working of VFD ,MATLAB simulation result of VFD

1. Subject: Control of Electrical Drives
Subject Code:2160913
Class: 6EE2
Prepared By,
Mayank Velani [160973109035]
PWM
INVERTER
FED VFD

2. 1. Theory
2. Circuit diagram
3. Simulation
4. conclusion
5. references
Index

3. The AC Induction Motor
Frequency is Speed
Where:
N = Speed in RPM
Fq = Frequency in Hz
P = The number of motor poles
120 is a constant for time conversion
P
f
N
*120


4. The AC Induction Motor
Voltage is torque
Where:
N = Speed in RPM
Fq = Frequency in Hz
P = The number of motor poles
5250 is a constant for time conversion
N
HP
Tq
5250*


5. Converter Inverter
Control
DC LINK
AC LINE
POWER
VARIABLE
FREQUENCY
AC VOLTAGE
CONVERTS 50/60 HZ
LINE POWER
INTO DC
INVERTS DC POWER
INTO ADJUSTABLE
FREQUENCY AC POWER
Variable Frequency CONTROL
Fig. Block Diagram of VFD

6. Variable Frequency CONTROL
SOLID STATE BLOCK
CONVERTER Dc capacitors
INVERTER

7. Variable Frequency Control
Converts AC power to DC power
DC Bus = RMS x 1.414

8. Variable Frequency Control
converter
PWM rectifier is an AC to DC power converter, that is
implemented using forced commutated power electronic
semiconductor switches. Conventional PWM converters are used
for wind turbines that have a permanent-magnet alternator.
Today, insulated gate bipolar transistors are typical switching
devices. In contrast to diode bridge rectifiers, PWM rectifiers
achieve bidirectional power flow. In frequency converters this
property makes it possible to perform regenerative braking. PWM
rectifiers are also used in distributed power generation applications

9. VFC Sections
 Inverts the DC Bus Voltage
into a PWM AC sine wave
 Monitors the motor Back
EMF to determine the load
Inverter
PWM wave

10. … At start up the the
discharged caps look as a
dead short to the AC line.
… The resistor allows the
caps to charge softly and
prevent fuse faults.
Soft Charge Circuit
Softchargecircuit

11. Simulation circuit

12. Simulation results
VOLTAGE WAVEFORM

13. CURRENT WAVEFORM

14. SPEED-TORQUE WAVEFORM

15. DC LINK WAVE FORM

16. THD ANALYSIS

17. Conclusion:
Thus, we concluded that when the motor works at
lower speed, then it will be the less energy utilize.
So, significant amount of power can be saved with
the help of Variable Frequency Drive (VFD).By
changing the frequency and supply voltage of
Induction Motor the speed of Induction Motor can
be changed. Thus, the Variable Frequency Drive
(VFD) can serve both in case of speed control as
well as Energy Saving.

18. References:
1. B.L.THERAJA,” A TEXTBOOK OF ELECTRICAL
TECHNOLOGY” PUBLIDHED BY S.CHAND
2. POWER ELECRONICS BY U A BAKSHI
3. POWER ELECTRONICS BY DR.PS BIMBHRA
4. MORDAN POWER ELECTRONICS AND AC DRIVE
BY BIMAL K. BOSE
5. FANDAMENTAL OF ELECTRICAL DRIVES BY
GOPAL K. DUBEY