Battery-Operated Electronic Ballast of Fluorescent Lamps for Photovoltaic Applications

Transcription

1 Baery-Operaed Elecronc Ballas of Fluorescen Lamps for Phooolac Applcaons Yng-Chun Chuang Yu-Lung Ke Deparmen of Elecrcal Engneerng Kun Shan Unersy Yung-Kang Cy, Tanan Hsen, Tawan, R.O.C. Hung-Shang Chuang Deparmen of Elecrcal Engneerng Kao Yuan Unersy Kaohsung Hsen, Tawan, R.O.C. e-mal: Absrac A noel baery-operaed elecronc ballas of fluorescen lamps for phooolac applcaons s presened n hs paper. In order o resere he elecrcal power ransformed from phooolac modules, a baery charger wh hgh performance, low swchng losses, low cos and hgh effcency should be desgned. Ths paper presens a noel baery charger wh elecronc ballas whch s characerzed wh smple srucure, less componen coun, small olume, lgh wegh, low cos, hgh effcency and hgh power densy. Moreoer, he elecronc ballas uses a curren-sourcng push-pull resonan nerer o supply a 4W fluorescen lamp. Ths new elecronc ballas srucure can accep DC olage npu o prode he power ha he lamp needs. Deraon and operang prncples of he proposed opology are performed. All swches n he sysem can achee zero-olage-swchng. Expermenal resuls show he funconaly of he oerall sysem as well as proe o be a good soluon for seeral phooolac applcaons. Keywords- phooolac modules; baery charger; elecronc ballas I. INTRODUCTION As he concerns of fossl fuel exhauson and enronmenal polluon ncrease, renewable energy conerson sysems become more and more arace. Among hem, phooolac power generaon sysems sand ou as an mporan soluon because hey can produce elecrcal power whou causng enronmenal polluon by drecly conerng he nexhausble solar energy no elecrcy. They can be used n arous applcaons such as hose for he household applances, for he solders n he remoe mssons, for he solar cars, and een for he elecrc arcrafs. Also, hey are ubquous n spacecrafs. Tawan s locaed n he subropcal zone, wh los of sunlgh and long sunny days. Therefore, solar energy should be he mos promnen canddae for green energy [,]. Snce he solar radaon changes wh me and he phooolac arrays hae a nonlnear olage-curren characersc, whch s subjec o ary wh he change of he operang condons, he phooolac modules sysem has o regulae he oupu olage by conrollng a DC/DC conerer nerposed beween he phooolac modules and he baery o ensure he effcen operaon. As he amoun of elecrcy produced by he phooolac modules durng he day drops o zero before dawn, baeres are normally used o sore he produced energy for a laer use. The lfe and capacy of he baeres depend on seeral facors, such as charge mode, manenance, emperaure, and age. Among hese facors, he charge mode has a grea mpac on baery lfe and capacy. The baery bank should be charged wh curren and olage leels wh low rpple. Therefore, a hgh performance baery charger s necessary n a phooolac power generaon sysem. In order o mnmze he losses, s essenal no o wase energy n he conerson process. In relaon o he power elecroncs and assocaed conrol schemes, he man requremen s o guaranee ha he chargng sysem s effcen. Therefore, opologes wh hgh swchng frequences were used o reduce he chargng curren rpple and exend baery lfe. Howeer, as he swchng frequency ncreases furher, swchng losses and EMI nose arse [3-6]. To sole hs problem, he swchng frequency s ncreased by reducng he swchng losses hrough a modfed seres-loaded resonan conerer. The modfed seres-loaded resonan conerer consss of an Lr-Cr resonan conerer wh a olage doubler opology. Ths modfed seres-loaded resonan conerer has an oupu of wce he peak alue of he radonal seres-loaded resonan conerer. Oscllang olage and curren, due o Lr-Cr resonance n he ank, are appled, and he conerer swches can be swched a zero olage and zero curren condons. On he oher hand, fluorescen lamps hae mporan mers oer ncandescen lamps ha her effcency s hree o fe mes hgher. Therefore, fluorescen lamps hae been he mos mporan lgh sources n our modern lfe. Howeer, fluorescen lamps hae negae mpedance characerscs n he desred operaon regon. Hence, hey canno be conneced drecly o he source, bu nsead requre some forms of curren-lmng dece o preen her desrucon by excesse curren,.e. ballas. The ballas mus prode he sarng and operang olage and also lm he lamp curren. In order o oban a compac elecronc ballas and elmnae undesrable feaures lke audble nose, flckerng and sroboscopc effecs, he operang frequency mus be rased. In he case of a fluorescen lamp operang a hgh frequency, 97-68/7/$5. 7 IEEE

2 he lumnous effcency ncreases by abou %, whch reduces he energy consumpon of he sysem [7,8]. For a baery-operaed lghng sysem, a boos-ype hghfrequency elecronc ballas s used o lgh up he fluorescen lamp. A new elecronc ballas wh curren-sourcng push-pull resonan nerer s nroduced n hs paper. The man adanage of he push-pull crcu s ha no more han one swch n seres conducs a any nsan of me. Ths can be mporan f he dc npu o he conerer s from a low-olage source, such a baery, where he olage drops across more han one swch n seres would cause a sgnfcan reducon n energy effcency. Also, he conrol dres for he wo swches hae a common ground. The objece of hs paper s o analyze and mplemen an elecronc ballas for baery and low npu olage applcaons. Then, a prooype of he baery-operaed elecronc ballas for phooolac applcaons s bul and esed o erfy he analycal predcons. II. SYSTEM CONFIGURATION The complee block dagram of he proposed phooolac llumnaon sysem s shown n Fg.. Generally, could be dded no wo pars: he chargng crcu whch sores he elecrc energy produced by phooolac modules no he baery, ogeher wh he elecronc ballas whch gnes he fluorescen lamp when he baery s dschargng. Phooolac modules Solar beam p C p - Conrol crcu Charger p sage Elecronc ballas - Baery Lamp Fg. The block dagram of he proposed phooolac llumnaon sysem A. Charger Sage The power swch sresses of radonal hard-swchng conerers can be reduced by connecng dsspae snubber crcus n seres and parallel wh he power swches n he conerers. Howeer, hese dsspae snubbers shf he swchng losses from he power swch o he snubber crcus, and herefore do no prode a reducon n he oerall swchng losses. Due o hgh swchng loss and EMI, he swchng frequency of he energy conerson echnology s lmed. To oercome such problems, resonan conerers hae been deeloped. The resonan conerers can reduce swchng losses and EMI leel sgnfcanly by shapng eher curren or olage snusodally. The phooolac modules oupu s conered o a DC-DC conerer wh a modfed seres-loaded resonan conerer. The componens Lr and Cr form he seres-resonan ank, and he curren hrough he resonan ank s recfed and feeds he baery. The baery olage across he fler capacor Co can be assumed o be a consan olage durng a swchng perod. The basc dagram of he modfed seres-loaded resonan conerer wh olage doubler opology s skeched n Fg.. p S C C s M M s D a D L r Lr C r cr DR C3 b DR C 4 Co o I o Baery Fg. Basc dagram of he modfed seres-loaded resonan conerer wh olage doubler opology The analyss of hs sysem s carred ou under he followng assumpons: (a Swchng elemens of he conerer are deal,.e. forward olage drops n on-sae ressances of he power swches are negleced. (b The equalen seres ressance of he capacance and sray capacances are negleced. (c Passe componens are assumed o be lnear, menaran and frequency-ndependen. Fgure 3 plos he equalen crcus and key waeforms of he modfed seres-loaded resonan conerer wh olage doubler opology. In one swchng cycle, he chargng crcu operaon of he modfed seres-load resonan conerer can be dded no four modes. p Lr Cr Lr O O β = p p p Lr = Lr = Lr = Lr T ω O Cr ω ω O M α D M ω O 3 Lr Cr Lr L r L r D I II III I ω O Cr C r Cr Fg. 3 The equalen crcus and key waeforms of he modfed seres-loaded resonan conerer Mode I: (beween ωo and ωo In he seady-sae symmercal operaon, boh power swches are operaed dencally. Smlarly, he wo dodes operae dencally. Therefore, s suffcen o analyze only

3 one-half cycle of operaon, snce he oher half s symmercal. Pror o ωo, freewheelng dode D s urned on, and conducs a curren ha equals he resonan ank curren Lr, and he power swch M s exced. A he nsan ωo, he resonan ank curren Lr reerses and naurally commuaes from dode D o he power swch M. In hs mode operaon, he power swches urn on naurally a zero olage and a zero curren. The nal condon of he capacor Cr s co. Then, he nsananeous resonan nducor curren and he olage across Cr can be ealuaed, respecely Lr p ( = - - sn co o p ( - p cr = co cosωo ( where he angular resonance frequency ω o = πf o = and he characersc mpedance LrCr Lr Z o =, respecely. Cr Mode II: (beween ωo and ωo A ωo, before he half-cycle of he curren Lr oscllaon ends, M s forced o urn off, hus forcng he pose curren o flow hrough he boom freewheelng dode D. Because of he negae dc olage appled across he resonan ank, he curren hrough he dode goes o zero quckly a ωo. Durng hs neral, he nducor curren Lr s expressed as ( p snω I cosω = (3 Lr c o L o where I L s he nal curren n he nducor Lr and p I ( - - L = Lr = co snβ. The olage cr across he capacor Cr can be dered as ( p ( I cosω L snω cr c c o o ωo where c s he nal olage across he capacor Cr and = (4 p ( - p c = cr = co cosβ The energy flowed no he baery durng he neral ωo ωoωo s W = o Lr (d p - - = sn d co ωo co ωo Defnng he followng erm p = - - ( - cosβ (5 p A - - co ( - cosβ (6 Then, he energy flowed no he baery durng he neral ωo ωoωo s gen by - ( W o = Lr d - p = - - -csnωo ILcosωo d = p - - -c( - cosα ILsnα (7 ωo Subsung Eqs. (3 and (4 no aboe equaon produces W o p p = co ωo Z o p co Z o ( cosα p - - co snβ snα Then, we defne he followng erm p p B - A co ( - cosα ( cosβ p - - co snβ snα (9 Therefore, he oal energy flowed no he baery durng he neral ωo ωoωo can be ealuaed W W W = = ( A B ( ωo The energy from he phooolac modules durng he neral ωo ωoωo s p W p p = ( d A Lr = ( ωo The energy from he phooolac modules durng he neral ωo ωoωo s p W - - ( p p = d - B Lr = ( ωo Therefore, he energy generaed by he phooolac modules s p Wp = Wp Wp = ( A - B (3 ωo For a lossless sysem, hese wo knds of energy are equal n he seady sae. Hence, he oupu olage s soled as A B = p (4 A B The mos mporan adanage of he modfed seresloaded resonan conerer s ha he maxmum oupu olage n Fg. can approach he source olage p. Ths s n conras o he radonal seres-loaded resonan conerer (8

4 where can only approach.5p. In oher words, he modfed seres-loaded resonan conerer mus swch only half as much curren for fxed alues of p and oupu power. Because of hs adanage, he modfed seres-loaded resonan conerer wll be he preferred confguraon for fas chargng applcaons of baeres. B. Baery-Operaed Elecronc Ballas The basc srucure of a smplfed curren-source pushpull resonan nerer s shown n Fg. 4 [9]. The curren In a he npu s a square wae curren ofin. I n C C Fg. 4 Smplfed curren-source push-pull resonan nerer Wh he nal condons o(== and L (==, he oupu olage o s gen by In α o ( = e snωr (5 ωrc where α = / RC. The damped-resonan frequency ωr s gen by ω r = (6 LC R C From aboe equaons, we can see ha he currensourcng push-pull resonan nerer can produce an approxmaely snusodal olage waeform a he oupu ermnals. Ths ype of nerer s commonly used n relaely fxed oupu applcaons (e.g., fluorescen lghng, nducon heang, or ulrasonc generaors. Due o he hgh swchng frequency, he sze of commuang componens s ery small. Fg. 5 shows he proposed crcu confguraon of he curren-sourcng push-pull resonan nerer elecronc ballas whch s dren by a baery. I consss of a baery, an npu nducor Ln, a resonan capacor Cp, a cener-apped ransformer T, and wo symmercally dren power swches Q and Q. Inducor L s he muual nducance of he ransformer and acs as he resonan nducor. A seres resonan nerer o supply he fluorescen lamp formed by nducor Ls, capacor Cs and lamp ressor RLamp s employed. Ths ransformer s beng used as a sep-up ransformer. Ths confguraon s relaely suable for solar-energy lghng applcaon. Alhough he work presened here has npu dc olage of, he same analyss can be exended for any npu olage hgher or lower han. A prooype has been assembled n he laboraory and he measuremens of olage and curren waeforms hae been presened and dscussed. To smplfy he analyss, he npu fler nducance Ln s assumed o be suffcenly large o be regarded as an deal dc npu curren source In durng a hgh-frequency resonan cycle. L L R R o Cp C p L Q CE CE Q CE CE BE BE I T n n T 3 n 3 : n L Feedback and Trgger sgnal T S L s L rr R LAMP Cs C s LAMP Fg. 5 Baery-operaed curren-sourcng push-pull resonan nerer elecronc ballas In accordance wh he conducng saus of he power swches, he operaon of he baery-operaed elecronc ballas can be dded no wo modes. In he seady-sae symmercal operaon, boh he power swches are operaed dencally. Therefore, s suffcen o analyze only one-half cycle of operaon, snce he oher half s symmercal. Fg. 3 llusraes he heorecal waeforms for each neral. S Cs CE BE CE CE BE CE LAMP LAMP Q ON Q ON Q ON Fg. 6 Theorecal waeforms of he proposed baery operaed elecronc ballas

5 Referrng he prmary componens no he secondary sde and neglecng he leakage nducances of he ransformer, he equalen crcu s drawn n Fg. 7. In hs fgure, he nducor Lrr s gen by L C p L rr = n Ls (7 ωr L C p where he symbol n represens he urns rao beween he urns on he secondary sde of he ransformer and he urns on he prmary sde of he ransformer. L rr S L rr L rr C s Cs R LAMP LAMP Fg. 7 Baery-operaed elecronc ballas wh he prmary sde referred o he secondary sde A he begnnng of he operaon of he proposed elecronc ballas, he power swch, Q, s urned on. Wh he nal condon Lrr (==ILrro, he olage across he capacor Cs can be dered as L ( I rr α Cs = Lrro e snωrr (8 C s where he dampng facor, R α = LAMP Lrr he resonan angular frequency, ωor = LrrCs and he damped-resonan frequency ωrr s gen by ωrr = L rrcs RLAMPCs The correspondng alue of he lamp curren s I ( ( Lro e LAMP = Lrr = α [ ωor cosωrr α snωrr] (9 Csωrr The lamp olage LAMP can be found R I ( LAMP Lrro α = e [ ωor cosωrr α snωrr] ( LAMP Csωrr III. EXPERIMENTAL RESULTS A. Baery Charger The npu of proposed modfed seres-loaded resonan conerer was conneced o a sysem conssng of a phooolac modules of oupu olage 4 and 5W. A prooype of he baery charger wh modfed seres-loaded resonan opology was esablshed n a laboraory o confrm he funconal operaons. The deeloped charger crcu s appled o a, 48AH lead-acd baery. The condons of he expermen were as follows: swchng frequency fs=khz, resonan frequency fr=khz, chargng curren Io=6.5A, chargng olage = 5, and he open crcu olage of baery oc =. Under hese operaon condons, he wo parameers of he modfed seres-loaded resonan conerer are chosen as follows: Cr=3.μF Lr=6μH The waeforms were measured wh he help of dgal mul-meer. Fgure 8 dsplays he waeforms of he rgger sgnals GS, and GS. Fgure 9 presens he waeforms of he resonan olage Cr and he resonan curren Lr. Fg. reeals he npu olage and oupu olage waeforms of resonan ank ermnals. Fgure dsplays he olage araon cure of he baery. The ermnal olage of he baery from.5 o 5.3 akes 5 mnues. Fgures and 3 plo he chargng curren and he chargng effcency, respecely. The chargng curren Io decreases as he olage of he baery ncreases. The chargng curren akes 5 mnues o fall below 5A. The mnmal and maxmal effcences of he baery chargng crcu are around 7% and 95%, respecely, and he aerage chargng effcency of he charger s 84.8%. GS GS CH:/d CH3: /d Tme:μs /d Fg. 8 The rgger sgnals of power swches

6 cr (A Lr CH:/d CH4:A /d Tme:μs /d Fg. 9 The resonan olage and curren waeforms a ( mnues 5 Fg. Chargng curren cure durng chargng perod (% b 75 7 CH:/d CH3: /d Tme:μs /d Fg. The npu and oupu olage waeforms of resonan ank ( (mnues Fg. Baery olage cure durng chargng perod ( mnues Fg. 3 Chargng effcency cure durng chargng perod B. Baery-Operae Elecronc Ballas To erfy he predced operaon prncples and heorecal analyss of he proposed new curren-sourcng push-pull resonan elecronc ballas of fluorescen lamps for phooolac applcaons, a laboraory elecronc ballas of Fg. 5 s bul o dre a fluorescen lamp of 4W. The crcu parameers are lsed n Table. Fg. 4 shows he measured expermenal waeforms of and cs of he noel baery operaed elecronc ballas, whch s que conssen wh he predcons. Fg. 5 dsplays he measured waeforms of ransformer olage and he npu dc curren I n. The expermenal resuls shown n Fgs. 6 and 7, demonsrae ha zero-olage swchng s acheed for he power swch. Therefore, he swchng losses for hs new elecronc ballas are praccally zero. Fg. 8 shows he measured ransformer oupu olages s and capacor olage cs,, lamp olage Lamp, and lamp curren Lamp waeforms when he baeryoperaed elecronc ballas s suppled from a DC npu olage of. Fgs. 4,5,6,7, and 8 show he measured expermenal waeforms of he expermen crcu, and hey are que conssen wh hose predced. The expermenally obaned effcency from he curren-sourcng push-pull elecronc ballas s equal o 88.3%. The cres facor (CF of he lamp curren equals.3 whch mees he requremens of lghng applcaons.

7 Table Crcu parameers Inpu olage s DC Swchng frequency fs 9kHz Inpu nducor Ln μh Inducor L 9μH Inducor Ls 8mH Capacor Cp.μF Capacor Cs 4.7nF CH CH CH CE BE CH: /d CH: 4/d Tme: 5μs /d Fg.7 Measured waeforms of CE and BE CH s CH Cp CH Cs CH: /d CH: A/d Tme: 5μs /d Fg. 4 Measured waeforms of and cp CH3 CH4 LAMP LAMP CH CH: K/d CH: K/d Tme: 5μs /d CH3: /d CH4:.5A/d Tme: 5μs /d Fg.8 Measured waeforms of s, cs, Lamp and Lamp I n I. CONCLUSIONS CH CH: /d CH: A/d Tme: 5μs /d Fg. 5 Measured waeforms of and I n CH CH CE BE CH: A/d CH: 4/d Tme: 5μs /d Fg.6 Measured waeforms of CE and BE In order o make he bes use of he solar energy and sore he energy no baeres, hs sudy composed he phooolac modules wh a smple srucure, low swchng loss, hgh effcency and hgh performance modfed seres-loaded resonan baery charger. Ths charger s desgned o deelop beer effcency of he phooolac module. Ths sudy presens he use of baery charger wh zero-olage-swchng echnology n he chargng es of a lead-acd baery charger o demonsrae he effeceness of he deeloped mehodology. The aerage crcu effcency of he chargng process exceeds 8%. In addon, he performance s obaned a lower cos as less number of componens are used. Besdes he charger, an elecronc ballas wh currensourcng push-pull resonan nerer has been dscussed n hs paper. Ths ype of nerer s well sued for baery applcaons when compared o half-brdge opology, snce doubles he olage on he nerer operaon whle he halfbrdge ddes. All he swches used n hs ballas are common ground and herefore he use of specal drers was no necessary, hus aanng an exra cos reducon for he ballas. Furhermore, he commuaons n he swches of he elecronc ballas are realzed a zero olage. The proposed elecronc ballas s a noel opon for fluorescen lamps

8 operang a hgh frequency and low npu olage. The measured performance showed good agreemen wh he heorecal predcons. REFERENCES [] L. J. Borle, M. S. Dymond, and C.. Nayar, Deelopmen and Tesng of a -kw Grd Inerace Phooolac Power Condonng Sysem n Wesern Ausrala, IEEE Transacons on Indusry Applcaons, ol. 33, No., pp. 5-58, March/Aprl 997. [] C.. Nayar, M. Ashar, and W. W. L. Keerhpala, A Grd-Inerace Phooolac Unnerrupble Power Supply Sysem Usng Baery Sorage and a Back Up Desel Generaor, IEEE Transacons on Energy Conerson, ol. 5, No. 3, pp , Sepember. [3] C. H. Rea, A. Emad, G. A. Wllamson, R. Jayabalan, and B. Fahm, Analyss and Conrol of a Buck DC DC Conerer Operang Wh Consan Power Load n Sea and Undersea ehcles, IEEE Transacons on Indusry Applcaons, ol. 4, No., pp , March/Aprl 6. [4] A. R. Prasad, P. D. Zogas, and S. Manas Analyss and desgn of a hree-phase offlne DC-DC conerer wh hgh-frequency solaon, IEEE Transacons on Indusry Applcaons, ol. 8, No. 4, pp.84-83, July/Augus 99. [5] B. J. Paella, A. Prodc, A. Zrger, and D. Maksmoc, Hgh-frequency dgal PWM conroller IC for DC-DC conerers, IEEE Transacons on Power Elecroncs, ol. 8, No., pp , January 3. [6] M. P. N. an Wesenbeeck, J. B. Klaassens, U. on Sockhausen, A. M. de M. Ancola,and S. S. alche, A mulple-swch hgh-olage DC- DC conerer, IEEE Transacons on Indusral Elecroncs, ol. 44, No. 6, pp , December 997. [7] E. E. Hammer, Hgh Frequency Characerscs of Fluorescen Lamps up o 5 khz, Journal of he Illumnang Engneerng Socey, pp. 5-6, Wner 987. [8] E. E. Hammer and T.K. McGowan, Characerscs of arous F4 Fluorescen Sysems a 6 Hz and Hgh Frequency, IEEE Transacons on Indusry Applcaons, ol. IA-, No., pp. -6, Jan./Feb [9] M. J. Ryan, W. E. Brumsckle, D. M. Dan, and R. D. Lorenz, A New ZS LCL-Resonan Push Pull DC DC Conerer Topology, IEEE Transacons on Indusry Applcaons, ol. 34, No. 5, pp , Sepember/Ocober 998.