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A MULTI-LEVEL INVERTER FOR SOLAR ENERGY APPLICATIONS
J.Harshavardhan V.Ghouse Basha
III B.Tech III B.Tech
Department of EEE Department of EEE
SSITS.Rayachoti, A.P, India, SSITS,Rayachoti, A.P, India,
Mobile:+91-8464836628 Mobile:+91-8790060994
E-mail:[email protected] E-mail:[email protected]
ABSTRACT
A new multi-level inverter topology based on a H-bridge structure with four switches connected to the dc-link.
Based on a new PWM method which requires only one carrier signal is suggested.
The switching sequence to balance the capacitor voltage.
The proposed topology requires minimum number of component count to increase the number of voltage level.
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Presentation outlineIntroductionVarious topologies of multilevel invertersModulating strategies & features of MLICircuit Diagram & its implementationSimulation implementation & its results Advantages & ApplicationsConclusionFuture-scope
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INTRODUCTION
MLI produces nearly sinusoidal output
MLI control the lower order harmonics
MLI introduced by grid connected system
Topologies of MLI– Neutral point clamped type– Flying capacitor type
– Cascade type
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VARIOUS TOPOLOGIES OF MULTILEVEL INVERTERS:
comparisons of components requirements per phase multilevel inverters
TYPES OF CONNECTIONS:
• Diodes protect the circulating current • Capacitor gives the supply to switches
Neutral point clamped (NPC) type:
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• Capacitors are directly connected to the switches• capacitors are used to charging and discharging at unbalance voltages
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Flying capacitor type
•There is no interruption • Levels can be increased by cascade connection
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Cascade type:
Modulation strategies for multilevel inverters:
Features of Multilevel Inverters:
It may be easier to produce high voltage, high power inverter with multilevel structure
They can operate with a lower switching frequency
By increasing number of voltage levels the harmonic content of output voltage waveform decreases
CIRCUIT DIAGRAM OF THE PROPOSED SYSTEM:
Fig.1: Single- phase MLI
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Output voltage
(Vo)
Switching condition
Tp+ Tp- TN + TN - TA+ TB-
TA- TB+
Vdc ON OFF OFF ON ON OFF
0.5Vdc
OFF ON OFF ON ON OFF
ON OFF ON OFF ON OFF
0 OFF ON ON OFF ON OFF
OFF ON ON OFF OFF ON
-0.5Vdc
OFF ON OFF ON OFF ON
ON OFF ON OFF OFF ON
-Vdc ON OFF OFF ON OFF ON
SWITCHING STATES
Vo= -VdcVo= Vdc
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Vo=0.5VdcVo=-0.5Vdc
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Switching states (contd.)
Vo=0 Vo=0
Vo=-0.5Vdc Vo=0.5Vdc
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Switching states(contd.)
SOLAR INPUT CIRCUIT DIAGRAM
Fig.2: Single phase inverter system of solar input16
DC-link voltage 200V
Output voltage 110 Vrms
DC- link capacitor 2200 µF
Filter inductor(Lf) 300 µH
Filter capacitor(Cf) 150 µF
Switching frequency(Fsw)
5 KHz
Output frequency(fo) 60 Hz
SIMULATION DIAGRAM:
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SIMULATION DIAGRAM FOR SOLAR INPUT:
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SIMULATION RESULTS:
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Fig.3:Out put voltage and current wave form for R = 9.3 Ω(R-load)
Fig.4:Out put voltage of a 5-level multi-inverter
ADVANTAGES:
• Simple structure • Low power Consumption • Reduces the switching losses• Operating at fundamental frequency• More reliable
APPLICATIONS:
• Applicable for Solar/wind power generation
• Hybrid vehicles • Grid energy supply
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CONCLUSION:
Number of devices of the proposed multi-level inverter is fewer than that of the conventional multi-level inverters. The proposed system is more reliable and cost effective than the conventional two-level and multi- level inverters.
Switching loss of the four switches (TA+, TA-, TB+, TB-) is almost negligible. Only one carrier signal is required to generate the PWM signals for 4 switching devices (TP+, TP-, TN+, TN-).
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FUTURE SCOPE:
The proposed topology can be easily
extended to 7-level or higher level with
minimized active device component count.
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REFERENCES:
Gui- jia su, senior member ,IEEE “Multilevel DC-Link Inverter ”, IEEE Trans. on Indapplications,
vol.41, issue 4, pp.724-738,may/june 2005.
Zhong Du, Member,IEEE, Leon M.Tolbert, senior member “Fundamental Frequency Switching
Strategies of a Seven – level Hybride Cascaded H-Bridge MultiLEVEL Inverter ”, IEEE Transactions
on, vol.24, no.1, JANUARY 2009
J. Rodriguez, J. Lai, F.Z. Peng: “Multilevel inverters: a survey of topologies,controls, and
applications,” IEEE Trans. on Ind. Electronics, vol.49, issue 4, pp.724-738, 2002.
Baiju, M.R., Gopakumar, K., Somasekhar, V.T., Mohapatra, K.K., and Umanand, L.: ‘A space vector
based PWMmethod using only the instantaneous amplitudes of reference phase voltages
inverters’, IEEE, Trans. Ind. Appl 2005, pp. 297–309.
B.P. McGrath and D.G. Holmes, “Multi-carrier PWM strategies for multilevel inverters”, IEEE
Transactions on Industry Applications, vol.49, no.4, pp.858-867,August 2002.
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control,” IEEE Power Electronics Specialists Conference,Vol.2,1999,pp.777-782.
P. Hammond, “A new approach to enhance power quality for medium voltage ac
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References (Contd…)
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