1. and promoting this critical input
Water for making Indian agriculture to
Conservation in the meet the
International challenges of
Field Farming productivity and cost of
production. This also helps in
(K.Rakesh Reddy) development of country.
ABSTRACT CONCEPT:
INTRODUCTION: We know the lack and improper
power in indiaespically remote
Farm mechanization helps in
effective utilization of inputs to areas where farmeris facing many
increase the problems.these helps in following:
productivity of land and labour.
first farmer has to estimate
Besides it helps in reducing the
drudgery in farm the time that takes to wet
operations. This modern motor the area and set
device performs following the timing in the timer
operation: provided in the motor.
Automatic irrigation system. He has to switch on the
Water management. motor, at that time current
Time management.
may or may not be there.if
Better yield in crops &
profit. current is there it flows the
Wide scope for modern time period mentioned over
agricultural system. there in motor.And if
power is lost in between
This paper reviews the easy & time after resuming from power
savingfarming for an the motor runs for
agriculturalist, including the remaining time period and
aspects of problems facing by the
gets turnoff.
farmer espically in remote villages
where modern agriculture is not
being used .These also can be
implemented of their adoption and
the role of different public and
private Institutions in supporting Advantages:

2. Helps the farmer for easy bucket or conductance type probes to
farming. measure rainfall. Wireless and wired
Farmer can do multiple versions both use similar mechanisms to
works at the same time. temporarily suspend watering by the
Helps in providing the irrigation controller — specifically they are
better yielding of crops connected to the irrigation controller's
The circuit comprises of sensor terminals, or are installed in series
moisture with the solenoid valve common circuit
sensors.microcontroller. The such that they prevent the opening of any
moisture sensor gives output as valves when rain has been sensed.
voltage. If the output voltage
from the moisture sensor is Some irrigation rain sensors also contain
below the threshold value, it a freeze sensor to keep the system from
will be considered that the soil operating in freezing temperatures
is dry and plants should be (typically freeze sensors are employed in
watered. Using microcontroller regions where irrigation systems are not
and relays, we drive the motor "blown-out" for the winter, yet there is
for watering the plants/soil.
sometimes a chance of overnight frosts,
The first is a water conservation device such as Florida, New Jersey, Minnesota,
connected to an automatic irrigation system
and Connecticut mandate the use of a rain
that causes the system to shut down in the
event of rainfall sensor in all new lawn sprinkler systems.
A new trend in "smart" sensors (like
the Virtual Rain Sensor) are using recent
Irrigation sensors weather observation data (rainfall,
sunlight, temperature, humidity, and
Rain sensors for irrigation systems are
pressure) to
available in both wireless and hard-wired
calculate evapotranspiration of water.
versions, most employing hygroscopic
Used in conjunction with forecast rain and
disks that swell in the presence of rain and
temperatures data these can direct home
shrink back down again as they dry out —
automation hardware at variable intervals
an electrical switch is in turn depressed or
and durations to optimize water savings.
released by the hygroscopic disk stack,
and the rate of drying is typically adjusted
by controlling the ventilation reaching the
stack. However, some electrical type
sensors are also marketed that use tipping

3. A DSP based
conversion stages, online UPSs have been
the most complex and expensive type of
On-Line UPS
systems. Today’s low cost, high
performance Digital Signal Processors(DSPs)
provide an improved and cost- effective
solution foronline UPSdesign, making them
(K.Rakesh Reddy &D.Praveen) software controllable, adding some facilities
like remote configuration and monitoring
and other network management facilities.
This paper presents the basic design
and merits of using real time digital signal
processing (DSP) control of UPS systems.
ABSTRACT
Many facilities such as patient
health care centers, data processing
systems, critical telecommunication links,
LAN servers, offices etc rely on
uninterruptible power supplies (UPS) to
maintain a continuous supply of power in
case of line outage. In addition to requiring
continuous power, many critical nonlinear
loads are sensitive to the incoming line
transients and input harmonic voltage
distortion. Conventional UPS systems INTRODUCTION:
operate to protect against such
disturbances using complex filtering
schemes, often employing large passive Un-interruptible power supplies
(UPS) play an important role in interfacing
components. Among the various UPS
critical loads such as computers, tele-
systems online UPS provides maximum communication links,data-processing
protection to such loads against any power systems, life supporting systems and
problems. Because of multiple power industrial controls,e.t.c to the power grid

4. .Among the various UPS topologies, on – 6. Frequency instability: defined as
line UPSs provides maximum protection to temporary changes in the mains
such loads against any utility power frequency.
problem, as it protects against power 7. Harmonic distortion: defined as a
blackout.However,because of multiple departure from the ideal
power conversion stages, on-line UPSs have sinusoidalwaveform expected on
been most complex and expensive type of the line.
systems.
Typical On-Line UPS:
A typical UPS consists of a rectifier
Today’s low cost, high performance supplied battery bank & a static inverter-
Digital Signal Processors (DSPs) filter system to convert a dc voltage to a
provide an improved and cost- sinusoidal ac output. Modern UPS systems
effective solution for online UPS minimize the harmonic content of the
inverter output voltage through the use of
design.
complex filtering schemes employing large
passive components.
Common power problems
The primary role of any UPS is to provide
short-term power when the input power
source fails. However, most UPS units are
also capable in varying degrees of
correcting common utility power problems:
1. Power failure: defined as a total Need for Pulse Width Modulation:
loss of input voltage.
2. Surge: defined as a momentary or PWM is nothing but the control of
sustained increase in the main UPS inverter switching, under feedback
voltage. control to realize the desired output
3. Sag: defined as a momentary or waveform and also to minimize the
sustained reduction in input harmonic content of the output voltage.
voltage. Pulses are generated whenever a carrier
4. Spikes, defined as a brief high signal & modulating signal crosses
voltage excursion. eachother.These pulses are given to
5. Noise, defined as a high frequency thyristors and pulsating output is
transient or oscillation, usually generated. Depending on the number of
injected into the line by nearby output pulses generated, switching
equipment. frequency of inverter is determined. Width
of the pulses is proportional to magnitude

5. of the output sine wave and if the number
of pulses per half cycle is more, lower order
harmonics will be eliminated.
General PWM techniques for UPS:
1. Using Analog devices:
Analog PWM uses natural sampling Then, Why DSP?
technique, which compares a sinusoidal
Most of the Microprocessor –
modulating wave form with a triangular
aided UPS systems continue to depend on
wave (from a time-base generator) to
the analog op-amp controls and they lack
generate pulses.
speed required for high frequency inverter
control.
Therefore, harmonics are not eliminated in
the output wave form, insisting on the large
output LC-filter circuit.
With the availability of low
cost- high performance DSP chips
characterised by the execution of most
instructions in one instruction cycle,
complicated control algorithms can be
executed with speed, making very high
2. Using Microprocessors:
sampling rate possible for digitally
A digital PWM signal generator is controlled inverters. High speed DSPs
interfaced with a microprocessor. It are now capable of executing over 30
calculates the pulse width at every sampling million instructions per second (MIPS).
instant. According to this calculated width,
the pulse generator generates the pulses
with a constant switching frequency. More reasons for using DSPs:

6. No analog circuitry. Thus no offsets(
i.e. installation & maintenance cost
saved)
High speed DSP control allows for
real time harmonic cancellation.
Flexible configuration for many
power sizes.
Sophisticated switching algorithm
saving overall system costs.
Features may be upgraded in the
Thus, the application of advanced signal
same hardware, to fulfill different
processing using a DSP operates to provide
incoming needs.
sinusoidal load voltages even under varying
load situations, while eliminating the need
DSP control of UPS systems: of large passive filters.
Most electronic loads served The figure shown gives the basic
by UPS systems are non-linear and thus block diagram of DSP control with
generate harmonic currents that must be PWM inverter control circuit:
filtered at the inverter output to reduce the
distortion to acceptable levels. The DSP
controlled UPS systems employs software
controlled harmonic conditioners with the
ability to dynamically adopt to changing
load conditions for compensating load
harmonics without manual intervention.
The functional block diagram is as
shown below:
Description:
The output of the UPS PWM
inverter is sampled and converted to an

7. rmsvoltage that is processed in a negative order to detect the real and imaginary
feedback loop. The actual inverter output is values of the 5th harmonic. This function can
compared to a software rms reference be written for phase ‘a’ as,
value to determine the error voltage. The
error voltage is then passed through a
proportional integral (PI) control to
eliminate any steady state errors present.
The result is the necessary error
compensation signal.A harmonic distortion Where va (n) is the output
correction signal is then subtracted from voltage of phase a for sometime n.
the error compensation signal and the
The distortion signal may be represented
result is applied to the input of PWM
more simply as
inverter.
The above mentioned harmonic
distortion correction signal is generated in
the negative feedback loop. The Digital
Signal Processor detects the harmonic
distortion signal within the output voltage Where λa5r is the real component of Aa5, and
waveform and determines the amplitude of λa5i is the imaginary component of Aa5.
real and imaginary parts of the harmonic
Once the harmonic distortion signal
components. This process will be described
(Aa5, Ab5 and Ac5) is detected by the signal
for the cancellation of the 5th harmonic,
correlation function, the amplitudes of the
however, any harmonic whose frequency is
real and imaginary components of the 5th
below half the sampling frequency can be
harmonic are computed by averaging the
cancelled in the same manner.
amplitude components of the three phases
Each frame of the converted digital as shown below.
output from the A/D converter passes to a
real and imaginary component harmonic
detectors for phases a,b and c. For example,
the harmonic distortion waveform (Aa5) is
processed by a signal correlation function in

8. The amplitude components are then
applied to a PI compensator to generate the
harmonic distortion correction signal
necessary to cancel harmonic distortion
from the output voltage. The resulting
harmonic distortion correction signal is then
subtracted from the error compensation
signal and applied to the input of the PWM
inverter to produce an output voltage
waveform free of harmonic distortion. The
same technique can be applied to eliminate
Hence, the DSP controlled inverter
still higher harmonics like 7th, 9thetc,
and harmonic conditioners operate
below figure shows the operation of
to provide
UPS without harmonic conditioner
Sinusoidal load voltages even under varying
non-linear load conditions while preventing
higher operating temperatures due to
additional harmonic currents.
Advantages of using DSP in UPSs:
High reliability and low
But with all-harmonic conditioners
dimensions:with the DSP, the
enabled, the output voltage wave is
number of electronic components is
like below: halved, thereby reducing processing
time and failure probability and
increasing reliability and eliminating
the use of redundant current and
voltage sensors.
Precision: the DSP controls the
electrical values directly,

9. guaranteeing extreme precision and The conventional methods of UPS
stability of output voltage and control and with using DSP, how the UPS
avoidance of noise due to distorting control can be made more users friendly, its
loads. advantages are discussed in the paper.
Interactive communication: DSP
No doubt, DSPs are going to lead
controls the UPS in its entirety and
the market of control inverters in near
outputs on a serial interface all the
future and already big players in the market
supervision reports, for automatic
like Texas Instruments, Eaton group, Intel
shutdown of servers, for
etc are in the arena to make use the
communication on a LAN network,
technology in a full swing.
the Internet and Intranet and for IT
maintenance which is carried out Bibliography:
without switching the equipment
(1)”DSP control of high-power UPS systems
off.
feeding nonlinear loads” by Annette Von
Knowing the history: The control
Jouanne and Prasad N.Enjetisen.IEEE
software provides users with
member, from IEEE transactions on
operating and historical data in the
Industrial Electronics,Vol 43,no.1,Feb,1996.
form of clear read-out monitors,
aiding them in taking any decisions. (2)”Digital signal processing based online
Moreover the control system UPS” manual by www.cranessoftware.com
upgrade can be implemented in software,
(3) “Power Electronics Analysis Design
making the latest features available to any
&Apllications” by Ned Mohan,Tore
compatible UPS without changes to the
M.Undeland, William P. Robbins
hardware.
(4)”Interfacing DSPs with high performance
analog converters” Jim Ryan, Raheen
Industrial estate, Ireland.
(5)WEMPEC-25th anniversary review
meeting, R&D dept.innovation center Eaton
Conclusion: Corporation.

10. VLSI Design
VLSI chiefly comprises of Front End Design and Back End design these days. While front end design
includes digital design using HDL, design verification through simulation and other verification techniques,
the design from gates and design for testability, backend design comprises of CMOS library design and
its characterization. It also covers the physical design and fault simulation.
While Simple logic gates might be considered as SSI devices and multiplexers and parity encoders as
MSI, the world of VLSI is much more diverse. Generally, the entire design procedure follows a step by
step approach in which each design step is followed by simulation before actually being put onto the
hardware or moving on to the next step. The major design steps are different levels of abstractions of the
device as a whole:
1. Problem Specification: It is more of a high level representation of the system. The major
parameters considered at this level are performance, functionality, physical dimensions, fabrication
technology and design techniques. It has to be a tradeoff between market requirements, the available
technology and the economical viability of the design. The end specifications include the size, speed,
power and functionality of the VLSI system.
2. Architecture Definition: Basic specifications like Floating point units, which system to use, like RISC
(Reduced Instruction Set Computer) or CISC (Complex Instruction Set Computer), number of ALU’s
cache size etc.
3. Functional Design: Defines the major functional units of the system and hence facilitates the
identification of interconnect requirements between units, the physical and electrical specifications of
each unit. A sort of block diagram is decided upon with the number of inputs, outputs and timing decided
upon without any details of the internal structure.

11. 4. Logic Design: The actual logic is developed at this level. Boolean expressions, control flow, word
width, register allocation etc. are developed and the outcome is called a Register Transfer Level (RTL)
description. This part is implemented either with Hardware Descriptive Languages like VHDL and/or
Verilog. Gate minimization techniques are employed to find the simplest, or rather the smallest most
effective implementation of the logic.
5. Circuit Design: While the logic design gives the simplified implementation of the logic,the realization
of the circuit in the form of a netlist is done in this step. Gates, transistors and interconnects are put in
place to make a netlist. This again is a software step and the outcome is checked via simulation.
6. Physical Design: The conversion of the netlist into its geometrical representation is done in this step
and the result is called a layout. This step follows some predefined fixed rules like the lambda rules which
provide the exact details of the size, ratio and spacing between components. This step is further divided
into sub-steps which are:
6.1 Circuit Partitioning: Because of the huge number of transistors involved, it is not possible to handle the
entire circuit all at once due to limitations on computational capabilities and memory requirements. Hence
the whole circuit is broken down into blocks which are interconnected.
6.2 Floor Planning and Placement: Choosing the best layout for each block from partitioning step and the
overall chip, considering the interconnect area between the blocks, the exact positioning on the chip in
order to minimize the area arrangement while meeting the performance constraints through iterative
approach are the major design steps taken care of in this step.
6.3 Routing: The quality of placement becomes evident only after this step is completed. Routing involves
the completion of the interconnections between modules. This is completed in two steps. First
connections are completed between blocks without taking into consideration the exact geometric details
of each wire and pin. Then, a detailed routing step completes point to point connections between pins on
the blocks.
6.4 Layout Compaction: The smaller the chip size can get, the better it is. The compression of the layout
from all directions to minimize the chip area thereby reducing wire lengths, signal delays and overall cost
takes place in this design step.

12. 6.5 Extraction and Verification: The circuit is extracted from the layout for comparison with the original
netlist, performance verification, and reliability verification and to check the correctness of the layout is
done before the final step of packaging.
7. Packaging: The chips are put together on a Printed Circuit Board or a Multi Chip Module to obtain
the final finished product.
Initially, design can be done with three different methodologies which provide different levels of freedom
of customization to the programmers. The design methods, in increasing order of customization support,
which also means increased amount of overhead on the part of the programmer, are FPGA and PLDs,
Standard Cell (Semi Custom) and Full Custom Design.
While FPGAs have inbuilt libraries and a board already built with interconnections and blocks already in
place; Semi Custom design can allow the placement of blocks in user defined custom fashion with some
independence, while most libraries are still available for program development. Full Custom
Design adopts a start from scratch approach where the programmer is required to write the whole set of
libraries and also has full control over the block development, placement and routing. This also is the
same sequence from entry level designing to professional designing.