Powe Electronics Unit 1 Ppt

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UNIT I

Power Semiconductor

Devices

Copyright by www.noteshit.com 102/20/16



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Introduction

• What are Power Semiconductor Devices (PSD)?They are devices used as switches or rectifiers in

power electronic circuits

• What is the difference of PSD and low-powersemiconductor device?

ar!e volta!e in the off state"i!h current capa#ility in the on state

202/20/16

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$lassification

%i!& '& The power semiconductor devices family

302/20/16




Important Parameters

• rea down volta!e&• *n-resistance&

Trade-off #etween #rea down volta!e andon-resistance&• +ise and fall times for switchin! #etween on

and off states&• Safe-operatin! area&

402/20/16




Power ,*S% T. Structure Power ,*S% T has much hi!her current handlin! capa#ility in

ampere ran!e and drain to source #loc in! volta!e(/0-'001)than other ,*S% Ts&

Fig.2.Repetitive pattern of the cellsstr ct re in power !"#F$%

&02/20/16




Power ,*S% T. +-1 $haracteristics

2n important parameter of a power ,*S% T is on resistance.

3 whereon S CH D R R R R= + +

( )CH n ox GS T

L R

W C V V µ =

−

%i!& 4& Typical + DS versus I D characteristics of a ,*S% T&

602/20/16




Thyristor. Structure• Thyristor is a !eneral class of a four-layer pnpn

semiconductin! device&

%i!&5 (a) The #asic four-layer pnpn structure& (#) Two two-transistor e6uivalent circuit&

'02/20/16




Three States.

+everse loc in!%orward loc in!%orward $onductin!

%hyristor( )*+ Characteristics

%i!&/ The current-volta!echaracteristics of the pnpn

device&

,02/20/16




2pplications

Power semiconductor devices have widespreadapplications.2utomotive

2lternator3 +e!ulator3 I!nition3 stereo tapentertainment

Power supplies3 stereo3 radio and television

2ppliance Drill motors3 lenders3 ,i7ers3 2ir conditioners

and "eaters-02/20/16




%hyristors

!ost important type of powersemicon ctor evice.

ave the highest power han lingcapability.they have a rating of 1200+ /1&00 with switching fre encies rangingfrom 1 to 20 .

1002/20/16




)s inherently a slow switching evicecompare to 5 % or !"#F$%.7se as a latching switch that can bet rne on by the control terminal b tcannot be t rne off by the gate.

1102/20/16




8ifferent types of %hyristors

#ilicon Controlle Rectifier 9#CR:.%R) C.

8) C.;ate % rn*"ff %hyristor 9;%":.

1202/20/16




#CR

#ymbol of#ilicon ControlleRectifier

1302/20/16




#tr ct re

}}}}

G a t e C a t h o d e

J3

J2

J1

A n o d e

1 0 c m1 7 - 3

1 0 - 5 x 1 0 c m1 3 1 4 - 3

1 0 c m1 7 - 3

1 0 c m1 9 - 3

1 0 c m1 9 - 3

1 0 c m1 9 - 3

n+

n+

p-

n–

p

p+

1 0 mµ

3 0 - 1 0 0 mµ

5 0 - 1 0 0 0 mµ

3 0 - 5 0 mµ

1402/20/16




8evice "peration

#implifie mo el of athyristor

1&02/20/16




+*)Characteristics

1602/20/16




$ffects of gate c rrent

1'02/20/16




%wo %ransistor !o el of #CR

⇒

1,02/20/16



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( ) ( )

' '

' '

' '

'

'

$onsiderin! P8P transistorof the e6uivalent circuit3

3 3 33

' '

E A C C

CBO CBO B B

B A CBO

I I I I I I I I

I I I

α α

α

= = =

= =

∴ = − − − − −

2002/20/16




( ) ( )

9 9 9

9 9

9 9

9

9

$onsiderin! 8P8 transistor

of the e6uivalent circuit3

3 3

9

C C B B E K A G

C k CBO

C A G CBO

I I I I I I I I

I I I

I I I I

α

α

= = = = +

= +

= + + − − −

2102/20/16




( )

9 '

9 ' 9

' 9

%rom the e6uivalent circuit3we see that

'

C B

g CBO CBO A

I I

I I I I α α α

∴ =

+ +⇒ =

− +

2202/20/16




( )

' 9

' 9

$ase '. When 0

'

g

CBO CBO A

I

I I I

α α

=

+=

− +

( )9 ' 9

' 9

$ase 9. When 0

'

G

g CBO CBO A

I

I I I I α

α α

≠

+ +=

− +

2302/20/16




% rn*onCharacteristics

on d r t t t = +

2402/20/16




% rn*offCharacteristi

A n o d e c u r r e n tb e g n ! t od e c r e a ! e

t C

t "

t

t

C o m m u t a t o nd

d t

# e c o $ e r % # e c o m b n a t o n

t 1 t 2 t 3 t 4 t 5

t r r t g r

t "

t c

&A '

(A

t " ) d e $ c e o * * t m e

t c) c r c u t o * * t m e

2&02/20/16




!etho s of %hyristor % rn*on

%hermal % rn*on.<ight.

igh +oltage.;ate C rrent.

v/ t.

2602/20/16




%hyristor %ypes

=hase*control %hyristors 9#CR>s:.Fast*switching %hyristors 9#CR>s:.

;ate*t rn*off %hyristors 9;%"s:.5i irectional trio e %hyristors 9%R) Cs:.Reverse*con cting %hyristors 9RC%s:.

2'02/20/16




#tatic in ction %hyristors 9#)% s:.<ight*activate silicon*controlle rectifiers9< #CRs:.F$% controlle %hyristors 9F$%*C% s:.!"# controlle %hyristors 9!C%s:.

2,02/20/16




=hase Control %hyristor %hese are converter thyristors.%he t rn*off time t 2 is in the or er of &0 to100 µ sec.7se for low switching fre ency.Comm tation is nat ral comm tation

"n state voltage rop is 1.1&+ for a 600+evice.

2-02/20/16




%hey se amplifying gate thyristor.

3002/20/16






5i irectional %rio e%hyristors 9%R) C:

3202/20/16




!o e*)

"peration

MT2 Positive,Gate Positive

P '

8 '

8 9

P9I !

I !

, T 9 ( : )

, T ' ( )−;1

( : )

3302/20/16




!o e*))

"peration

MT2 Positive,Gate Negative

P '

8 '

8 9 8 4

P9

I !

, T 9 ( : )

, T ' ( )−;

1

% i n a lc o n d u c t i o n

I n i t i a lc o n d u c t i o n

3402/20/16




!o e*))) "peration

MT2 Negative,Gate Positive

P '

8 '

8 5

8 9

P9

I !

, T 9 ( )−

, T ' ( : );( : )

3&02/20/16




!o e*)+ "peration

MT2 Negative,Gate Negative

P '

8 '

8 5

P9

I !

, T 9 ( )−

, T ' ( : ) 8 4

;( - )

3602/20/16




%riac Characteristics

3'02/20/16




BJT structure

note: this is a !rrent o" e#e trons $n%n ase& and so theon'entiona# !rrent "#o(s "ro) o##e tor to e)itter*

heavily doped < '0='/ provides the carriers li!htly doped < '0=> li!htly doped < '0=

3,02/20/16




BJT characteristics

3-02/20/16




BJT characteristics

4002/20/16




BJT modes of operation

!o e EBJ CBJ

Cutoff Reverse Reverseor!ardactive

Forwar Reverse

"everseactive Reverse Forwar

#aturation Forwar Forwar

4102/20/16




Cutoff . In cutoff3 #oth @unctions reverse #iased& There is very little current flow3 whichcorresponds to a lo!ical AoffA3 or an open switch&

Forward-active (or simply3 active ). The emitter-#ase @unction is forward #iased and the #ase-collector @unction is reverse #iased& ,ost #ipolar transistors are desi!ned to afford the!reatest common-emitter current !ain3 B " in forward-active mode& If this is the case3 thecollector-emitter current is appro7imately proportional to the #ase current3 #ut many timeslar!er3 for small #ase current variations&

Reverse-active (or inverse-active or inverted ). y reversin! the #iasin! conditions of theforward-active re!ion3 a #ipolar transistor !oes into reverse-active mode& In this mode3 theemitter and collector re!ions switch roles& Since most CTs are desi!ned to ma7imisecurrent !ain in forward-active mode3 the B " in inverted mode is several times smaller& Thistransistor mode is seldom used& The reverse #ias #rea down volta!e to the #ase may #e anorder of ma!nitude lower in this re!ion&

Saturation . With #oth @unctions forward-#iased3 a CT is in saturation mode and facilitatescurrent conduction from the emitter to the collector& This mode corresponds to a lo!icalAonA3 or a closed switch&

BJT modes of operation

4202/20/16

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BJT structure $active%

current of electrons for npn transistor

conventional current flows fromcollector to emitter&

BB

CCEEIIEE IICC

IIBB

&&

''

(( BEBE (( CBCB

&&

''

''&& (( CECE

4302/20/16




; %$ electro e is place above 9electrically ins latefrom: the silicon s rface? an is se to control theresistance between the #"7RC$ an 8R )@ regions

NM)#* @*channel !etal"Ai e #emicon ctor

n p * t y p e s i l i c o n

o A i / e i n s l a t o r n

+

+ B channel length

!etalD 9heavilyope poly*#i:

B channel wi th

!"#F$%

#)U"CE

-".IN

G.TE

4402/20/16




Eitho t a gate*to*so rce voltage applie ? no c rrent canflow between the so rce an rain regions.

bove a certain gate*to*so rce voltage 9 thresholdvoltage V T :? a con cting layer of mobile electrons isforme at the #i s rface beneath the oAi e. %heseelectrons can carry c rrent between the so rce an rain.

N&channe/ M)# ET

n

p

oAi e ins lator gate

n

8rain#o rce

;ate

ID

I;

IS

4&02/20/16




@*channel vs. =*channel!"#F$%s

For c rrent to flow? V ;# V %

$nhancement mo e( V % 0

8epletion mo e( V % G 0 H %ransistor is "@ when V ; B0+

p-type Si

n: poly-Si

n-type Si

p: poly-Si

NMOS PMOS

n: n: p: p:

For c rrent to flow? V ;# G V %

$nhancement mo e( V % G 0

8epletion mo e( V % 0 H %ransistor is "@ when V ; B0+

(“n+” denotes very heavily doped n-type material; “p+” denotes very heavily doped p-type material)

4602/20/16




M)# ET Circuit #0m1o/s

p*type #i

nI poly*#i

NM)#

nI nI

n*type #i

pI poly*#i

PM)#

pI pI

G G

G G

S

S S

S

5o y

5o y4'02/20/16




%he voltage applie to the ; %$ terminal etermines whether

c rrent can flow between the #"7RC$ J 8R )@ terminals. H For an n*channel !"#F$%? the #"7RC$ is biase at a lower

potential 9often 0 +: than the 8R )@9$lectrons flow from #"7RC$ to 8R )@ when V G V T :

H For a p*channel !"#F$%? the #"7RC$ is biase at a higher potential 9often the s pply voltage V DD : than the 8R )@9 oles flow from #"7RC$ to 8R )@ when V G G V T :

%he 5"8K terminal is s ally connecte to a fiAe potential. H For an n*channel !"#F$%? the 5"8K is connecte to 0 + H For a p*channel !"#F$%? the 5"8K is connecte to V DD

!"#F$% %erminals

4,02/20/16




V GS

#

semicon ctor oAi e

;

V DS

I−

I−

8

always eroL

I G

V GS

%he gate is ins late from thesemicon ctor? so there is nosignificant stea y gate c rrent.

I G

NM)# ET I G vs. V GS Characteristic

Consi er the c rrent I G 9flowing into G: vers s V GS (

4-02/20/16




V GS

#

semicon ctor oAi e

;V DS

I D

I−

I−

8

I D

ero if V GS G V T

V DS

@eAt consi er I D 9flowing into - : vers s V DS ? as V GS is varie (

Be/o! thresho/d3 $( G# 4 ( T%* no charge no con ction

.1ove thresho/d $( G# 5 ( T%*inversion layerD of electrons

appears? so con ctionbetween # an - is possible

V GS V T

NM)# ET I D vs. V DS Characteristics

&002/20/16




The M)# ET as a Contro//ed "esistor

%he !"#F$% behaves as a resistor when V DS is low (

H 8rain c rrent I D increases linearly with V DS

H Resistance R DS between #"7RC$ J 8R )@ epen s on V GS

R DS is lowere as V GS increases above V T

NM)# ET E6amp/e*I D

I DS B 0 if V GS G V T

V DS

V GS B 1 + V T

V GS B 2 +

Inversion charge densit0 Q i $ x % 7 &C ox 8V GS &V T &V $ x %9!here C ox ox : t ox

oAi e thicMness ≡ t ox

&102/20/16




I D vs. V DS Characteristics

%he !"#F$% I D&V DS c rve consists of two regions(

;% "esistive or Triode3 "egion* < 4 ( -# 4 ( G# ( T

2% #aturation "egion*

( -# 5 ( G# ( T

( )

oxnn

T GS n

DSAT

C k

V V L

W k I

µ =′

−′

=

where

9

9

oxnn

DS DS

T GS n D

C k

V V

V V L

W k I

µ =′

−−′=

where

9

process transc onductance parameter

CUT) 3 region* V G 4 V T &202/20/16



=art )( 5ipolar =ower %ransistorsThe Evo/ution )f IGBT

5ipolar =ower %ransistor 7ses +ertical #tr ct re For!aAimi ing Cross #ectional rea Rather %han 7sing =lanar#tr ct re

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=art ))(=ower !"#F$%The Evo/ution )f IGBT

=ower !"#F$% 7ses +ertical Channel #tr ct re +ers s%he <ateral Channel 8evices 7se )n )C %echnology





<ateral !"#F$% str ct re

&&02/20/16



The Evo/ution )f IGBT

8iscrete 5 % I 8iscrete =ower !"#F$% )n 8arlingtonConfig ration

=art )))( 5 %9 iscrete: I =ower !"#F$% 9 iscrete :




=art )+( 5 % 9physics: I =ower !"#F$% 9physics: B IGBT


!ore =owerf l n )nnovative pproach )s %o Combine=hysics "f 5 % Eith %he =hysics "f !"#F$% Eithin #ame#emicon ctor Region

%his pproach )s lso %erme Functional Integration OfMOS And i!olar "h#sics

7sing %his Concept? %he Insulated Gate i!olar Transistor

$IG T% $merge

# perior "n*#tate Characteristics? Reasonable #witching#pee n $Acellent #afe "perating rea

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);5% Fabricate 7sing +ertical Channels 9#imilar %o 5oth%he =ower 5 % n !"#F$%:

=art )+( 5 % 9physics: I =ower !"#F$% 9physics: B IGBT

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-evice )peration "peration "f );5% Can 5e Consi ere <iMe =@=

%ransistor Eith 5ase 8rive C rrent # pplie 5y %he !"#F$%

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8R)+$R C)RC7)% 95 #$ / ; %$:

)nterface between control 9low power electronics: an 9high power: switch.

F nctions( H amplifies control signal to a level re ire to rive power switch

H provi es electrical isolation between power switch an logic level

CompleAity of river varies marMe ly among switches. !"#F$%/);5% rivers are simple b t ;%" rivers are very complicate an eApensive .

6002/20/16




$<$C%R)C < )#"< %)"@ F"R 8R)+$R#

)solation is re ire to prevent amages onthe high power switch to propagate bacM tolow power electronics.

@ormally opto*co pler 9shown below: or highfre ency magnetic materials 9as shown inthe thyristor case: are se .

6102/20/16




$<$C%R)C < )#"< %)"@ F"R 8R)+$R#

=ower semicon ctor evices can be categori e into 3types base on their control inp t re irements(

a: C rrent* riven evices H 5 %s? !8s? ;%"sb: +oltage* riven evices H !"#F$%s? );5%s? !C%sc: = lse* riven evices H #CRs? %R) Cs

6202/20/16




C7RR$@% 8R)+$@ 8$+)C$# 95 %:

=ower 5 % evices have low c rrent gain e toconstr ctional consi eration? lea ing c rrent than wo lnormally be eApecte for a given loa or collector c rrent.

%he main problem with this circ it is the slow t rn*off time.!any stan ar river chips have b ilt*in isolation. ForeAample %<= 2&0 from %oshiba? = 31&0 from ewlett*=acMar ses opto*co pling isolation.

6302/20/16

$<$C%R)C <<K )#"< %$8 8R)+$ C)RC7)%#



Copyright by www.noteshit.com 6402/20/16

$N !=<$( #)!=<$ !"#F$% ; %$ 8R)+$R



@ote( !"#F$% re ires +;#

BI1&+ for t rn on an 0+ tot rn off. <!311 is a simple amp with open collectoro tp t O 1 .

Ehen 5 1 is high? = ; conducts . + ;# is p lle to gro n .

!"#F$% is off.

Ehen 5 1 is low? = ; !i// 1e off . + ;# is p lle to + ;; . )f + ;; is set to I1&+? the !"#F$% t rns on.

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