1. 3-Ø MULTILEVEL INVERTER USING SPWM
submitted
by
BATCH : 09EEE19
N MOHAN SAI KIRAN (09L31A0257)
P RAVI TEJA (09L31A0268)
MD ASIA PARVEZ (09L31A0254)
Y VINAY SUDGUN (09L31A0290)
Under the esteemed guidance of
Mr. K SRAVAN KUMAR
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
VIGNAN’S INSTITUTE OF INFORMATION TECHNOLGY :: VISAKHAPATNAM
2/23/2013 1
2. CONTENTS
Introduction of Inverters
Operation of Basic Inverter & its Output
Advantages of Multilevel Inverter (MLI’s)
3-Ø, 5 level inverter
Gate Control with SPWM technique
Simulink Schematic of 1-ph 3-level MLI & its Waveform
Simulink Schematic of 1-ph 5-level MLI & its Waveform
Comparison of 3-level and 5 level MLI’s
Work Completed
Future Work
Conclusion
References
2/23/2013 2
3. INTRODUCTION OF INVERTER
• DC AC at required voltage and frequency
• Controllable devices –SCRs' are used
• Main application
-uninterruptable power supply
-speed adjustment in ac drives
-hvdc transmission lines
2/23/2013 3
4. WORKING OF BASIC INVERTER
• T1, T2 –positive voltage
• T3,T4-negative voltage
• Magnitude of the output is
Controlled by the turn on time of
Thyristors.
2/23/2013 4
5. OUTPUT WAVEFORM OF BASIC INVERTER
• We observe the output is
a square Wave with
positive and negative
cycles.
• What we need is a sine wave
or an approximate wave of its kinds.
2/23/2013 5
6. Advantages of Multilevel Inverter (MLI’s)
• Multilevel inverters are well suited for reactive power
compensation
• It is easier to produce a high power ,high voltage inverter
with the multilevel structure as voltage stresses are
controlled
• As the number of voltage levels increases, the harmonic
content of output voltage waveform decreases
significantly
2/23/2013 6
9. SPWM TECHNIQUE
• By giving two inputs namely reference wave(sine) and carrier
wave(triangular) to the comparator we get the pulses as the
output
• When the reference wave is greater than the carrier wave then
the output is logic ‘1’ and when the reference wave is less
than the carrier wave then the output is logic ‘0’.
• Thus we are able to generate the required pulses
2/23/2013 9
17. Work Completed
• Design of single phase 3-level and 5-level Multi Level
Inverters using SPWM in MATLAB/SIMULINK.
• THD of single phase 3-level and 5-level Multi Level Inverters
for different Modulation Indexes.
2/23/2013 17
18. Future Work
• Formulating the schematic of the 3 phase, 5-level and its
waveforms along with its THD.
• After five level we may even go for the formulation of
schematic of the 3 phase , 7-level and its waveform with THD.
• Comparison of THD’s for both 5 and 7 level for different
modulation indexes.
2/23/2013 18
19. CONCLUSION
• We conclude that by the technique of pulse width modulation
we can control the switching of MOS-FET’s.
• We conclude the THD is less for higher the level of the
inverter.
• We even say that the THD decreases for the higher values of
modulation index.
2/23/2013 19
20. REFERENCES
• D. G. Holmes and T. A. Lipo, “Pulse width modulation for power
converters,” IEEE Press Series on Power Engineering, 2003.
• Leon M Tolbert and Thomas G Habetler, “Novel Multilevel inverter Carrier
based PWM method”, IEEE Transactions on Industry Applications, Vol.
35,no.5, pp. 1098-1107, Oct.1999.
• Zhong Du, Leon M. Tolbert, Burak Ozpineci, and John N. Chiasson,
“Fundamental Frequency Switching Strategies of a five-Level Hybrid H-
Bridge Multilevel Inverter”, IEEE Trans. On Power Electronics, Vol. 24,
No. 1, pp. 25- 33, Jan 2009
• Power electronics (circuits ,devices and applications) by Muhammad
H.Rashid
Power electronics by DR .P.S Bhimbhra
2/23/2013 20
