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A‘. s. FuscssA
2,4%,8413 i
APPARATUS FOR ELECTRICAL CONTROL
Filed sept. 9. 1956
2 sheets-sheet 1
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Ar'ToRNEY. '[
0d. 8, 1946.'
A,
RlGGS
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2,498,813
APPARATUS FOR ELECTRICAL CONTROL
Filed Sept. 9, 1936
2 Sheets-Sheet 2
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IN VEN TOR. ‘
`
BY
ÖH@ e. 41ML?
ATTORNEY .
r//0^
-
_
2,408,813
Patented Oct. 8, 1946
UNITED STATES PATENT OFFICE
2,408,813
APPARATUS FOR ELECTRICAL CONTROL
Alger S. Riggs, Washington, D. C., assignor, by
direct and mesne assignments, to Sperry Gyro
scope Company, Inc., Brooklyn, N. Y., a cor
poration of New York
Application September 9, 1936, Serial No. 100,017l
'7 Claims. (Cl. 172-239)
1
2
sectional view of another form of phase chang
My invention relates broadly to a method of
ing controller embodying my invention; Fig. 6 is
producing alternating current voltages of prede
termined wave form, primarily for control pur
poses, as functions of rotational speeds, and more
particularly to a method and apparatus> for ob
taining high degrees of stability and accuracy
a transverse sectional vView taken on line 6-6 of
Fig. 5; Fig. 7 is a longitudinal sectional View
a circuit arrangement for a follow-up control
troller where it is desired to add a damping com
taken through a combined phase changing con
troller and a “Selsyn” motor employed in the
system of »my invention; Fig. 8 is a perspective
in control system for follow-up purposes.
view of the rotor in the apparatus of my inven
One of the objects of my present invention is
tion; Fig. 9 is a diagrammatic View showing the
to provide a circuit arrangement for a follow-up
control system in which a high degree of stability 10 control system of my invention; and Fig. l0 is a
detailed diagrammatic view showing the arrange
and freedom from hunt and surge is obtainable.
ment of the windings in my phase changing con
. Another object of my invention is to provide
system wherein the controlled object may be
made to- run in _absolute agreement with the 15
transmitted data.
Still another object of my invention is the pro
ponent.
‘
My invention relates broadly to a method of
producing alternating current voltages, primarily
for control purposes, as functions of rotational
speeds. In electrical control circuits utilizing am*
plifier systems for the remote control of heavy
a receiving device is made to follow a transmit
ting device in angular displacement with any pre 20 objects, such as searchlights and guns, there is
frequently a need for a device producing alter
determined amount of lag or lead which may be
nating
current voltages as functions of rotational
controllably selected.
,
speeds.y A conventional commutator type gener
A further object of my invention is the con
ator is unsuitable for this `purpose because the
struction of an apparatus from which an alter
nating current voltage functional upon rotative 25 ripple produced by the commutator may detri
mentally affect the control circuits.
speed‘may be derived from a rotating system for
By the use of a device of the character de
control purposes without taking torque from the
scribed herein, a smooth alternating current volt
rotating system.
age depending upon rotational speed may be pro
A still further object of my invention is the
duced. Moreover my device requires negligible
provision of an apparatus for producing an al
driving torque, inasmuch >as it is not a true gen,
ternating current voltage, as a function of rota
erator, but a speed actuated phase changing con
tional speed, having freedom from commutator
vision of a synchronized control system in which
ripple which is present in generating equipment
of conventional character.
Another object of my invention is the provision
of means for producing an alternating current
signal from a “Selsyn” data transmitting system,
for control purposes, which is a function of the
angular velocity of rotation of the “Selsyn” transm
mitter without in any Way loading the “Selsyn”
system by producing said voltage.
Other and further objects of my invention re
side in the method and circuit arrangement for
an electrical control system as set forth more
fully in the speciñcation hereinafter following by
reference to the accompanying drawings in
which:
troller.
>
-
-
Due to the negligible torque required to drive
. my device, it is practicable to utilize it for the
production of alternating current voltages as a
function of rotational speed where the taking of
high driving torque may give rise to inaccura
cies in the control system.`
For instance, in data transmitting systems op
40
erating from a so-called “Selsyn” system, the use
_of my invention permits of designing an electri
cal control for positioning heavy objects which
may be operated in exact agreement or synchro
Ll 5 nism at all speeds, i. e., mono-periodically.
My invention utilizes the so-called generator
action of an induction type alternating current
motor, and is best understood by reference to the
Figure 1 is a fundamental diagram by which
operation of such a motor from zero speed up
the principle of operation of my device may be
understood; Fig. 2 is a vector diagram explana~ 50 to its synchronous speed.
Referring to Fig. 1, which is a diagrammatic
tory of the circuit of Fig. l; Fig. 3 is a vertical
drawing of a two phase squirrel cage type induc
sectional View through one form of phase chang~
tion motor, the» windings L1 and Lz are arranged
ing controller constructed in accordance with my
so that their flux axes are at 90° relation to
invention; Fig. 4 is a transverse sectional View
taken on line 4_4 of Fig. 3; Fig. 5 is a vertical 55 each other-consequently-when the rotor is at
3
2,408,813
4
rest and an alternating current voltage is ap
plied to the winding L1, which I term the primary,
there is no voltage present at the terminals of L2,
the displacement control is augmented by the
difference in speeds between the data angular
velocity and the speed of the controlled member.
Since the diiîerence between these two speeds
which I term the secondary winding. If now the
rotor is revolved, its motion in the primary iiux
produces a voltage due to rotation which is
inductively conveyed from the rotor to the second
represents the absolute rate of approach or reces
sion from agreement between data and controlled
member, a voltage resultant oi these two speeds
provides means for production of dead-beat iol
ary coil Lz-this voltage is proportional to rota
tional speed up to the speed corresponding to
synchronous speed and is 90° out of phase with
the voltage applied to the primary winding L1.
The vector diagram of Fig. 2 shows the phase rela
tion of the terminal voltages of the machine
low-up action.
Referring to the drawings in detail, Fig. 3 shows
one form of my device for producing a voltage
proportional to rotative speed, composed of the
laminated stator 1 having distributed windings
I ü; the stator is held by means not shown, be
the vector representing e2 (the secondary, or
speed voltage) is 90° from the primary voltage
and varies in magnitude substantially as a linear
function of speed, up to synchronous speed and
reverses sign upon reversing direction oi7 rota
tion.
Though generator action is present in produc 20
ing the secondary or speed voltage e2 it is also
a fact that a corresponding motor action is
present-any power taken from the winding L2
is supplied in reality from the power source con
nected to the primary L1, and not from the source
of original rotation of the rotor.
tween the end frames 8 and El. The rotor con
sists of the laminated core I5 which is pressed
on the shaft i4; the laminated rotor core I5 is
completely surrounded by the non-magnetic but
electrically conductive cylinder or sleeve I6 which
performs the function of the squirrel cage illus
trated diagrammatically in Fig. l. The rotor
shaft is supported in the bearings l I and l2, and
a cap I3 is provided near the end of the shaft
opposite the driving end. Fig. 4, having like parts
similarly designated
Fig. 3 is a transverse
section at 4_4 of Fig. 3. In Fig. 4 the general
In practical use of the device for control pur
means of locating the windings is illustrated, the
poses it is sometimes objectionable for the motor
coils lil being held in the slots by wedges i8 as
component to be present, since once started the
device tends to run as a single phase A. C. motor. 30 in conventional motor practice. The rotor is free
to revolve in the stator which it clears by the air
The motor component may be reduced to a negli
gap shown at I1.
gible quantity by electrically loading the second
Fig. 5 is an improved form of my device in
ary winding, and may be still further reduced by
which the entire magnetic core is stationary, and
the dynamic braking action of the rotor in re
having as a rotor only the conducting non-mag
volving in a D. C. ñeld.
netic shell 24. Referring to Fig. 5, the stator
In order to provide damping action for the
core
is made up of the laminated core 1, held be
device when required, I provide a separate wind
tween the end frames I9 and 2€), and the lami
ing upon the stator having a different number
nated core 25 attached by the bolt 26 and nuts 21
of poles than the A. C. windings as illustrated
for example in Fig. 10 and energized from a suit 40 and 28 to the frame 2t. The laminated core 25
is the counterpart of the rotor core I5 in Fig. 3.
able source of D. C. power. For instance, in
The spacer 30 holds the inner core 25 in correct
one form of my invention I have wound the A. C.
relation to the main stator core ‘.'. The rotor
windings for two pole and the D. C. damper wind
consists of the conductive but non-magnetic cyl
ing for four pole-both windings in the same
inder 24 which is attached at 29 to the shaft 23
slots.
In electrical control circuits employing ampli
ñcation, the secondary or speed voltage of the
machine must have a high degree of wave forni
purity-so that the “ripple” caused by the squir
and supported on bearings 2| and 22.
The con
struction shown in Fig. 5 provides a stationary
magnetic structure composed of the main stator
core 1 and the concentrically located inner core
In such cases 50 25 with a double air gap l1 and lla in which
moves the rotor 24. Fig. 6 is a transverse section
I provide a rotor having laminated discs with
of Fig. 5 on the line S-ß and clearly shows the
out slots and simulate the squirrel cage effect
concentric relation of the rotor 24, main stator
by a conductive sleeve pressed and/or shrunk
core 'l and inner core 25.
rel cage is seriously detrimental.
over the laminated core. I show a rotor of such
construction in Fig. 3. In some instances even .M
the rotation of the laminated portion of the
rotor gives rise to production of detrimental wave
form distortion, and to prevent this I provide
a still further form of rotor consisting of a con
ducting sleeve rotatably mounted, with provision
for the iron core corresponding to the rotor core
remaining stationary with the stator of the ma
chine, the construction is shown in Fig. 5. Where
it is desired to provide a voltage functional
upon the angular velocity (or rotational speed)
of a "Selsyn” data system I propose to directly
connect and rigidly attach a device of the type
shown in Fig. 5 to a conventional “Selsyn” type
receiver or synchro motor, this I have shown in
Fig. 7.
For purposes of illustrating the utility of my
invention I show in Fig. 9 a circuit whereby a
heavy object may be controlled in angular posi
tion from a “Selsyn” transmitter. The system
possesses extreme stability at all speeds because
Fig. '7 is a section of another form of my device
which I refer to as a “data speed responsive con
troller,” composed of a device as shown in Fig. 5
directly connected to a “Selsyn” type of repeater
motor. Referring to Fig. 7 the stator core 1 is
held between the end frame 32 and the “bonnet”
3|; the inner core 25 is held by the bolt 26, and
the nuts 21 and 23 to the end frame 32 and spaced
therefrom by the spacer 3D. The rotor 24 is at
tached to the shaft 31 at 3B. The shaft 31 is
mounted in the bearings 39 and 40 to rotate the
rotor 24 and the rotor 34 of the Selsyn repeater
motor.
The “Selsyn” repeater motor is shown
for purposes of illustration as composed of the
stator 32 held between the end frame 33 and the
bonnet 3| and the rotor 34 operating in the stator
32. A “surge” damping device as usually em
ployed on “Selsyn” type repeater motors is shown
at 3S.
Fig. 8 is a perspective view of the rotor 24 of
Figs. 5 and 7.
Fig. 9 is a diagrammatic drawing of my pres
2,408,813
5
ent invention employed in an improved form of
electrical control system for follow-up purposes
6
devices, AA, F and E, consists of a “Selsyn” type
repeater motor directly connected by the shaft
15 to a speed responsive device as disclosed in this
in which the telescope 4| through the vcontrol
application. A complete device is shown in Fig.
system causes the searchlight 62 to be synchro
7. The rotation of the rotor 16 (counterpart of
nously controlled in agreement with the telescope.
24 of Fig. 5 and Fig. 7) in the flux of the primary
The hand crank 42 through the gears 43, 44,
winding 18 produces a voltage in the secondary
shaft 12, gears 45, 45a, shaft 14, gears 46, 41 and
winding 19 which varies in magnitude and direc
shaft 13 is adapted to drive the telescope 4|
tion as a function of speed and direction of ro
angularly. The shaft 12 also rotates the rotor
tation of the rotor 15. Likewise the “motor speed
10
48 of the “Selsynî’ type of transmitter B. The
responsive device” F consists of the rotor 83
polyphase stator windings 49, 59, 5| of the trans
(counterpart of 24 in Fig. 5) which when rotated
mitter are connected to the corresponding wind
the field of the primary 84 produces a voltage
ings 52, 53, 54 oi‘ a “Selsyn” type displacement
in the secondary winding~85 which varies in mag
voltage controller C by the leads 89, 90, 9|. The
nitude and direction as a function of the speed
corresponding windings 68, 69, 1|) of the “Selsyn”
and direction of rotation of the rotor 83 which
type repeater motor forming a part of the “data
is `driven from the motor E by the shaft 82.
speed responsive controller” are also connected
>The main amplifier AA is connected at its out
to the transmitter by the wires 92, 93, 94. The
put terminals 99, |09, IUI, |02 to the reversible
rotor 48 of the transmitter and the rotor 1| of the
motor E having a field 66 and armature 61, power
“Selsyn” type receiver are connected to a source 20 being supplied to the main amplifier at terminals
of alternating current power as designated.
The searchlight is driven by the reversible motor E through the gears 65, 64, the shaft 63, gears
59, 69, and the shaft 6|, at the same time the
“Selsyn” type displacement voltage controller is
driven from the shaft 53 through the gears 58,
51 and the shaft 59. The gear ratios are such
||1, H9. I have not shown they details of the
ampliiier AA which may be of the electron and/or
gas tube type, or may be of tubeless construction,
such as shown in my copending application, now
Patent No. 2,176,101 dated October 17, 1939, or of
the type shown in Edwards Patent No. 1,985,982.
However, the amplifier is preferably of a type
that the rotor 48 and the rotor 55 are at the same
which for a given value of input voltage at termi
geared ratio to the telescope and searchlight re
nals 91, 98 produces a finite speed of motor rota
30
spectively. When the telescope and light are in
tion regardless of motor torque.
_
positional angular alignment the rotor 55 is at
Now assume that the voltages applied to the
90° from the field in the receiver C and a dis
windings. 19, 84 are of correct magnitude and
placement to either side of agreement position,
phase, and that their relative polarities are such
whether arising from movement of the light or
that:
from movement of the telescope produces a volt
(a) The voltage produced in 85 opposes (through
age across the terminals 95, 99 of the device C,
the amplifier) the signal tending to drive the
which voltage through the amplifier AA ener
gizes the motor E to drive the light in a direction
to reduce the voltage again to zero.
motor.
However, the voltage at the terminals 95, 98 `
if applied to control the motor through the am
plifier would give rise to jerky response of the
motor, and the condition known as hunting and
surging would be present. The use of my pres
ent invention permits of a control free from the
ill effects of surge and hunt, and also permits of
operating the searchlight in absolute agreement
with the telescope.
'
(b) The Voltageproduced in 19 is of polarity to
drive the motor (through the amplifier) in the
direction of rotation of the transmitter B.
(c) The voltage produced at the terminals 95, 96
is of such direction as to (through the ampli
'
fier) drive the motor in a direction to remove
l
the displacement, that is, to bring the light into
agreement, angularly with the telescope.
With the above polarity conditions We have at
the amplifier input terminals 91, 98 a voltage as
The circuit operation is best understood by
consideration of the amplifier input circuit shown 50 follows:
in heavy lines.
It will be seen that the amplifier
input is composed of three separate and distinct
components; a voltage from the displacement
Now if the two systems are running at exactly
the
same speed, and the voltages at the windings
controller C, applied at terminals 95, 96, a volt
age from the “data speed responsive controller” 55 18, 84 are correctly adjusted for this condition,
the control voltage consists only of the voltage ed
D, applied at points 8D. 8| and a voltage from
the “motor speed responsive controller” applied
at points 86, B1.
(the voltage due to displacement, at terminals
95-99), since es (at terminals 86--81 due to mo
tor speed) and es’ (at terminals 89---8| due to
G0 data speed) are of equal magnitude and opposite
eczactual voltage at ampliiier terminals 91, 98.
polarity and therefore cancel. Under this con
ed=voltage at terminals 95, 96 of the displace
dition the system is operating under control of
ment controller C due to displacement from
the relative displacement between the light and
agreement position between light and telescope.
the telescope, the light “lagging” behind the tele
eszvoltage at terminals 8S, 81 of the “motor speed 65 scope by sufficient displacement to produce a volt
age at 95-~99 to drive the motor at the correct
responsive controller” F, and
es’=voltage at terminals 88, 8| of the “data speed
speed.
Suppose now that the voltage required at ter
responsive controller” D.
minals Y’i1-«98 under this speed condition is pro
The phases and magnitudes of the voltages es T() duced by a disagreement between the transmit
and es’ are determined by motor speed and data
ter B and the displacement controller C of say
speed respectively, and the voltages applied at
5°. If now the voltage applied to the primary
the respective terminals of the primary windings
winding 1B is increased .in any suitable manner
18 and B4. The device D, which is positioned
as by shifting the position of adjustable tap 13
remotely from the transmitter B and may be ad 75 on the secondary of a supply transformer 12, re
Now the voltages are designated as follows:
jacent the signal generator C and its associated
7
2,408,813
sulting in an increase of the voltage supplied by
winding 19, the relative angular position of the
controlling and controlled objects will change,
that is, the position of the controlled object will
be advanced, since the difference of the speed
voltages, es’ and cs, is no longer zero but now
supplies a portion` of the operating voltage ap
plied to terminals 9T, S8 of amplifier AA and
therefore less disagreement voltage ed is required
to make up the required amplifier input, which
is substantially constant at a given operating
speed. When, in increasing the voltage applied
to primary 1B, a value is reached which causes
voltage cs’ (produced in winding 19) to be higher
than cs (produced in winding 85) by an amount
corresponding to the voltage produced at 9‘5-95
by a 5° displacement. then the light will run in
absolute agreement with the telescope and no dis
8
be controlled angularly by "Selsyn” type data
systems.
Though I have shown specific apparatus for i1
lustration and description of the invention, I de
sire to be limited only by the scope of the ap
pended claims.
‘What I claim as new and desire to secure by
Letters Patent of the United States is as follows:
l. In a positional follow-up control system, in
combination with a controlling and a driven ob
‘ect, means for producing a signal from relative
displacement between said controlling and said
driven object, a rotatable sleeve of non-magnetic
but electrically conductive material, an inner sta
tionary iron core for said sleeve, means for driv
ing said sleeve from said controlling object, two
iield windings adjacent said sleeve arranged in
quadrature, one of said windings being excited by
placement signal will be necessary to keep the
motor running, the entire control voltage being 20 alternating current, and a motor for driving said
driven object controlled by the signal produced
supplied by the difference of the two speed volt
by the first said means combined with the output
ages, es' and es. Obviously at values of the exci
of the second of said windings.
tation of iield 'i8 other than this critical value,
2. In a positional follow-up control system, in
the controlled object will either lag or lead the
combination with a controlling and a driven ob
controlling object, in the one case because the
ject, means for producing a signal from relative
difference of the speed voltages is less than the
displacement between said controlling and said
total required operating voltage and in the other
driven object, a rotatable sleeve of non-magnetic
case because this difference is greater.
but electrically conductive material, an inner sta
If from any steady condition, either at rest or
while running at some finite speed, the displace 30 tionary iron core for said sleeve, said sleeve being
rotated by said driven object, a set of two field
ment changes by the light lagging or leading with
windings adjacent said sleeve and arranged in
respect to the telescope, heavy damping compo
quadrature, a second rotatable sleeve of non
nents due to differences between es and es’ are
magnetic but electrically conductive material, an
impressed upon the amplifier. In fact the dif
ference between the voltages es and es’ repre 35 inner iron core for said sleeve, said second sleeve
being driven by said controlling object, a second
sents the rate at which the displacement is
set of two field windings adjacent said second
changing and opposes (through the amplifier)
sleeve and arranged in quadrature, one winding
any displacement change.
in each of said sets being excited by alternating
The follow-up control in Fig, 9 is capable of
great accuracy and stability and is permanent in 40 current, and a motor for driving said driven ob
ject controlled by the signal produced by the first
its adjustments.
said means combined with the outputs of the
Fig. 10 is a diagrammatic showing of a speed
other windings of said sets of windings.
responsive device made in accordance with my
3. An electric transmission system including a
present invention having three complete sets of
transmitter and at least one receiver arranged to
windings, a primary composed of the coils iBS
be capable of mono-periodic operation with re
|04 connected to the terminals Hit-H4, a sec
spect to one another, comprising means for intro
ondary composed of the coils IE5-|56 connected
ducing into the control of the receiver a force
to the terminals IIS-_l I6, and a damper wind
which contains a component in magnitude pro
ing composed of the coils Iû'l--IIJß-lflS-Ili!
portional to the degree of positional displace
ment which may exist between the receiver and
connected to the terminals |l|~l|2_ The pri
mary coils I03--I04 are two pole and the second
ary coils |05~-|06 are two pole windings at right
the transmitter director member, and means for
introducing into said control .a further compo
nent which is a function of the difference in
angles to the primary, the damper windings com
pose ay four pole winding having poles as shown
and the primary and secondary and damper
windings are all inductively non-reactive upon
each other. The D. C. iiux produced by the
damper winding drags the rotor and prevents
motor torque being developed by the speed re
sponsive controller which might produce detri
mental effects when driven by a “Selsyn” type re
peater motor. This specilic type of speed respon
sive generator, however, is not claimed herein, but
in applicant’s divisional application, now ma
tured into Patent No. 2,206,920, dated July 9,
1940, for Apparatus for electrical control.
Though I have shown my invention as embod
ied in preferred forms, and a system incorporat
ing my invention as applied to driving a search
light in accordance with a telescope, I do not
desire to be limited thereby, inasmuch as the
general system shown in Fig. 9 may be employed
in any application where apparatus such as a
gun or searclilight or steering mechanism is to
agreement be
(i)
tween the transmitter
receiver may be main
tained when the displacement signal is zero.
4. In a positional control system, e, controlling
object, a remotely located controlled object, an
electrical positional data transmitter arranged
for operation by one of said objects, a transmis
sion line connected thereto, a signal generator
actuated by said other object and connected to
said line for generating a control signal propor
tional to the positional disagreement of said two
objects, a receiver also connected to said trans
mission line to operate synchronously with said
transmitter, generator driven by said receiver
for obtaining a control signal proportional to the
velocity of said receiver, driving means for said
controlled object, and means for controlling said
driving means jointly in accordance with said
disagreement and said velocity signals.
5. The method of operation of a positional con
2,408,813
trol system having a controlling and a controlled
object, whereby the controlled object may be
caused to lag or lead the controlling object by any
desired amount, comprising generating a control
Atransmitter director member, and means for in
troducing into said control a further component
which is a function of the diiïerence in speed of
the receiver and the transmitter director mem
signal proportional to the positional disagree Ut ber but which is not zero when said speeds are
the same, whereby lag or lead in the receiver with
ment of said two objects, generating control sig
respect to the transmitter may be maintained.
nals respectively functions of the velocities of said
7. The method of operation of a positional con
two objects but which may be relatively varied,
trol system having a controlling and a controlled
combining said last tvvo signals to obtain the dif
object, whereby exact synchronism as to both po
sition and speed is maintained, comprising gen
nal and the difference of said velocity signals
erating a control signal proportional to the posi
jointly to a motor driving the controlled object,
tional disagreement of said two objects, generat
and adjusting the magnitude of at least one of
ing control signals respectively functions of the
said velocity signals so that the controlled object
may be caused to assume the desired lag or lead 15 velocities of said two objects lbut in which the
signal from the controlling object is greater than
over the position of said controlling object.
the signal from the controlled object when said
6. An electric transmission system including a
speeds are equal, combining said last two signals
transmitter and at least one receive;1 arranged
to obtain the diiîerence thereof, and applying said
to be capable of mono-periodic operation with re
spect to one another, comprising means for in 20 displacement signal and the difference of said
velocity signals jointly to a motor driving the
troducing into the control of the receiver a force
controlled object.
which contains a component in magnitude pro
ALGER S. RIGGS.
portional to the degree of positional displacement
which may exist between the receiver and the
ference thereof, applying said disagreement sig
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