This paper presents the development of a universal controller board to control the speed of single or three phase induction motors. The controller uses a microcontroller and pulse width modulation inverter to generate variable frequency supply to the motor. MATLAB Simulink was used to simulate a three phase inverter circuit controlling an induction motor. Hardware was also implemented including power, control, and driver circuits. Testing showed the fan load speed could be varied by changing the modulation index with the selector switch, demonstrating variable speed control of the induction motor. The designed system provides a low-cost and versatile solution for motor speed control applications.

1. INDUCTION MOTOR
Paper: Speed Control of Induction Motor Drive Using Universal Controller
Arthors: Talukder, P.
Electron. & Electr. Eng., Heriot Watt Univ., Dubai, United Arab Emirates
Soori, P.K. ; Aranjo, B.
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2. Presented by:
Group -01
Members:
Gauhar Ali 1403081
Arif Shahriar 1403094
Utsha Barua 1403095
Radheshyam Nath Jisu 1403098
Mustafizur Rahman 1403099
Nirvik Barua 1403118
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3. Index terms:
Induction Motor
Microcontroller
Pulse Width Modulation Inverter
Speed control
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4. Basic Principle of Induction Motor:
 Due to flow of 3 phase AC current through stator winding coils , a revolving
flux is created.
 This revolving flux is cut by rotor windings which creates a induced voltage
hence current flows
 According to Lorentz's law, a magnetic force produces torque that rotates the
rotor
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5. At what speed the rotor will rotate?
 The rotor speed will never be equal to synchronous
speed. If rotor rotates at synchronous speed So there will
be no relative speed between rotor and revolving flux and
rotating loop will experience a constant magnetic field so
there will be no induced e.m.f and current. This means
zero force on rotor bars so the rotor will gradually slow
down, so induced e.m.f and voltage will rise again and the
rotor will speed up. In short the rotor will never be able
to catch up with the synchronous speed. It rotates with an
constant speed which is slightly less than the synchronous
speed
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6. Speed of an induction motor
depends upon the the AC supply,
more specifically it changes with the
frequency of the Alternating Current
proportionally.
When connected to main power supply, induction motors run at their
rated speed, however there are many applications where variable speed
operations are required.
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7. Speed Controlling of induction motor:
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Although a range of induction motor control techniques
are available, generating variable frequency supply is a
popular control technique, having a constant voltage to
frequency ratio in order to attain constant (maximum)
torque throughout the operating period. This control
technique is called as variable frequency control.

8. The synchronous speed of the stator revolving flux is given
by,
Where f is the supply frequency in Hz and P is the number of
poles.
As the number of poles is not variable, varying the supply
frequency would result in the variation in speed of the
induction motor.
To maintain the motor flux, the (E1/f1) ratio has to be kept
constant 8

9. Micro-controller used:
 The AT89C52
microcontroller is used,
which unlike a manual
controller, is able to store
all the commands to
generate the necessary
waveforms to control the
frequency of the inverter
through proper design of
switching pulses
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Microcontroller:A microcontroller is a small computer (SoC)
on a single integrated circuit containing a processor core,
memory, and programmable input/output peripherals.

10. This paper presents the development of an
efficient and versatile universal board which
is used to control the speed of single or three
phase machines with very minor
modifications in software and hardware.
This paper is divided into two parts. The first part is
the MATLAB Simulink simulation. The second part is
the hardware implementation of the developed
circuit.
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11.  Three Phase inverter simulation
The abselute circuit consists of a DC Voltage Source, PWM generator, Universal Bridge, A
synchronous machine and a Scope that displays the signals generated throughout the
simulation.
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12. The technique used to control the frequency of the three
phase voltage supplied to the motor from the Insulated Gate
Bipolar Transistor (IGBT) inverter circuit is Pulse Width
Modulation (PWM), which allows the speed to be varied with
respect to the frequency of the reference signal, input to the
PWM generator. The carrier frequency and the modulation
index were set to 1080Hz and 0.8 respectively. The simulation
was done twice, first with no-load and then with a constant
torque of 11.9N-m
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13. Insulated-Gate Bipolar Transistor (IGBT): is a three-terminal power
semiconductor device primarily used as an electronic switch .
Pulse Width Modulation ( PWM) : is a technique for getting analog
results with digital means.
Index Modulation : The modulation index of a modulation scheme
describes by how much the modulated variable of the carrier signal varies
around its unmodulated level.
Carrier Signal
Modulation Index ,h = _________________
Unmodulated Level
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14. 14

15.  Hardware Implementation
A. Power Supply Circuit
B. Control Circuit
C. Driver Circuit
D. Power Circuit
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16. The following test was
conducted in the laboratory. A
fan load was connected at the
output of the inverter and the
modulation index was varied
using the selector switch.
Hardware circuit consisting of the control, driver and
power circuit
Laboratory Test and Results
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17. As the modulation
index was varied, it
was noticed that the
speed of the fan
changed accordingly.
The variation of the inverter output voltage with modulation
index 17

18. Applications:
 It can be used in many different applications like stepper motor control.
 This universal board can hence be used for different kinds of laboratory
applications and can also help in enhancing the learning of different courses
such as Electrical Energy Systems and Electromechanical system.
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Many other variable frequency drive circuits have been
proposed by several authors, but none of them turned
out to be user friendly

19. References:
[1] B. Ismail, S.Taib, A.R Mohd Saad, M. Isa and I. Daut, “Development of Control
Circuit for Single Phase Inverter Using Atmel Microcontroller,” in Proc. 2006 ICoMMS
International Conference on Man-Machine Systems, September 15-16, Malaysia.
[2] Thida Win, Nang Sabai, and Hnin Nandar Maung, “Analysis of Variable
Frequency Three Phase Induction Motor Drive,” in Proc. 2008 World Academy of
Science, Engineering and Technology 42 2008.
[3] Mohd Fakhizan bin Romlie, Mohammad Fadhil Pesol, and Khairul Nisak Md
Hasan, “PWM Technique to Control Speed of Induction Motor using Matlab/xPC
Target Box,” in Proc. PECon 2008 Power and Energy Conference.
[4] Datasheet: Atmel 8-bit Microcontroller with 8K Bytes Flash
[5] Muhamad Zahim Bin Sujod, “Single-phase motor speed control using SPWM
inverter,” Honors dissertation, Dept. Electrical & Electronics Eng., Univ. of
Malaysia, Pahang, 2008.
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20. The designed system was
successfully fabricated and tested in
the laboratory.
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Thank you!