5. vertical axis wind mill new

7/30/2019 5. Vertical Axis Wind Mill New

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V e r t i c a l A x i s W i n d M i l l W i t h S P W M I n v e r t e r

1 | P a g e D e p a r t m e n t o f E L E C T R I C A L 2 0 1 1 G E C , S U R A T


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Vertical axis windmills have a feature that is

particularly attractive- they accept wind from any

horizontal direction and do not need the complicated head

mechanisms of conventional horizontal axis windmills. The

resulting mechanical simplification is sufficient to warrant

interest in any new vertical axis concept that arises.

This wind turbine is a rotating machine which

captures the kinetic energy of the wind and converts it into

electrical energy.

In this project we are trying to utilize the maximum

energy of the wind to rotate the wind turbine n by using shaft

work we can generate the electrical energy.

In this project we are using the Neo-Aero Dynamic

type of blades to run the turbine. Its having four blades and

also it can be operated for any directional wind direction.

Here we are using the Proto type of generator of axial flux

machine principle to convert the mechanical energy to the

electrical energy. We are using for four pole proto typegenerator of a four permanent magnet of NdFeB

(Neodymium Iron Baron) material.

And at the last stage of this project we are making a

SPWM inverter for converting the DC current in to the AC

current for operating any electrical apparatus up to 30Watt.

In 2005, wind accounted

for 1% of the totalelectricity production in

the world. The United

States was third in

utilization of wind energy,

with Germany being the

leading producer.

According to the

Department of Energy,

offshore wind farms could

provide enough energy to

power the entire nation.

In 2006, India overtook

Denmark to become the

fourth largest producer of

wind energy in the world.

According to the latest

study released by Global

Wind Energy Council, the

wind could generate a

'considerable share' of

India's power and the

country's total installed

capacity for wind power

could go up five times to

231GW by 2030.


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During the early seventies, South & Rangie (1971,

1972) conducted wind tunnel tests on a novel Vertical axis

configuration at the National Research Council, Canada, which

showed that the device worked efficiently at high tip speed

ratios but had poor starting torque, In effect, the new device

behaved much like a low solidity horizontal axis machine but

was conceptually a great deal simpler.

It appears that the configuration was originally

discovered and patented by Darrieus. A wide variety of VAWT

configurations have been proposed, dating from the Persian

VAWTs used for milling grain over a thousand years ago,

through to the Darrieus turbine, invented in 1926 by Georges

Darrieus, which has been used extensively for power

generation.

We refer to this configuration as the Darrieus rotor and

when used as a turbine as the vertical axis wind Turbine

(VAWT).The Darrieus rotor (figure) consists of a number of

curved blades rotating about the vertical axis through their

ends, Sections of any blade, in planes normal to the slope of

the major (lengthwise) axis, are of aerofoil shape with the

chords aligned in the azimuthally (azimuth - angular distance

from a north or south point of the horizon to the intersection

with the horizon of a vertical circle passing through a given

celestial body) direction.

Figure1. (The rotor

geometry. The blades

rotate about the vertical

axis.)

Egyptians used wind

energy to sail ships on

the Nile River over 5,000

years ago, whilewindmills were

developed in Persia

about 500 to 900 A.D. to

automate grain-grinding

and water-pumping.

Charles Brush was the

first to use a large

windmill to generate

electricity in Cleveland,

Ohio, in 1888.

Wind energy theory was

discovered in 1919 by

German physicist Albert

Betz and published in his

book Wind-Energy


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Fig. 3.1: Block diagram of project


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Understanding of Block diagram of project:

The block diagram of the project is shown in above figure. It contains main five blocks.

i. The first block is of input device. Here is the input of mechanical energy given bythe wind turbine. And the wind turbine is run by the wind.

ii. The second block is of generator with rectifier. Here the mechanical energy isconverted in electrical energy by means of generator. Here we are using six pole

PROTO type AC generators n this AC output is converted in DC output by using

full wave bridge rectifier.

iii. Third part of this project block diagram is of control circuit which controlling theoutput of the generator and gives the charging current to the battery for charging

the battery. Here we are using liquid battery for backup.

iv. Fourth block contains inverter. Here we made SPWM (sinusoidal pulse widthmodulator) inverter to convert the batterys dc power in to the AC pow er up to

40watt.

v. Output port provides the constant 40watt AC supply.

By using these five parts we made our project. There are main 2 part of this project 1 st

is a charging part and 2nd part is discharging part. First of all we have to run this project

mode in charging part when batteries are fully charged then we can use these batteries in

discharging modes by using the SPWM inverter.


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Neo-Aerodynamic introduces a new, history making technology to extract kinetic

energy from a flowing fluid, providing unheard-of amounts of electricity as the final

result; this rate has not been seen before. During the development of this technology we

have gone from one surprising result to the other. At times we could not believe our eyes

when we read the measurements; in the end we had to settle for what the equipment tells

us.

Neo-Aerodynamic indeed sparks a new energy revolution by providing for the first

time in history a concrete means for humans to harness most of their energy needs through

a renewable resource. For example: a 2m diameter by 2m height hydro Neo-Aerodynamic

device could generate a net power of several megawatts. Neo-Aerodynamic provides the

most inexpensive means to generate electricity even when compared to fossil fuel engines.

Neo-Aerodynamic has a high sensitivity to the fluid stream and a superb rate of

energy return allowing it to be economically deployed in almost every corner of the world.

With wind, you feel it you get it. With water, you see it you get it.

Fig 4.1: Neo aero blades design

In our project we are using this kind of blades. In which a plastic sheet of 0.3 cm

and height is of 121cm and width is of 48 cm. It is mounted on the semicircular PVC pipes

of circumference of circle. The length of this circumference is nearly about 51cm.


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plastic blades are holed by clamps from the top and the bottom. Here all the blades are at

apart from each other. The main axis of this wind mill is also of PVC pipe of 2cm

diameter and 0.4cm thickness.

Fig.4.2: Actual Neo Aero Blade of Project

When wind is blowing this structure is rotates on the least friction vertical bearing.

And this both bearing is tightly holed by means of metallic supports.


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The gear ratio of 1:8 is used to increase the RPM of the blades. The total rpm of this

structure are 42 - 45. And by using gear ratio we get the rpm up to 336 360. And this is

used as an input mechanical work of generator.

A. The Background.

Fluid always goes from high to a low-pressured place. In fluid aerodynamic; when

something stands in its flow it then causes the flow facing front having higher pressure.

Using airfoil in the path of the flow; its aerodynamic effect will cause a lift, like it works

with an airplane.

B. The dynamic.

On the wind facing (wind make) side; the flow are then redirect outward from the

center. It then causes the lift on airfoils to push it turning. Once the device is turning it

causes the center to have lower pressure; the outside air then rushes in to fill those

vacuums. This flow is then redirected to cause lift on the airfoil.

When turning; the special arrange of the airfoil allowing the volume of the air

passing through the upper chamber are always more than of the lower chamber. This also

causes the lift to make the device turn.

In short; Neo-Aerodynamic uses the artificial flow of the air to cause the lift on its

airfoils. That's why it's called Neo-Aerodynamic.

C. The Swept Area.

In case of a horizontal axis propeller it's easy to understand that its swept area is on

the surface that is parallel to the cross section of it axis. In this case it is the same as the

wind facing surface.

In case of a Neo-Aero-Dynamic device the swept area is the same area as the cross

section of the airfoils sweep. It is the surface that's parallel to the cross section of its axis.

Therefore as of the wind, the swept area of a Neo-Aero-Dynamic device is on a horizontal

plane. This concept is very important because we will use the swept area to calculate the

output of a Neo-Aero-Dynamic device.

Its also very important that the commonly understood swept area that we use to

calculate the rated output of the horizontal propeller does not apply to this device because:


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There's no wind move through its airfoils. Turbulence and the attack angle of each airfoil changes at every moment. On each airfoil; the pressure posing on the upper chamber and the lower chamber

are different and constantly changing.

As the result; known methods such as "Betz" limit become useless. Everything weuse to calculate the output has to come from actual measurements on either wind

tunnel test models or real life installation.

Advantages & disadvantages of this type of wind blades

Advantages:

Neo-Aerodynamic works on "you feel it you get it", it does not require years ofobservation and gathering data.

Neo-Aerodynamic mainly works on pneumatic force of the wind therefore it's noteffect by turbulence or wind drag.

Neo-Aerodynamic has phenomenally high capture rate; because its capture rate isat least proportional to its diameter.

Neo-Aerodynamic does not require a tower, allowing equipment to be maintainedat or close to the ground.

Neo-Aerodynamic can be scaled independently its width and or its height to fityour application.

Neo-Aerodynamic works on low wind speed while other technologies provide toolittle.

Neo-Aerodynamic increases its effectiveness along with the density of the medium(air and water) while other decrease.

Neo-Aerodynamic are simple to operate; no yawing, no controller to have it facingto the wind.

Neo-Aerodynamic is safe in reaction to the wind rush. Neo-Aerodynamic are low profile; not being scenic pollution. Neo-Aerodynamic is silent. Neo-Aerodynamic does not have shadow nuisances. Neo-Aerodynamic can be adapted to city/subdivision residential area or backyard. Neo-Aerodynamic works in both air and water medium.


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Hydro Neo-Aerodynamic can be either float or bottom dwelling. Both Hydro and aero devices are compact; easy to be transported or making it

portable.

Disadvantages: As of any technology, there may be a limit of how width and or how high it can be

built.

As of any technology, there may be a new, better "invention"? Being backed by actual models; despite the fact that Neo-Dynamic has the same or

better tip-speed, it usually requires a higher ratio gearbox (more expensive) to take

advantage of capturing the energy when the wind speed is slow.


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The biggest problem with using car alternators for wind power is that they aredesigned to rotate at too high a speed to be practical in wind power applications without

significant modifications. Even a small, seemingly fast windmill might do most of its

work at 600 rpm, not nearly fast enough for a car or truck alternator. This means that

gearing up with pulleys or other methods is needed, so lots of power is lost to friction--a

big problem with wind or water power, but not a problem with a internal combustion

engine.

A standard car or truck alternator is electromagnetic-- meaning that some of the

electricity produced by the unit must be used internally and sent to the armature through

brushes and slip rings to make the magnetic field. Alternators that use electricity to

generate the field current are less efficient and more complicated. They are quite easy to

regulate, however, since the magnetic flux inside can be changed by adjusting the field

power.

Also, the brushes and slip rings wear out, requiring more maintenance. Car and

truck alternators can also be rewound to produce power at lower speeds. This is done by

replacing the existing stator windings with more turns of smaller gauge wire. This project

is not for the faint of heart, but check the inexpensive booklet Alternator Secrets by

Thomas Lindsay if you are interested.

5.1Alternator and Generator Comparison for Wind Power5.1.1 Induction Motor Conversion Alternators

* Advantages: cheap, easy to find, fairly easy to convert, good low-rpm performance.

* Disadvantages: power output limited by internal resistance, inefficient at higher speeds,

machining needed.

* Suitability for Wind Power: OK

Armature converted with permanent magnets:

A normal AC induction motor can be converted into a permanent magnet

alternator at very low cost. Our experiments have shown that these conversions produce


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significant power at very low speeds, but become inefficient quickly at higher power

levels.

An induction motor has a center core with no wires in it, just alternating plates of

aluminum and steel (it will look smooth from the outside). If you rout a groove in this

center core to accept permanent magnets, the unit becomes a permanent magnet alternator!

In practice, wind generators made with these do quite well until they reach 10-20

amps of output. At this point, they become inefficient quickly--it takes a large increase in

wind speed to make only slightly more power, and the rest is wasted as heat inside the

unit. The induction motors are wound with wire that's simply too thin for generating large

amounts of power.

In tests, DanB's PM induction motor conversion windmill peaks at around 25 amps

in 30 mph winds, with a 7-foot diameter prop. By comparison, a 7-foot prop on an

efficient PM alternator made from scratch gives peaks of 50-60 amps in similar winds!

Converted motors also have the tendency to "cog" when starting...you can feel the

resistance when you turn the shaft. This affects low-speed startup somewhat.

If the lesser output in high winds is acceptable to you, these units can make for a

pretty easy wind generator project. Look for AC induction motors of the lowest rpm rating

possible. 3-phase motors will perform better than single phase. Since alternators produce

alternating current (AC), the power must be converted to DC with bridge rectifiers.

5.1.2 DC Generators

* Advantages: Simple and pre-assembled, some are good at low rpm.

* Disadvantages: High maintenance, most are not good at low rpm, large sizes very hard

to find, small ones have limited power output.

* Suitability for Wind Power: POOR to OK

Generators make DC current, and batteries need DC for charging. Generators were

used in automobiles until around 1970, when alternators became more practical (due to the

availability of cheap, small diodes). Even old car generators must spin too fast to be

practical for wind power, but there have been many good plans for modifying them.

Generators are fairly complex compared to alternators. They must have brushes,

and complex commutations. Brushes require maintenance, and commentators can wear

out. For most purposes, alternators are more practical today, although generators do have

certain advantages at times.


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Certain low rpm DC motors can be purchased as

surplus and work very well as 12 volt low rpm generators.

These are from old mainframe computer tape drives, and are

sometimes available in local and mail-order electronics stores,

and on EBay. They don't make a whole lot of power...you can

expect only 100-200 watts of output...but these motors are

almost a science project in a box! Slap on a frame and a 3-4 ft

prop, and you have a small working wind generator.

5.1.3 Induction Motors as Alternators

It's possible to make a 3-phase induction motor produceelectricity, either 3-phase or single phase. This requires a

controller and capacitor. The generator must run at a fairly

constant speed. For this reason, this type of generator is more

suitable for constant-speed hydro power installations than for

wind, where speed varies--though it can be done. We have not

experimented with this technique yet, since we don't have a

suitable hydropower source.

5.1.4 Homemade Permanent Magnet Alternators

* Advantages: Low cost per watt of output, very efficient,

huge power output possible, extremely sturdy construction

* Disadvantages: A time-consuming, somewhat complicated

project, machining needed.

* Suitability for Wind Power: GOODHugh Piggott in Scotland was the pioneer in building

permanent magnet alternators from scratch. Experiments have

consistently shown that homemade PM alternators are the most

powerful and cost-effective solution for building a wind

generator. Their low-rpm performance is excellent, and at high

speeds they can really crank out the amps thanks to their

efficiency.

PM alternators have been based on disc brake

Features of NdFeB:

NdFeB magnets are

sensitive to changes in

temperature.

Additionally, Neodymium

Iron Boron magnets are

prone to rapid oxidation;

salt spray, salt water, and

hydrogen are very harsh

on the magnet.

Coating or plating is

generally recommended

unless using advanced

alloys. Advanced grades

are developed specifically

for applications which

have oxidation rates that

are far below the average

Neodymium Iron Boron

alloys, making them ideal

for applications that

require post assemblyprocessing, due to tight

tolerances in the final

assembly state.

The selection of


magnets in your

applications will depend

on your working

environment. If you usethe magnets at elevated

temperatures, select the

alloys that have a high

intrinsic coercivity (Hci). If

you use the alloy at lower

temperatures (such as

room temperature), you

may select higher Br

materials.


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assemblies, which are very sturdy and have thrust bearings

built into the unit. Larger units are "Disc" or "Axial"

designs...a flat plate of magnets rotating next to a flat plate of

coils. Smaller PM alternators are "Radial" designs, where the

magnets are fastened to the outside radius of the armature.

Since all alternators produce AC, the output must be converted

to DC with bridge rectifiers for battery charging.

These designs are usually single phase for ease of

construction. Three-phase alternators have some advantages

(they are somewhat more efficient, and make better use of

available space), but they are somewhat more difficult to

build.

Here we have made a Permanent Magnet Alternator of 6 poles.

Rotor of alternator:In this project the rotor is made up of a 40 cm diameter

and 0.5 cm thick wooden circular plate on which the 6

permanent magnets are holed by screw arrangement

apartfrom each other.

Fig. 4 shows the practical design of the rotor. In this

alternator we are using a belt conveyor system to convert

higher torque lower RPM of wind blades in lower torque high

RPM of ratio 1:8. Rotor contains a ball bearing. In a ball

bearing, the load is transmitted from the outer race to the ball

and from the ball to the inner race. Since the ball is a sphere,it only contacts the inner and outer race at a very small point,

which helps it spin very smoothly.

In this project the permanent magnets are used of a

3500 gauss NdFeB (Neodymium Iron Baron) material. Sizes

of the magnets are 5*5 cm and 2cm thick. And the thickness of

the axis which is passing through it is of 1.5cm diameter.

NdFeB magnets are mechanically strong and give the best

NdFeB Magnet:


magnetsabbreviated as

NdFeB are a type of rareearth alloy that typically

has two atoms of

Neodymium (Nd), 14

atoms of Iron (Fe), and

one atom of Boron

(B)as its primary elements,

(Nd2Fe14B).There are other

elements that are used to

increase the coercivity, to

gain lower oxidation

characteristics, and to

obtain other desirable

characteristics, which are

generally found in small

quantities (


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fields possible in permanent magnets. The temperature coefficient of Br is higher than

Samarium Cobalt, so the material is more sensitive to temperature changes, ranging from

0.10%/C - 0.13%/C. Neodymium Iron Boron magnets are less expensive, since the main

elements Nd and Fe are abundant, and are mechanically stronger.

Fig.5.1:permanent Magnet Rotor of Alternator

Stator:Here we made a stator which having a total 24 coils 12 coils are of square shaped

of 5 * 5 cm, 21 SWG (standard wire gauge) copper wires having a 45 turns. The coil

winder we used probably wound the coils a little taller than needed, so the unit could be

improved by making the coils a little smaller.

All coils are 30 apart from each other. Bellow figure shows that coils on stator.

Now the upper end of this coils are connected with the another coils which having a

copper wire of 36 SWG, 2300 turns wounded on the round shaped wonder.

After each coil is wound, it is carefully set aside to be glued and clamped over the top of

the stator at a later time. And the thickness of this coil is 2cm. Here it was to line them up

around the stator and put them in exactly the right place.

Totally 12 coils are used, so each of them must occupy a 30 degree arc around the stator.


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Fig.5.2: Stator Coils of 45 turns

Fig.5.3: Stator coil of 2300 turns


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Since there are 4 coil groups, each one must occupy a 90 degree arc around the

stator. This is actually easily estimated by first perfectly aligning the magnets around the

armature (the brake disk), placing all the coils down around the stator (pictured above),

and then placing the brake disc down over the stator, making sure that there is 1 coil

located exactly under each magnet. Sometimes it was necessary to squeeze the coils by

hand so that they would fit in the space provided. Once everything is lined up properly, we

fix it with glue.

Then we took the rotor, centered over the stator, and clamped the whole thing

together tightly. It is very important! When clamped, the thickness of all the coils around

the stator should be the same. Otherwise, when completed the gap between magnets and

coil will be wider in one part of the alternator than another.

Fig.5.4: Stator with both Coils connected in series

So, when one side had thicker coils than another, we would simply adjust the

clamps until it willbe even all around. The thickness of the coil is 2 cm and the air gap

created between coils and magnet is 0.6 cm.


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The generator also has excellent part load efficiency. This is primarily due to the

use of permanent magnet excitation whilst the simple stator core minimizes iron loss.

The stator is of 2 phase. Each phase having 6 coils.And the each coil having 2345turns.

Coil WinderIf we're going to build a generator or a motor, then we're going to need some coils.

Even with permanent magnet rotors as used here, we 'll still need armature windings. Its

pretty hard to get out much power otherwise. Some kind of winder will make the task of

producing consistent coils much easier. The photos below show a simple coil winder of 45

turns coils.

Fig.5.5: Coil winder of 45 turns coil

This is made up of one piece of wood skewed at a square shaped 4.5 cm * 4.5 cm.

For winding 2300 turns coils we use a round shaped winder of Teflon tape which is

shown below.


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Fig.5.6: Coil winder of 2300 turns coil

After winding all the coils we applied an insulation varnish to hold winding. All

coils were wound in the same direction and so that the last turn come out on the same side

of the coil as the first turn. For each coil, the wire extending from the first turn was

arbitrarily chosen to be the "positive" coil lead, and a small loop was twisted in its end in

order to identify it after removing the coil from the winder.

Prior to removing a coil from the coil winder a few inches of fiber reinforced

strapping tape was wrapped around the circumference of its windings to hold them in

place. The reinforced tape was chosen because it holds well, even when moist, and also

because it tears uniformly lengthwise so that a width of tape that covered the spread of the

coils but did not adhere to the coil forms could easily be obtained without having to

actually try to cut the tape lengthwise. Once the windings were taped in place the wire

extending from the spool was cut, (becoming the "negative" coil lead), and the coil was

removed from the winding form, with no danger of the coil unwinding itself.

A hole was drilled in the center of the backing wooden groove circle for the axle to

pass through. The backing wooden groove was turned in high enough up the stator frame

piece to allow clearance for the rotor to spin freely on its axle when the entire generator

unit is assembled on its base.


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Coil Lead ConnectionThe machine is of 2 phase. In a three phase system, the phases are electrically120

degrees apart. But, the stator coils are not (necessarily) physically spaced at 120 degree

intervals on the stator frame. The total number of coils on the stator and the number ofcoils used for each phase affects the physical placement of coils around the stator frame.

Here we are using a 2 phase system as there are a 6 poles and stator having 12 coils

30 apart from each other.

For the generator being described here, there are twelve stator coils, which allow 6

coils to be connected for each of the 2 phases. And, 12 coils means they will be spaced at

thirty degree intervals around the 360 degree perimeter of the stator frame.

The phases are referred to as A, B, and, starting from the right one of the topmostpair of coils on the stator frame, the coils are identified in the clockwise direction as

follows: A1, B1, A2, B2, A3, B3, A4, B4, A5, B5, A6, B6.Where B6 is the left one of the

topmost pair of coils. Each indexed letter of the alphabet refers to one of the coils in the

group of coils that comprises on phase coil set, e.g., coils A1, A2, A3, A4, A5 and A6 are

the coils wired together for phase A.

In phase A A1 is in series with A4.Such that A2 and A3 are in series with A5 and

A6. Then they are connected parallel to get a somewhat higher current.

Fig.5.7 Coil Connections in phase 1 in stator


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But in phase B coils B1, B2, B3, are connected in series with B4, B5, and B6 just

like phase A, but at last they all are connected in series as per the polarity considered at

some instant.

Fig.5.8 Coil Connections in phase 2 in stator

To work properly, at any instant in time each coil in a phase must be contributing

current to the phase of the same polarity and magnitude. Whether a coil is being energized

by the North Pole or the south pole of a magnet determines the polarity of the current

produced in the coil. The distance in its rotating path a magnet is from a coil determines

how much it contributes to the magnitude of the current generated in the coil. (A changing

magnetic field is required to generate current in a wire coil, and motion of the magnets

results in a changing magnetic field.)

Because there are alternating north and south magnet poles, the separate phase

coils cannot be simply connected in series, as the resulting currents generated in the

individual coils in a phase will not match.


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Fig.12: Waveform of the Output of this Generator

Fig.5.9: Side View of Generator

Fig.5.10: Rectifier used to convert AC to DC


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Fig.5.11: Output of the Generator before Rectified


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6.1 What is Inverter (power inverter)?

Many people are confused on two products: inverters (power inverters) and

frequency inverters. Although both have the word of inverter, they are different.

Then what exactly is an inverter (power inverter)? An inverter (power inverter) is

an electrical device that converts DC power or direct current (DC) to AC power or

alternating current (AC). The converted alternating current (AC) can be at any required

voltage and frequency with the use of appropriate transformers, switching, and control

circuits. An inverter (power inverter) allows you to run electrical equipment off your car

or marine battery for mobile applications, emergencies or simple convenience.

Power inverters (inverters) are small rectangular electrical devices that have a

trailing wire with a jack that plugs directly into the cigarette lighter on the dashboard.

Power inverters (inverters) might also come with jumper-like cables for connecting

directly to a battery.

6.2Type of inverter1. Pure Sine Inverter

A pure sine wave inverter, also known as a true sine wave inverter, uses sine

waves, which oscillate regularly in order to produce electrical energy to power appliances.

The sine wave inverter produces sine waves with AC machinery that rotates and creates

the type of electrical wave that is usually produced by the utility company with the use ofa generator. There are many benefits to using a pure sine inverter since all electronic

equipment is designed to be used with sine waves. Additionally, some appliances such as

light dimmers cannot work without the use of sine wave power and microwaves cannot

operate at full output without sine wave power. Pure sine wave inverters are more

expensive than other types of inverters.


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2. Modified Sine InverterA modified sine inverter differs from a pure sine inverter because it operates by

creating step waves instead of regular oscillating waves. As a result of this, most

appliances cannot work with this type of inverter because they require a regular energy

output that cannot be produced using step waves. However, some appliances can operate

with modified sine inverters though they require more power to run since the level of

energy output from the inverter is irregular.

3. Square Wave InverterSquare wave inverters make electrical energy conversions using a series of waves

that have a rectangular form. The signal from the inverter is very noisy and most

appliances cannot function with electrical currents produced by a square wave inverter.

The square wave inverter is one of the earliest types of inverters and, as such, the device is

incompatible with most modern types of electrical equipment. Moreover, the power

produced by this type of inverter can damage some electronic equipment that is sensitive

to the square waves of electrical power.

6.3 Principal of Inverter

An inverter is an electrical device that converts direct current (DC) to alternating

current (AC); the converted AC can be at any required voltage and frequency with the use

of appropriate transformers, switching, and control circuits.

6.4 The working principle of InverterFrom basic principles in terms of application, Inverter is a device that contains

stored energy in order to inverter as the main component, regulated stable frequency

output power protection equipment. Mainly by the rectifier, batteries, power inverters

and static switch of several components.

1) Rectifier

Rectifier is a rectifier device, simply means that the exchange of (AC) into direct

current (DC) devices. It has two main functions: First, the alternating current (AC) into


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direct current (DC), through the supply of filtered load, or the supply inverter; second, to

provide battery charging voltage. Therefore, it is also play a role in charger.

2) BatteryInverter battery is used as a storage energy device, which consists of several cells in series,

with a capacity to maintain its size determines the discharge (supply) time. Its main

function is: When the wind mill is rotating and electricity is generate through Generator,

the energy converted into chemical energy stored in the battery internal; when the

electricity fails, the chemical energy into electrical energy provided to the inverter or the

load.

3) Inverter

Popular speaking, the inverter is a DC (DC) into alternating current (AC) device. It

consists of inverter bridge control logic and filter circuit.

4) Sensing Relay

When there is electricity is available relay is sense the voltage and already in

operated condition. Voltage is applied to relay by step down transformer 230 12 volt.

But suddenly if electricity is not available relay come in its normal position and the

contact of inverter makes. So Relay provides automatic operation of inverter.

Most inverters do their job by performing two main functions: first they convert

the incoming DC into AC, and then they step up the resulting AC to mains voltage level

using a transformer. And the goal of the designer is to have the inverter perform these

functions as efficiently as possible. So that as much as possible of the energy drawn from

the battery or solar panel is converted into mains voltage AC, and as little as possible is

wasted as heat.

Modern inverters use a basic circuit scheme like that shown in Fig.1. As you can

see the DC from the battery is converted into AC very simply, by using a pair of power

MOSFET (Q1 and Q2) acting as very efficient electronic switches. The positive 13.8V DC

from the battery is connected to the centre-tap of the transformer primary, while each

MOSFET is connected between one end of the primary and earth (battery negative). So by

switching onQ1, the battery current can be made to flow through the top.Half of the


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primary and to earth via Q1.Conversely by switching on Q2 instead, the current is made to

flow the opposite way through the lower Half of the primary and to earth.

Therefore by switching the two MOSFET on alternately, the current is made to

flow first in one half of the primary and then in the other, producing an alternating

magnetic flux in the transformers core. As a result a corresponding AC voltage is induced

in the transformers secondary Winding, and as the secondary has about 24 times the

number of turns in the primary, the induced AC voltage is much higher, around 650V peak

to peak. By the way if youre wondering why MOSFET are used as the electronic

switches, to convert the DC into AC, its because they make the most efficient high-

current switches.

When they are off they are virtually an open circuit, yet when they are on they are

very close to a short circuit (only a few milliohms). So very little power is wasted as heat.

6.5 Pulse Width Modulation

There are many forms of modulation used for communicating information. When a

high frequency signal has amplitude varied in response to a lower frequency signal we

have AM (amplitude modulation). When the signal frequency is varied in response to the

modulating signal we have FM (frequency modulation). These signals are used for radio

modulation because the high frequency carrier signal is needs for efficient radiation of the

signal. When communication by pulses was introduced, the amplitude, frequency and

pulse width become possible modulation options. In many power electronic converters

where the output voltage can be one of two values the only option is modulation of

average conduction time.

Here we are using SPWM technical to switching the mosfet.

6.6 Sinusoidal Pulse Width Modulation

Instead of, maintaining the width of all pulses of same as in case of multiple pulse

width modulation, the width of each pulse is varied in proportion to the amplitude of a

sine wave evaluated at the center of the same pulse. The distortion factor and lower order

harmonics are reduced significantly. The gating signals are generated by comparing a

sinusoidal reference signal with a triangular carrier wave of frequency F c. The frequency

of reference signal Frdetermines the inverter output frequency and its peak amplitude AR,


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controls the modulation index M and RMS output voltage VO. The number of pulses per

half cycle depends on carrier frequency.

Sinusoidal pulse width modulation (SPWM) is widely used in power electronics to

digitize the power so that a sequence of voltage pulses can be generated by the on and off

of the power switches. The Sinusoidal pulse width modulation inverter has been the main

choice in power electronic for decades, because of its circuit simplicity and rugged control

scheme. SPWM switching technique is commonly used in industrial applications or solar

electric vehicle applications. SPWM techniques are characterized by constant amplitude

pulses with different duty cycle for each period. The width of this pulses are modulated to

obtain inverter output voltage control and to reduce its harmonic content. Sinusoidal pulse

width modulation is the mostly used method in motor control and inverter application.The

proposed alternative approach is to replace the conventional method with the use of

microcontroller. A use ofP89V51RD2 microcontroller brings the flexibility to change the

real-time control without further changes in hardware. It is also low cost and has a small

size of control circuit for the single phase full bridge inverter. The microcontroller has the

built in dead time control circuit.

6.7 Block Diagram of SPWM inverter

Fig.6.1: Block Diagram of SPWM Inverter


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As per the block diagram we can say that its very simple concept to make an

inverter. There are 7 main parts.

a) control circuit:It is the main part of the inverter where SPWM signals are generated by using

P89V51RD2. 4 Output port of the controller is given to the Mosfet connected in

H-Bridge, which gives proper switching to the Mosfet.

b) Mosfet Driver Circuit:It is made up of a 4 Mosfet IRF3205 connected in H-bridge to give the Output. The

Output of the Control Circuit is primarily fed to an IC TLP250 and then it gives

signal to H-bridge.

c) Step up transformer:Here we are using a transformer of 10v at its primary side and 250v at secondary.

Also secondary transformer has a tapping of 220v and 250v.

d) LC filter:This inverter contains the LC filter for filtration. It is having proper values of

inductor and capacitor to give effective and proper output wave form.

e) Output Port:It provides the output of 230v constant even if main supply fails.

f) Sensing Circuit:Here one Relay is used for sensing that mains supply is on or off. If mains supply

is fails this relay will trip and inverter automatically starts to give the Constant

Output. A switching time of inverter is very less up to 0.5-1 sec.

g) Battery:For backup we have used 2 batteries. Both having same ratings.2 batteries are of12 v, 3.5 AH.

Electrical safety in case of battery: There is no danger of electric shock from a 12

volt battery. But if the wind generators disconnected from the battery, and running fast,

then the voltage will be higher than 12 volts, maybe as high as 50 volts. Do not run the

Generator at high speed without a battery connected.


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6.8 Actual Hardware schematic


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Explanation of the schematic diagram:

Here in our project we have use a P89V51RD2 controller. It is using 5v supply

from the main battery through voltage regulator IC 7805. We used only 4 output pin and

Vcc of the controller for switching the mosfet to generate the Output signal. SPWM can

be generated through the programming of controller. And look up table for SPWM

technique can be made up from the PC software PSIM. From this software we can get the

intersection points of the carrier waves and Sine wave which can be shown below. From

that software we can get SPWM look up table also it is shown below.

6.9 System Design

6.9.1 Overview 8051 Microcontroller

Descripssion:

The P89V51RD2 is a low-power, high-performance CMOS 8-bit microcomputer

with 4K bytes of Flash programmable and erasable read only memory (PEROM). The

device is manufactured using Philipss high-density non-volatile memory technology andis compatible with the industry standard MCS-51 instruction set and pin out. The on-chip

Flash allows the program memory to be reprogrammed in-system or by a conventional

non-volatile memory programmer. By combining a versatile 8-bit CPU with Flash on a

monolithic chip, the PhilipsP89V51RD2 is a powerful microcomputer which provides a

highly-flexible and cost-effective solution to many embedded control applications.

VCC

Supply voltage. +5.0V

GND

Ground.

Port 0

Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can

sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high


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impedance Inputs. Port 0 may also be configured to be the multiplexed low order

address/data bus during accesses to external program and data memory. In this mode P0

has internal pull-ups. Port 0 also receives the code bytes during Flash programming, and

outputs the code bytes during program verification. External pull-ups are required during

program verification.

Port 1

Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 output

buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins they are pulled

high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are

externally being pulled low will source current (IIL) because of the internal pull-ups. Port

1 also receives the low-order address bytes during Flash programming and verification.

RST

Reset input. A high on this pin for two machine cycles while the oscillator is

running resets the device.


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ALE/PROG

Address Latch Enable output pulse for latching the low byte of the address during

accesses to external memory. This pin is also the program pulse input (PROG) during

Flash programming. In normal operation ALE is emitted at a constant rate of 1/6 the

oscillator frequency, and may be used for external timing or clocking purposes. Note,

however, that one ALE pulse is skipped during each access to external Data Memory. If

desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit

set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is

weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in

external execution mode.

PSEN

Program Store Enable is the read strobe to external program memory. When the

AT89C51 is executing code from external program memory, PSEN is activated twice each

machine cycle, except that two PSEN activations are skipped during each access to

external data memory.

EA/VPP

External Access Enable. EA must be strapped to GND in order to enable the device

to fetch code from external program memory locations starting at 0000H up to FFFFH.

Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA

should be strapped to VCC for internal program executions. This pin also receives the 12-

volt programming enable voltage (VPP) during Flash programming, for parts that require

12-volt VPP.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating

circuit.

XTAL2

Output from the inverting oscillator amplifier.


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6.9.2Basic Power Circuit of P89V51RD

6.9.3Power Supply

Simple 12Vdc power supply:

Brief description of operation: Gives out well-regulated +12V or 5v dc output from 12v acinput.

Circuit protection: Built-in overheating protection shuts down output when regulator ICgets too hot

Circuit complexity: Very simple and easy to build Circuit performance: Very stable +12V or 5v dc output voltage, reliable operation Availability of components: Easy to get, uses only very common basic components Design testing: Based on datasheet example circuit, I have used this circuit successfully as

part of many electronics projects

Works on 12v dc input. Here three power supply of this type are used, as shown in circuit above.


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The grounds of this power supply are different.6.9.4 Circuit description

This circuit can give +12V or 5vdc dc output when 12V ac I/P given. The circuit

has over overload and terminal protect

6.9.5Mosfet driver

There are 2 mosfet named IRF3205 are connected in half-bridge. Which are given to

the 2 IC TLP250 and output of the controller is also fed to this IC. Outputs of ICs aregiven to the mosfet which are connected in Half-Bridge. Also battery supply is fed to all

the mosfet. Finally output is given to transformer and that can be filtered by LC filter.

Output waveform is shown in fig.

The power circuit topology and output voltage of half bridge inverter is shown in

Figure. The inverter circuit consists of two controlled static switching elements. The

switching elements can be BJT, MOSFET, and IGBT. The switching elements are labeled

Q1 and Q2 and each of switches has an anti-parallel diode.

It is evident from the presence of the diodes that the switching devices Q1 and Q2

need not have the capability to block the reverse voltages. If the switching element is

power MOSFET, there may not be a need to use the anti-parallel diodes because the

devices structure has an anti-parallel diode. The basis operation of half bridge inverter can

be divided into two operations. If switch Q1 turned on for period ofT/2, the instantaneous

output voltage across the load equal to Vdc/2. If switch Q2 turned on for period ofT/2 to T,

the instantaneous output voltage

Vdc/2 will appear.


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The switching strategy for switch Q1 and switch Q2 must be designed to make

sure both switches not turn on at the same time. If that happens, it is equivalent to a short

circuit across the DC input, resulting in excessive current and possible damage to the

switching element.

Fig.6.2: Single Phase Half Bridge Inverter configuring and waveform

Fig.6.3: Output from the Half bridge


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Fig.6.4 Compare Mainoutput or H bridge Output

6.9.6 Lc Filter

The power circuit section is composed of four parts namely half bridge inverter

circuit, DC power supply, LCfilter and load. SPWM inverters include semiconductor

devices with nonlinear characteristics and can generate dominant harmonics in the system.

The waveform quality of the sensitive load is improved by putting an LC filter at the

output of the SPWM inverter. In order to design an LC filter, there are many methods

available. Optimum performance can be obtained by using in simulation and experimental

studies. A rule of thumb in control theory is that the frequencies of such a configuration

have to have at least a factor of 10 between them to decouple the effects. According to this

rule, for 50-Hz fundamental frequency, resonance frequency has to be at least 500-Hz,

pulse frequency of the inverter output has to be at least5000-Hz. Resonance frequency isdetermined by the product of L and C.


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W =

6.9.7 Software

Fig.6.5: PSIM software outlook for SPWM look up table

Fig.6.6: Intersection between reference sinewave and carrier waves


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From the software PSIM we take the example of the SPWM circuit and take

the output waveform of the 4 mosfet h-bridge. Here we took the two frequency one

is carrier waves of a 1500hz and another is reference sine waves of 50 hz. By

compairing them we get the intersection points and make look up table according to

this intersection points. We use this lookup table to start and stop timer 0 in the

software to generatate SPWM waveforms and it is given to the mosfet h-bridge

circuit.

Table 1


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6.9.8 Flow cart

START

Initialize Timer 0

Start Timer 0

If (i=29)

Yes

No

i=0

j=~j

If Timer 0 Overflow

Interrupt Occures?

i++

If (J=0x00)

TL0=LSB[i]

TH0=MSB[i]

Timer 0 ON

L1 OFF

L2=onoff[i]

(Make L2 ON/OFF according to

SPWM lookup Table)

If (J=0xFF)

TL0=LSB[i]

TH0=MSB[i]

Timer 0 ON

L2 OFF

L1=onoff[i]

(Make L1 ON/OFF according to

SPWM lookup Table)

No

Yes

Yes

No

No

Yes


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6.9.9 Inverter hardware photo

Control circuit :

Fig.6.7: PCB Lay out of Control Circuit and Sensing Circuit

Driver circuit :

Fig.6.8: PCB Layout of mosfet Driver circuit


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Filter circuit:

Fig.6.9: PCB Layout of LC filter

Transformer .(10vac to 220vac):

Fig.6.10: Transformer for step up voltage


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Fig.6.11: Our Inverter

6.9.10 About Battery (Volts, Amps and Watts)

Watts are the units of power. A hairdryer full-on might be 500 watts; on the low-

power setting it might be 200 watts. Higher the power the bigger the charger. Voltage

must be matched to the equipment in use and will be either 12 volts or 24 volts in a boat.

Current indicates the flow of energy from the battery and is measured in amperes (or

amps). Zero current and the battery are not discharging. The higher the current the fasterthe battery will discharge.

A battery is rated in AmpereHour (abbreviated Ah) and this is called the battery

Capacity. For example, a small boat might have a 12 volt 100Ah battery. This battery will

Provide 100 AMPERE-HOURS before needing to be re-charged. This may be taken from

the

Battery as

1 AMP for 100 hours

2 AMPS for 50 hours


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10 AMPS for 10 hours etc.

WATTS are VOLTAGE multiplied by CURRENT, so taking the above example

with the 12 volt Battery

1 AMP x 12 VOLTS = 12 WATTS for 100 hours

2 AMPS x 12 VOLTS = 24 WATTS for 50 hours

10 AMPS x 12 VOLTS = 120 WATTS for 10 hours.

6.9.11 Battery size calculation

The backup time is simply the number of hours, Inverter will be able to run

Lighting load, during Power Failure.

The backup time in hours can be calculated using following Formula:

Backup Time =AH x 12V x N x P.F. x Efficiency of Battery (0.9)

Load in (VA)

Where,

AH stands for Ampere Hour Capacity of Battery

N stands for Number of 12 V Batteries needed

P.F. stands for Power Factor of Inverter

EFF stands for Efficiency of Battery

Load stands for Number of Tubes and Fans

6.9.12 Battery Recharging

Re-charging a battery follows the same principle. The requirement is usually to re-

charge the battery over-night - say in 10 hours. Because a battery is not totally efficient at

converting electrical energy into chemical energy and vice-versa, re-charging a 100Ah

battery requires about 120Ah to be put back into it, and this can be achieved by either

120 Amp-hours / 10 hours = 12 Amps for 10 hours

120 Amp-hours / 15 hours = 8 Amps for 15 hours

120 Amp-hours / 24 hours =5 Amps for 24 hours etc.

Current = watts / volts therefore if, say, the lights add up to 36 WATTS and the battery

Voltage is 12 Volts then The Current taken from the battery will be

36 Watts / 12 Volts = 3 Amps


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If these lights are on whilst the battery is being charged, then the battery charger

must also provide an extra 3 AMPS to power them.

6.9.13 Use of inverter

Inverter should be noted that the use of items:

Do not bring inductive load, such as the Counter, fluorescent lights, air-conditioning so as to avoid damage.

Inverters output load control is about 60% of the best, most reliable. Inverter with load is too light (for example, 1000VA, UPS with 100VA load) may

cause the battery depth of discharge, will reduce the battery life, should be

avoided.

Appropriate discharge, contribute to the activation of cells, such as the long-termnon-stop electricity, every three months to be artificially cut off electricity to use

UPS with a load-discharge time, so you can extend battery life.

For most small Inverter, to work to open Inverter, with load at boot time to avoidstartup, work should be shut down Inverter; for network computer room UPS,

because most of the network is 24 hours, so Inverter must also be running around

the clock.

Inverter charge promptly after discharge to prevent battery damage due toexcessive self-discharge.


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There is low environmental impact. There is no air pollution after manufacture. A massive tower structure is less frequently used, as

VAWTs are more frequently mounted with the lower bearing

mounted near the ground.

Designs without yaw mechanisms are possible with fixedpitch rotor designs.

The generator of a VAWT can be located nearer theground, making it easier to maintain the moving parts.

VAWTs have lower wind startup speeds than HAWTs.Typically, they start creating electricity at 6 m.p.h. (10 km/h).

VAWTs may be built at locations where taller structuresare prohibited.

These are well proven and occupy a relatively smallamount of land in proportion to their electrical output.

VAWTs situated close to the ground can take advantageof locations where mesas, hilltops, ridgelines, and passes funnel

the wind and increase wind velocity.

Modern wind energy converter systems can be set up forindividual houses, or as part of an electricity grid system

interconnected with other types of generating plant.

Because of their smaller footprint, vertical axis turbinesare the perfect solution for the urban setting.

Types of wind turbines

1. Horizontal axis(HAWT)

2. Vertical axis(VAWT)

Problem with HAWT:

The tall towers and

blades up to 45 meters

long are difficult to

transport.

Transportation can

now amount to 20% of

equipment costs.

Reflections from tall

HAWTs may affect side

lobes of radar

installations creating

signal clutter, although

filtering can suppress it.

HAWTs require an

additional yaw control

mechanism to turn the

blades and nacelle

toward the wind.

In order to minimize

fatigue loads due towake turbulence, wind

turbines are usually

sited a distance of 5

rotor diameters away

from each other, but

the spacing depends on

the manufacturer and

the turbine model.


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This means that even if you live in an apartment in themiddle of a bustling city, you can quite easily and practically fit

a vertical axis wind turbine to your building without causing too

much disruption

They also have a number of features attached to them thatmake them much more attractive if one thinks of the usual

objections towards horizontal axis turbines.

In this second post of a very short series, we will look atthese features, and the advantages that make vertical axis

turbines a real alternative to the conventional kind.

When it comes to planning applications, it may be a loteasier to get planning permission for a vertical axis wind turbine,

simply due to the fact that it does not take up as much space, and

in the built environment that is always an advantage.

They emit less noise. There is now ay around this, andthis will annoy those who own horizontal axis turbines. The

vertical turbines do officially make less noise than their

horizontal counterparts. This is obviously a bug winner for some

people, and answers one of the bigger arguments against wind

power outlined in the previous post.

When it comes to wildlife, a vertical axis turbineprovides less of a danger to birds, who will most probably not fly

into one. With a horizontal wind turbine, there is always the

chance that birds will fall foul of the machine, and therefore this

has another impact on the environment.

Problem with HAWT:

Tall HAWTs are difficult

to install, needing very

tall and expensive

cranes and skilled

operators.

Massive tower

construction is required

to support the heavy

blades, gearbox, and

generator.

Their height makes

them obtrusively visible

across large areas,

disrupting the

appearance of the

landscape and

sometimes creating

local opposition.

Downwind variants

suffer from fatigue and

structural failure

caused by turbulence

when a blade passes

through the tower's

wind shadow (for this

reason, the majority of

HAWTs use an upwind

design, with the rotor

facing the wind in front

of the tower).


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A VAWT that uses guy-wires to hold it in place puts stress on the bottom bearingas all the weight of the rotor is on the bearing. Guy wires attached to the top

bearing increase downward thrust in wind gusts. Solving this problem requires a

superstructure to hold a top bearing in place to eliminate the downward thrusts of

gust events in guy wired models.

The stress in each blade due to wind loading changes sign twice during eachrevolution as the apparent wind direction moves through 360 degrees. This

reversal of the stress increases the likelihood of blade failure by fatigue. While VAWTs' components are located on the ground, they are also located under

the weight of the structure above it, which can make changing out parts very

difficult without dismantling the structure, if not designed properly.

First, most of the turbines of this type only has an energy-producing capacitywhich is fifty percent less efficient than those produced by horizontal axis wind

turbines. Because there is no tower structure required, they cannot take full

advantage of the higher wind speeds that are available on higher, elevated

locations.

They also require energy to start the turning of blades due to their low startingtorque. They will have parts which are difficult to change without disassembling

the entire turbine should it not be assembled properly.


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There is no doubt that the Vertical axis windmills are a high speed device of

efficiency comparable to horizontal axis windmills.

It seems likely that this device will find use in the conversion of wind energy to

electric power especially if used on a large scale in conjunction with the grid.

In fact a 200 kW turbine driving a generator is at present being tested in Canada.

With such large devices it is quite feasible to have adequate control systems for

starting and controlling the system.

In India, however, the mean wind speeds are generally so low that it is unlikely

that wind power can be economically converted to electric power for grid augmentation.

The most practical use for wind power is likely to do direct water pumping for

drinking water and minor irrigation purposes.

The water pumping application generally implies high starting torque and low

control costs.

Hence it appears that Darrieus turbines arc not likely to be of much use in the

Indian context.

Single Phase Domestic Inverter is implemented and generated output near to sine

wave. SPWM technique reduces harmonic of generated output of Single Phase Domestic

Inverter which is required for Single Phase Domestic Electrical Appliances. SPWM

technique is difficult to implement but it requires less component, hence less costly and

viable for domestic use.


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Books

Electrical Machine Design of DHANPAT RAI & CO. by A.K.SAWHNEY. A text book of electrical technology (VOLUME 1) B.L. THERAJA &

A.K.THERAJA.

Engineering Electromagnetic ( SEVENTH EDITION) TATA McGraw HILL Power Electronics of Khanna Publisher by Dr. P.S. BIMBHRA. Muhammad Ali Mazidi, The 8051 Microconteroller and Embedded system,

2ndEddition.

Ramakangayakvad, Op-amps and linear integrated circuits

Websites

www.wikipedia.com/gps/index.shtml

www.datasheetcatalog.com

The Department of Energy, Utilities and Sustainability website at:

www.deus.nsw.gov.au/

The West wind Turbines website at: www.westwind.com.au/

The POWERCORP website at: www.pcorp.com.au/

The W.D. Moore & Co. website at: www.wdmoore.com.au/

The Country Energy website at: www.countryenergy.com.au/

The power-technology.com website at: www.power-technology.com

International Energy Agency website at: www.iea.org/
http://www.deus.nsw.gov.au/http://www.westwind.com.au/http://www.pcorp.com.au/http://www.wdmoore.com.au/http://www.countryenergy.com.au/http://www.power-technology.com/http://www.iea.org/http://www.iea.org/http://www.power-technology.com/http://www.countryenergy.com.au/http://www.wdmoore.com.au/http://www.pcorp.com.au/http://www.westwind.com.au/http://www.deus.nsw.gov.au/

5. vertical axis wind mill new

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