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Патент USA US3041515

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June 26, 1962
H_ R. A, HANSEN
3,041,514
D.C. ADJUSTABLE SPEED DRIVE
Filed Dec. 13, 1960
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SPEED — POTENTIOMETER SETTING (PER CENT)
ATTORNEYS
United States Patent 0 MIC@
3,041,514
Patented June 26, 1962
2
1
3,041,514
D.C. ADJUSTABLE SPEED DRIVE
Hans R. A. Hansen, Milwaukee, Wis., assignor to The
Louis Allis Co., Milwaukee, Wis., a corporation of
Wisconsin
Filed Dec. 13, 1960, Ser. No. 75,586
11 Claims. (Cl. 318-154)
the motor ?eld ampli?er and an electronic switch which
automatically selects either the modi?ed voltage or the
feedback voltage to be fed back to the input of the motor
eld ampli?er. The cross-over network operates in two
phases; in a ?rst phase the output of the motor ?eld am
pli?er is maximum and constant and the output of the
generator ?eld ampli?er is variable in accordance with
the setting of the speed selector, and in the second phase
the output of the generator ?eld ampli?er is at a maxi
The present invention relates to a direct current ad
justable speed drive system and more particularly to a 10 mum and constant and the output of the motor ?eld
ampli?er is variable in accordance with the speed volt
control circuit for effecting a cross-over between the arma
age signal as modi?ed. Negative feedback may also be
ture voltage speed regulation range .and the ?eld voltage
speed regulation range of an adjustable speed direct cur
provided to the generator ?eld ampli?er from the gen
erator for purposes of maintaining the generator arma
One of the most frequently used systems for variable 15 ture output and, accordingly, the motor armature input
proportional to the energization provided to the gen
speed drives is the Ward-Leonard system. When a wide
erator ?eld ampli?er by the cross-over network. By
speed range is required, it is often economical to use a
virtue of this arrangement, the speed of the D.C. motor
combination of armature voltage regulation and motor
rent motor.
?eld regulation. Regulation of armature voltage is used
in the low speed range while motor ?eld regulation is
used in the high speed range. Generally, it is preferred
to effect this regulation of armature and ?eld by means
of a single control, but it has been found that with such
an arrangement, not only is motor speed not linear with 7
may be accurately controlled over a wide range.
Further objects and features of the invention pertain
to the particular structural arrangement whereby the
above-identi?ed and other objects of the invention are
obtained.
The invention, both as to its structure and manner
control setting, but good “cross-over” is di?icult to 25 of operation, will be better understood by reference to
the following speci?cation and drawings, forming a part
achieve.
thereof, wherein:
A cross-over circuit with a single speed potentiometer
FIGURE 1 is a schematic representation of a variable
and inherently good linearity is disclosed in application
speed drive arrangement in accordance with the inven
Serial No. 811,499, ?led May 6, 1959, now Patent
2,929,975, for a D.C. adjustable speed drive, and assigned 30 tion;
to the same assignee as the instant application.
How
ever, such a cross-over circuit has one disadvantage in
FIGURE 2 is a chart showing the operational charac
teristics of a D.C. motor controlled in accordance with
that the speed reference signal provided by the potenti
the drive arrangement of FIGURE 1; and
speeds.
10 and a D.C. motor 12.
FIGURE 3 is a schematic representation of an alter
ometer is a position signal and not a voltage signal there
by making it di?icult to apply controlled acceleration 35 nate variable speed drive arrangement in accordance
with the invention.
and deceleration and almost impossible to use such a cir
With reference now to the drawings, there is shown
cuit for speed follower systems.
in FIGURE 1 a schematic representation of a preferred
Therefore, it is the principal object of this invention
drive arrangement in accordance with the invention. In
to provide an improved direct current drive system for
machinery and the like that is e?fective for accurately 40 the arrangement there is included a generator-motor set
of the Ward~Leonard type including a D.C. generator
regulating drive speed over a wide range of operating
Generator 10 has an armature
14 and ?eld winding 16 and‘ motor 12 has an armature
17 and a ?eld winding 18. A suitable prime mover 20
an improved control circuit for an adjustable speed direct
current drive that effects a smooth and continuous tran 45 mechanically drives generator armature 14 at a substan
Another object of the present invention is to provide
sition between the armature voltage speed regulation
range and the ?eld voltage speed regulation range of the
tially constant speed. The electrical output of armature
14 is transmitted via conductors 22 and 23 to motor
armature 17 which in turn drives an output shaft 24
which may be connected to any desired load. Addition—
proved D.C. adjustable speed drive system having in 50 ally, there is provided a motor ?eld ampli?er 26 for
energizing ?eld winding 18 of motor 12 via .a conductor
herently good linearity and utilizing only a single speed
D.C. motor.
A further object of this invention is to provide an im
selecting potentiometer without the necessity of tachom
eter feedback.
28, a generator ?eld ampli?er 30 for energizing ?eld
winding 16 of generator 10 via conductor 32, a poten
tiometer 34 for providing a signal voltage eJr propor
A more speci?c object of this invention is to provide an
improved cross-over circuit for a D.C. adjustable speed 55 tional to the desired speed of motor 12, and a cross-over
network 36 connected to the output of motor ?eld ampli
drive in which the speed selecting reference signal is a
?er 26 for providing a feedback control to ampli?er 26
voltage signal rather than a position signal for permitting
and also for modifying signal er, which modi?ed signal
accurate control of the acceleration and deceleration of
is applied to the input of generator ?eld ampli?er 30 so
the D.C. motor as well as to render such a system suitable
as to maintain constant the energization of generator ?eld
for use as a speed follower.
winding 16 when the motor is operating in its ?eld volt
The foregoing objects are accomplished in a preferred
age speed regulation range.
embodiment of this invention by providing a control cir
Potentiometer 34 consists of a resistance element 38
connected
between the terminals of a conventional D.C.
armature voltage speed regulation range and motor ?eld
40, such as a battery, and a wiper arm 42 which
speed regulation range, wherein the control circuit in 65 source
acts to tap off a portion of the battery voltage from re
cuit for a generatonmotor set characterized as having an
cludes a generator ?eld ampli?er and a motor ?eld am
pli?er, a source of reference signal for the motor ?eld
sistor 38 in accordance with the position of wiper arm 42
relative to resistor 38. 'In this case, the tapped-off voltage
ampli?er, a motor speed selector which produces a speed
is termed a speed signal er and appears on conductor 44.
signal in accordance with the desired speed of the motor,
Any suitable constant direct current source is provided
a circuit for modifying this speed voltage in accordance 70 to apply a constant D.C. reference signal via conductor
with the output of the motor ?eld ampli?er, a feedback
46 to the input of motor ?eld ampli?er 26.
circuit connected between the output and the input of
Cross-over network 36 consists of a feedback resistor
3,041,514
3
48 connected to output conductor 28 of ampli?er 26. A
diode 50‘ is connected to the other side of resistor 48 and
is poled to provide a feedback path via conductor 52
along which signal efb may be applied as signal em to
the input of motor ?eld ampli?er 26.
4
fore, recti?er 60 is rendered reverse biased and non-con
Connected to the output of potentiometer 34 via con
ductor 44 is a function multiplier 54. Signal er is one in—
ducting whereas recti?er Stl is rendered forward biased
and conducting. Consequently, signal em is blocked
from the input of motor ?eld ampli?er 26 and signal en,
becomes the negative feedback signal cm which is applied
to the input of motor ?eld ampli?er 26 in opposition to
the reference voltage E. Such an arrangement provides
put or factor applied to multiplier 54 and the other is
a self-regulating effect on motor ?eld ampli?er 26 so
a control voltage cm developed by a resistor 56 connected
that its output voltage er and, therefore, the energization
to conductor 23 in the output of motor ?eld ampli?er 26. 10 of ?eld winding 18 remains substantially constant in
The output of multiplier 54 is a control voltage em which
phase I.
is proportional to the product of e, and era; i.e.,
Signal em appears on conductor 58 and may be applied as
signal are via conductor 62 to the diode 69 which in turn
is connected via conductor 52 to the input of motor ?eld
ampli?er 26.
Signal em is also applied via conductor 64 to the input
of generator ?eld ampli?er 30. Also applied as a nega
tive feedback signal to the input of ampli?er 30 is a
control voltage ‘egg which is developed across resistor 66
connected between the output of generator armature 14
and the input of ampli?er 30. The + and -— signs indi
cate the relative polarities of the various signals.
7 In this arrangement, there are two phases of opera
tion dependent upon the position of wiper arm 42 rela
tive to resistance element 33 of potentiometer 34. In
phase 1, where control voltage cm is less than control
However, let us now look at generator ?eld ampli?er
30. ‘Control voltage em is applied via conductor 64 to
the input of ?eld ampli?er 30 whose output voltage eh
appears across generator ?eld winding 16 to produce a
?eld current in which provides the field energization for
generator 16. Therefore, it can be seen that, as the speed
of motor 12 is varied by adjusting wiper arm 42 to in
turn vary speed signal e, and control voltage em in
the phase I operation, the ?eld winding energization of
generator It‘? varies proportionately to effect the desired
speed control of motor 12.
For example, as signal er is increased in phase I, gen
erator ?eld Winding voltage eh increases and the genera
tor armature voltage ea increases accordingly since gen
erator armature 14 is driven at substantially constant
speed by prime mover 24}. In addition, feedback resis
tor 66 connected to generator armature 14 provides a
negative feedback voltage egg to the input of generator
voltage efb, diode 50 is forward biased and rendered con 30 ?eld ampli?er 36) to maintain armature voltage ea sub
ducting while diode 60‘ is reverse biased and rendered non
stantially proportional to the control voltage em. It is
conducting so that the control voltage efb becomes equal
also understood that suitable ‘IR drop compensation may
to the negative feedback voltage are which voltage is main
be provided by signal egb derived by means of the shunt
tained constant by the regulating of the output of ampli?er
67 in the armature circuit and the impedance 68 pro
26. Consequently, since the output voltage at of ?eld 35 viding positive feedback at the input to ?eld ampli?er 30.
ampli?er 26 is maintained constant, the energization of
In phase II, the system is operating in its motor ?eld
motor ?eld winding 18 is also maintained constant.
regulation range, i.e., the speed of the motor has been
In phase II, where control voltage em is greater than
increased beyond the point where the ?eld voltage eh
control voltage efb, diode 60 is now forward biased and
across generator ?eld winding 16 has reached its rated
conducting while diode 50 is reverse biased and non
conducting so that negative feedback voltage efc becomes
equal to control voltage em. Therefore, in phase II,
as speed signal 6,, increases, control voltage em tends to
increase, and control voltage efc also tends to increase.
However, since an is applied in opposition to the con
stant reference signal at the input etc which in turn de
creases ?eld ampli?er output voltage ef of ampli?er 26
in the manner of a negative feedback signal, ampli?er
output voltage er and the motor ?eld winding energiza
tion decrease in proportion to the increase in em. This
decrease is sensed by resistor 56 so as to correspondingly
reduce signal em which in turn is a'component of em.
Since signal em is proportional to signal em, signal cm
is reduced correspondingly so that for any given setting
of wiper arm 42 in the phase II range, signal em is main
tained constant at its crossover value, i.e., the value at
which em became equal to efb.
As a matter of convenience, the values of resistors 48
and 66 may be chosen such that when signal em equals
signal am at cross-over, output voltage eh of generator
value which is also the cross-over point at which em
becomes equal to efb. Further increases in speed caused
by increases in speed signal er tend to increase control
voltage em to a value larger than en, so that diode 60
becomes forward biased and conducting whereas diode
53 becomes reverse biased and nonconducting. This in
effect makes negative feedback voltage etc equal to the
control voltage em.
Therefore, as voltage em tends to
increase, voltage etc, acting in opposition to input volt
age E, also tends to increase. Consequently, the re
sultant input signal to ampli?er 26 is reduced so that
the output voltage er of motor ?eld ampli?er 26 decreases.
The regulating effect of ampli?er 26 in phase II op
eration to maintain signal etc, and thereby voltage em,
constant is provided by resistor 56 which develops the
control voltage em, a component of control voltage em.
By virtue of the function of multiplier 54, voltage em is
made directly proportional to em and, since em re?ects or
senses the decrease in output voltage ef due to the in
crease in feedback signal em, voltage cf, also decreases
?eld ampli?er 3i} is equal to the rated voltage of the 60 and proportionately reduces signal em to its value at the
cross-over point and maintains it constant at that value.
generator ?eld winding and output voltage er of motor
Therefore, it can be seen that as signal er is'increased to
?eld ampli?er 26 is equal to the rated voltage of the
increase the speed of motor \12, control voltage em re
motor ?eld winding.
mains constant due to the regulating effect of motor ?eld
In operation, the constant D.C. source applies a con
stant D.C. reference voltage E via conductor 46 to the 65 ampli?er 26 and control voltage em and, consequently,
generator ?eld winding voltage eh and generator armature
input of motor ?eld ampli?er 26. The output voltage
voltage ea remains constant. In addition, because of the
er of ampli?er 26 appears across motor ?eld winding 18
tendency of feedback signal em to increase the regulating
and produces a current if therethrough to provide the
effect of motor ?eld ampli?er 26, output voltage cf is
?eld winding energization for motor 12.
Assuming the arrangement operating in phase I, the 70 reduced. Therefore, the energization of motor ?eld
winding .18 also decreases so that, with constant motor
speed signal voltage e, tapped off by wiper arm 42 of
armature voltage and decreasing motor ?eld excitation,
potentiometer 34 is of such magnitude that the control
the speed S of motor 12 is increased in accordance with
voltage em appearing on conductor 62 is less than the
the increase in speed signal e,..
control voltage en, developed by resistor 43 connected
in the output circuit of motor ?eld ampli?er 26. There 75 In the phase I operation, it can be seen that since the
3,041,514
5
motor ?eld ampli?er output voltage e, is maintained
constant, control voltage am is also maintained constant
and, therefore, voltage em and motor speed S remain
proportional to speed signal er.
In phase II, when signal er is increased so that voltage
em is greater than voltage efb, the operation of diodes
50 and 60 of the static switch forming the cross-over
network render voltage etc equal to voltage em, and the
regulating effect of motor ?eld ampli?er 26 tends to
maintain voltage em constant which in turn maintains
generator and motor armature excitation ea constant.
Therefore, since
(1)
em=k.er.eIa
we ?nd that
(2)
ere?a=constant
In this sense, it is appreciated that
variations and modi?cations may be made in the arrange
ments shown herein without departing from the scope of
the invention.
What is claimed is:
1. In a motor ‘generator drive arrangement including
a D.C. motor the speed of which is to be controlled in
accordance with excitation provided by the armature and
the ?eld winding thereof and including a generator for
10 controlling the motor armature voltage in accordance
with the excitation provided to the generator armature by
the generator ?eld winding; a ?rst control ampli?er hav
ing an output circuit connected to said motor ?eld wind
ing and having an input circuit, means for applying a ref
15 erence signal to said input circuit, a second control am
pli?er having an output circuit connected to the generator
?eld winding and having an input circuit, means for pro~
viding a speed signal, means for modifying said speed
signal in accordance with the output of said ?rst control
or
(3)
6
or vacuum tubes.
20 ampli?er to produce a ?rst control signal, means con
e =constant
nected in the output circuit of said ?rst control ampli?er
efa
neglecting saturation in motor ‘12 we also have:
to produce a second control signal, switch means re
S = constant. :5
sponsive to said ?rst and second control signals for ap
plying the greater signal to said input circuit of said ?rst
control amplifier in opposition to said reference signal in
where S is the speed of the D.C. motor 12, and since ea
order to control the output thereof to maintain the said
(4)
e
greater signal substantially constant, and means for ap
plying said ?rst control signal to said input circuit of said
constant
second control ampli?er for controlling said generator
s=-—
(5)
eta
30 ?eld excitation in accordance with said speed signal
whereby the speed of said motor is regulated through the
In other words, in phase II operation, from Equation
armature and ?eld winding thereof in accordance with
5 speed S of D.C. motor '12 is controlled by the motor
the selected speed signal.
?eld excitation which is directly proportional to ?eld
2. The motor generator drive arrangement as de?ned
winding voltage ef and thereby to the control voltage eta. 7
However, as seen from Equation 2, cm is inversely pro 35 in claim 1 further comprising means for deriving 1a third
signal proportional to said generator armature excitation
portional to signal 6,. Therefore, motor speed S is di
and means for applying said third signal in a negative
rectly proportional to speed signal er in phase II as well
feedback relationship to said second control ampli?er
as in phase I.
for establishing the generator armature voltage propor
A graph showing the operating characteristic of D.C.
motor 12 in both speed ranges is shown in FIGURE 2. 40 tional to said ?rst control signal whereby the speed of
said motor is regulated through the armature and the
It can be seen then that in phase I operation, curve
?eld winding of said motor in accordance with said speed
70 representing ef, the motor ?eld winding energization
is a constant, We have:
is maintained constant while armature excitation a, rep
resented by curve 72 increases proportionately with in
creases in the speed signal voltage 2,. represented by
‘curve 74 to cause in turn a proportionate increase in
motor speed S as represented by curve 76.
In phase -II
operation, curve 72 is a ?xed value to indicate that arma-‘
ture excitation ea is maintained constant; however, curve
signal.
-
3. In a motor generator drive arrangement including
a D.C. motor the speed of which is to be controlled in
accordance with excitation provided by the armature and
?eld winding thereof and including a generator for con
trolling the motor armature voltage in accordance with
excitation provided in the generator armature by the gen
70 representing motor ?eld Winding energization 8f de 50 erator ?eld winding; a control source providing a constant
reference signal, a ?rst ampli?er for energizing said motor
creases in a substantially inversely proportional relation
?eld winding from said constant reference signal, ad
ship with respect to the increasing speed signal eI to
justable means for providing a speed signal in accordance
result in an increase in speed S which is proportional
with the setting thereof, means for deriving a ?rst con
Referring to FIGURE 3, there is illustrated another 55 trol signal in accordnace with the energization of said
motor ?eld winding, means for deriving a second con—
embodiment of the invention. FIGURE 3 is identical to
trol signal in accordance with said speed signal and said
FIGURE 1 with the exception that line 62 leading from
?rst control signal, a second ampli?er for energizing said
the multiplier 54 to the diode 60‘ appearing in FIGURE
generator ?eld winding in accordance with said second
1 is omitted in FIGURE 3 and a line extending from line
22 to the diode 60 is added in FIGURE 3.
60 control signal, means for providing a third control signal
in accordance with said motor ?eld Winding energization,
The voltage Ga appearing on line 22 is proportional
switch means responsive to said second and third con
to the voltage Cm appearing at the output of the multi
trol signals for applying the greater of said second and
plier 54 as can be readily understood from the foregoing
third control signals to said ?rst ampli?er in order to
description of the invention. Therefore as an alternate
scheme, the voltage C,, is applied to the diode 60 in the 65 control the output thereof to maintain the greater signal
substantially constant, and means for applying said sec
embodiment of the invention illustrated in FIGURE 3
ond control signal to said second ampli?er for controlling
and the voltage Cm is applied only to the input of ampli
the output of said second ampli?er and thereby said gen
?er 30. The'operation of the embodiment illustrated
erator armature excitation in accordance with said speed
in FIGURE 3 corresponds to the operation of the em
bodiment of the invention illustrated in FIGURE 1 and 70 signal.
4. A motor generator drive arrangement as de?ned in
therefore need not be described in detail.
claim 3 further comprising means for deriving a fourth
The ampli?ers utilized in the speed drive systems il
control signal in accordance with said generator armature
lustrated may be either electronic, magnetic or rotating
excitation, and means for applying said fourth control
amplidyne or metadyne ampli?ers and diodes 5t} and
60 may be of any suitable type such as crystal recti?ers 75 signal to said second ampli?er as a negative feedback
to e,.
3,041,514
signal to maintain said ‘generator ?eld energization and
the greater of said second and third control voltages
said generator armature excitation substantially propor
substantially constant, and means connected to said mul
tional to said second control signal.
tiplying means for applying said second control voltage
5. The combination set forth in claim 4 wherein the
to the input circuits of said second ampli?er whereby
speed of said generator armature is maintained substan Cl the speed of said motor is regulated through the arma
tially constant, said adjustable means is a potentiometer
ture and ?eld winding thereof in accordance with said
and said switch means is of the static type.
6. In a motor generator drive arrangement includ
ing a DC. motor the speed of which is to be controlled
speed signal.
and third control voltages for applying the greater volt
age thereof to said ?rst ampli?er in opposition to said
reference signal in order to control the output thereof
to maintain said greater voltage substantially constant,
means to apply said second control voltage to said gen
erator ampli?er in order to control the energization of
said generator ?eld winding in accordance with said
applying said second control signal to said second ampli
?er for controlling the output of said second ampli?er
and thereby said generator armature voltage, means for
providing a third control signal in accordance with said
8. The combination as set forth in claim 7 further com
prising third resistance means connected between said
in accordance With excitation provided by the armature 10 generator armature and said input circuit of said second
and the ?eld winding thereof and including a generator
ampli?er to derive a fourth control voltage, and means
for controlling the motor armature voltage in accord
to apply said fourth control voltage as a negative feed
ance with the excitation provided to the generator arma
back signal to said input circuit of said second ampli?er.
ture by the generator ?eld winding; a control source
9. In a motor ?eld generator drive arrangement in
providing a constant reference signal, a motor ?eld am
cluding a DC. motor the speed of which is to be con
pli?er having an output circuit connected to said motor
trolled in accordance with excitation provided by the
?eld winding, means to apply said reference signal to
armature and the ?eld winding thereof and including a
> said ampli?er, a generator ?eld ampli?er having an out
generator for controlling the motor armature voltage in
put circuit connected to said generator ?eld winding, a
accordance with the excitation provided to the generator
potentiometer for providing a motor speed signal volt
armature by the generator ?eld winding, a control source
age, means connected in the output circuit of said motor
providing a constant reference signal, a ?rst ampli?er for
ampli?er for producing a ?rst control voltage in ac
energizing said motor ?eld winding from said constant
cordance with the energization of said motor ?eld wind
reference signal, means for providing a speed signal,
ing, means for multiplying together said speed voltage
means for deriving a ?rst control signal in accordance
and said ?rst control voltage to produce a second con
o with the energization of said motor ?eld winding, means
trol voltage, means connected in the output circuit of
for providing a second control signal in accordance with
said motor ampli?er for producing a third control volt
said speed signal and said ?rst control signal, a second
age in accordance with said motor ?eld winding ener
ampli?er for energizing said generator ?eld winding in
gization, static switch means responsive to said second
accordance with said second control signal, means for
second control voltage, means connected to said ‘gen
erator armature to produce a fourth control voltage,
and means to apply said fourth control voltage as a
motor ?eld winding energization, switch means, means
-‘ for applying a signal proportional to said third control
signal and a signal proportional to said ‘second control
signal to said switch means, said switch means response
to said last mentioned means for applying the greater of
said signals proportional to said third control signal and
said second control signal to said ?rst ampli?er in order
to control the output thereof to maintain the greater
negative feedback signal to said generator ampli?er for
establishing the generator armature voltage propor
tional to said second control voltage whereby the speed
signal substantially constant.
of said motor is regulated through the armature and
the ?eld winding thereof in accordance vwith said sec
10. In a motor generator drive arrangement includ
ing a DC. motor the speed of which is to be controlled
ond control voltage.
45 in accordance with excitation provided by the armature
7. In a motor generator drive arrangement including
a DC motor the speed of which is to be controlled in
and the ?eld winding thereof and including a generator
for controlling the motor armature voltage in accordance
accordance with excitation provided by the armature
with the excitation provided to the generator armature
and the ?eld winding thereof and including a generator
by the generator ?eld winding, a control source providing
for controlling the motor armature voltage in accordance
a constant reference signal, a ?rst ampli?er for energizing
with excitation provided in the generator armature by
said motor ?eld winding from said constant reference
the generator ?eld winding; a control source for providing
signal, means for providing a speed signal, means for
a constant D.C. reference signal, a ?rst ampli?er having
deriving a ?rst control signal in accordance with the
an output circuit connected to said motor ?eld winding
energization of said motor ?eld winding, means for pro
and an input circuit, means for applying said reference 55 viding a second control signal in accordance with said
signal to said input circuit, a second ampli?er having an
speed signal and said ?rst control signal, a second ampli
output circuit connected to said generator ?eld winding
?er for energizing said generator ?eld winding in accord
and an input circuit, a potentiometer for producing a
ance with said second control signal, means ‘for providing
voltage speed signal in accordance with which it is desired
a third control signal in accordance with said motor ?eld
to control the speed of said motor, ?rst resistance means 60 winding energization, means for providing a fourth con
connected in the output circuit of said ampli?er for de
trol signal in accordance with said generator armature
riving a ?rst control voltage proportional to said motor
output signal, switch means responsive to said fourth
?eld energization, means for multiplying together said
control signal and said third control signal for applying
speed voltage and said ?rst control voltage to produce a
the greater of said fourth control signal and said third
second control voltage, second resistance means con 65 control signal to said ?rst ampli?er in order to control
nected in the output circuit‘of said motor ?eld ampli?er
the output thereof to maintain the greater signal sub
to derive a third control voltage proportional to said mo
stantially constant, and means for applying said second
tor ?eld energization, a pair of oppositely poled unidirec
control signal to said second ampli?er for controlling
tional current conducting devices connected back to back
the output of said second ampli?er and thereby said
between said multiplying means and said second resist 70 generator armature excitation and thereby said fourth
ance means, and means connected between the juncture
control signal in accordance with said speed signal.
11. In a motor generator drive arrangement including
of said devices and said input circuit of said ?rst ampli?er
a DC. motor, the speed of which is to be controlled in
for applying as a negative feedback signal thereto the
accordance with excitation provided by the armature and
greater of said second and third control voltages in order
to control the output of said ?rst ampli?er to maintain 75 the ?eld winding thereof and including a generator for
3,041,514.
9
10
controlling the motor armature voltage in accordance
with the excitation provided in the generator armature
by the generator ?eld winding, a control signal for pro
viding a constant D.C. reference signal, a ?rst ampli?er
having an output circuit connected to said motor ?eld
winding and an input circuit connected to said reference
signal, a second ampli?er having an output circuit con
nected to said generator ?eld winding and an input cir
cuit, a potentiometer for producing a voltage speed sig
tional to the armature voltage of said generator, a pair of
tion, means for multiplying together said speed voltage
input circuit of said second ampli?er whereby the magni
oppositely poled unidirectional current conducting device
connected back to back between said second resistance
means and said means for deriving a fourth control volt
age proportional to said generator armature voltage,
means connected between the juncture of said devices
and said input circuit of said ?rst ampli?er for applying
as a negative feedback signal thereto the greater of said
third and said fourth control voltages in order to con
nal in accordance with which it is desired to control the 10 trol the output of said ?rst ampli?er to maintain the
greater of said third and said fourth control voltages sub
speed of said motor, ?rst resistance means connected in
stantially constant and means connected to said multiply
the output circuit of said ?rst ampli?er for driving a ?rst
ing means for applying said second control voltage to the
control voltage proportional to said motor ?eld energiza
and said ?rst control voltage to produce a second control 15 tude of said fourth control voltage and the speed of said
motor is regulated through the armature and ?eld wind
voltage, second resistance means connected in the output
circuit of said motor ?eld ampli?er to derive a third con
ing thereof in accordance with the speed signal.
trol voltage proportional to said motor ?eld energiza
tion, means for deriving a fourth control voltage propor
No references cited.
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