Forharsha basha

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 multilevel 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

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P. Hammond, “A new approach to enhance power quality for medium voltage ac

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C. Hochgraf, R. Lasseter, D. Divan, and T. A. Lipo, “Comparison of multilevel inverters

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References (Contd…)

THANK YOU

Engineering

Forharsha basha