Chapter 10 Single Phase Motors EE 342

7/27/2019 Chapter 10 Single Phase Motors EE 342

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END OF CHAPTER 7

(Induction Motors)

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(Page#633)

Single-Phase and

Special-PurposeMotors


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Split Phase or Resistance Start Single Phase Induction Motor

Not self starting.

Single phase winding produces alternating flux along one

space axis only not revolving.

Stator windings are similar to three phase except wound for

single phase.

Rotor construction is similar to the squirrel cage motor rotor.

Almost constant speed (like 3-phase induction motor)


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How to make it self-starting

Single phase stator winding is temporary (permanent )

converted into two phase for starting.

Starting (or auxiliary) winding is placed in parallel (900 degree

electrical apart) with the stator (or main) windings.

This produces 900 phase difference between the two (Is & Im)

currents, as a result revolving flux is produced.

Centrifugal switch automatically disconnect the startingwindings at 70 to 80 % of the rated speed.


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Xm.>>Xs Hence Im lags Is and applied Voltage (V)

I

V

Is

Im

T

80%Spee

d

200%

Rm

.


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Xm.>>XsRm


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T

80%

Speed

200%


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Transformer

Secondary

Centrifugalswitch

WAPDA1-Phase

220 Volts

50 Hz

Line

Neutral

Xs

Rs

Xm

Rm

I

Is Im

Xm.>>Xs Hence Im lags Is and applied Voltage (V)

Rm.


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Shaded-Pole Single Induction Motor Self-starting due to its

construction. Manufactured in rating of horse power. Rotor

construction is similar to the cage motor. Stator has even

numbers of salient poles connected in series for alternatepolarity.

A.C

Supply

Main

Field

Rotor

Shading pole

N


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Universal Motor

Operated on both on single phase ac and dc at same speed andoutput.

In construction it is exactly like dc series motor.

It has high starting torque ( T I2 ) and variable speed.

They are run on load, without load the speed is very high.

Application

Vacuum cleaner, mixers, drill machines, sewing machines,

automobile starters to crank engine.

Construction

Armature, Field windings, carbon brushes, commutator.


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http://www.radioelectronicschool.net/files/downloads/relay.gif

Relay


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Tacho Meter

(DC Generator)

Accelerometers areone of the latest

application of MEMS

technologies.

The most successful

MEMS accelerometersare based on

capacitive effects.


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Stepper Motors


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Operation principle of stepper motor:

There are many kind of stepper motors. Unipolar type, Bipolar type, Single-

phase type, Multi-phase type... Single-phase stepper motor is often used for

quartz watch. On this page, I will explain the operation principle of the 2-phase

unipolar PM type stepper motor.

In the PM type stepper motor, a permanent magnet is used for rotor and coils

are put on stator. The stepper motor model which has 4-poles is shown in the

figure on the left. In case of this motor, step angle of the rotor is 90 degrees.

As for four poles, the top and the bottom and either side are a

pair. coil, coil and coil, coil correspond respectively. For

example, coil and coil are put to the upper and lower pole. coil

and coil are rolled up for the direction of the pole to become opposite when

applying an electric current to the coil and applying an electric current to thecoil. It is similar about and, too.

The turn of the motor is controlled by the electric current which pours into , ,

and . The rotor rotational speed and the direction of the turn can be

controlled by this control.


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Unipolar Motors

This attracts the rotor into the

position shown. If the power

to winding 1 is removed and

winding 2 is energized, the

rotor will turn 30 degrees, or

one step.

To rotate the motor continuously,we just apply power to the

two windings in sequence.

Assuming positive logic,

where a 1 means turning onthe current through a motor

winding, the following two

control sequences will spin

the motor illustrated in the

figure.


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Animation of Unipolar

Unipolar Half Step


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St M t


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Stepper Motors


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http://sciences-physiques.ac-dijon.fr/documents/MPI/SortiesLogiques/MoteurPasAPas/Moteur3.htm

SWITCHED RELUCTANCE MOTOR


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SWITCHED RELUCTANCE MOTOR

A four-phase 8/6 switched-reluctance motor is shown in

cross section. In order to produce continuous shaft

rotation, each of the four stator phases is energized and

then de-energized in succession at specific positions of therotor as illustrated.


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Irfan :This is another concept of wind energy, generator fitted with balloon in

the air, its only for you information : Read from next slide about this

SEE ANIMATION: with slide show

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Chapter 10 Single Phase Motors EE 342