Multi-level Inverter_ppt

7/29/2019 Multi-level Inverter_ppt

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MULTI-LEVEL INVERTERCASCADE H-BRIDGE INVERTER


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INVERTER

y The voltage source inverters produce avoltage or a current with levels either 0

or V dc they are known as two levelinverters.

y To obtain a quality output voltage or a

current waveform with a minimumamount of ripple content, they requirehigh switching frequency.

y

In high power and high voltageapplications, these two level inverters,however, have some limitations in

operating at high frequency.


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MULTI-LEVEL INVERTER

y The multi-level inverter is to synthesizea near sinusoidal voltage from several

levels of dc voltages.y As number of levels increases, the

synthesized output waveform has moresteps, which provides a staircase wavethat approaches a desired waveform .

y

Also, as steps are added to waveform,the harmonic distortion of the outputwave decreases, approaching zero as the

number of voltage levels increases


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TYPES OF MULTI-LEVEL

INVERTERy The Multi-level inverters can be

classified into three types.y 1. Diode clamped Multi-level inverter

y 2. Flying capacitor Multi-level inverter

y 3. Cascade Multi-level inverter


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Diode- clamped Multi level

inverterExtension of NPC

Based on concept of using diodes to limitpower devices voltage stress

Structure and basic operating principle Consists of series connected capacitors that divide DC bus

voltage into a set of capacitor voltages

A DCMI with nl number of levels typically comprises (nl-1)capacitors on the DC bus

Voltage across each capacitor is VDC/(nl-1)

( nl nodes on DC bus, nl levels of output phase voltage , (2nl-1) levels of output line voltage)


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Flying capacitor multilevel

inverter

Capable of solving capacitor voltage unbalanceproblem and excessive diode count requirement in

DCMI

Also known as imbricated cell multilevel inverter

(capacitors are arranged to float with respect toearth)

Structure and basic operating principle Employs separate capacitors precharged to

[(nl-1)/(nl-1)xVDC], [(nl-2)/(nl-1)xVDC] {[nl-(nl-1)]/[nl-1]xVDC}

Size of voltage increment between two capacitors defines size of

voltage steps in ICMI output voltage waveform


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Cascade H-bridge

Referred to as cascaded-inverters with SeparateDC Sources (SDCs) or series connected H-bridgeinverters

Structure and basic operating principle Consists of (nl1)/2 or h number of single-phase H-bridge inverters

(MSMI modules)

MSMI output phase voltage

Vo = Vm1 + Vm2 + .. Vmh

Vm1 : output voltage of module 1Vm2 : output voltage of module 2

Vmh : output voltage of module h

x Structure of a single-phase nl-level MSMI


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Circuit diagram


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.

The above circuit diagram can beexplained broadly by classifing into four

sub-circuits.

1. Dc power supply circuit.

2. Microcontroller circuit.

3. Driver circuit.4. Mosfet circuit.


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Dc power supply circuit

y It consists of step down transformer,diode bridge rectifier, regulators, capacitor,

resistance and led.Step down transformer:-

In the primary winding the supply is 230v ac

supply and at the secondary winding theoutput is 15v ac supply.

Diode bridge rectifier:-

The secondary winding output 15v acsupply is given and to diode full bridgerectifier.which rectifies the ac supply convert

to dc supply rated 12-15v dc supply.


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.

Regulators:-The output voltage 12-15v dc supply is regulated

to 12v by regulator Im7812 and 5v by regulatorIm7805.Capacitor:-

The capacitor filters the voltage.Resistance:-The resistance is used to with stand high current

from regulators and to give low voltage to LED.Led:-To show that supply is there.


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Microcontroller circuit

y Microcontroller circuit is used to give to

pulses to mosfet circuit.y It can give the pulses upto 5V.


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Driver circuit

y It acts just like a pulse generator .

y

It consists of IR2110 .y IR2110 can with stand the voltage upto

500volts

y The MOSFET requires 10-15v supply to

operate.


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Mosfet circuit

y The mosfet circuit is connected in MATLABstimulation way.

y Here we are considering IRFZ44n MOSFET.

y There are eight mosfets.

y In which S1,S2S5,S6 are positively connected.

y In which S3,S4,S7,S8 are negatively

connected.y In which S1,S2,S6,S8 are switched on and

other are switched off.


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APPLICATIONS

1. Reactive power compensator

2. Back to Back intertie3. Utility compatible adjustable speed

drives


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THANK YOU

Multi-level Inverter_ppt

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