Speed control in induction motors using VFD's

1. Presented by
Lajin B S
Jiji Prabhash
Meghana Jayakumar
Nithin Joseph
Malini Mohan
Guided by: Mr. Rahul R S

2. OVERVIEW OF PRESENTATION
 AIM
 INTRODUCTION
 FUNCTIONAL BLOCK DIAGRAM
 WORKING PRINCIPLE

3. CONTND…
 FIRST PHASE
 ADVANTAGES
 DISADVANTGES
 APPLICATIONS

4. AIM
 Design of variable frequency drives for speed
control in single phase induction motor

5. PHASES OF PROJECT
 FIRST PHASE
• Experimental set up of the drive using basic knowledge
 SECOND PHASE
• Microcontroller programming
 THIRD PHASE
• Hardware design, assembling & installation

6. INTRODUCTION
 Most of the industries use induction motors as the
drives
 Rising energy price create a need for energy efficient
motor
 VFDS are useful in energy saving
 It reduces the motor speed as demand decreases
 VFDs consists of
 Electronic actuator-controller
 Driving electrical machines – motor
 Driven machine – pump, fan, blower…

7. FUNCTIONAL BLOCK DIAGRAM

8. WORKING PRINCIPLE
 Torque of IM depends on flux
 Flux α V/f ratio
 Hence torque α V/f ratio
 Speed = 120 * f/ P
 With load change, speed also changes
 By retaining V/f ratio constant, torque is
maintained

9. TORQUE SPEED CHARACTERISTICS OF IM

10.  Serving as the prime power sources for a seemingly
limitless array of small-horsepower applications in
industry and in the home.
 Single phase AC electrical supply is what is typically
supplied in homes, three phase electrical power is
commonly only available in a factory setting.
 Correctly sized and rated -- can last a lifetime with little
maintenance.
WHY SINGLE PHASE INDUCTION MOTOR?

11. PWM INVERTERS?
 Characterized by constant amplitude pulses
 Width of these pulses is modulated
 Different PWM techniques – Single pulse
modulation, Multiple pulse modulation and
Sinusoidal pulse modulation
 These techniques differ each other in harmonic
content
 Choice – on permissible harmonic content in
input

12. SINUSOIDAL PULSE WIDTH MODULATION
 Pulses over half cycle of unequal widths are
 generated
 Pulse width is a sinusoidal function of angular
 position of each cycle
 By comparing a sinusoidal wave against a triangular
 carrier wave
 Simple and ease of implementation
 No: of cycles is decided by ratio of triangular
 carrier frequency to that of modulating sinusoidal
 frequency

13. WAVEFORMS

14. CONTND…
 PWM inverter model has four sections
o Power supply section
o Power circuit section
o Load circuit section
o Gate control section

15. BASIC CIRCUIT

16. HARDWARE
Bridge
Rectifier
DC Chopper
PIC Microcontroller
Basic circuit
Keypad
& LCD
Connect
ion
Dead Band time
Generator
3-Phase Bridge
Driver
IGBT
3-Phase Inverter

17. COMPONENTS
 Diode rectifier- KBPC 35-10, Maximum recurrent
peak reverse voltage 1000 V. Maximum average
forward rectified current 35 A
 Supply source – 220V, 50 Hz ac
 Power circuit section – 4 No: of 2MBI50L-120 IGBTs,
1200V, 50 A,400 watts, Vgth > 20V
 Load circuit section –single phase induction motor
 Gate control section- PIC 16F877A, 5V
 Gate driver – IR21363, Gate drive supply voltage
10-20V

18. EXPERIMENTAL SETUP
 Software used- PROTEUS
 Microcontroller – 8051

19. PROGRAM
ORG 0000H
ST:
JNB P1.0,A1
JNB P1.1,A2
JNB P1.2,A3
JMP ST
A1:
CLR P2.0
CALL DELAY1
SETB P2.0
CALL DELAY1
JNB P1.1,A2
JNB P1.2,A3
JMPA1
DELAY1:

20. MOV R0,0FH
L1:MOV R1,0FFH
DJNZ R1,$
DJNZ R0,L1
RET
A2:
CLR P2.0
CALL DELAY2
CALL DELAY1
SETB P2.0
CALL DELAY2
CALL DELAY1
JNB P1.0,A3
JNB P1.2,A1
CONTND…

21. JMPA2
DELAY2:
MOV R0,0FH
L2:MOV R1,0FFH
DJNZ R1,$
DJNZ R0,L2
RET
A3:
CLR P2.0
CALL DELAY3
CALL DELAY1
CALL DELAY3
CALL DELAY1
CALL DELAY2
CONTND…

22. SETB P2.0
CALL DELAY3
CALL DELAY3
CALL DELAY1
CALL DELAY2
CALL DELAY1
JNB P1.0,A1
JNB P1.1,A2
JMPA3
DELAY3:
MOV R0,03FH
L3:MOV R1,0FFH
DJNZ R1,$
DJNZ R0,L3
RET
END
CONTND…

23. ADVANTAGES
 Rising energy prices creates a need for energy
efficient motor
 To reduce energy losses we select VFDs
 Improved operating performance
 Good control capability
 Efficient energy saving
 Consume less energy

24. DISADVANTAGES
 High cost
 System resonance
 Increased noise& vibration
 Shortens life
 Reduce service factor

25. APPLICATIONS
 Boiler pumps , fans& HVAC system
 Cooling towers
 Compressors
 Stairway & packing ventilation
 Kitchen hoods
 Roof top units
 Air handlers
 Elevators & escalators