International Journal of IT, Engineering and Applied Sciences Research (IJIEASR)
Volume 2, No. 2, February 2013
ISSN: 2319-4413
Power Electronics Latest Advances in Current Scenario
Shiyani Dendavey, Asst Prof, Dept of ETX, UCOE,Nagpur
Siddharth Kumar Sarjare, Asst Prof, Dept of ETX, UCOE,Nagpur
ABSTRACT
The knowledge of power electronics has departed
during fast technological progression through the last
four decades, and lately, its request are fast increasing
in industrial, commercial, residential, military and
utility environments. In the global industrial
automation, energy conservation and environmental
pollution control trends of the 21st century, the
extensive crash of power electronics is predictable. The
paper begins with a conversation on global energy
generation scenario and also discusses Resistivity and
the Rapping Frequency and Hopper control.
Keywords
Energy Scenario, Adaptive Rapping with Simultaneous
Voltage Control, Resistivity and the Rapping Frequency
I.
INTRODUCTION
POWER electronics has now determinedly recognized
its significance as essential tool in manufacturing
process applications after decades of scientific
evolution. Luckily, we are now living in an era of
manufacturing renaissance when not only power
electronics but also computers, communication,
information, and transportation technologies are go
forward rapidly. The advancement of these technologies
has brought the geographically remote areas in the
world closer day by day. We now exist in a truly global
society, chiefly with the development of internet
communication. The nations of the world have now
become gradually more reliant on each other as a result
of this closeness. In malice of great assortment among
nations, one thing we can safely forecast with assurance
that in the 21st century, wars in the world will be fought
on Economic rather than military fronts. In the new
global market, free from trade barriers, the nations
around the world will face fierce industrial
competitiveness for endurance and improvement of
living standards. In the highly automated industrial
environment struggling for high quality products with
low cost, it appears that two technologies will be most
dominating: computers and power electronics with
motion control.[4]
and passive components— chiefly transformers,
inductors, and capacitors. The input and output may be
alternating current (ac) or direct current (dc) and may
be different in magnitude and frequency. The exchange
at times involves multiple phases with two or more
converters associated in a cascade. The end goals of a
power electronic converter are to achieve high
efficiency of conversion, minimize size and weight, and
achieve desired regulation of the output. [4]
II.
APPLICATION EXAMPLES
Power electronic converters can be classified into four
different types on the basis of input and out-put, dc-dc,
dc-ac, ac-dc,and ac-ac,named with the first part
referring to the input and the second to the output. The
diode bridge rectifier is the front end for most lowpower converters. It converts line frequency ac (e.g.,
from a wall outlet) to an unregulated dc voltage, and the
process is commonly called rectification. In a dc-dc
converter, both the input and the output are dc, and in
the simplest case the output voltage needs to be
regulated in presence of variation in load current and
changes in the input voltage. A computer power supply
has a diode bridge front end followed by a dc-dc
converter, the combination of which converts line
frequency ac voltage to several regulated dc voltages.
Electronic ballasts for compact fluorescent lamps
consist of a line frequency rectifier followed by a dc to
high-frequency ac converter (frequency range of 20 to
100 kHz) whose output is connected to a resonant tank
circuit that includes the load. In an adjustable speed
motor drive application (Fig. 22-3), the input is a 3phase ac supply, and the output is a 3-phase ac whose
magnitude and frequency are varied for optimum
steady-state operation and dynamic requirements of the
drive.
Power electronics is an enabling skill that achieves
conversion of electric power from one form to another,
using a mixture of high-power semiconductor devices
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International Journal of IT, Engineering and Applied Sciences Research (IJIEASR)
Volume 2, No. 2, February 2013
ISSN: 2319-4413
III . ENERGY AND ENVIRONMENTAL
MATTER
Figure 22-1 Application of power electronic
converters
Development of power semiconductors with very high
voltage and current ratings has enabled the use of power
electronic converters for utility applications. In
transmission systems, power electronic converters are
being utilized to control power flow, damp power
oscillations, and enhance system stability. At the
distribution level, power electronic converters are used
for enhancing power quality by means of dynamic
voltage restorers, static very compensators, and active
filters. Power electronic converters also play a
significant role in grid connection of distributed
generation and especially renewable energy sources;
their functions include compensation for steady state
and dynamic source characteristics leading to optimal
energy transfer from the source, and protective action
during contingencies.
Future automotives are expected to have a large number
of power electronic converters performing various
functions, for example, electric power steering, active
suspension, control over various loads, and transferring
power between the conventional 14-V bus and the
recently proposed 42-V Power Net[1]. Hybrid electric
and all-electric vehicles also utilize controlled power
electronic converters for interfacing the battery and
motor/generation.
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A. Energy Scenario
Energy has been the life-blood for continual progress of
human civilization. Since the beginning of
manufacturing revolution approximately two centuries
ago, the global energy expenditure has augmented by
leaps and bounds to gather speed the human living
standard, mainly in the developed nations of the world.
In fact, per-capita energy utilization has been a
barometer of a nation’s economic prosperity. The USA
has the maximum living standard in the world. With
only 5% of world population, it use 25% of total
energy. Japan, on the other hand, consumes 5% of total
energy with 2% of world population. India and China
together, with 38% of world population, use only onetenth of that of USA. 87% of total energy is make from
fossil fuel (coal, oil and natural gas), 6% is generated in
nuclear plants, and the remaining 7% comes from
renew-able sources (mainly hydro and wind power) [1].
The U.S. energy generation roughly follows the same
pat-tern [2]. As indicated, 42% of U.S. energy comes
from oil most of which is consumed in automobile
transportation. Currently, USA imports more than 50%
oil from outside. The electricity generation of USA,
Japan, China and India by different types of fuel [3]. In
USA, 37% of total energy is produce in electrical form
of which 55% comes from coal and 20% comes from
nuclear plants. It is attractive to note that China and
India generate most of the electricity from coal (74%
and 71%, respectively) B. Environmental Issues
Unfortunately, environmental pollution and safety
problems contributed by increased energy consumption
are recently becoming domination issues in our society.
Nuclear power plants have safety problems. Besides,
nuclear plant waste remains radioactive for thousands
of years. Even with the latest technology, we do not
know how to satisfactorily dispose of the nuclear waste.
The U.S. society vehemently opposes expansion of
nuclear power in spite of having stringent safety
standards by Nuclear Regulatory Commission (NRC).
Anti-nuclear slogan is now spreading in many countries
of the world. Burning of fossil fuels emits gases, such
as CO,SO,NO , HC, O and CO, besides generation of
fly ash by coal. These gases create environmental
pollution problems, such as global warming (green
house effect), acid rain and urban pollution. Global
warming (a few degrees in hundred years) may cause
melting of polar ice cap and corresponding inundation
of low-lying areas of the world. In addition, the
resulting world climate change may adversely affect our
agriculture and vegetation. Of course, preserving the
world’s rain forests and widespread forestation can
alleviate this problem. The acid rain, mainly caused by
SO and NO due to coal burning, damages vegetation.
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International Journal of IT, Engineering and Applied Sciences Research (IJIEASR)
Volume 2, No. 2, February 2013
Then, of course, there is urban pollution problem
mainly by IC engine vehicles.
IV. COORDINATED VOLTAGE AND
RAPPING
Keeping track of the key variables of the ESP units
installed in TENT A1 and A4 since their installation, it
has been found that the key requirement for the filtering
efficiency is the proper operation of the input zone. The
input zone of the ESP collects major part of the flying
ashes weight. Collected particles are mostly of a larger
diameter. Roughly speaking, the input zone collects the
particles with D > 10-20 µm, accounting for more than
80% of the overall weight. Flue gas exiting the input
zones caries small particles (D<10 µm) to middle zones.
[4]
Low sulfur coals in Serbia are highly resistive. Thick
layers of the collected dust are highly resistive.
Therefore, the spatial electric current (electric wind)
causes significant voltage drop within the dust layer. As
a consequence, resulting electric field keeps the dust
sticky and presses the dust layers against the collection
plates. In such conditions, rapping does not provide for
the complete cleansing of the plate, and it has to be
repeated more frequently. On the other hand, frequent
rapping contributes to mechanical wear of the filter and
increases the particle re-entrance into the gas stream.
A. Solution: Adaptive Rapping with Simultaneous
Voltage Control
ESP controller [5] tracks the voltage and current
waveforms during the ON pulses of the intermittent
power supply, as well as during the OFF intervals.
Their time change and spectral characteristics comprise
sufficient information for determining the thickness of
the dust layer. Hence, the rapping can be performed
when really needed, avoiding in such way the
Unnecessary
rapping
instances,
inherent
to
conventional, pre-programmed rapping sequences.
Prior to rapping, the last OFF interval of the intermittent
Power supply is extended, in order to relax space
charges and have the dust layers ready to be detached
from the plates.
As the rapping of the input zone collection plates
begins, certain small voltage is re-applied, in order to
reduce the particle re-entrance into the gas stream
during the rapping interval. Whenever mechanical
construction of the filter allows, the rapping hammers
hitting individual plates should be phase shifted, in
order to avoid simultaneous rapping of all the plates at
the same instant.
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ISSN: 2319-4413
B. Resistivity and the Rapping Frequency
There is no fixed threshold for the dust layer thickness
that will trigger the rapping. Namely, the ESP unit
increases the rapping frequency in cases when the dust
resistivity increases. This is done in order to increase
the overall efficiency of the filter.
In cases with an increased resistivity, the plates
withstand more or less the same voltage as they do with
the normal resistivity of the dust. Yet, the spatial
current (electric wind) is reduced, and the current
density drops significantly below desirable 1 mA/m2.
Any attempt to increase the current by increasing the
voltage results in sparking. When the input zone
operates in such condition, collection is notably
reduced, and vast quantity of dust passes in the
subsequent sections, compromising the overall
efficiency. In order to alleviate the queer consequences,
the rapping frequency is increased, giving in turn a
reduced average thickness of the dust layers.
C. Hopper Control
The outcome of the ESP intermittent power supply is an
increased quantity of dust collected in the input zones.
At the same time, adaptive rapping with simultaneous
voltage control provides for rather even surfaces and
uniform thickness of the dust layers. All these
consequences are positive, yet, there is one aspect that
needs particular attention. Adaptive rapping and
intermittent control do increase the quantity of ashes
falling into the hopper during one single rapping
session. Therefore, it is suggested the hopper be
equipped with adequate number of sensors, securing a
proper and timely operation of the dust removal system.
If the above measures are not fulfilled, there is an
increased risk of the hopper getting full, which
dramatically increases re-entrance of the collected
particles into the gas stream. In some cases, even short
circuits between the plates have been noted, with the
short circuit current passing through the top dust layers
of the over-spilling hopper.
CONCLUSION:
This Paper discusses various techniques which are
applicable in the various power electronics scenario.
And also discuss the energy and environmental issue.
REFERENCES:
[1] G. R. Davis, ―Energy for planet earth, ‖Scientific
American, pp. 1–10,1991.
[2] U.S. Department of Commerce Statistical
Abstract of the United States, 114th ed., 1998.
[3] S. Rahman and A. D. Castro, ―Environmental
impacts of electricity generation: A global
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International Journal of IT, Engineering and Applied Sciences Research (IJIEASR)
Volume 2, No. 2, February 2013
ISSN: 2319-4413
perspective,‖IEEE Trans. Energy Conv., vol. 10,
pp.307–313, June 1995.
[4] Bimal K. Bose, Life Fellow ―Energy,
Environment, and Advances in Power
Electronics. IEEE transactions on power
electronics, vol. 15, no. 4, july 2000
[5] J. R. Roth, Long term global energy issues, in
Industrial Plasma Engi-neering, Institute of
Physics Publication, Philadelphia, PA, vol. 1,
1995
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