the pilot device.
of the motor I2 is connected by means of con
In carrying the invention into effect in one
ductors M. The generator i3 is an armature re
form thereof, means responsive to positional dis
action excited dynamoelectric machine and is
agreement of the pilot device and driven object
driven at a speed, which is preferably substan
are provided for producing a signal voltage cor
responding to the error or positional disagree
ment of the pilot device and driven object. This
signal voltage is ampli?ed by suitable means such
as an electric valve type ampli?er, and the ampli
?ed signal voltage is used to control the supply ~
of voltage to the follow-up motor so as to cause
the motor to drive the object toward correspond
ence with the pilot device. If the driven object
possesses a substantial amount of inertia or if
tially constant, by any suitable driving means,
such, for example, as an induction motor 1 5. The
axis of the magnetic ?ux which is produced by
the short-circuited armature brushes I 3a is re
ferred to as the short circuit axis, and the axis
which is displaced 90 electrical degrees from the
short circuit axis is referred ‘to as the control
axis. The net ?ux along the control axis is pro
duced by two opposing control ?eld windings 13c
and l3d, a series compensating ?eld winding lite,
the system is designed for a high degree of ac 25 and the armature reaction of the load current
curacy of correspondence, violent hunting or
itself. The flux along the short circuit axis of
oscillation of the driven object with respect to the
position of correspondence will result unless
special means are provided for counteracting the
tendency of the system to oscillate. For the pur 30
pose of preventing hunting, the frequency of
oscillatory motion which is applied to the pilot
device is not permitted to exceed a certain
arbitrarily chosen value which is substantially
less than the natural period of oscillation of the I
system itself. In addition, connections are pro
vided between the follow-up motor and the input
circuit of the electric valve ampli?er and a high
pass ?lter, constituting an anti-hunt network, is
included in these connections. This ?lter has a
cutoff frequency above the maximum frequency
of oscillatory movement of the pilot device under
normal conditions but below the natural fre
quency of oscillation of the follow-up system
itself. Thus when a tendency of instability of
the system is present, the oscillating component
is strongly set back into the ampli?er in such
machine 13 is produced by the armature reaction
of the short circuit current, and if it is desired
to limit the short circuitcurrent to a low value,
a portion 'of the flux along the short circuit axis
may be produced by means of a shunt ?eld wind
ing (not shown). This short’ circuit axis ?ux
generates the voltage which appears across the
load brushes 13b, and the control axis flux pro
duces the voltage which appears across the short
circuited brushes l3a and causes short circuit
current to flow.
The compensating ?eld winding IE6 is so de
signed and connected that it neutralizes the
armature reaction produced by the load current
substantially 100 per cent. Consequently, the
main control ?eld windings I30 and l3d are only
required to produce the amount of flux necessary
to cause current to flow in the short circuit. Since
the resistance of the short circuit is so low as to
be almost negligible, the control ?eld windings
13c and [3d are only required to produce a very
phase as to counteract the oscillation.
small ?ux in order to produce a large current in
For a better and more complete understanding
the short circuit and a correspondingly large
of the invention, reference should now be had to 50 armature flux. Furthermore, since the ?ux of
the following speci?cation and to the accompany
the control ?eld winding need only build up to
ing drawing, the single ?gure of which is a simple,
such a low value, and since the reactance of the
diagrammatical illustration of an embodiment of
short-circuited armature is very low, full load
the invention.
current in the short circuit axis will be obtained
Referring now to the drawing, an object I0 is 65 in an exceptionally short time. The important
2,406,143
3
4
The stator and rotor windings are arranged in
inductive relationship with each other so that the
characteristics of this armature reaction excited
machine is are its exceptionally high speed of
alternating magnetic ?eld produced by the cur
rent ?owing in the primary winding induces volt»
response, and its extremely high ampli?cation
factor, i, e., the ratio between the magnitude of
the current ?owing in the control ?eld winding
l3c or IM and the magnitude of the current
which ?ows in the output circuit of the machine.
ages in the elements of the secondary winding.
The receiver regulator 28 is in all respects iden
tical with the transmitter 21 and the terminals of
electric valves l6 and H which constitute a single
stage ampli?er. Although electric valves l6 and
the stator Winding of the transmitter cause cur
rents to ?ow in the stator winding of the receiver
its stator winding are connected to the terminals
The control ?eld windings I30 and [301 on the
of the stator winding of the transmitter by means
control axis of the armature reaction generator
l3 are connected in the cathode-anode circuit of 10 of conductors 29 so that the voltages induced in
1? may be of any suitable type, they are prefer
ably screen grid transmitter type quick heating
tubes connected for duplex operation, and pro
regulator, thereby producing a magnetic ?eld
similar to the magnetic ?eld produced by the cur
15 rent flowing in the rotor winding of the trans
vided with a self-biasing resistor l8. Fixed volt
ages are applied to the screens and anodes of
valves l5 and H by means of a transformer is
having a primary winding 19a and a plurality of
mitter.
The rotor of the transmitter 21 is mechanically
connected through suitable gearing (not shown)
to the movable element of the pilot device H.
secondary windings I91), I90 and I9d. As shown, 20 For the purpose of increasing the accuracy and
sensitivity of the control, the ratio of this gearing
the primary winding I9a is supplied from a suit
between
the pilot device and the rotor of the
able source of alternating voltage which is indi-q
transmitter can be made as large as is desired,
cated in the drawing by the two supply lines 2%].
for example, the‘ratio may be as great as 72:1,
The cathode-anode circuits of valves It and H
are traced from the midpoint of the secondary 25 i. e., for each degree that the pilot device is ro
tated, the rotor of the transmitter is rotated 72
winding of the ?lament transformer 2i through
degrees. The rotor of the receiver regulator 28
the self-biasing resistor 18 and conductors 22 and
is connected either to the shaft of the motor P2
23 to the junction point of the control ?eld wind
or to the shaft of the driven object it by means
ings E30 and Kid and thence through these two
?eld windings in parallel and the secondary wind 30 of suitable gearing (not shown) having the same
ratio as the gearing between the pilot device and
ings I90 and I901 of anode transformer is to the
the transmitter.
anodes lea and Na of valves l5 and ill. The
The initial relative arrangement of the rotors
cathode grid circuits of valves is and H are
of the transmitter 2'? and receiver regulator 28
traced from the midpoint of the secondary wind
ing of the ?lament transformer 2i through the 35 is such that when the system is in correspond
ence, the axis of the rotor winding of the receiver
self-biasing resistor I8, resistors 24 and 25 in par
28 is at right angles to the axis of the magnetic
allel, the secondary windings 26a and 26b of grid
?elds produced by the currents flowing in the
transformer 26 to the control grids ltb and Ill).
stator winding so that the voltage induced in the
The voltages of the grids i621 and Ill), respec
rotor winding is zero. Rotation of the rotor mem
tively, as a result of the inclusion of the biasing
ber of the transmitter causes a voltage to be in
resistor l 8 in the anode-cathode circuits of valves
duced in the rotor winding of the receiver owing
[6 and I7 are such that both valves 56 and ii
to the shift in the position of the axis of the mag
normally conduct equal amounts of current. This
netic ?eld of the receiver relative to the axis of
condition of equal conduction in both valves l6
the coil of the rotor member, and the magni
and H occurs when the follow-up system is in
tude of this induced voltage depends upon the
correspondence, i. e., when the driven object I!)
relationship of the axis of this winding to the
is in positional agreement with the pilot device
axis of the magnetic ?eld, e. g. when the axes
ll.v The currents conducted by the valves in and
of the magnetic ?eld and of the rotor winding
l‘! excite the control ?eld windings I30 and 13d
of the armature reaction excited generator I3. 50 are parallel, the induced Voltage is maximum,
whereas when these axes are at right angles with
However, since the control ?eld windings‘ £30 and
each other, the induced voltage is Zero. It will
ltd act in opposition to each other, the net ex
therefore be clear that rotation of the rotor of
citing ?ux along the control axis of the generator
the transmitter or of the receiver regulator, will
l3 is zero and therefore the voltage at the load
vary the magnitude of the component voltage
brushes 13b is zero.
supplied to the grid circuit of the electric valves
In order to vary the bias voltages of the grids
I5 and IT which, in turn, will result in varia
It?) and ill), a component voltage of variable
tion in the relationship of the current ?owing
magnitude is supplied to the grid circuit substan
in the anode-cathode circuits of these valves.
tially in phase with the anode voltage through
the transformer 26, whose secondary windings 60 The connections between the control grids l6?)
and ill) are such that when the voltage applied
26a and 26b are connected in the cathode grid
to one of the grids is increased, the voltage ap
circuits of the valves [6 and H, as explained in
the foregoing, and whose primary winding 250
is connected to the single phase alternating cur
rent source 28 through rotary induction appa
ratus illustrated as comprising a rotary induction
device 2'! referred to as the transmitter and a
similar rotary induction device 28 referred to as
plied to the other grid is simultaneously de
creased and consequently when the current sup»
plied to one ofthe control ?eld windings of the
generator I3 is increased, the current supplied
to the other is correspondingly decreased. The
large gear ratios between the transmitter 27 and
pilot device H and between the receiver 23 and
the receiver regulator. The rotary induction de
vice Z'l comprises a rotor member 2111 provided 70 driven object W provide a very ?ne and a very
accurate control. If the ratio is 72:1 as assumed,
with a single phase primary winding (not shown)
then for each ?ve degrees of rotation of the pilot
and a stator member 21b provided with a dis
device, the rotor of the transmitter 2'! is rotat~
tributed three-element winding (not shown‘)
ed 360 degrees. However, since the axes of the
which is physically similar to the polyphase winds
rotor winding of the receiver 28 andthe mag
ing of an ordinary wound rotor induction motor.
2,406,143
netic ?eld of the stator are parallel at two points
in each complete revolution of the transmitter,
i. e., at zero degrees revolution and
grees revolution of the transmitter,
clear that the pilot device and the
lect must not be allowed to become
at 180 de
it will be
driven ob~
more than
21/2 degrees out of correspondence with each
other, while under the control of the high speed
?ne control system, because when this amount
to the control grids 16b and Nb and is thereaf
ter effective in controlling the valves I Band IT.
For .the purpose of preventing hunting in the
operation of the system, an antihunting network
35 is provided. This antihunt network is in
cluded in the connecting lines between the fol
low-up motor l2 and the grid or input circuit of
the electric valves l6 and l‘! and. it comprises
the capacitor elements 36 and 31, the resistor
10 element 38, and inductance element 39, and re
sistor elements 24 and 25. The capacitor ele
of positional disagreement occurs, the same re
lationship exists ‘between the rotors of the trans
mitter and the receiver as exists when the pilot
ments 36 and 31 are connected in series in the
device and driven object are in correspondence
connecting lines between the armature terminals
with each other. Under actual operating con
of motor [2 and the input circuit of valves l6
ditions, the rotor of the transmitter often does 15 and I7, and resistor 38 and inductance 39 are
become more than 21/2 degrees out of corre
connected in series with each other across the
spondence with the driven object, and a coarser
connecting lines. Similarly, the resistors 24 and
system is therefore provided for taking over the
25 are connected in series with each other across
control from the high speed ?ne control system
the connecting lines. The antihunt network op
before this amount of positional disagreement is
erates as a high pass ?lter having a cutoff fre
exceeded. This coarse system is illustrated as
quency that is greater than fa which is the
comprising a transmitter
that is, identical
highest frequency of any oscillatory component
with the transmitter 27 and a receiver regulator
of motion of the pilot device ll so that the out
3| that is identical with the receiver regulator
put of the antihunt network is minimum in the
28. The single phase rotor winding of the trans 25 region of fa. The antihunt network is designed
mitter 30 is connected to the alternating voltage
to have a maximum output in the region of fb
source 20, and the single phase rotor winding of
which is the natural frequency of oscillation of
the receiver regulator Si is connected to the ter
the system.
minals of the primary winding 32:; of the trans
The system is designed so that ft is several
former
the terminalsv of the secondary wind
times as great as fa- The connections from the
ing 32b of which are connected to the grids it?)
antihunt network to the follow-up motor l2 and
and ill) through electric valves
and 3%. The
from the antihunt network to the input circuit
midpoint of this secondary winding 32b is co‘
of' the electric valves are such that the voltage
nected to the junction point of the resistors
fed from the network to the input circuit is 180
and 25. The stator winding-s of the transmitt 35 degrees out of phase with any oscillation or in
30 and the receiver regulator 3| are connected to
cipient oscillation of the load l0 with respect to
each other by means of conductors
the position of correspondence. In addition, the
The rotor of the transmitter 38 is directly con~
design of the antihunt network is such as to
nected to the rotatable member of the pilot de~
pass substantially zero out of phase components.
vice II by means of suitable gearing having a V40 In other words, the network is not sharply tuned
ratio such, for example, as 2:1,
the rotor
to any frequency less than it.
member of the receiver regulator 35 is connect
The foregoing desired characteristics of the
ed through suitable gearing (not shown) having
antihunt network may be obtained by designing
a similar ratio, to the driven object it. Thus it
the network so that the elements thereof have
will be seen that the transmitter
the re 45
ceiver regulator 3! constitute a low speed sys
tem and provide t -e desired coarse control.
The electric valves 33 and 34 may be of any
the following values:
(1)
300,060
03a: ML
(2)
c37=-——‘20%O‘/LC“
suitable type but are preferably of the two—elec~
24--25
trode type into the envelopes of which a small 50
in Which,
quantity of an inert gas such, for example, as neon
is introduced. A characteristic of a valve of this
L is the inductance of coil 39 in henries,
character is that when a voltage of less than a
predetermined value is applied to its terminals,
the valve does not conduct current and that when
this volt-age is exceeded, the neon gas becomes
ionized and the valve becomes conducting.
The transformer
preferably
a very high
step-up ratio of the order of 56:1, so that when
C36 is the capacity of capacitor 36 in microfarads,
C37 is the capacity of capacitor 31 in microfarads,
R24-25 is the resistance of resistors 24 and 25 in
ohms,
ft is the natural frequency of oscillation of the
system in cycles per second,
fa is the highest frequency of any oscillating
the positional disagreement of the pilot device and 60
component of motion of the pilot device.
driven object is less than a predetermined
amount, e. g. 21/2 degrees or less, the voltage ap
plied to valves 33 and 31% is less
the ioniza
tion or breakdown voltage of these valves, but
equals or exceeds the ionization voltage when
the positional disagreement equals or exceeds
this predetermined amount. Thus, when the po
sitional diagreement is less than this predeter
mined amount, the control connections between
the coarse control system and the grids of valves
l6 and I‘! are interrupted and the coarse con cl
system is ineiiective, and when the disagreement
equals or exceeds this amount, the valves become
conducting and the voltage induced in the sec
ondary winding of the transformer 32 is applied
The value L of inductance coil 39 may be arbi
trarily chosen and the resistance of resistor 33
may best be ‘determined empirically after the
values L, C36 and C37 have been determined. The
resistance of resistors 24 and 25 and the induct
ance of coil 39 should be as large as is convenient
in order that the capacitors 3S and 3‘! may be of
reasonable size.
With the foregoing understanding of .the ele
ments and their organization in the completed
system, the operation of the system itself will
readily be understood from the following detailed
description. Since the operating coil of the relay
4!] is connected across the source 20, the relay
75 picks up and its movable contacts 40d and 40b
2,406,143
engage the stationary contacts 40d and 40a, re
spectively. Contacts 40a and 4001 in closing com
plete an energizing circuit for the ?eld winding
l2a of the follow-up motor, and contacts 401)
and 40c in closing remove a short circuit about
a portion of the compensating ?eld winding [36
of the armature reaction excited generator 13.
Assuming that the pilot device H and the
8
Had the departure from correspondence been
in the opposite direction, the operation of each of
the elements would be similar but opposite to that
of the operations thus far described with the re
sult that the motor l2 would have driven the
driven object in the reverse direction.
Whenever the positional disagreement of the
pilot device and driven object becomes less than
the predetermined amount at which the valves 33
driven object it) are in positional agreement, the
system is in its normal deenereized condition in 10 and 34 become ionized, the voltages applied to the
valves 33 and 34 will become less than the ioniza
which it is illustrated. As previouslyv pointed
tion voltage of these valves, and the valves will
accordingly become non-conducting. The result
I‘! are conducting equal amounts of current so
of this is to interrupt the control connections be
that the opposing control ?eld win-dings I30 and
l3d of generator 13 are equally excited and the 15 tween the low speed coarse control system and the
input circuit of the valves 18 and ll, thereby to
output voltage of the generator I3 is zero. Man
out, when in this condition, both valves l6 and
ual or power driven rotation of the pilot device
ll effects a corresponding but multiplied rota
tion of the rotor of transmitter 21, causing a
rotation of the magnetic ?eld of the stator of
receiver regulator 28 so that a voltage is in
duced in the rotor winding of the receiver regu
render the low speed coarse control system in
effective and to re-transfer the control to the
high speed ?ne control system.
.As previously pointed out, the operation of the
system as described in the foregoing is modi?ed
during acceleration and deceleration by the ac
tion of the antihunt network. Whenever there
lator proportional to the amount of rotation of
exists a tendency of the system to oscillate as
the pilot device ll. This induced voltage is ap
plied to the grid circuits of electric valves [6 25 usually occurs during acceleration or deceleration,
an oscillating component of voltage derived from
and i7 and results in increasing the current ?ow
the follow-up motor 22 is very strongly fed back
ing in one of the valves and decreasing the
through the antihunt network 35 to theinput cir
current ?owing in the other valve. Assuming
cuit of the amplifier valves 16 and l"! in such a
that the direction of rotation of the pilot device
is such as to increase the current ?owing in the 30 phase as to counteract the oscillation. In other
words, for rapid changes of velocity having an
valve [6 and to decrease the current ?owing
oscillating component of motion, a high feed—
through the valve H, the excitation of control
back exists, while for constant velocity no feed
?eld winding I30 will be increased and the ex
back exists.
citation of control ?eld winding 13d will be de
creased. The difference in excitations of the two 35 Although in accordance with the pro-visions of
the patent statutes this invention has been ex»
opposing ?eld windings I30 and Kid produces a
plained as being embodied in concrete form and
net excitation along the control axis of the gen
the principle thereof explained, together with the
erator l3, and as a result, the generator l3 sup
best mode in which it is now contemplated ap
plies current to the armature of the follow-up
motor l2 in such a direction that the motor is 40 plying that principle, it will be understood that
the apparatus shown and described is merely il
caused to rotate in a direction to drive the object
lustrative and that the invention is not limited
I0 toward correspondence with the pilot de
thereto, since alterations and modifications will
vice II.
readily suggest themselves to persons skilled in
If the driven object IQ can not follow the
the art without departing~ from the true spirit of
rapid movement of the pilot device ll so that
this invention or from the scope of the annexed
the positional disagreement of the driven object
claims.
and pilot device equals or exceeds the prede
What I claim as new and desire to secure by
termined amount, the voltage induced in the
Letters Patent of the United States is:
secondary winding of the transformer 32 becomes
1. A follow-up control system comprising in
so great that the voltages across electric valves _
combination, a pilot device, a driven object, an
33 and 34 exceed the ionization voltages of these
valves and cause them to become conducting.
Voltages continue to be induced in the second
ary windings 26a and 26b of the transformer
25 after the electric valves 33 and 34 have be- ;
come conducting, but owing to the high resist
ance of resistors 4| and 42, the voltages induced
in the secondary windings 26a and 261) are no
electric motor for driving said object, means re
sponsive to disagreement of said pilot device and
driven object for producing a signal voltage cor
responding to said positional disagreement, am
pli?er means responsive to said signal voltage for
supplying a voltage to said motor to cause said
motor to drive said object toward correspondence
with said pilot device, an antihunt means com
longer effective and the electric valves I6 and H
are controlled solely by the voltage induced in (30 prising a high pass ?lter having a cutoff frequency
substantially lower than the frequency of the
the secondary Winding 32b of transformer 32.
natural period of oscillation of said system and
Thus when the electric valves 33 and 34 become
connected between the armature terminals of said
conducting, the control connections between the
motor and the input to said ampli?er.
low speed coarse control system and the electric
2. A remote follow-up control system for a pilot
valves 16 and I’! are completed and the control
device and driven object in which the frequency
of the follow-up system is effectively transferred
of oscillatory movement of the pilot device is sub—
from the high speed ?ne control system to the
stantially less than the natural frequency of oscil
low speed coarse control system. As a result, a
lation of said system comprising in combination,
voltage is applied to the input circuit of electric
valves [6 and ll of such magnitude that the cur 70 an electric motor for driving said object, an elec
tric valve type ampli?er provided with an input
rent supplied by armature reaction excited gen
ircuit and with an output circuit operatively as
erator l3 to the follow-up motor i2 causes the
sociated with said motor, means responsive to po
latter to drive the driven object ill at maximum
sitional disagreement of said pilot device and
speed in the same direction as that in which the
75 driven object for supplying a signal voltage to said
pilot device H is moving,
2,406,143
input circuit corresponding to said positional dis
agreement thereby to control the Voltage sup
plied to said motor to cause said motor to drive
said object toward correspondence with said pilot
device, and antihunt means responsive to the
terminal voltage of said motor for supplying a
feedback voltage to said input circuit comprising
a high pass ?lter having a cutoff frequency inter
mediate said frequency of movement of said pilot
device and said natural frequency of said system.
3. In a follow-up control system for causing a
driven object to follow the movements of a pilot
device and in which the frequency of oscillatory
movement of said pilot device is substantially less
than the natural period of oscillation fb of said
system, an electric motor for driving said object,
an electric valve type ampli?er provided with an
output circuit operatively connected to said motor
and with an input circuit, means responsive to
positional disagreement of said pilot device and 20
driven object for supplying a signal voltage to said
input circuit corresponding to said positional dis
10
agreement thereby to control the voltage supplied
to said motor, and antihunt means comprising
means for deriving a voltage from said motor, and
a high pass ?lter connected between said voltage
deriving means and said input circuit and com
prising a connecting line having lumped resist
ance R1 and lumped impedance L connected in se
ries with each other and in shunt across said line,
and a ?rst lumped capacitance C1 in series with
said connecting line substantially equal to
$0,000
1100292
and a second lumped resistance R2 in shunt across
said connecting line and a second lumped capaci
tance C2 in series with said connecting line and
equal substantially to
zoom/f6?
R2
SIDNEY GODET.
Документ
Категория
Без категории
Просмотров
0
Размер файла
811 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа