DSP Based Online UPS_Sreevidhya@Students

8/2/2019 DSP Based Online UPS_Sreevidhya@Students

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A DSP Based On-line UPS


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Role of UPS in daily life: As an auxiliary power source in case of lineoutage, particularly useful to sensitive loads.

Maintains quality of the powersupply,i.e,eliminates harmonics.

Supplies power according to the loaddemand.

Among various UPS topologies, on-line UPS provides maximum protection to the loads against any utility power problem.


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TYPICAL ON-LINE UPS

Block diagram:

POWERSOURCE

STATICBY -PASS

RECTIFIER INVERTER CRITICALLOAD

BATTERYBANK

FILTER

INVERTER

BATTERY

BANK


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PULSE WIDTH MODULATIONNeed for PWM: To control inverter switching. To realize desired output waveform. To minimize the harmonic content in the output

wave.Mechanism of PWM:


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Different PWM techniques Analog PWM circuits. Using Micro-processors. With Digital Signal Processor chips.

Significance of using DSPs: Sophisticated switching algorithm. Flexibility in configuration. No analog circuitry. Chance for up gradation.


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DSP control of UPS systems.Basic block diagram:

surgefilter

rectifier

Userinterface

Softwarecommunication

batterycharger

inverter

battery

o/pfilter

DSPcontroller


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Internal architecture of DSP controller:

50 Hz sine wave

r.m.s Voltage compensator PWM inv . filter

A/D

Real harmonicdetector

Imaginary harmonicdetector

PIcompensator

PI

compensator

5 th harm

rms voltage

5 th harm .

rms setvalue


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Mathematically, a harmonic function to beeliminated is studied as fallows:

for eg; for a 5 th harmonic, the signal correlationfunction for harmonic distortion waveform iswritten as,

Therefore considering the 3 phases a,b,c andcalculating the average value of the distortion wavefor real and imaginary parts seperately,we get,


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and these amplitude components are

applied to a PI compensator to generate adistortion correction signal, necessary to cancelout harmonics from o/p voltage.

In the same way, any harmonic 7 th ,9 th etccan be eliminated.


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Merits of using DSP:Software controllable.Remote monitoring.Network management.High execution speed (30 MIPS).

Algorithm for DSP processors is generally written in any language like C, C++ etc.


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Flow chart for voltage control:start

if V=S

V=output rms voltageS= set value

error=0 Non zeroerror

To PWMinverter

To PIcompensator

stop To PWMinverter

Yes No


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DSPs vs. Microprocessors

1.Per cycle access:1-8 instructions 1-4 instructions

2.Software compatibility:Can be linked with MATLAB Can be linked with GUI

3.Performance:

Compound instructions RISC instructions performperform multiple single operation.Operations.

eg:multiply+load+modifies eg: add ,load or store.the address register.

4.SIMD:Limited SIMD features. No SIMD support.

5.Real time DSP chips used 5.Microprocessors used areare TMC62X, Blackfin etc P4,powerpc etc


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Advantages of using DSP in UPSs:

High Reliability.Low dimensions.Precision.

Interactive communication.Compact and sleek form factor.


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Closing thoughts:

To include more intelligent systems in itsarchitecture.

Cutting the cost by making its use extensive.Increasing the efficiency of electronic

components.


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REFERENCES1.DSP control of high -power feeding non- linear loads by

Annette Von Jouanne & Prasad N.Enjeti ,from IEEE transactions onIE,vol 43,no.1,Feb 1996.2.Digital Signal Processor based online UPS manual by

www.cranessoftware.com

3.Power electronics Analysis design & applications by Ned Mohan, Tore M.Undeland,William.P.Robbins4.Interfacing DSPs with high performance analog converters JimRyan5.WEMPEC-25 th anniversary review meeting ,R&D innovation centerEaton Corp.6. 2004 Bores Signal Processing : web pages..7.Kenton Wilson, Berekely design technology Inc, Calif..USA.
http://www.cranessoftware.com/http://www.cranessoftware.com/


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Questions ????

THANK YOU!!

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DSP Based Online UPS_Sreevidhya@Students