-
Hall Current Sensor
and Its Application
In the modern
society, the information demand is huger and
huger, and sensors
play
an
important
role
in
the
information
acquisition.
They
can
turn
all
kinds
of
physical
information,
according
to
certain
rules,
into
measurable
electrical
signal.
Based
on
the
changes
of
electrical
signals
we
measured,
and
the
related
physical
information
relationship, we can gain the measured physical
information changes or
size.
According to the working principle of
the sensor, we can divide the sensors into
many
types,
such
as
photoelectric
sensor,
charge
sensors,
potential
type
sensor,
semiconductor sensor, the electricity
sensor, magnetic sensor, resonant sensor, electric
chemical formula sensor etc.
Hall sensor is the use of hall element
based on the Hall effect principle, which
can concert the physical information,
such as current, magnetic field, the displacement,
pressure, etc, into electromotive force
output. It belongs to the potential type sensor.
At
present,
this
kind
of
sensor
is
mainly
hall
integrated
circuit
and
the
core
unit
is
based on
the Hall effect, which is made through the
integrated circuit technology. So
it is
not only a kind of integrated circuit, but a kind
of magnetic sensor.
According to the
actual application, this article is mainly about
the hall current
sensor.
1.
Hall effect
When we place a metal or semiconductor
wafer in a magnetic field, and if there
is
a
current
through
it,
it
will
produce
electromotive
force
in
the
perpendicular
direction of
the electric and magnetic field, calling this kind
of physical phenomenon
Hall effect.
Figure 1 Hall effect
principle diagram
Under the action of
the Lorentz force generated in the magnetic field,
the carrier
of
energized semiconductor chip, deflect and
accumulate respectively on both sides of
the chip, thus forming a electric
field, called the Hall electric field. Hall
electric field
produces electric field
force which is contrary to the Lorentz force,
hindering carrier
to continue to pile
up, until the hall electric field force equal with
the Lorentz force.
At this time, it
will set up a stable voltage on both sides of the
chip, and this is the hall
voltage.
2.
Hall current
sensor
Along with the urban population
and the expansion of the construction scale of
the city, and the increasing of all
kinds of electric equipment, power consumption is
bigger
and
bigger.
The
power
supply
equipment
of
the
city
often
overload
,
while
power environment
becomes more and more bad, the
and more
serious. Thus, the problems in the power supply
come out more and more
apparently .
Now, small power supply equipment has been
combined with more and
more
new
technology.
For
example,
switch
power
supply,
hard
switch,
soft
switch,
parameter
voltage
regulator,
linear
feedback
voltage
regulator,
magnetic
amplifier
technology,
numerical
control
pressure
regulation,
PWM,
SPWM,
electromagnetic
compatibility,
etc.
The
actual
demands
directly
promote
power
technology
development
and progress.
In order to
detect
and display current
automatically, and
the
automatic
protection
function
and
more
advanced
intelligent
control
when
the
harm
such
as
over
current,
over
voltage
occurs,
the
power
supply
technology
with
sensing detection,
sensing sampling and sensing protection becomes a
trend. Sensors
of
detecting
current
or
voltage,
called
Hall
current
sensor,
come
into
being,
and
quickly become the favorite of the
designers of the power supply in our country.
2.1 The performance characteristics of
Hall current sensor
Hall
current
sensor
has
superior
performance,
and
it
is
a
kind
of
advanced
electric
detecting
element,
which
can
isolate
the
main
circuit
loop
and
electronic
control circuit. It has all the
advantages of transformers and shunts, and at the
same
time,
overcomes
their
disadvantages
(transformer
can
be
only
applied
to
the
power
frequency measurement, 50 Hz; shunt is
unable to do isolation measurement). Using
the same one hall current sensor module
detecting element not only can test AC, but
also can detect DC, even can detect
transient peak. It has the following performance
characteristics.
●
Measure
the
arbitrary
waveform
current,
such
as
DC,
AC,
and
even
to
transient peak parameters
measurement;
●
High precision. General Hall current
sensor module’s precision in the work
area is higher than 1%, and the
precision is suitable for any waveform
measurement;
●
The linearity is better than
0.5%;
●
Good
dynamic
performance.
The
dynamic
response
time
of
general
Hall
sensor module is less
than 7μs,
and the tracking speed di/dt
is above 50
A/μs;
●
Working band wide. It can work in the
frequency range from 0 to 20 KHZ
very
well;
●
Strong overload ability. Wide
measurement range
（
0
～
±
10000A
）
;
●
High
reliability.
The
average
trouble-free
working
is
more
than
5
x
10000
hours;
●
Small size,
light weight, easy to install and it will not
bring any loss to the
system.
In view of the above high performance
characteristics, the
Hall current
sensors
gain the wide applications.
2.2 The principle of Hall current
sensor
Hall current sensor can measure
all kinds of current, from DC to AC of dozens of
thousand Hertz. The basis principle of
working is mainly Hall effect principle.
2.2.1
Open loop
current sensor
When the primary side
current
Ip flows
through a long
wire, it will
produce
a
magnetic field
around the wire, and the size of the magnetic
field is proportional to
the
current
through
the
wire,
the
magnetic
field
gathering
inside
the
magnetic
ring.
Through the Hall
element between the magnetic ring gap, it measures
and output the
amplification
result,
the
output
voltage
Vs
reflecting
the
primary
side
current
Ip
accurately. The general rated output is
4V
.
Figure 2
open loop current sensor principle diagram
This
way
has
many
advantages.
It
has
simple
structure
and
is
measurable
DC,
AC
and
various
waveform
current.
Besides,
the
precision
and
linearity
of
the
measurement result is higher. But its
measuring range and bandwidth are limited to a
certain
extent.
In
this
application,
Hall
device
is
a
magnetic
detector,
It
detects
the
magnetic
induction
intensity
in
core
magnetic
circuit
air
gap.
After
the
current
increases, core may reach saturation;
Along with the frequency increasing, the eddy
current loss
and hysteresis loss of the core also will
increase. These will influence on
the
measuring accuracy.
Through
this m
ethod, the result will output in
the form of voltage signal and it’s
easy to come true in the attachment.
2.2.2
Closed loop
current sensor
Figure 3
closed loop current sensor principle diagram
Magnetic balanced current sensor Is
also called compensation sensor. It means
th
e magnetic field which is produced by
the primary side current Ip in poly beads space
of generated was compensated with the
magnetic fields which is produced by a
secon
dary coil current. Its offset
current Is an accurate reflection of the original
edge curren
t Ip, so that the hall
device stay in the detecting zero flux working
condition.
Closed
loop
current
sensor
is
also
called
compensation
sensor.
It
means
the
magnetic field which is generated by
the primary side current Ip in poly beads space
was compensated through the magnetic
fields which is generated by a secondary coil
current. Its offset current Is reflects
the primary side current Ip accurately, so that
the
Hall device stay in the detecting
zero flux working condition.
The
specific
work
process
of
the
magnetic
balanced
current
sensor
is:
when
a
current
flows through the
main circuit, the magnetic field
generated on the wires is
gathered
by
poly
beads
and
inducted
to
the
hall
device,
using
the
output
signal
to
drive
power tube and make it conduct, so that we can get
a compensation current Is.
The current
then produce a magnetic field through multicircuit
winding, contrary to
the
one
that
generated
by
the
measured
current,
thus
compensating
the
original
magnetic
field
and
making
the
Hall
d
evice’s
output
decrease
gradually.
When
Ip
becomes
the
same
as
the
magnetic
fields
produced
by
the
number
of
turns
multiplication, Is will no longer
increase. At the time, the Hall device can
instruct the
zero flux. and we can test
Ip though Is. When Ip changes, the balance will be
damaged
and the
Hall device will have a output signal, so, then it
will repeat the above process
to
achieve
balance
again.
Any
changes
of
the
measured
current
will
disrupt
the
balance. Once the magnetic field is out
of balance, Hall device will have signal output.
After
the
power
amplifier,
there
will
have
corresponding
current
through
the
secondary
winding
to
compensate
the
unbalanced
magnetic
field
immediately.
The
time for magnetic field
to change from unbalance to balance
agai
n needs less than 1 μ
s
in theory. This is a dynamic balance process.
Therefore, from the macroscopic point
of view, the ampere-turns number of the
secondary compensation current is the same
as the ampere turns of primary measured
current in any time.
When it becomes
balance, Hall device will stay in zero flux state.
The magnetic
induction intensity of the
core is extremely low (ideal state should be 0).It
won’t make
the core saturation, and
also
won't
produce big
hysteresis loss
or eddy
current
loss.
Choosing
the
core
materials
and
line
element
properly
can
make
out
excellent
zero
magnetic power circuit
sensors.
The output that measured in
this way will be the current signal. If you want
the
voltage signal, you can connect a
load at the output, and then it can be converted
into
voltage output.
2.3
The
application
of
Hall
current
sensor
in
intelligent
power
grid
Because the Hall
current sensor can measure all kinds of current
and it has a very
big measuring range,
high precision, good linearity, and ease of
installation, so it has a
very widely
used. Here is the main explanation in the
application of intelligent power
grid.
Along with
the vigorous
development
of the modern society, not
the industrial
electricity,
but life electricity increases in a sharp, making
all kinds of work constantly
increase
which greatly increase the burden of the staff. In
order to have a reasonable
electricity
distribution, as well as complete circuit fault
detection more efficiently, we
use
the
Hall
current
sensor
in
power
grid,
along
with
all
kinds
of
infrastructure,
to
realize the intelligent power network,
so as to realize the high efficiency utilization
of
electricity.
Because
the
installation
of
Hall
current
sensor
is
simple,
we
articulate
hall
current
sensor
module
directly
in
measuring
circuit,
if
enough,
covering
the
area
is
quite large, so that it
can gain the current information of each branch.
Complementary
with wireless
communication module, it can transmit the measured
signal to console
in time. In console,
we can process these signals very well, and then
accurately obtain
the
whole
grid
electricity
information
at
this
time,
so
that
we
can
distribute
the
electricity reasonably.
In a
period of time, if some branches broke down, we
only need to operate the
console
and
inquiry
those
abnormal
current
detection
signal.
Then,
according
to
relevant position
information, we can quickly narrow the scope of
the failure, so as to
realize efficient
troubleshooting and solving.
In
our
experiment,
we
adapt
the
open
loop
current
sensor,
CS020G
.
Its
circuit