Download Long Range Distance Measurement Using Surge Currents

International Journal of Recent Advances in Engineering & Technology (IJRAET)
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Long Range Distance Measurement Using Surge Currents
1
Ananth Bhat, 2Aayush Shah, 3Pawan Borra
1,2,3
Dept. of Electronics Engineering, Dwarkadas Jamnadas Sanghvi College of Engineering, Vile Parle, Mumbai, India
Abstract: Switching power supplies, AC motors, and
lighting ballasts can develop extremely high peak inrush
currents at Ton unless inrush current protection is used.
Without protection, the only limits on the amount of inrush
current drawn is the line impedance, input rectifier drop,
and capacitor equivalent series resistance. High inrush
current can affect electrical systems by tripping fuses and
circuit breakers unnecessarily. Inrush current can be as
high as 100 times the normal steady state current and
normally lasts for less than 1/2 a normal 60 hertz cycle.
This paper provides a new perspective to the surge
currents. It tells you how surge currents can be used to our
advantage and also used to improve the efficiency of a
device. In this paper we have limited ourselves to IR LEDs.
We have backed this research with appropriate analysis
and experimentation and the results obtained are very
close to our research and assumptions.
Keywords: surge currents, Infrared LEDs, Driver Circuit
I. INTRODUCTION:
Surge currents or input surge currents is the maximum,
instantaneous input current drawn by an electrical device
when first turned on.[1] A surge current is a sudden
increase in current usually caused by a voltage
imbalance. [2] High surge currents can affect electrical
systems by tripping fuses and circuit breakers
unnecessarily. [3] However surge currents can also be
used to increase the efficiency of a system by taking
consideration of power dissipation of and heating
requirements of a system. This research aims to use
surge currents for increasing the instantaneous
luminosity of an IR (Infrared) LED using surge currents
as the input the LED. Using the IR LED as the
transmitter and a receiver (a diode or a BJT), the
incoming radiation is converted to a corresponding
voltage. Hence by using surge currents, longer distances
can be measured by using an IR transmitter and receiver
pair.
II. SYSTEM MODEL:
The block diagram below show an overview of the
entire project
The Pulse Generator:
The basic principle behind production of surge currents
is instantaneous charging and dis-charging of the
capacitor via a driver circuit. The switching
characteristics of the FETs are used for the charging and
dis-charging of the capacitor. The aforementioned
switching is done using voltage pulses. The duty cycle
of these pulses is an extremely crucial parameter to the
magnitude of the surge. Hence, to produce high
accuracy and easily programmable pulses for any value
of duty cycle, using a Microcontroller is highly
advantageous. Various techniques for producing pulses
of a particular duty cycle are mentioned below:
Microcontroller based Technique:
The programming approaches for generating PWM
signals are explained below.
1) Sequential approach
2) Time multiplexed approach
3) Delay Line Approach

Sequential approach
In this approach microcontroller core processor monitors
the timing generation for “ON” and “OFF” status. The
input to this program is the digitized error signal
generated from the plant. Digital version of the error
signal is generated from the A to D converter used prior
to this system. The program can be explained as the
input in the form of 8 bits is obtained from the plant and
then Ton, Toff timing values are calculated depending
on the error.
These timing values are fed to timer of the 8051
controller and the processor of the 8051 monitors these
values and make the PWM output from the 8051 high
and low representing “ON” and ”OFF” status of the pin.

Time multiplexed approach:
This approach uses timer and external interrupt of 8051.
These interrupts will produce an interference to current
process and make the processor to respond it. To
respond the interrupt the microcontroller executes an
interrupt handler program which is also called as
Interrupt Service Routine (ISR). At this location the
respective instructions are saved which will be executed
when the processor transfers the program control here.
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International Journal of Recent Advances in Engineering & Technology (IJRAET)
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
Delay Line approach:
As previously stated in section 3.2.2, delay line method
came into picture to circumvent the drawbacks of
counter comparator method. Delay line method used for
high speed requirement. Main disadvantage of delay line
method is that the variation in delays of each element
due to variation in semiconductor properties caused by
change in temperature.
In this approach the logic of Delay line is implanted
through program in 8051 microcontroller. The objective
is to validate the proposed method in section 3.3.3 with
this method.
The Transmitter Unit:
The basic function of the transmitter unit is to provide
surge currents or impulse currents to the IR LED. The
surge currents are basically high impulse currents (high
amplitude in a short time interval). To introduce a high
inrush (surge) current, a capacitor can be used. The
capacitor can charge and discharge extremely quickly
into the LED, thus producing a surge current. Different
paths for charging and discharging will be needed and
the same capacitor will be used for it. Therefore
switching between these two paths will need a switching
element such as a MOSFET. When using a switching
device like a MOSFET, a pulse generator as explained
above will be required to automate the switching
between the charging and discharging path. Depending
upon the different types of Logic Families used, the
transmitter circuit will need a driver circuit.
This driver circuit will be responsible in adhering to the
voltage requirements of the system. The transmitter
circuit has been described below:
a) The surge currents are high amplitude currents
produced for a short time interval. Therefore the power
dissipated is too high for a MOSFET to handle.
Therefore,
b) POWER MOSFETS should be used as switching
devices.
c) The need for higher levels of Gate to source voltage
(Vgs) as compared to the output voltage of the pulse
generator arises because of the need to reduce the
channel resistance of the POWER MOSFET. By
keeping a higher Vgs, the channel resistance can be
reduced. However, if this is done, a driver circuit will be
needed to convert the different logic levels.
d) Another factor to be considered in the fan out
capability of the pulse generator. If a microcontroller
unit is used, the fan out capability of the pin needs to be
sufficient to drive the gates of two POWER MOSFETS.
The Receiver Unit:
The receiver unit can either be either incorporate a
photo-transistor or a photo-diode.
1. Photodiode: A Photodiode is a type of photo detector
capable of converting light into either current or voltage,
depending upon the mode of operation. The common,
traditional solar cell used to generate electric solar
power is a large area photo diode.
Advantages:

The responsivity of a photodiode is high.

The photodiode of very economical.

Disadvantages:

Photodiodes usually have a slower response
time as compared to a phototransistor.

The dark current of a photodiode is larger is
compared to a phototransistor.

The noise equivalent power is also average.
2. Photo-transistor: A phototransistor is a light-sensitive
transistor. A common type of phototransistor, called a
photo bipolar transistor, is in essence a bipolar transistor
encased in a transparent case so that light can reach the
base–collector junction.
Advantages:

Phototransistors have a faster response time as
compared to a photodiodes.
One of the most critical parameters necessary while
designing the transmitter circuit is the RC time constant
of the charging and discharging cycles.

The dark current of a phototransistor is very
small is compared to a photodiodes.
𝜏≅𝑅 𝑋 𝐶

The noise equivalent power is very good.

Phototransistors are also quiet economical.
Where R is the resultant resistance in the charging and
discharging path and C is the resultant capacitance in the
charging and discharging path.
The following points need to be considered:
Disadvantages:

The responsivity of a phototransistor is low as
compared to photodiodes.
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International Journal of Recent Advances in Engineering & Technology (IJRAET)
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Calibration and Display Unit:
Calibration plays a very important role when measuring
the distance using this method. Though surge currents
can produce a large instantaneous intensity such that the
longer distances can be measured, the resultant light
detected by the photodiode or photo transmitter will
include the overall light in the room. This includes the
ambient light and the reflected IR rays.
The biggest challenge would then be to detect only the
reflected IR rays. But if the ambient light and the
resultant light could be detected and a corresponding
voltages could be obtained, then by subtracting the
voltage corresponding to the ambient light from the
voltage corresponding to the resultant light, the
corresponding voltage for the reflected IR rays can be
obtained. A one to one mapping or a linear relationship
between the calibrated voltage and the measured
distance can be then be obtained. Therefore an equation
can be obtained to convert the voltage to distance.
Using a microcontroller or a processing element, this
equation can be fed into the computing device. The
distance can then be displayed using many display
devices like a 7 segment LCD display or maybe a
computer display. For a compact system, a
microcontroller along with an interfaced 7 segment
display can be used.
III. CONCLUSION:
Surge currents have been looked at as a disadvantage in
all the systems till date, which is not wrong as it causes
serious damages to the device. This paper provides a
totally new perspective to surge currents. Hence, we
have not only shown how surge currents can used to our
advantage but also shown how it can be used to improve
the efficiency of a system, which we have backed with
appropriate analysis and experimentation.
REFERENCES:
[1]
Wikipedia, 'Inrush current', 2015. [Online].
Available:
https://en.wikipedia.org/wiki/Inrush_current.
[Accessed: 11- Nov- 2015].
[2]
G. Legazpi, 'What Is a Surge Current?’,
wiseGEEK,
2015.
[Online].
Available:
http://www.wisegeek.com/what-is-a-surgecurrent.htm. [Accessed: 11- Nov- 2015].
[3]
Ametherm.com, 'Surge Current Causes and
Prevention | Ametherm', 2015. [Online].
Available:
http://www.ametherm.com/inrushcurrent/surge-current-causes-andprevention.html. [Accessed: 11- Nov- 2015].
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