The research paper published by IJSER journal is about Design of Dc-Dc Converter with Maximum Power Point Tracker Using Pulse Generating (555 Timers) Circuit for Photovoltaic Module 1
ISSN 2229-5518
Design of Dc-Dc Converter with Maximum Power
Point Tracker Using Pulse Generating (555
Timers) Circuit for Photovoltaic Module
Ainah Priye Kenneth
—————————— ——————————
A c c or d i n g t o [ 1 ] D C - D C c on ve r t e r s a r e w i d e l y u se d i n r e g u l a t e d sw i t c h mo d e D C p ow e r su p pl i e s. Th e i n pu t of t h e se c o n ve r t e r s i s u n r e g u l a t e d D C vol t a g e , w h i c h i s ob t a i n e d b y P V a r r a y a n d t h e r e f or e w i l l b e f l u c t u a t e d d u e t o c h a n g e i n r a d i a t i on a n d t e m pe r a t u r e . R e n e w a b l e e n e r g y i s g r ow i n g r a pi d l y a n d i t i s b e c o mi n g si g n i f i c a n t i n ou r w or l d t o d a y a n d i n t h e f u t u r e t o c o m e . P h ot ov ol t a i c ( P V ) i s on e of t h e m o st i m p or t a n t a r e a i n t h e f i e l d of r e n e w a b l e e n e r g y a n d h a s a t t r a c t e d l ot s of r e se a r c h . I n t h e pa st y e a r s, P V p ow e r g e n e r a t i on sy st e m s h a ve a t t r a c t e d a t t e n t i on d u e t o t h e e n e r g y c r i si s a n d e n vi r on m e n t p ol l u t i on . P h ot o v ol t a i c p ow e r g e n e r a t i o n sy st e m s c a n mi t i g a t e e f f e c ti ve l y e n vi r on me n t a l i s su e s su c h a s t h e g r e e n h ou se e f f e c t a n d pol l u t i on [ 2 ] . O n e ma j or pr ob l e m w i t h ph ot ov ol t a i c m od u l e i s t h a t t h e e l e c t r i c al ou t pu t po w e r d e pe n d s on t h e w e a t h e r c on d i t i on t h a t i s; t h e ou t pu t i s c h a n g i n g w i t h a c h a n g e i n w e a t h e r c on d i t i on w h i c h ma k e s ph ot ov ol t a i c mo d u l e n on l i n e a r p ow e r s ou r c e . D u e t o t h e w e a t h e r c on d i t i on me n t i on a b ove a n d ot h e r f a c t or s l i st e d b e l ow i n ( 2 . 0 ) , t h e ma x i mu m p ow e r p oi n t of t h e ph ot ov ol t a i c m od u l e a s d e sc r i b e b e l ow i n f i g u r e ( 5 , 6 ) w i l l sh i f t a w a y f r o m t h e ma x i mu m o pe r a t i n g poi n t of t h e m od u l e . B a se on t h i s r e su l t a ma x i mu m po w e r poi n t t r a c k e r ( M P P T) e m pl o y i n g D C - D C c o n ve r t e r i s d e ve l o p a n d u s e d
t o ma i n t a i n t h e ma x i mu m po w e r poi n t ( M P P ) of t h e m od u l e . M a n y M P P T me t h od s h a v e b e e n d e ve l o p ov e r t h e y e a r s t o a c h i e ve t h e ma x i mu m p ow e r p oi n t of t h e P V mo d u l e i n d i f f e r e n t pa pe r s; e x a m pl e s a r e t h e i n c r e m e n t a l c on d u c t a n c e ( I C ) me t h od [ 3 ] , pe r t u r b a t i on a n d ob se r ve ( P & O ) me t h od [ 2 ] , t h e f u z z y l og i c [ 2 ] , mi c r oc on t r ol l e r b a se me t h od [ 4 ] [ 5 ] e t c . I n t h i s pa pe r i t i s i n t e n d e d t o d e si g n a n e a sy t o u se D C - D C c on ve r t e r ( b o o st c on ve r t e r ) w i t h ma x i mu m p ow e r p oi n t t r a c k e r f or ph ot ov ol t a i c mo d u l e t o c on t r ol t h e ph ot ov ol t a i c i n t e r f a c e so t h a t t h e o pe r a t i n g p oi n t of t h e l oa d a n d ph ot o v ol t a i c m od u l e me e t a t t h e ma x i mu m p ow e r p oi n t n o ma t t e r t h e e l e c t r i c a l pow e r ou t p u t of t h e m od u l e . Th e c on ve r t e r w i l l b e c on n e c t e d b e t w e e n t h e p h ot ov ol t a i c m o d u l e a n d t h e l oa d ( a l e d b a se d l i g h t w i t h n o mi n a l v ol t a g e of 2 4 V ) w i t h ou t a b a t t e r y so a s t o su p pl y t h e l oa d w i t h
2 4 V a t a l l t i me . Th e d e si g n w i l l b e u se d b y b o t h sk i l l e d a n d u n sk i l l e d pe o pl e , a n d w i l l b e b o t h p or t a b l e a n d pr a c t i c a l i n t h e f i el d o f e n g i n e e r i n g a n d r e n e w a b l e e n e r g y . Th e me t h od i n t h i s pa pe r i s a f e e d b a c k mi c r oc on t r ol l e r b a se d M P P T c on t r ol me t h od w i t h a b o o st c on ve r t e r o pe r a t i n g i n c on t i n u ou s c on d u c t i on m od e . Th i s c h a r a c t e r i st i c of c on t i n u ou s i n pu t c u r r e n t ma k e s t h e b o o st c on ve r t e r s u i t a b l e a s ph ot ov ol t a i c i n t e r f ac e . Th e b l oc k d i a g r a m of t h e a d o pt e d me t h od i s d e sc r i b e d b e l ow i n f i g u r e 3 . Th e c om p on e n t u se d i n t h e pr o p o se c o n t r ol d e si g n i s a pu l se g e n e r a t or
IJSER © 2012
The research paper published by IJSER journal is about Design of Dc-Dc Converter with Maximum Power Point Tracker Using Pulse Generating (555 Timers) Circuit for Photovoltaic Module 2
ISSN 2229-5518
( 5 5 5 t i me r c i r c u i t ) t o c h a n g e t h e d u t y c y c l e , a mi c r oc on t r ol l e r a n d a g a t e . I n t h e pr oj e c t w e w i l l
a l so d e si g n a n d i mpl e me n t t h e D C - D C c o n ve r t e r
( b o o st c on ve r t e r ) .
P h ot ov ol t a i c c e l l a l so k n o w n a s sol a r c e l l i s u s e d t o c o n ve r t e n e r g y f r o m t h e su n d i r e c t l y i n t o e l e c t r i c al e n e r g y w i t h ou t a n y f or m of r ot a t i on a l pa r t s. P h ot ov ol t a i c c e l l s r e pr e se n t t h e b a s i c f u n d a me n t a l p ow e r c on ve r si on u n i t of ph ot ov ol t a i c sy st e m. T h e se c e l l s a r e ma d e f r o m se mi c on d u c t or s a n d l i k e a n y ot h e r s ol i d - st a t e e l e c t r on i c d e vi c e s e . g d i od e , t r a n si st or s a n d i n t e g r a t e d c i r c u i t , t h e y h a ve si mi l a r b e h a vi o r . P h ot ov ol t a i c c e l l s a r e u su a l l y a r r a n g e d i nt o m od u l e s a n d a r r a y w h e n a p pl i e d pr a c t i c a l l y [ 6 ] . Th e r e a r e d i f f e r e n t t y pe s of ph ot o vol t a i c c e ll s a va i l a b l e on t h e ma r k e t a n d y e t d i f f e r e n t ot h e r t y pe s of c e l l s a r e u n d e r d e ve l o p me n t e . g . d y e - se n si t i z e d N a n d - c r y st a l l i n e c e l l s. Th e r e a s on f or d i f f er e n t t y pe s of ph ot o v ol t a i c c e l l , ma t e r i a l s a n d st r u c t u r e i s t o e x t r a c t ma x i mu m po w e r f r om t h e c e l l a n d t o ma i n t a i n c o st t o a mi n i mu m. A c c or d i n g t o [ 6 ] e f f i c i e nc y a b ove 3 0 % h a ve b e e n a c h i e ve d i n l a b or a t or y a n d e f f i c i e n c y of pr a c t i c a l a ppl i c a t ion i s u su a l l y l e s s t h a n h a l f of t h i s va l u e . C r y st a l l i n e si l i c on t e c h n ol og y i s w e l l e st a b l i sh e d a n d i t s c e l l i s m or e e x pe n si ve b u t st i l l c on t r ol s a ma j or pa r t of t h e p h ot o vol t a i c ma r k e t w i t h e f f i c i e nc y a p pr oa c h i n g 1 8 % . O t h e r t y pe s of ph ot o v ol t a i c c e ll s l i k e a mor ph ou s t h i n f i l ms a r e l e s s e x pe n si ve b u t w i t h d i sa d va n t a g e of po or e f f i c i e n c y . Th e r e a r e se v e r a l f ac t or s t h a t a f f e c t t h e el e c t r ica l pe r f or ma n c e of a ph ot o v ol t a i c mod u l e f r o m o pe r a t i n g a t o pt i ma l o pe r a t i n g poi n t . Th e se f a c t or s a r e ( 1 ) S u n l i g h t i n t e n si t y / i r r a d i a t i on ( 2 ) C e l l t e m pe r a t u r e ( 3 ) L oa d r e si st a n c e a n d ( 4 ) S h a d i n g a n d t h e u se of ph ot o v ol t a i c a r r a y a n d ma x i mu m p ow e r p oi n t t r a c k e r ( M P P T) t o c u r b t h e se c h a l l e n g e s a r e d e ve l opi n g r a pi d l y .
3 OVERVIEW O F DC -DC CONVERT ER:
DC - D C c on ve r si on t e c h n ol og y i s a ma j or su b j e c t a r e a i n t h e f i e l d of pow e r e l e c t r on i c , p ow e r e n g i n e e r i n g a n d d r i ve s. Th e c o n ve r si on me t h o d s h a ve a p pl i c a t i on i n i n d u st r i e s su c h a s t e l e c om mu n i c a t i on s, a u t o m ot i ve , r e n e w a b l e e n e r g y , r e se a r c h e t c a n d h a ve g on e u n d e r se r i e s of
d e ve l o p me n t a l st a g e s f or m or e t h a n si x t y ( 6 0 y e a r s) . Th i s c on ve r si on t e c h n i q u e i s w i d e l y
a d o pt e d i n i n d u st r i a l a p pl i c a t i on a n d c om pu t e r h a r d w a r e c i r c u i t s. Th e i d e a s of D C - D C c on ve r si on t e c h n i q u e a n d d e ve l o p me n t h a ve b e e n on f or ov e r
8 0 y e a r s. Th e si m pl e st D C - D C c on ve r si on
t e c h n ol og y i s a vol t a g e d i vi d e r , p ot e n t i o me t e r a n d
s o on . B u t t h e e f f e c t of t h e se si mpl e c on ve r si on t e c h n i q u e s r e su l t e d i n p o or e f f i ci e n c y d u e t o f a c t t h a t t r a n sf e r ou t pu t v ol t a g e i s l ow e r t h a n t h e i n pu t vol t a g e . A c c or d i n g t o [ 7 ] , t h e r e h a ve b e e n m or e t h a n 5 0 0 pr ot ot y p e s of D C – D C c o n ve r t e r d e ve l o pe d f or m or e t h a n 6 0 y e a r s. A l l n e w t o pol og y a n d pr e se n t l y e x i st i n g D C - D C c on ve r t e r s w e r e d e si g n t o me e t s o me sor t of i n d u st r i a l or c om m e r c i a l a p pl i c a t i on s. Th e y a r e u su a l l y c a l l e d b y t h e i r f u nc t i on , f or e x a mpl e , B u c k c on ve r t e r , b oo st c on ve r t e r , b u c k - b oo st c on ve r t e r a n d z e r o - sw i t c h i n g ( Z C S ) a n d z e r o vol t a g e sw i t c h i n g ( Z V S ) c on ve r t e r s w h i c h a r e u se d t o r e d u c e , i n c r e a se vol t a g e < . r e s pe c t i ve l y . D C - D C c on ve r t e r s ( e . g . b oo st , b u c k , b u c k b o o st , e t c ) a r e a l s o i m pl e me n t e d w i t h ot h e r d e vi c e s a s ma x i mu m p ow e r p oi n t t r a c k e r s ( M P P T) f or ph ot o v ol t a i c m od u l e , f or e x a m pl e i n [ 8 ] a r e a l t i me M P P T e m pl oy i n g a D C - D C b oo st c on ve r t e r o pe r a t i n g i n c on d u c t i on mo d e i s u se d . I t a l so i n c l u d e s a pa ss i ve n o n d i s si pa t i ve t u r n on t u r n of f sn u b b e r i n or d e r t o a c h i e ve h i g h e f f i c i e n c y a n d t o r e d u c e E M I l e ve l d u e t o so f t sw i t c h i n g .
Th e d e si g n e d D C - D C b o o st c o n ve r t e r i s c on n e c t e d b e t w e e n t h e ph ot o v ol t a i c mod u l e a n d t h e l oa d s o a s t o e n a b l e t h e m od u l e o pe r a t e s a t ma x i mu m p ow e r a t a l l t i me . B o o st c on ve r t e r i s ma d e of u p f ou r e l e me n t s a s sh ow n b e l ow i n f i g u r e 1 , t h e y i n c l u d e t h e i n d u c t a n c e , d i od e , c a pa c i t or a n d M 0 S F E T. A s t h e n a me of t h e c on ve r t e r i mpl i e s, i t st e p s u p t h e i n pu t v ol t a g e w h i c h ma k e s t h e ou t p u t vol t a g e g r e a t e r t h a n t h e i n pu t v ol t a g e . T h e c on ve r t e r i s c on t r ol t h r ou g h t h e M O S F E T w h i c h a c t a s a sw i t c h . Th e O N a n d O F F of t h e sw i t c h ( M O S F E T) c o n t r ol s t h e ou t pu t vol t a g e b y c h a n g i n g t h e v ol t a g e of t h e i n d u c t a n c e s o a s t o e n a b l e t h e ph ot ov ol t a i c m od u l e pow e r t h e l oa d a t ma x i mu m vol t a g e . Th e o pe r a t i o n of t h e c on ve r t e r i s a n a l y z e d i n d i f f e r e n t ope r a t i n g c o n d i t i on . Th e o pe r a t i on of t h e c on ve r t e r i s a n a l y si s i n c on t i n u ou s c on d u c t i on m od e .
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The research paper published by IJSER journal is about Design of Dc-Dc Converter with Maximum Power Point Tracker Using Pulse Generating (555 Timers) Circuit for Photovoltaic Module 3
ISSN 2229-5518
D i vi d i n g b ot h si d e s of e q u a t i on ( 1 ) b y T s a n d r e a r r a n g i n g t e r m s y i e l d t h e t r a n sf e r f u n c t i on of
t h e c on ve r t e r . S e e t r a n sf e r f u n c t i on of t h e c on ve r t e r i n e q u a t i on ( 2 )
( 2 ) [ 9 ]
A n d e q u a t i on ( 2 ) c on f i r m s t h a t t h e ou t pu t v ol t a g e i s g r e a t e r t h a n t h e i n pu t .
A s su mi n g a l o s se s c i r c u i t , P d = Po ,
F i g u r e 1 S t e p u p d c - d c c o n v e r t e r [ 9 ] .
I n c on t i n u ou s c on d u c t i on m od e t h e i n d u c t a n c e c u r r e n t f l ow s c on t i n u ou s [ i L ( t ) > 0 ] a s i l l u st r a t e d w i t h t h e st e a d y st a t e w a ve f or m b e l ow i n f i g u r e 2 .
Th e r e f or e V d I d = V o I o
A n d
( 3 ) [ 9 ]
Th e t i me i n t e g r a l of t h e i n d u c t or vol t a g e o ve r o n e t i me pe r i od mu st b e z e r o i n st e a d y st a t e .
V d t on + (V d – Vo )t o f f =0 ( 1 )
W h e n t h e sw i t c h ( M O S F E T ) i s t u r n e d O N , t h e d i od e i s r e ve r se b i a se d , t h u s d i sc on n e c t i n g t h e ou t pu t st a g e . Th e i n pu t t h e n d e l i ve r s e n e r g y t o t h e i n d u c t or . W h e n t h e s w i t c h ( M O S F E T) i s t u r n e d O F F , t h e ou t pu t st a g e i s n ow r e c on n e c t e d a n d r e c e i ve s e n e r g y f r o m t h e i n d u c t or a s w e l l f r om t h e i n pu t . I n t h e st e a d y st a t e a n a l y si s pr e se n t e d h e r e , t h e ou t pu t f i l t e r c a pa c i t or i s a s su me d t o b e ve r y l a r g e t o e n su r e a c o n s t a n t ou t pu t vol t a g e V o ( t ) ~ V o [ 9 ] .
F i g u r e 2 . 0 E q u i v a l e n t C i r c u i t f o r b o o s t c o n v e r t e r i n c o n t i n u o u s c o n d u c t i o n m o d e ( C C M ) ; ( a) s w i t c h O N ; ( b ) s w i t c h O F F .
A ma x i mu m p ow e r p oi n t t r a c k e r i s a h i g h - e f f i c i e n c y D C - D C c on ve r t e r , w h i c h f u n c t i on s a s a n o pt i ma l e l e c t r i c a l l oa d f or ph ot ov ol t a i c c e l l , mo st c om m on l y u se d f or a s ol a r pa n e l or a r r a y a n d c on ve r t s t h e p ow e r t o a v ol t a g e or c u r r e n t l e ve l w h i c h i s m or e su i t a b l e t o w h a t e ve r l oa d t h e sy st e m i s d e si g n t o d r i ve . P V c e l l s h a ve a si n g l e o pe r a t i n g poi n t w h e r e t h e va l u e s of c u r r e n t a n d vol t a g e r e su l t i n a ma x i mu m p ow e r ou t pu t f or t h e c e l l [ 1 0 ] . M ax i mu m po w e r p oi n t t r a c k e r ( M P P T) i s b a si c a l l y a n e l e c t r on i c sy st e m t h a t c o n t r ol s t h e d u t y c i r c ui t of t h e c on ve r t e r t o e n a b l e t h e ph ot ov ol t a i c mo d u l e o pe r a t e a t ma x i mu m o pe r a t i n g p ow e r a t a l l c on d i t i on a n d n ot s o me s o r t of me c h a n i c a l tr a c k i n g sy st e m t h a t ph y si c a l l y r ot a t e t h e ph ot o v ol t a i c mod u l e s t o f a c e su n l i g h t d i r e c t l y . Th e a d va n t a g e s of M P P T r e g u l a t or s a r e g r e a t e st d u r i n g c l ou d y or h a z y d a y s, c ol d w e a t h e r or w h e n t h e b a t t e r y i s d e e pl y d i sc h a r g e d . Th e r e a r e d i f f e r e n t t y pe s of ma x i mu m po w e r p oi n t t r a c k e r me t h od s d e ve l o pe d o ve r t h e y e a r s a n d t h e y a r e l i st e d b e l ow a s f ol l ow s ( 1 ) P e r t u r b a n d ob se r ve me t h od , ( 2 ) I n c r e me n t a l c on d u c t a n c e me t h od , ( 3 ) A r t i f ic i al n e u t r a l n e t w or k me t h o d , ( 4 ) F u z z y l og i c me t h o d , ( 5 ) P e a k p ow e r p oi n t me t h o d , ( 6 ) O pe n c i r c u i t vol t a g e me t h od , a n d ( 7 ) Te mp e r a t u r e me t h od e t c . Th e M P P T pl a y s a ve r y si g n i f i c a n t r ol e b e c a u se w i t h ou t t h e M P P T t h e d e si r e ou t pu t e l e c t r i c a l pow e r w i l l n ot b e a c h i eve w i t h c h a n g i n g w e a t h e r c on d i t i on s. T h e a d opt e d
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The research paper published by IJSER journal is about Design of Dc-Dc Converter with Maximum Power Point Tracker Using Pulse Generating (555 Timers) Circuit for Photovoltaic Module 4
ISSN 2229-5518
t o pol og y f or t h e M P P T d e si g n w i l l c o m pr i se f o u r pa r t s, n a me l y M i c r oc on t r ol l e r , pu l s e g e n e r a t or
( 5 5 5 Ti me r C i r c u i t ) a n d a G a t e w h i c h ac t a s a b u f f er .
F i g u r e 3 s ys t e m b l oc k d i a g r a m
F r o m t h e b l oc k d i a g r a m a b ove , t h e D C - D C c on ve r t e r i s u se d a s a ph ot o vol t a i c i n t e r f ac e b e t w e e n t h e ph ot ov ol t a i c m od u l e a n d t h e l oa d t o p ow e r t h e l oa d ( L e d b a se l i g h t , 2 4 V ) . Th i s i s a c h i e ve d b y c on t r ol l i n g t h e d u t y c y c l e of t h e DC - D C b oo st c on ve r t e r . F r o m f i g u r e 3 , t h e mi c r oc on t r ol l e r t e n d t o ma x i mi z e t h e ou t p u t p ow e r f r om t h e ph ot o v ol t a i c mod u l e b y a d j u st i n g t h e d u t y c y c l e s o t h a t t h e ph ot ov ol t a i c m od u l e w i l l a l w a y s b e a t i t s ma x i mu m p ow e r a t a l l t i m e s. Th i s i s d on e b y c on t i n u ou sl y c ol l e c t i n g sa m pl e s of vol t a g e a n d c u r r e n t f r o m t h e ou t pu t of t h e ph ot ov ol t a i c mo d u l e i n c l u d i n g a r ef e r e n c e vol t a g e f r om t h e ou t pu t of t h e c on ve r t e r a s sh ow n i n f i g u r e 3 a n d e mpl oy i n g t h e mi c r oc on t r ol l e r t o i n c r e a se or d e c r e a se t h e v ol t a g e a p pl i e d t o t h e pu l s e g e n e r a t or ( P W M ) i n or d e r t o c h a n g e t h e d u t y c y c l e of t h e c on ve r t e r .
Th e d e si g n of t h e D C - D C c on v e r t e r r e q u i r e s i n p u t p ow e r w h i c h w i l l b e ob t a i n e d f r o m a ph ot ov ol t a i c m od u l e . Th e po w e r w i l l b e d e f i n e b y t h e I - V a n d P - V c h a r a c t e r i st i c c u r ve a s i l l u st r a t e d i n f i g u r e 5. 0 a n d 6 . 0 . To d e t e r mi n e t h e se c h a r a c t e r i st i c c u r ve s, t h e ph ot o v ol t a i c m od u l e w i t h g i ve n s pe c i f i c a t i on s w a s t e st e d i n t h e l a b . S e e s pe c i f i c a t i on i n t a b l e 1 .
Th e t e st w a s d on e i n t h e l a b or a t or y u si n g l a b se t u p sh ow n b e l ow i n f i g u r e 4 , t o a c h i e ve t h e
i n pu t v ol t a g e a n d c u r r e n t of t h e D C - D C c on ve r t e r . Th e t e st w a s d on e w i t h r a d i a t i on of 1 0 0 0 W / m2 a n d w i t h va r i a t i on of l oa d r e si st a n c e u si n g oh m’ s l a w ( V = I R ) , t o d e t e r mi n e t h e i n pu t vol t a g e a n d c u r r e n t . A l so 6 6 0 W / m 2 , 3 7 0 W / m2 w e r e a l so u se d t o a sc e r t a i n t h e va r i a t i on of p ow e r w h e n r a d i a t i on i s c h a n g e .
F i g u r e 4 , l a b o r a t o r y s e t u p f o r p h o t o v o l t a i c m o d u l e
F r o m f i g u r e 5 , e a c h n u mb e r r e pr e se n t d i f f e r e n t c om p on e n t i n t h e se t u p a n d t h e y a r e 1 : h a l o g e n l a m p, 2 : P y r a n o me t e r , 3 : P h ot ov ol t a i c m od u l e , 4 : A m me t e r , 5 , 6 : V ol t me t e r s a n d 7 : l oa d ( r h e o st a t ) .
Ta b l e 2 ; r e pr e se n t t h e l a b or a t or y t e st r e s u l t s of t h e ph ot ov ol t a i c m od u l e a t d i f f e r e n t i r r a d i a ti on . A l s o F i g u r e 5 a n d 6 d e m on st r a t e t h e p ow e r , v ol t a g e a n d c u r r e n t a t ma x i mu m p ow e r poi n t w h i c h i l l u st r a t e t h e c h a n g e s i n ma x i mu m ou t pu t p ow e r of t h e m od u l e w h e n r a d i a t i on c h a n g e s. I n t h e l a b or a t o r y t e st , a h a l o g e n l a m p i s u se a s su n r a y a n d a py r a n o me t e r , t o me a su r e i r r a d i a t i on a t d if f e r en t l e ve l . Th e py r a n o me t e r ou t pu t i s l i n e a r , 0 . 2 m V pe r W / m2 . A t st a n d a r d t e st c on d i t i on ( S T C ) , t h e ph ot ov ol t a i c mo d u l e pa r a me t e r s a r e sh o w n i n t h e t e c h n i c a l d a t a sh e e t i n t a b l e 1 . Th e ou t pu t p ow e r of t h e l a b or a t or y t e st r e su l t a t 1 0 0 0 W / m 2 w a s q u i t e d i f f er e n t t o t h a t of t h e t e c h n i c a l d a t a sh e e t of t h e ph ot ov ol t a i c mod u l e d u e t o t h e f a c t t h a t th e e x pe r i me n t w a s d on e i n d o or w i t h a h a l og e n l a m p w h i c h a f f e c t e d t h e i n t e n si t y of t h e r a d i a t i on on t h e m od u l e .
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The research paper published by IJSER journal is about Design of Dc-Dc Converter with Maximum Power Point Tracker Using Pulse Generating (555 Timers) Circuit for Photovoltaic Module 5
ISSN 2229-5518
2.5
PV CHARACTERISTIC CURVE
T a b l e 1 : T ec h n i c a l d a t a s h e e t of p h o t o v o l t a i c m o d u l e
Pmpp
2
1.5
1000W/m2
660W/m2
370W/m2
MPP
T a b l e 2 : p h o t o v o l t a i c m o d u l e t e s t r es u l t a t d i f f er e n t r a d i a t i o n .
IV CHARACTERISTICS CURVE
0.2
1
0.5
0
F i g u r e 6 , P - V C u r v e a t d i f f e r e n t i r r a d i a t i o n l e v e l .
A s st a t e d a b o ve t h a t D C - D C b o o st c on ve r t e r i s u se d a s ph ot ov ol t a i c i n t e r f ac e a n d i s d e si g n t o b oo st t h e ou t pu t v ol t a g e t o 2 4 V t o me e t t h e r e q u i r e me n t of t h e l oa d ( l e d b a se l i g h t ) . B a se d on t h i s f a c t s o me s pe c i f i c a t i on of t h e b o o st c o n ve r t e r w a s a s su me d t o me e t t h e l oa d d e ma n d , se e t a b l e 3 a n d b oo st c on ve r t e r d e si g n e q u a t i on s a s l i st e d i n e q u a t i on ( 5 ) , ( 6 ) ( 7 ) a n d ( 8 ) . E q u a t i on ( 1 ) r e pr e se n t t h e b o o st c on ve r t e r t r a n sf e r f u n c t i on w h e r e V o = ou t pu t v ol t a g e , V i = i n pu t vol t a g e a n d D r e pr e se n t
d u t y c y c l e . A l so F s = sw i t c h i n g f r e q u e n c y , L o = b oo st
Isc
Impp
0.15
0.1
0.05
0
MPP
1000W/m2
660W/m2
370W/m2
0 2 4 6 8 10 12 14 16 18 20
i n d u c t a n c e a n d C o r e pr e se n t ou t pu t c a pa c i t a n c e . ( 5 )
Δ I= ( 6 )
Δ V= ( 7 )
P i = P o = V i * I i = V o* I o ( A s su me 1 0 0 % e f f i c i e n c y of c on ve r t e r ) ( 8 )
voltage (V)
Vmpp Voc
F i g u r e 5 , I - V c h a r ac t er i s t i c c u r v e a t d i f f e r e n t i r r a d i a t i o n l e v e l
IJSER © 2012
The research paper published by IJSER journal is about Design of Dc-Dc Converter with Maximum Power Point Tracker Using Pulse Generating (555 Timers) Circuit for Photovoltaic Module 6
ISSN 2229-5518
current of photovoltaic module at 1000W/m2) | ||
Out put voltage | 24 | Volts |
Voltage ripples (5%) | 1.2 | Volts |
Current ripples (10%) | 0.0159 | Amps |
Input power (output power of photovoltaic module at 1000W/m2) | 2.55 | Watts |
Switching frequency | 20000 | Hertz |
T a b l e 3 : d e s i g n s p ec i f i c at i o n s .
W i t h t h e se e q u a t i on s a b o ve , I o, L , C a n d D w e r e c a l c u la t e d a n d l i st e d i n Ta b l e 4 u si n g r e si st i ve l oa d ( 2 2 5 . 6 Ω ) . S e e a p pl i c a t i on of c a l c u l a t e d va l u e s i n f i g ur e 8 w i t h si mu l a t i on r e su l t s i n f i g 9 –f i g 1 4 u si n g P s pi c e . I t i s a l s o u se f u l t o a d j u st t h e va l u e s of e a c h c o m p on e n t i n c l u d i n g t h e d u t y c y c l e t o a c h i e ve t h e r e q u i r e d r e su l t .
CALCULATED | VALUE | UNIT |
Duty cycle, D | 33 | Percent |
Load resistance, Ro | 225 | Ohms |
Output current, Io | 0.1064 | Amps |
Inductance, L | 16.5 | Henry |
Capacitor, C | 1.463µ | Farad |
T a b l e 4 : d e s i g n c a l c u l a t i o n
F i g u r e 7 D C - D C b o o s t c o n v e r t e r s i m u l a t i o n s C i r c u i t .
F i g u r e 8 O u t p u t v o l t a g e o f b o o s t c o n v e r t e r .
F i g u r e 9 : o u t p u t v o l t a g e r i p p l e , ∆ V
F i g u r e 1 0 : i n d u c t a n c e c u r r e n t r i p p l e
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The research paper published by IJSER journal is about Design of Dc-Dc Converter with Maximum Power Point Tracker Using Pulse Generating (555 Timers) Circuit for Photovoltaic Module 7
ISSN 2229-5518
F i g u r e 1 1 : i n d u c t a n c e c u r r e n t ( L 1 ) , c a p a c i t a n c e c u r r e n t
( C 3 ) a n d d i o d e c u r r e n t ( D 1 )
F i g u r e 1 3 : M O S F E T O N a n d O F F t i m e , ( s wi t c h i n g c u r r e n t )
F i g u r e 1 3 c o n v e r t e r s i m u l a t i o n d u t y c y c l e a t 3 3 % ( PW M )
To e n a b l e t ot a l c on t r ol of t h e ma x i mu m p ow e r p oi n t of t h e ph ot ov ol t a i c m od u l e , t h e p ow e r M O S F E T ( sw i t c h ) of t h e b o o st c on ve r t e r mu st b e sw i t c h i n g O N a n d O F F a s f a st a s p o s si b l e t o a v oi d sa t u r a t i on of t h e i n d u c t or . Th e ve r i f i c a t i on of t h e r e s po n s e of t h e d e si g n D C - D C c on ve r t e r h a s b e e n d on e f r o m t h e a b ove si mu l a t i on r e su l t s a n d i n ove r a l l i t pr ove s t h a t t h e c on ve r t e r w or k s w e l l a n d c a n b e u se d a s ph ot ov ol t a i c i n t e r f ac e .
P u l se g e n e r a t or c i r c u i t ( P W M ) i s on e of t h e ma j or c om p on e n t i n t h e pr o po se M P P T d e si g n i n t h e
pr oj e c t b e c a u s e c on t i n u ou s c h a n g i n g of t h e d u t y c y c l e d e t e r mi n e s t h e st e a d y st a t e ou t pu t vol t a g e of t h e b o o st c on ve r t e r w i t h r e g a r d s t o t h e i n p u t vol t a g e . I n t h i s pa pe r , a n a st a b l e mu l t i vi b r a t or ( 5 5 5 t i me r c i r c ui t ) , a c u rr e n t sou r c e a n d t h e ou t p u t vol t a g e of t h e mi c r oc on t r ol l e r a r e u se d t o pr od u c e t h e pu l se w a ve m o d u l a t i on ( P W M ) / d u t y c y c l e .
Th e mi c r oc on t r ol l e r pl a y s a n i m p or t a n t r ol e i n c h a n g i n g t h e d u t y c y c l e of t h e b o o st c on ve r t e r b y se n d i n g D C v ol t a g e t o t h e pu l se g e n e r a t i n g c i r c ui t a f t e r c a lc u l a t i n g a n d c o m pa r i n g t h e ma x i mu m p ow e r s of t h e ph ot ov ol t a i c m od u l e a n d r e f e r e n c e ou t pu t vol t a g e of t h e c on ve r t e r a t d i f f e r e n t i n t e r va l s. Th e mi c r oc on t r ol l e r ope r a t i on w i l l b e b a se d on t h e f l ow c h a r t . Th e mi c r oc on t r ol l e r w a s n ot a p pl i e d b u t w h e n t e st i n g t h e d e si g n sy st e m a vol t a g e s ou r c e w a s u se d i n pl a c e of t h e c on t r ol l e r t o c h a n g e t h e d u t y c y c l e w h e n t h e ou t pu t of t h e ph ot ov ol t a i c mo d u l e ( v ol t a g e s ou r c e ) w a s a l t e r e d t o a c h i e ve ou r d e si r e d ou t pu t .
IJSER © 2012
The research paper published by IJSER journal is about Design of Dc-Dc Converter with Maximum Power Point Tracker Using Pulse Generating (555 Timers) Circuit for Photovoltaic Module 8
ISSN 2229-5518
F i g u r e 1 4 s c h e m a t i c of p r o p o s e s ys t e m d i a g r a m
Th e d e si g n w a s i m pl e me n t e d w i t h t h e se l e c t e d pa r t s a n d u si n g a vol t a g e s ou r c e t o r e pr e se n t t h e P i c mi c r oc on t r ol l e r a s sh ow n i n f i g u r e 1 5 . A s t h e i n pu t v ol t a g e r e pr e se n t i n g t h e ph ot ov ol t a i c m od u l e c h a n g e s t h e r e i s a c or r e s po n d i n g c h a n g e i n ou t pu t v ol t a g e t h e n t h e v ol t a g e sou r c e r e pr e s e n t i n g t h e P i c mi c r oc on t r ol l e r i s a l t e r e d t o c h a n g e t h e d u t y c y c l e s o a s t o i n c r e a se t h e ou t p u t vol t a g e t o t h e d e si r e d va l u e . S e e r e su l t s f or ph ot ov ol t a i c ou t pu t of 1 5 . 9 V , 1 4 . 2 V a n d 1 3 . 6 V w i t h d u t y c y c l e of 3 1 % , 3 9% a n d 4 3 % r e spe c t i ve l y .
F i g u r e 1 5 I m p l e m e n t e d s ys t e m d i a g r a m w i t h s e l e c t e d p a r t s .
F i g u r e 1 6 O u t p u t v o l t a g e of b o o s t c o n v e r t e r ( 2 3 . 8 V ) a n d d u t y c yc l e ( 3 3 . 6 % ) a t M O S F E T g a t e .
Th e si mu l a t i o n r e su l t s of f i g u r e ( 8 ) a n d ( 1 3 ) of t h e t h e or e t i c a l d e si g n c on ve r t e r ma t c h e s w i t h t h e r e su l t of t h e pr a c t i c a l a ppl i c a t i on of t h e b oo st c on ve r t e r t h a t i s, 3 3 % d u t y c y c l e a n d ou t p u t vol t a g e of 2 4 V w i t h a n i n pu t v ol t a g e of 1 5 . 9 V r e pr e s e n t i n g t h e ou t pu t of p h ot o vol t a i c m od u l e . A
d i f f er e n t w a s ob se r ve i n pe a k t o pe a k vol t a g e of P W M si g n a l w i t h t h e si mu l a t i o n h a vi n g a v ol t a g e of 1 6 V pe a k t o pe a k w h i l e t h e pr a c t i c a l a ppl i c a t ion h a s 6 . 5 6 V w h i c h i s a s a r e su l t of t h e va l u e of r e si st a n c e c on n e c t e d t o t h e i n pu t of t h e M O S F E T t o i n c r e a se t h e M O S F E T g a t e c u r r e n t ( I D ) w h i c h i s d i f f er e n t f or b ot h c a se s. Th e ou t pu t v ol t a g e a n d d u t y c y c l e w h e n a 1 5 . 9 V i s a p pl i e d f r o m t h e ph ot ov ol t a i c mod u l e w a s a c h i e ve d w i t h a vol t a g e of 3 . 4 V ( vol t a g e s ou r c e ) a s su me t o b e g e n e r a t e d b y t h e mi c r oc on t r ol l e r . Th e pr a c t i c a l i mpl e me n t a t i on al so c on f i r m s t h e t r a n sf e r f u n c t i on e q u a ti on of b oo st c on v e r t e r ( ) .
F i g u r e 1 7 o u t p u t v o l t a g e r i p p l e
Th e c a pa c i t or of t h e b o os t c on ve r t e r d e t e r mi n e s t h e v ol t a g e r i p pl e of t h e ou t pu t vol t a g e b u t d o e s n ot h a ve a n y si g n i f i c a n t i mpa c t o n t h e ma g n i t u d e of t h e ou t pu t v ol t a g e . I n t h e t h e or e t i c a l c a l c ul a t ion a vol t a g e r i p pl e of 1 . 2 V w a s e st i ma t e d u si n g a s ma l l e r c a pa c i t or a s i l l u st r a t e d i n f i g u r e 9 , b u t d u r i n g t h e pr a c t i c a l i mpl e me n t a t i o n a b i g g e r c a pa c i t a n c e ( 4 . 7 u ) w a s u se w h i c h a f f e c t e d th e vol t a g e r i ppl e t o 1 . 6 V a s sh ow n a b o ve i n f i g u r e 1 7 b u t i t d oe s n ot c h a n g e t h e ou t pu t v ol t a g e of 2 4 V . i t w a s a c c e pt e d b e c a u se i t su i t a b l e w i t h o u r pr e se n t l oa d v ol t a g e ( L e d b a se l i g h t , n o mi n a l vol t a g e of 2 4 V ) . Th e r e su l t sh ow s t h a t w h e n t h e ou t pu t of t h e ph o t ov ol t a i c m od u l e c h a n g e s t h e d e si g n b oo st c o n ve r t e r i s c a pa b l e of b o o st i n g t h e p ow e r t o ma x i mu m p ow e r w i t h a c h a n g e o n t h e d u t y c y c l e .
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The research paper published by IJSER journal is about Design of Dc-Dc Converter with Maximum Power Point Tracker Using Pulse Generating (555 Timers) Circuit for Photovoltaic Module 9
ISSN 2229-5518
w h i c h a g r e e w i t h b oo st c on ve r t e r t r a n sf e r f u n c t ion e q u a t i on ( ).
F i g u r e 1 8 o u t p u t v o l t a g e o f b o o s t w h e n i n p u t v o l t a g e i s
1 4 . 2 V a n d d u t y c y c l e i s 3 9 % a n d i n p u t c u r r e n t 0 . 2 8 A wi t h
o u t p u t v o l t a g e o f m i c r o c o n t r o l l e r as 3 . 2 V .
F i g u r e 1 8 r e pr e se n t t h e ou t pu t vol t a g e a n d d u t y c y c l e ( P W M ) w h e n a 1 4 . 2 V i s a p pl i e d a t t h e i n p u t of t h e b oo st c on ve r t e r . Th e ou t pu t vol t a g e t e n d s t o me e t a ve r a g e v ol t a g e of 2 3 . 6 V w h e n t h e mi c r oc on t r ol l e r ( a s su me v ol t a g e s ou r c e ) w a s a l t e r e d t o 3 . 2 V , t h i s a c t i on c h a n g e s t h e d u t y c y c l e t o 3 9 % w h i c h i s a l m o st e q u a l w i t h t h e c a l c u l a t e d va l u e of 4 0 % u si n g t h e b oo st t r a n sf e r f u n c t ion e q u a t i on ( ) .
F i g u r e 1 9 o u t p u t of b o o s t c o n v e r t e r w h e n i n p u t v o l t a g e i s
1 3 . 6 V a n d d u t y c yc l e i s 4 3 % a n d i n p u t c u r r e n t 0 . 3 A w i t h o u t p u t v o l t a g e o f m i c r o c o n t r o l l e r as 3 . 0 V .
F i g u r e 1 9 r e pr e se n t t h e ou t pu t v ol t a g e of t h e b o o st c on ve r t e r a n d d u t y c y c l e w h e n 1 3 . 6 V w a s a p pl i e d a s t h e i n pu t v ol t a g e ( ou t pu t of ph ot ov ol t a i c m od u l e ) of t h e c on ve r t e r . Th e ou t pu t vol t a g e w a s
2 3 . 9 V d u e t o t h e c h a n g e of ou t pu t v ol t a g e of
mi c r oc on t r ol l e r ( vol t a g e s ou r c e ) t o a b ou t 3 . 0 V . t h i s a c t i on t e n d t o a d j u s t t h e d u t y c y c l e t o 4 3 . 8%
Th e a i m of t h e pa pe r i s t o d e si g n a D C b oo st
c on ve r t e r a n d a M a x i mu m p ow e r p oi n t t r a c k e r t o o pt i mi z e e f f i c i e n c y a t al l t i me s. Th i s w a s d o n e t h r ou g h c a r e f u l ex a mi n a t i on of t h e ph ot ov ol t a i c m od u l e d a t a sh e e t t o a c h i e v e a mo st d e si r a b l e ou t c o me , pa r t i c u l a r l y wi t h ma x i mu m p ow e r . T h e d e si g n w a s f i r st c a r r i e d ou t t h r ou g h a c a r e f u ll y d e si g n sc h e ma t i c s of t h e sy st e m. Th e d e si g n of t h e DC - D C b o o st c on ve r t e r , pu l se g e n e r a t or ( P W M ) f or t h e pr oj e c t w a s su c c e s sf u l l y c om pl e t e d b u t a n a u t o ma t e d ma x i mu m po w e r p oi n t t r a c k e r w a s n ot su c c e s sf u l l y a c h i e ve d a n d w i l l b e l o ok a t se pa r a t e l y . Th e pr a c t i c a l i mpl e me n t a t i on t e st i n g e x pl a i n s t h e b e h a vi or of t h e mo d u l e d u r i n g d i f f er e n t i r r a d ia t i on a n d a l so t o ob se r ve pr a c t i ca l c on t r ol of t h e M P P T. Th e D C b o o st c on ve r t e r s o pe r a t i n g i n c on t i n u ou s c on d u c t i on mo d e s w i t h ma x i mu m p ow e r p oi n t t r a c k e r s h a ve b e e n s t u d i e d a n d pr o po se d .
N e x t st e p s w i l l b e :
A s si g n a mi c r oc on t r ol l e r
D e ve l o p M P P T A l g or i t h m/ F l ow c h a r t a n d o pe r a t i on .
I mpl e me n t a t i on on t h e pr o po se d d e si g n .
I am grateful to Dr Author Williams for his immerse contributions towards the success of this work and also the University of Nottingham for using the school of electrical and electronic laboratory.
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