This document presents a project to control the speed of an induction motor using a variable frequency/variable voltage (V/F) method. The project team includes 6 members and is guided by Arun Kumar. The system uses a microcontroller to provide easy control over and adjustable speed capability for the induction motor. It consists of electronic components, a microcontroller, and an LCD display. The motor speed can be selected and adjusted to user-defined speeds under various load conditions, with the V/F ratio maintained constant to keep the air gap flux stable. Experimental results showing motor speed at different voltages, frequencies and loads are presented in a table.

1. PROJECT GUIDE
I.Arun Kumar.
TEAM MEMBERS
Ch.v.manoja(106K1A0237)
S.Ivan (106K1A0232)
B.Jyotsnadevi(106K1A0209)
M.Harish (106k1A0234)
R.Anjaneyulu (116k5A0207)

2.  Induction motors are widely used ac motors in industrial
area. Advanced semi conductor technology and uses of
microcontroller have made the speed control of induction
motor easier. The proposed paper presents variable speed
control application of induction motor using vf method.
 In this system, the speed of induction motor can be
adjusted to user defined speed. Microcontrollers can provide
easy control over induction motor. Microcontroller based
speed control system consist of electronic component,
microcontroller and the LCD. The system is tested and
experimental results are recorded for variable speed under
various load conditions.

3.  Microcontrollers can easily provide control over
induction motor
 Voltage and frequency is varied in accordance with
certain ratio, which in turn adjusts directly the motor
speed
 v/f ratio is maintained constant so as to keep air gap
flux constant
 Speed is displayed according to the difference
between reference or selected speed and measured
speed

4. MOSFET
BRIDGE
DRIVER
IC
MICRO
CONTR
OLER
POWER
SUPPLY
RESET
CRYSTAL
OSCILLATOR
SWITCHES
LOAD
LCD
BLOCK DIAGRAM

5. Motor speed
range
selection
Load Line voltage at
motor
terminal(volts)
Frequency(Hz) v/f
ratio
Motor
speed
(rpm)
Motor without load
S3(500rpm) 0 94 17 5 505
S2(1200rpm) 0 144 35 4 1217
S1(1440
rpm)
0 184 45 4 1428
Motor with load
S3(500 rpm) 500 132 36 3 504
S2(1200rpm) 500 162 44 3 1128
S1(1440rpm) 500 164 45 3 1156

6.  Wide range of operation.
 Speed is accurate .
 Simple control scheme.
 The speed is constant which means it will not vary
even by varying the load.
APPLICATIONS
 Used in industries for variable speed applications.