Title of Invention

"A LINEAR BIPOLAR CURRENT REGULATED DC POWER SUPPLY FOR INDUCTIVE LOADS.

Abstract This invention relates to a linear bipolar current regulated DC power supply for inductive loads comprising a bipolar source of input signal (1) connected to an error amplifier (2) characterized in that said amplifier connected to a bipolar output stage (3) through an integrator (2a) comprising resistance R6 and capacitor C2 to decide the output ramp rate such as herein described, the output of the bipolar output stage connected to a load (4) through a shunt (5), an output filter (4a) connected across the output of the power supply, a feedback circuit (6) connected between the output of the power supply and the input of the error amplifier and the input of the integrator, a zero ampere start (7) circuit being connected across the integrator capacitor.
Full Text s 2 i
This invention relates to a linear bipolar
current regulated DC potter supply for inductive loads.
The power supply is used -for precision beam transport
applications. The power supply is designed to energise
a steerer magnet with direct current stabilized to 25 to
50 ppa of max i mum output current.
The power supply is a DC current bipolar
output power supply with extremely low cross over
distortion designed -for use with beam steerer where high
stability is required. The bipolar power supply is as
such known in the art and comprises a bipolar source o-f
input signal connected to an error amplifier. The
output o-f the error amplifier ia connected to a bipolar
output stage which is connected to the load through a
shunt. A feed back quiscient current control circuit is
connected between bipolar output stage and the ccMuson
terminal of input signal and error amplifier.
There are certain disadvantages associated
with the prior art. One of the main disadvantage is
that programmable ramp rate control required to avoid
large back e.m.f generated by the magnet, for the safety
of the power supply and the magnet is not there.
s 3 s
Another disadvantage is that the conventional
power supply does not. have the means to compensate the
inductive loads.
Yet another disadvantage is that the zero
ampere start -facility of the current is not there with
the conventional power supply which is required to
avoid output spikes when main power is turned ON.
Still another disadvantage is that the
stability o-f the current of the conventional powersupply
is poor.
There-fore the main object o-f this invention
is to provide a power supply which obviates the
disadvantage associated with the conventional power
supply.
Another object o-f this invention is to
provide a power supply having the weans to provide zero
ampere start facility o-f the current.
: 4 :
Yet further object of this invention is to provide a power supply having
means to provide programmable ramp rate control facility.
Still another object of this invention is to provide a power supply having
the means to compensate the inductive loads.
According to this invention there is provided a linear bipolar current
regulated DC power supply for inductive loads comprising a bipolar source of
input signal connected to an error amplifier characterized in that said amplifier
connected to a bipolar output stage through an integrator comprising
resistance Re and capacitor Ca to decide the output ramp rate such as herein
described, the output of the bipolar output stage connected to a load (4)
through a shunt, an output filter connected across the output of the power
supply, a feedback circuit connected between the output of the power supply
and the input of the error amplifier and the input of the integrator, a zero
ampere start circuit being connected across the integrator capacitor.
s 5 i
In accordance with this invention the linear
bipolar current regulated DC power supply for inductive
load has an integrator connected in between error
amplifier and bipolar output stage. Further an output
filter is provided across the output of the power
supply. Also a zero ampere start circuit is connected
to the integrator. The feed back circuit according to
this invention is connected to the bipolar output stage
through a shunt. The integrator is provided to decide
the output ramprate. The zero ampere start is provided
to discharge the integrator when the power supply is in
Off condition to ensure a zero ampere start when the
power supply is put ON irrespective of the input.
Further a output filter consisting of a capacitor is
provided to compensate for the large inductive loads
and to make the power supply less susceptible to
osci 1 lations.
A linear bipolar current regulated DC power
supply for inductive loads according to a preferred
embodiment is herein described and illustrated in the
accompanying drawings wherein:
Fig. 1 shows the block diagram of the conventional pouter
supply.
Fig. 2 shows the block diagram of the power supply
of the present invention and,
Fig. 3 shows the circuit diagram of the power supply.
Referring to the drawings particularly fig. 1
linear DC power supply as known in the art comprises a
bipolar source of input signal 1 the output of which is
connected to the input terminal of an error amplifier 2
which is connected to the input terminal of a bipolar
output stage 3. The output terminals of the bipolar
output stage 3 is connected to a load 4 through a shunt
5. Further the bipolar stage 3 is interconnected with a
feed back quiscient current control circuit 6. The
quiscient current control circuit 6 is also connected to
the common terminal of the bipolar source 1 and error
amplifier 2. A load 4 is connected to an output
terminal of the bipolar output stage 3 through a shunt
5. The common terminal of the shunt 5 and load 4 is
connected to the quiscient current control circuit 6.
8 7 S
The current control circuit 6 is provided to establish
the quisclent current in both the positive and negative
pass transistors to eliminate the cross over distortion.
Reference is now made to fig. 2 which shows
the block diagram of the linear bipolar current
regulated DC power supply for inductive loads of the
present invention. The power supply comprises a bipolar
source of input signal 1 connected to an error amplifier
2- The output of the error amplifier is connected to an
integrator 2a which is provided to decide the output
ramp-rate. The output of integrator 2a is connected to
a bipolar output stage 3 which is connected to a load 4
through a shunt 5. An output filter 4a is connected
across the output of the power supply. The output
filter 4a comprises a capacitor provided to compensate
the large inductive loads and to make the regulator/
supply less susceptible to oscillations. The common
terminals of the load 4, shunt 5 and output filter 4a is
connected to a feed back circuit 6 which is connected to
I 8 s
the common terminal of the bipolar source 1 and error
amplifier 2. A zero amplifier start 7 its connected to
the common point of the error amplifier 2, integrator 2a
and feed back circuit 6. The zero ampere start is
provided to keep the integrator discharge t*hen the
regulator/power eupply is in Off condition. When the
regulator is put ON the output always starts from zero
ampere regardless to the input control signal.
Reference is not* made to fig. 3 wherein the
circuit diagram of bipolar current regulator/power
supply is shown. The bipolar current regulator is
basically a voltage regulator regulating the voltage
across the shunt and the voltage across the shunt is
directly propotional to the load current. As the
current regulator is a bipolar current regulator it
comprises an output stage having two type of transistors
connected in a push-pull configuration. Transistor 02
is an NPN type transistor whose collector is connected
to the positive terminal of voltage source 1. Transistor
QT is PNP type transistor whose collector is connected to
8 9 8
the negative terminal of the voltage source 2. The
emitter* of the transistor Q-^ ant* ®3 are connected
together and form a common point G for the control
circuit. The negative side terminal of the positive
voltage source i is connected to the positive terminal
o-f the voltage source 2. which are connected together and
is connected to the load 4. The other end of the load 4
is connected to the common point 6 through a shunt
resistance ft 12. The shunt R 12 is connected in series
with the load 4 so that the voltage developed across the
shunt R12 is directly propotional to the load current.
The control circuit consist of a limited gain limited
bandwidth error amplifier 2 connected to a integrator 2a
through the resistance Rg and R^. The control circuit is
provided to compare the control input voltage with the
voltage from the shunt RJ2 *nd regulates the output
voltage through the output stage transistor Q^ And 63 in
the control circuit. The error amplifier 2 is a noninverting
difference amplifier with a DC gain of 3000.
: 10 s
The gain is kept so high that even a small error between
the input signal and feed back can be amplified for
output correction. This stage also has a reactive -feed
back in order to limit its frequency bandwidth to
reduce the noise. A capacitor Cj is provided across
feed back resistance R^ to Minimise output voltage error
due to the noise. Capacitor C^ shunts feed back
resistance R^ at high noise frequencies. in case of DC
the capacitor C| acts as an open circuit so that the
effective feed back impedance remain equal to the
resistance R^ only and hence the gain remain 5000
apprOKimatly. But when frequency increases the
capacitive reactance of capacitors decreases and the
effective feed back impedance decreases and hence the
gain decreases. Therefore the high frequencies are not
amplified and hence stability of the power supply
against the noise increases. The error amplifier 2 is
followed by the integrator 2a for the purpose to limit
the rate of rise of the output current. When there is
: 11
no error the output of the error amplifier 2 is
virtually zero. If the control input changes the output
from the error amplifier 2 at point C is clamped in
positive or negative direction depending on the polarity
of the error at a level determined by the variable limit
circuit 5. The output of the variable limit circuit 5
is set between 0.2V to IV. Resistance R6 and capacitor
G£ now acts as components of a simple integrator with
operational amplifier 2A. Now the integration speed is
determined by resistance R^, Capacitor (>> and the input
voltage to the integrator. To calculate the ramp time
formula is t-
Vo » -yjt wherein
Re
Vo r Output erf the integrator which
is voltage across shunt (R12>
Vi - Input to the integrator which
is clamped voltage at Point
t - Time required to reach the
output ramp to the set value.
RC -
s 12 s
Suppose the regulator its set 4 or +5A th«r» the
voltage across shunt (R^* will be =*~0.5V
So Vo - 8.5V
Vi - is the output of error amplifier which can be 8.2V
to IV
if limitter is set to min - 0.2V
Vo - 0.5V
R^ - 3M
C2 - 3.3uF
tm_v «-VoXRC - a. max . . ~ ~ ~5X5X5. 3
Vimin 0.2
*• 24.75 sec.
if limitter is set to Vo - 0.5V
R6 - 3M
C2 * 3.3uF
tmin -VoXRC - 0.5X3X5.5
Vimax 1
» 4.95 SBC.
From the calculation it is clear that the
•full scale ramp time can be set -fro* 4.95 sec to 24.75
sec, so t*e can programe the ramp by setting the variable
limit circuit to any value between 0.2V to IV.
i 13
The resistance R7 and the relay R^ are
provided to atop the generation of spikes when main
power 11 and 22 is switched ON. The contact of relay
RLJ is normally in close position, when the regulator is
in the Off position it discharges C2 through th*
resistance R7. When the power is switched ON the contact
of relay RL1 becomes open and the capacitor C2 starts
charging always from zero volt. Hence the regulator
always starts at zero ampere and then ramp to the value
which is set by the input control signal 1.
The amplifier 2A with driver Transistor Qj
form the driver for the output transistors Qg and Bhj.
The transistor Ql« 32, Q3 and 2A makes a single
amplifier with capacitive feedback as C2 having output
at point . The output of 2A is provided with A
filter Output filter capacitor C4 is provided to
compensate for large inductive load. For high current
bipolar regulators a high value bipolar
5 14 I
capacitor is required. Two electrolytic capacitors are
connected back to back to make a big bipolar capacitor.
A resistor R^j is also connected in series with C^ to
limit initial surg currents.
To ensure stability and repeatability a
thermally stable SHUNT is used. Because of this
the resistance of the SHUNT will not change with time
due to heating. So the output remain free of thermal
drift.
gf power supply working through Exaf>plas
The regulator /power supply ha» a feedback
resistance R2 and input resistance Rj. The gain of the
regulator depends upon Rj and R^ anc* *9 «Qual
to &QQ-R2/R1. The ratio between R^ and R2 i« 20i 1
corresponds to the ratio of the input signal (10M) and
0,5V for 5A of aax current across 0. 1R shunt resistance.
i 15 :
Example!- for +§A output current for a +10V input
signal.
The control input voltage -from source 6 is
fed to the percision resistor Rj, another per ci si on
resistor 1^ gives direct feedback from reference shunt.
The junctions of the resistor point is fed to the
non—inverting input of error amplifier 2. initially
point A is +ve so the output of 2 goes +ve and clamped
to 0.2V. The output of 2A will go We and emitter of
Qj(D> becomes +ve. This way Qj will conduct and Qg
remains OFF because +ve at the base. The current starts
flowing from 6 to 3 and a -ve voltage is developed
across SHUNT until the voltage across SHUNT (R12> became* .
As soon as it becomes -0.5V point (A) will be zero and
the error ampere output becomes zero, hence the input to
the integrator becomes zero, so no more increase in base
drive Q^. This way circuit stabilizes. This way the
output current locks to +5A.
: 16 s
Examples- for -5A output current for a -10V input
signal.
If a -10V signal is fed to the input
resistance fij, point
becomes -ve, s»o the output of
the error amplifier will be clamped to -0.2V. The
output integrator driver op - amp. emitter of Q* (D) becomes -ve. This time Q-? will conduct •* •-/
and Q'j remains off because of +ve base drive1. The
current start flowing from 8-M3 and keep on increasing
until the voltage across shunt 'Rj-?) becoines +0.5V. As
soon as shunt voltage becomes 0.5V point, A will be QV
and the error amplifier output becomes 0V. Hence the
jjuput to the ivstegr «st-or becomes GV» so no tta.it & incifeaae
in base drive to Q-T. This way the output current \J
stabilize to -5A.



WE CLAIM:
1. A linear bipolar current regulated DC power supply for inductive loads
comprising a bipolar source of input signal (1) connected to an error
amplifier (2) characterized in that said amplifier connected to a bipolar
output stage (3) through an integrator (2a) comprising resistance R6 and
capacitor C2 to decide the output ramp rate such as herein described,
the output of the bipolar output stage connected to a load (4) through a
shunt (5), an output filter (4a) connected across the output of the power
supply, a feedback circuit (6) connected between the output of the power
supply and the input of the error amplifier and the input of the
integrator, a zero ampere start (7) circuit being connected across the
integrator capacitor.
2. A linear bipolar as claimed in claim 1 wherein said zero ampere
comprises a resistance and a relay connected in series.
3. A linear bipolar as claimed in claim 1, wherein said output filter
comprises a capacitor adapted to be connected across the output of said
power supply.

4. A linear bipolar current regulated DC power supply for inductive loads substantially as herein described and illustrated.



Documents:

459-del-1999-abstract.pdf

459-del-1999-claims.pdf

459-del-1999-correspondence-others.pdf

459-del-1999-correspondence-po.pdf

459-del-1999-description (complete).pdf

459-del-1999-drawings.pdf

459-del-1999-form-1.pdf

459-del-1999-form-19.pdf

459-del-1999-form-2.pdf

459-del-1999-form-3.pdf

459-del-1999-form-6.pdf

459-del-1999-gpa.pdf


Patent Number 245062
Indian Patent Application Number 459/DEL/1999
PG Journal Number 01/2011
Publication Date 07-Jan-2011
Grant Date 30-Dec-2010
Date of Filing 23-Mar-1999
Name of Patentee NUCLEAR SCIENCE CENTRE
Applicant Address ARUNA ASAF ALI MARG, NEW DELHI-110067, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 RAJESH KUMAR NUCLEAR SCIENCE CENTRE ARUNA ASAF ALI MARG, NEW DELHI-110067, INDIA.
2 A. MANDAL NUCLEAR SCIENCE CENTRE ARUNA ASAF ALI MARG, NEW DELHI-110067, INDIA.
PCT International Classification Number H02M 7/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA