127335665 Variable Frequency Drive Ppt

8/11/2019 127335665 Variable Frequency Drive Ppt

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Submitted byT.VANI SANTHOSHI09W91A0252

CH.ASHWINI - 09W91A0217

V.PRIYANKA GOUD09W91A0256

D.BASAVESHWAR07W91A0208

E.RAVI RAJA - 08W91A0239

Under the guidance of

M.Spandana,M.tech

Asst.Prof, EEE department

Malla Reddy Institute of Engineering and Technology

VARIABLE FREQUENCY DRI


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A variable-frequency drive (VFD) is a typeof adjustable-speed drive

It is used in electro-mechanical drive systems to

control AC motor speed and torque by varying motor inputfrequency and voltage.

INTRODUCTION


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Systems employed for motion

control are called drives andmay employ any of the prime

movers such as diesel or petrol

engines ,electric motors, for

supplying mechanical energy

for motion control .

Drives employing electrical

motors are known as electrical

drives.

ELECTRICAL DRIVES


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There are two types of electrical drives mainly

1. DC Drives

2. AC Drives

DC drives are dc motor control systems

AC drives are AC motor speed control systems

TYPES OF ELECTRICAL DRIVE


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It controls the rotational speed of an AC

motor by controlling the frequency of

electrical power supplied to motor.

Its a specific type of adjustable speed

drive

What is a VFD


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Danfoss = First company to mass produce a.c. variable frequency drives (VFD)

EVOLUTION OF VFD

199819931988198319731968


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A variable frequency drive generally consists

of following:

Ac motor

Main controller assembly

Operator interface

DESCRIPTION OF VFD


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It is usually a 3phase inductionmotor.

An AC motor is an electric

motor driven by an alternating current.

The magnetic field on the rotor is eithergenerated by current delivered through

slip rings or by a permanent magnet.

AC MOTOR


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It is a solid state power electronic conversion device. It consist

main parts

Bridge rectifier

DC link

Inverter

MAIN CONTROLLER ASSEMBL


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It converts AC input power to DC intermediate power using a r

converter.

BRIDGE CONTROLLED RECTIF


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DC intermediate power is then

converted to quasi sinusoidal AC

power using inverter switching

circuit

DC LINK


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It changes DC energy into three channels of AC energy that can be

BASIC INVERTER


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The operator interface often includesan alphanumeric display and/or

indication lights and meters to

provide information about the

operation of the drive.

A serial communications port is also

often available to allow the VFD tobe configured, adjusted, monitored

and controlled using a computer

OPERATOR INTERFACE


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CIRCUIT DIAGRAM OF VFD

WORKING OF VFD


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AC motor characteristics

require the applied voltage

to be proportionally

adjusted whenever

frequency is changed in

order to deliver the ratedtorque

BLOCK DIAGRAM OF VFD
http://en.wikipedia.org/wiki/File:VFD_System.png


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There are many methods of control forfrequency in variable frequency drives

Among them PWM is mostly used becauits own advantages.

METHODS OF CONTROL


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Pulse-width modulation (PWM),

or pulse-duration modulation

(PDM), is a commonly used

technique for controlling power

to inertial electrical devices,

made practical by modernelectronic power switches.

PULSE WIDTH MODULATIO


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VFDs use their output devices (IGBTs, Transistors, thyristor

as switches.

They can be classified as

Voltage source inverter fed drives i.e. constant voltage

Current source inverter fed drives i.e. constant current

TYPES OF VFD


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Constant voltage converter : intermediate DC link vremains constant during each output cycle

Constant current drives : large inductor is placed beinput rectifier and the output bridge, so the current dnearly constant

CONSTANT CURRENT AND

VOLTAGES DRIVES


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Cooling of the motor is usually not good in low speedrange

.

When frequency reaches zero, motor is shut off.

The motor shall require a load reactor and filters if thepump leads from the VFD exceed certain conditions

FACTORS AFFECTING SPEED CON


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ENERGY SAVINGS

Example : vfd for cen

Flow is proportiona Power varies to the

speed change

20% reduction in sp

= 50% reduction in e

50% reduction in sp

= 80% reduction in e


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VFD controllers designed to operate at 111v volts

to 690v are often classified as low voltage units.

Typically designed for use with motor rated to

deliver 0.2 k.watts up to several mega watts.

Medium voltage VFD controllers are designed tooperate at 2400/4162 volts (60hz), 3000 volts(50

hz )

VFD RATINGS


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VFDs are frequently used to control motors for: Fans, Pump

Mills.

Oil & Gas, petroleum, petro chemistry: oil transfer pumps, c

pumps, etc.

Mining: mortar pumps, fans, etc.

Water and waste water: water supply pump, etc.

APPLICATIONS


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Hence variable frequency drives are mainly used because of thfollowing reasons:

Stable and reliable performance

Saves energy and therefore reduces energy costs

Isolated control signal provided by fibre optics between

Power cell and Controller

CONCLUSION


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QUERIES ???


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THANK YOU

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127335665 Variable Frequency Drive Ppt