MLI PPT(july31)

5/21/2018 MLI PPT(july31)

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Multilevel Inverter for 690V Applicatio

Guiding by,

Mr . CHELLADURAI J

MUT


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Literature Review : Multilevel Inverter:

MLI features:

Ability to reduce the voltage stress on each power device dueutilization of multiple levels on the DC bus

Important when a high DC side voltage is imposed by an appli

(e.g. traction systems)

Even at low switching frequencies, smaller distortion in the minverter AC side waveform can be achieved (with stepped modulation te

They can generate output voltages with extremely low distortlower dv/dt.

They draw input current with very low distortion.

They generate smaller common-mode (CM) voltage, thus redstress in the motor bearings. In addition, using sophisticated modulatio

CM voltages can be eliminated.


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Topologies:


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Modulation Techniques:


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Topology1:Diode Clamped multilevel inverte

The main concept of this inverter is to use diodes to limit the devices voltage stress. The voltage over each capacitor and each switch

An n level inverter needs (n-1) voltage sources, 2(n-1) switchinand (n-1) (n-2) diodes.

Formula:Number of switches=2(n-1)

Number of diodes= (n-1) (n-2)

Number of capacitors= (n-1)


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Topology2:Flying capacitor multilevel inverter

This inverter uses capacitors to limit the voltage of the power de

The configuration of the flying capacitor multilevel inverter is like

clamped multilevel inverter except that capacitors are used to divide thvoltage.

The voltage over each capacitor and each switch is Vdc.

Formula:

Number of switches=2(n-1)

Number of clamped capacitors= (n-1)*(n-2)/2Number of DC bus capacitors=(n-1)

For,5-level MLI For,9-level MLI

Number of Switches = 16 Number of Switches = 8

Total number of Capacitors = 10 Total number of Capaci


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Topology3:Cascaded H-bridge multilevel inver

The concept of this inverter is based on connecting H-bridge inseries to get a sinusoidal voltage output.

The output voltage is the sum of the voltage that is generated cell. The number of output voltage levels are 2n+1, where n is the numb

An n level cascaded H-bridge multilevel inverter needs 2(n-1) sdevices

where,

n is the number of the output voltage level.


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WEIGHT AND COST COMPARISON:


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SIMULATION

Documents

MLI PPT(july31)