Performance of Inverter Fed Induction Motor Under

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Performance of Inverter Fed Induction

Motor under

Open Circuit DC link Capacitor

Technical Presentation – II

Faculty in chargeMs.R.Jeyanthi

Assistant Professors

Department of EEE

Presentation by,

S.HEMAA!HA

ME "PED# $ % &ear3/27/2015 1 TECHNICAL PRESENTATON - II



'()!E)!S

Abstract

Introduction

Faults In Inverter Fed IM

Reason For Capacitor FailureProblem Description

imulation etup

Operation

!"perimental Result#aveforms

Conclusion

References

$%&$'&$()* T!C+,ICA- PR!!,TATO, . II



A*S!RA'!

Induction motors are /idel0 used in industr0

Ma1orit0 of induction motors are used in inverter baseddrives in industrial setups2

-iterature discusses the failure of electronic

Components like

po/er MOF!T3

Optocoupler failure3

Failure of pulse 4eneration card etc2

This research /ork is a continuation of fault anal0sis

studies

This paper presents the effect of dc link capacitor open

circuit on the performance of inverter fed induction

motor2

3/27/2015 TECHNICAL PRESENTATON - II 3



%)!R(D+'!%()

%nuction motors

#ide used in the industr0 due to

hi4h efficienc03

lo/ maintenance3

!ase in control mechanism5sed /ith po/er electronic based control s0stem to

achievin4 the re6uired mechanical characteristics

Po/er electronics s0stem needs to have a ver0

accurate tolerant s0stem for smooth operation ofindustrial /ork

43/27/2015 TECHNICAL PRESENTATON - II



Faults in inverter fed IM

Transistor failure3

DC link capacitor fault 7open circuit or short circuit83

9ate drive pulse failure and

Inverter le4 fault2

DC link capacitor The semiconductor failure /as mainl0 due to pulse

/idth modulation 7P#M8 control chips

the0 /ere not that reliable and sophisticated2ince3 the volta4e source inverters 7:I8 re6uired to

have a smooth dc link volta4es

Therefore capacitors are used in the dc link




Reason for capacitor failure

the a4ein4 of capacitor results in the increase of

e6uivalent series resistance 7!R82

This is a bi4 issue in s/itchin4 circuits

because !R can combine /ith the s/itchin4 fre6uenc0causes self heatin4 and indirectl0 leads to/ards the

failure of capacitor2

Capacitor open circuit ma0 occur due to dr0 solderin4 or

due to an error in the s0stem fabrication sta4e2

;%&$'&$()* T!C+,ICA- PR!!,TATO, . II



Problem Description

For a three phase :I used a DC link capacitor for smoothin4 the volta4e2

This capacitor also acts as a volta4e damper and provides a

sort of rid throu4h capabilit0 for an0 sa4 or s/ell in the input

volta4es2 This capacitor is fi"ed in shunt /ith the rectifier and the

inverter

therefore3 an0 fault in it can affect the performance of both

inverter and the rectifier2 In case of open circuit of DC link capacitor3 the inverter 4ets

dc input volta4e /ith ripples3 the fre6uenc0 of /hich is

dependent on the t0pe of input2

'%&$'&$()* T!C+,ICA- PR!!,TATO, . II



Continued22

For e"ample

if the three phase :I is fed via a sin4le phase rectifier

then the ripples at the input of inverter /ill be double

the source fre6uenc02

+o/ever3 if a three phase suppl0 is rectified for

obtainin4 volta4es at DC bus then the ripple fre6uenc0

/ill be si" times the source fre6uenc02

Therefore This paper discusses the anal0sis of capacitor

open circuit fault on the performance of inverter2

%&$'&$()* T!C+,ICA- PR!!,TATO, . II <



imulation setup

=%&$'&$()* T!C+,ICA- PR!!,TATO, . II



(peration

The fault in the DC link capacitor is reali>ed b0 an ideals/itch l3 that is connected in series /ith the DC link

capacitor2

The s/itch l acts as a short circuit /hen O,

completel0 cuts off the connection of DC link capacitor

/hen OFF2

A step chan4e is applied to the s0stem b0 turnin4 off the

s/itch l at time t?%sec2

%&$'&$()* T!C+,ICA- PR!!,TATO, . II )(



Propose moel

The parameters of induction motor used in this stud0 are asfollo/s

◦ Rated Po/er ? * hp

◦ Rated :olta4e ? @;( :

◦

Rated Fre6uenc0 ? ;( +>◦ Rated RPM ?)'*( rpm

MOF!Ts are used as po/er electronic s/itches in the

inverter2

The control method is based on inusoidal Pulse #idth

Modulation 7P#M8 /ith follo/in4 parameters2

◦ Carrier fre6uenc0 ? $(*( +>

◦ Control fre6uenc0 ? *( +>

◦ Amplitude modulation ratio ? (2<

◦

Fre6uenc0 modulation ratio ? @)))%&$'&$()* T!C+,ICA- PR!!,TATO, . II



Continued..

The motor is mechanicall0 loaded in terms of appliedtor6ue2

A step tor6ue of %2* ,.m is applied to the motor for

sin4le

< ,.m is applied for three phase input respectivel0 attime t?)2* sec2




Results

The induction motor is connected /ith sin4le and three phase suppl0 /here the input line volta4e is %<) :p 7for

$$( :8 /ith *(+> fre6uenc02

The 4enerated ripple fre6uenc0 is )(( and %(( +>

respectivel0 for sin4le and three phase input2 t/o comprehensive anal0sis studies of induction motor

behavior are carried out

#ithout creatin4 a fault

0 creatin4 a fault at DC link capacitor

%&$'&$()* T!C+,ICA- PR!!,TATO, . II )%



%n-erter -oltages an stator currents

ithout fault





• For a sin4le phase suppl0

• The ripple fre6uenc0 is onl0 )(( +> /hich means that for

sure a lar4e value capacitor is re6uired for smoothin4 of DClink volta4e2

• Fi4ure2 sho/s the effect of capacitor fault on DC link

volta4es2

•

The ripples are ver0 hi4h and about to touch the >ero level2



At time t?% sec fault is created that results in the

destruction of motor parameters as sho/n in Fi42




+i4h spikes are visible in stator current and volta4e/aveform3

the speed of the motor be4ins to decelerate sho/in4

clearl0 that the motor is no more able to /ithstand the

applied tor6ue2 The electroma4netic tor6ue also sho/s disturbance

after the capacitor 4ets open circuited







For three phase suppl0

The input is %)$ :p /ith *( +> fre6uenc02The 4enerated ripple fre6uenc0 is %(( +> /hich is ;

times the input fre6uenc02

The hi4h ripple fre6uenc0 is an advanta4e of usin4 three

phase s0stems and as sho/n in Fi42 ; the dc linkvolta4es contains ripple but the0 does not 4o to >ero2

in Fi42'2 The disturbance in stator current is ver0 minor

and the motor runs

but due to applied tor6ue and the ripples in the inverteroutput volta4e its speed is decreased2

The electroma4netic tor6ue also sho/s the chan4e after

the load tor6ue and the fault are applied2




'()'+S%()

This paper mainl0 hi4hli4hts the follo/in4 aspects

◦ Possible reasons of DC link capacitor open circuit2

◦ Investi4ated the chan4e in electrical and mechanical

parameters of a machine drive s0stem2

The failure of DC link capacitor could be a serious issue

if motor is runnin4 /ith sin4le phase suppl02

It is ver0 much clear that the use of three phase suppl0

for an inverter has a 4ood ride throu4h capabilit0 under

DC link capacitor failure2

$(%&$'&$()* T!C+,ICA- PR!!,TATO, . II



REFERE)'ES

A2 Mendes and A2 Cardoso3 BPerformance anal0sis of three.phase induction

motor drives under inverter fault conditions2B in Dia4nostics for !lectric

Machines3 Po/er !lectronics and Drives3 $((%2 D!MP!D $((%2 @th I!!!International 0mposium on2 I!!!3 $((%3 pp2 $(*.$)(2

A2 -ah0ani3 P2 :enet3 92 9rellet3 and P2 :iver4e3 BFailure prediction of

electrol0tic capacitors durin4 operation of a s/itchmode po/er suppl03 Po/er

!lectronics3 I!!! Transactions on3 vol2 )%3 no2 ;3 pp2 ))==.)$('3 $(($2

F2 Fuchs3 Bome dia4nosis methods for volta4e source inverters in variable speed

drives /ith induction machines.a surve03B in Industrial !lectronics ociet03 $((%2

I!CO,(%2 The $=th Annual Coriference of the I!!!3 vol2 $2 I!!!3 $((@3 pp2

)%'<.)%<*2

D2 Eastha and 2 ose3 BInvesti4ation of fault modes of volta4e.fed inverter

s0stem for induction motor drive3B Industr0 Applications3 I!!! Transactions on3

vol2 %(3 no2 @3 pp2 )($<.)(%<3 $(($2 !2 !brahim and ,2 +ammad3 BFault anal0sis of current.controlled P#Minverter

fed induction.motor drives2B in Properties and Applicationsmof Dielectric

Materials3 $((%2 Proceedin4s of the 'th International Conference on3 vol2 %2

I!!!3 $((%3 pp2 )(;*.)('(

$)%&$'&$()* T!C+,ICA- PR!!,TATO, . II

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Performance of Inverter Fed Induction Motor Under