This presentation prepared base on two research paper and electrical machine by NTPL IIT Madrash. Basic presentation on speed control introduction and method of speed control.

1. LUKHDHIRJI ENGINEERING COLLEGE
MORBI-2
( DEPT. OF ELECTRICAL ENGG. )
BASIC PRESENTATION ON
SPEED CONTROL OF INDUCTION MOTOR
SUBMITTED BY
130313109001 VISHAL BALDANIYA
130313109002 NILESH BAMBHANIYA
130313109003 TULSI BHATT
130313109004 MEHUL CHAUHAN
130313109005 DINESH CHUDASAMA
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2.  Flow of Presentation
 Introduction
 Requirement of speed control
 Type of method to control of induction motor
 Advantage and disadvantage
 Conclusion
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3. Introduction
Various method of controlling of speed of induction motor can
be visualized by equation
Rotating magnetic field with constant magnitude is produce
rotating with a speed
Where f = Frequency
p= No. of pole
(1 S)S sN n 
120
S
f
pN 
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4. Requirement of speed control
 Speed control means change the drive speed as desired by the process to maintain
different process parameter at different load.
 Energy saving.
 Speed control is different concept from speed regulation where there is a natural
change in speed due to change on load on the shaft.
 Speed control either done is manually by the operation or by the means of some
automatic control device.
 Low speed starting requirement.
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5.  Method of speed control of induction motor
Stator voltage control
Stator frequency control
Stator current control
V/F control
Static rotor resistance control
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6. Stator voltage control
 Synchronous speed
 Toque equation
120
S
f
pN 
2
T w
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7. • ROTOR RESISTANCE R2 IS CONSTANT AND SLIP IS SMALL TO
Sx2 IS SO SMALL THAT CAN BE NEGLETED THERE FOR T
proportional to sE2^2 , WHERE E2 IS ROTOR INDUSE EMF AND
HENCE T PROPRTINAL TO V^2
• THIS METHOD ESSY AND SIMPLE.
• STIL RARELY USE BECAUSE.
• A LARGE CHANGE IN SUPPLY VOLTAGE IS REQUIRMNET FOR
RELATIVELY SMALL CHANGE IN SPEED
• LARGE CHANGE IN SUPPLY VOLTAGE WILL RESULT IN LARGE
CHANGE IN FLUX DENSITY, HENCE DISTURBING THE
MAGNETIC CONDUCTIN OF MOTOR.
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8. Variable terminal voltage control
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9. Frequency control method
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10. By changing the frequency we can control the speed of above
and below the rated speed .
It offered high range of speed control.
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11. Stator current control method
Starting torque of induction motor Ts is proportional to sqare
of stator current
It is independent of supply of frequency.
It is independent of rotor resistance.
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12. A constant current o 3 phase induction motor can be obtain 3
phase CSI.
Inductor convertor the DC voltage as constant current source
CSI Regulated the output frequency and hence torque of
induction motor.
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13. How to speed control using VFD.
 RECTIFIRE
Rectifier use in VFD controller in convert ac to dc
 DC BUS
Dc output power flow through dc link to invertor input.
 IGBT
The insulated gate bi polar transistor is a common choice of VFD controller.
The IGBT through use control method name is pulse width modulation.
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14. V/f control
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15. ADVANTAGE & DISADVANTGE
ADVANTAGES
• EASSY SPEED CONTROL
• MAINTANACE IS LESS
• AC MOTOR IS LESS EXPENSSIVE.
• PROVIDE LOW SPEED STARTING
FACILITY.
• SAVE ENERGY
• REDUSE THERM AL AND MECH.
STRESS
DISADVANTAGES
• POWER CONVERTOR FOR FOR
CONTROL OF AC MOTOR ARE
MORE COMPLICATED.
• POWER CONVERTOR FOR AC
MOTOR ARE MORE
EXPENSSIVE.
• GENARATE HARMONIC OR
DISTURBUNCE.
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16. CONCLUSION:

 incase of squirrel cage induction motor the slip can not be increase
above certain limit the operating speed range is very less.
 By applying the v/f control we can get the large operating range by
keeping v/f ratio constant .
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17. Reference
[1] Electrical Machine by G.S. Rao and P.S. Rao BY NTPL IIT Madras.
[2] Speed control of a three-phase induction motor based on robust
optimal preview control theory M.M.M. Negm, M.H. Swedi IEEE
Transactions on Energy Conversion.
[3] SPEED CONTROL OF INDUCTION MOTOR DRIVE USING DC LINK
MEASUREMENT BY GOWTHAM S., PROF.ALLIRANI S (iCIRET2013)
2016

18. Thank you
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