A Non-isolated Hybrid Boost Three Level DC-DC Converter with High Step-up Conversion Ratio Meenu George 1 Thomas Mathew 2 Thanuja Mary Abraham 3

Transcription

1 IJSRD - Itertiol Jourl for Scietific Reserch & Develomet Vol. 3, Issue, 25 ISSN (olie): A No-isolted Hyrid Boost Three Level DC-DC Coverter with Hih Ste-u Coversio Rtio Meeu Geore Thoms Mthew 2 Thuj Mry Arhm 3 PG Scholr 2,3 Assistt Professor,2,3 Dertmet of Electricl& Electroics,2,3 MG Uiversity, Idi Astrct Nowdys reewle eery sources re icresily used to meet the world s icresi demd for eery. I rid coected hotovoltic (PV) eertio systems, sile PV rry c suly lower dc volte. I order to coect PV rry to the rid, the volte hs to e oosted to hiher levels tht is demded y the rid side. A hyrid oost three level dc-dc coverter sed o trditiol sile hse three level diode clmed iverter c e used to coect low volte PV rry to the hih volte rid. Oly oe iductor, two ccitors i series, d those ower switches d diodes, which re eeded to estlish the tooloy with hih volte i. Pulse width modultio (PWM) cotrol method is used for the cotrol of ower switches. Power switches of this coverter works with duty cycles closer to.5. This hyrid three level dc-dc coverter works with hih i without trsformer or couled iductor. I dditio, voltes cross the ccitors i series re lced i oth stedy d dymic sttes. Therefore ccitor volte lci circuitry c e voided. Also, locki voltes of the ower switches re hlf of the outut dc volte. This hyrid coverter is suitle for PV eertio systems coected to the rid with rllelcoected low-volte PV rrys. Key words: PV hotovoltic, NPC- eutrl oit clmed, Pulse width modultio I. INTRODUCTION The eertio systems sed o the reewle eery sources hve ridly develoed i recet yers. Photovoltic is imortt rt of reewle eery sources. It is fst rowi reewle eery source i my coutries sice it is cle, ollutio-free d hihly relile. A PV rry c eerte oly low outut volte. This eerted volte of PV does t stisfy hih volte requiremets [4]. To coect PV rry to the rid, the eerted PV volte must mtch with the rid volte. There re severl solutios for coecti PV to the rid. For stisfyi hih volte requiremets, seriescoected PV rrys re the covetiol solutio. It requires more umer of ower devices d the cost is hih. Also, ower level of series-coected PV system is ffected y shdows, which re cused y trees, clouds, uildis, ower lie cles etc. Thus efficiecy of series-coected PV system is retly reduced [5]. This solutio is ot effective for rid-coected lictios. Due to the limittios of series-coected PV system, rllelcoected PV cofiurtio is used s solutio. For residetil lictios, rllel-coected PV is most suitle. It is more efficiet th series-coected PV due to PV erformce. Low volte is eerted with the rllelcoected system. The ower eertio level c e imroved y extedi the rllel-coected PV rrys [6]. Due to limited outut, rllel- coected PV system loe cot e used for rid-coected lictios. Sice ove two solutios re ot effective for hih volte requiremets, some eery coversio systems hve to e used i etwee the rllel-coected PV systems d existi rids. No-isolted hih ste-u DC-DC coverters re required i the idustril lictios. I hotovoltic rid coected systems, oost coverters with hih volte i is eeded to coect PV rrys with the hih volte rid. This hih ste-u oost coverters elimites the volte mismtch etwee PV rrys d rid. Commoly used oost coverters re two level d three level oost coverters. I two level oost coverters, the extreme duty cycles of the ower switches limits its volte i. Also volte stress of the ower switch is hih. So these two level oost coverters re ot suitle for hotovoltic eertio lictios. Covetiol three level oost coverter reduces the volte stress of the ower switches. Its oertio t lre duty cycles limit its volte i d switchi frequecy. I order to oti hih volte i oertio, ew hyrid oost three level dc-dc coverter is roosed. This hyrid oost coverter is sed o covetiol eutrl oit clmed (NPC) iverter. It is comitio of three level coverters. The oertio of this coverter is such tht the duty cycles of the ower switches closer to.5 d thus rovides hih volte i. Volte stress cross the ower switches re lso reduced i this coverter. The hih volte i of the coverter mkes it suitle for hotovoltic eertio lictios. II. HYBRID BOOST THREE LEVEL CONVERTER The hyrid oost three-level coverter is derived from covetiol three-level eutrl oit clmed iverter. This coverter icludes the dvtes of covetiol threelevel oost coverters with some dded fetures. Fi. : Block dirm of Hyrid oost three-level dc dc coverter. All rihts reserved y 7

2 A No-isolted Hyrid Boost Three Level DC-DC Coverter with Hih Ste-u Coversio Rtio (IJSRD/Vol. 3/Issue /25/52) Fi. shows the lock dirm of hyrid oost three level dc-dc coverter. DC iut is ive to the coverter d oosted outut is otied cross the lod. Pulse Width Modultio (PWM) cotrol method is used for roduci switchi ulses. Hyrid oost coverter with cotroller is eeded for mki costt volte t the outut side. Proortiol-Iterl (PI) cotroller cotrols the outut y feedck mechism. Hlf Bride I D Dc Cf V=V Hlf Bride II Fi. 2 shows the hyrid oost three-level dc-dc coverter. It is comitio of two hlf rides, ech hlf ride is three level oost coverter. This hyrid coverter cosists of four switches -, diodes, oe iductor, two ccitors (Cf, ) d lod. Vi is the DC iut to the coverter d Vo is the DC outut volte. V d V re the three level voltes of the two hlf rides. V is the outut volte of the hyrid coverter, which is otied y the differece etwee V d V. A. A. Switchi Sequeces for Oerti Sttes: Tle shows the switchi sequeces for the hyrid oost three-level dc-dc coverter. By roer switchi of the ower switches differet oerti modes re otied. Vi V V Fi. 2: Hyrid Boost Three-Level Dc Dc Coverter Mode V V V Q -Q 4 D -D 4 L f D c -D c4 C f C f2 Vcf+Vcf2 Vo tr. ch. toether 2 Vcf+Vcf2 Vcf2 Vo/2 tr. ch. disch. 3 Vcf2 Vo/2 tr. disch. ch. 4 st. disch. toether 5 Vcf+Vcf2 Vcf+Vcf2 st. disch. toether Tle : Switchi Sequece for Hyrid Coverter ) Mode: I this mode, switches - re i OFF ositio d diodes D- re coducti. Ccitors Cf d i series re chred toether throuh Vi---D-Cf-- --Vi. Iductor trsfers eery duri this mode. Outut volte V is the volte cross ccitors (Vcf+vcf2). Outut volte of the hyrid coverter (V) is equl to V. Vi D Dc Cf V=V Fi. 3: Equivlet Dirm of Mode 2) Mode2: I this mode, switches - re i OFF ositio d switch, diodes D,, re coducti. Ccitor Cf is chred y Vi d is dischred for the lod. Iductor trsfers eery duri this mode. Outut volte of the hyrid coverter (V) is equl to V/2, which is the volte cross Cf. All rihts reserved y 7

3 A No-isolted Hyrid Boost Three Level DC-DC Coverter with Hih Ste-u Coversio Rtio (IJSRD/Vol. 3/Issue /25/52) D Dc Cf V=V Fi. 6: Equivlet dirm of mode 4 5) Mode 5 I this mode, switches, d diodes D, re coducti. Ccitors Cf d re dischred toether for the lod. Iductor stores eery throuh diodes d D duri this mode. Outut volte of the hyrid coverter (V) is equl to. Vi D Cf Fi. 4: Equivlet dirm of mode 2 3) Mode 3: I this mode, switch d diodes,, re coducti. Ccitor Cf is dischred for the lod d is chred y Vi. Iductor trsfers eery duri this mode. Outut volte of the hyrid coverter (V) is equl to V/2, which is the volte cross Vcf2. Vi D Dc Cf V=V Vi Dc V=V Fi. 7 Equivlet dirm of mode 5 B. PWM Cotrol Techique: The outut three-level volte V of the hyrid coverter c e descried s V = V V The switchi fuctios of three level voltes V d V sed o Tle is ive y ( ) ( ) ( ) Fi. 5: Equivlet dirm of mode 3 4) Mode 4: I this mode, switches, d diodes, re coducti. Ccitors Cf d re dischred toether for the lod. Iductor stores eery throuh diodes d duri this mode. Outut volte of the hyrid coverter (V) is equl to. Vi D Dc Cf V=V stte. Where - re the corresodi switchi Accordi to the ove equtios, the switchi fuctio of V for the hyrid coverter c e writte s [( ) ( ) ] ( ) Fi. 8 shows the PWM method of ulse eertio. For PWM sil eertio, two triulr crriers tht re hse shifted y 8 derees re used. These crriers re comred with costt vlues m d m d thus roduce switchi ulses. m > Vcrrier, = m > Vcrrier 2, = m > Vcrrier, = m > Vcrrier 2, =. All rihts reserved y 72

4 A No-isolted Hyrid Boost Three Level DC-DC Coverter with Hih Ste-u Coversio Rtio (IJSRD/Vol. 3/Issue /25/52) m.5 m V V V il Crrier_.5 to to2 Vo/2 Vo/2 Vo/2 Vo Crrier_2 T/2 T to3 to4 Vo Vo () () (c) (d) (e) (f) () (h) (i) i ll oerti modes. Duri the oertio of coverter, whe two diodes D, or, coduct toether, there occurs icresed volte dro cross these diodes. To reduce the ower loss due to diodes, we re coecti ower switch cross these diodes. By usi ower switches isted of diodes, we c reduce the volte dro. Fi. 9 shows the ew hyrid oost three-level dc-dc coverter with reduced volte dro. Worki of this coverter is similr to tht of sic hyrid oost three-level coverter. Oly differece is the coductio of switches isted of diodes. This ew tooloy is most suitle for hih ower lictios. For low volte lictios, cost is hih d ower svi is less. Whe two diodes coduct toether, ech diode hs volte dro of out.7v. Also, hih curret flows throuh the diodes. This cuses lre ower loss i diodes. To reduce these ower losses, ower switches re used isted of diodes. The switches re ted o the eriod whe the two diodes coduct toether. By usi switches isted of diodes duri the oertio of the coverter, some mout of ower c e sved. Eve thouh the umer of switches icreses, the cotrol mechism is simle. Usi simle loic tes, we c eerte the switchi ulses for the switches Q5 d Q6. Oly AND d NOR tes re eeded to eerte switchi ulses for dditiol switches. Thus cotrol is ot comlicted. Disdvte is the icresed cost for dditiol comoets. D. Oertio Hih Volte Gi: Whe V =, eery is stored i the iductor otherwise, eery is trsferred from the iductor. For the lysis, cosider tht eery stored i the iductor d eery trsferred from the iductor re sme. Duty cycles of ower switches c e descried s Vcf d = d4 = - m d2 = d3 = m Vcf2 (j) where, d-d4 re the duty cycles of the ower switches -. (k) Volte i of the tooloy is ive y Fi. 8: Oerti Sttes C. Modified Hyrid Boost Coverter: Q5 D Cf Dc V=V Vi Q6 ( ) By djusti the vlues of m d m, duty cycles of the ower switches c e vried d thus volte i of the coverter c e djusted. Wide re of volte i c e chieved y usi this coverter. As to the ive volte i M, there is ifiite umer of solutios to m d m. However, trdeoff etwee the o-extreme duty cycles of ower switches d the fluctuti mlitude of the iductor curret must e well cosidered, d the etter solutio i this letter is descried s Fi. 9: Modified Circuit Dirm of Hyrid Boost Coverter From the worki of the hyrid coverter, it is cler tht, two diodes i the sme ride coducts toether All rihts reserved y 73

5 A No-isolted Hyrid Boost Three Level DC-DC Coverter with Hih Ste-u Coversio Rtio (IJSRD/Vol. 3/Issue /25/52) Fi 3 shows the three-level voltes of the coverter. From fiure, V d V re the three level voltes of the two hlf rides. V is the outut volte of the hyrid coverter, which is lso three level oe. V is otied s the differece etwee V d V. Fi. : Duty Cycles Curves Versus Volte Gi By usi the ove metioed equtios, the reltioshi etwee the duty cycles of the ower switches d the volte i c e deicted i Fi.. It is idicted tht the hiher M occurs whe the duty cycles of switches closer to.5. III. SIMULATION RESULTS Fi. 3: Three Level Voltes of Hyrid Boost Coverter IV. HARDWARE ANALYSIS Fi. 4 shows the exerimetl set u of the hyrid threelevel oost coverter. Fi.: Simultio Model of Three Level Hyrid Boost Coverter Fi. shows simultio model of three level hyrid oost coverter i closed loo. It cosists of 4 switches, 8 diodes, oe iductor, 2 ccitors d lod. PWM cotrol method is used to eerte switchi ulses. Proortiol-Iterl (PI) cotroller is used to cotrol the outut volte. Iut DC volte of 5V is ive s the iut to the coverter. Fi. 4: Exerimetl Set U of The Hyrid Coverter It cosists of ower circuit, driver circuit, d cotrol circuit. The results of the hrdwre rremet re lyzed with the hel of DSO. Fi. 2: Outut Volte of Three Level Hyrid Boost Coverter Fi 2 shows the outut volte of the hyrid three level coverter. Here iut volte of 4.2V is ive d outut of 35V is otied. Here the coverter oertes with switchi frequecy of 7.4kHz. Fi. 5: Outut Volte Wveform This hyrid oost three-level coverter oertes t switchi frequecy of out 7.4 khz. Fi. 5 shows the outut volte wveform of the hrdwre. A iut volte of out 4.2V is ive to the hyrid coverter d outut volte of out 36.2V is otied i the outut. All rihts reserved y 74

6 A No-isolted Hyrid Boost Three Level DC-DC Coverter with Hih Ste-u Coversio Rtio (IJSRD/Vol. 3/Issue /25/52) V. CONCLUSION The hyrid oost three-level dc dc coverter is sed o the covetiol sile-hse diode clmed three-level iverter. It oertes with duty cycles ower switches closer to.5 d rovides icresi volte i. By djusti duty cycles, volte i c e vried. Moreover, the ccitor voltes c e lced oth i dymic d stedy sttes y the roosed PWM cotrol method d the locki voltes of the ower switches re hlf of the outut dc volte. The roosed coverter is suitle for PV eertio systems coected to the rid with rllelcoected low-volte PV rrys. REFERENCES [] Yu Zh, Ji-To Su, d Yi-Fe W, Hyrid oost three-level DC DC coverter with hih volte i for hotovoltic eertio systems, IEEE Trsctios o Power Electroics, Vol. 28, No. 8, Auust 23. [2] M. Thomso d D. G. Ifield, Imct of widesred hotovoltics eertio o distriutio systems, IET Reew. Power Geer., vol., o.,. 33 4, Mr. 27. [3] M. Liserre, R. C rdes, M. Molis, d J. Rodr ıuez, Overview of multi-mw wid turies d wid rks, IEEE Trs. Id. Electro., vol. 58, o. 4,. 8 95, Ar. 2. [4] V. V. R. Scr, S. Buso, d G. Sizzi, Lowcomlexity MPPT techique exloiti the PV module MPP locus chrcteriztio, IEEE Trs. Id. Electro., vol. 56, o. 5, , My 29. [5] G. Acciri, D. Grci, d A. L. Scl, Hiher PV module efficiecy y ovel CBS yss, IEEE Trs. Power Electro., vol. 26, o. 5, , My 2. [6] W. Li d X. He, Review of oisolted hih-ste-u DC/DC coverters i hotovoltic rid-coected lictios, IEEE Trs. Id. Electro., vol. 58, o. 4, , Ar. 2. [7] S. Che, T. Li, L. Y, d J. Che, A sfety ehced, hih ste-u DC DC coverter for AC hotovoltic module lictio, IEEE Trs. Power Electro., vol. 27, o. 4, , Ar. 22. [8] X. Ru, B. Li, Q. Che, S. T, d C. K. Tse, Fudmetl cosidertios of three-level DC DC coverters: Tooloies, lyses, d cotrol, IEEE Trs. Circuits Syst. I, Re. Pers, vol. 55, o., , Dec. 28. [9] Q. Zho d F. C. Lee, Hih-efficiecy, hih ste-u DC DC coverters, IEEE Trs. Power Electro., vol. 8, o., , J. 23. [] R. Wi d R. Du, Hih ste-u coverter with couled-iductor, IEEE Trs. Power Electro., vol. 2, o. 5, , Se. 25. [] R. Wi d R. Du, Hih-efficiecy ower coversio for low ower fuel cell eertio system, IEEE Trs. Power Electro., vol. 2, o. 4, , Jul. 25. [2] W. Li, Y. Zho, J. Wu, d X. He, Iterleved hih ste-u coverter with widi-cross-couled iductors d volte multilier cells, IEEE Trs. Power Electro., vol. 27, o., , J. 22. [3] H. Wu d X. He, Sile hse three-level ower fctor correctio circuit with ssive lossless suer, IEEE Trs. Power Electro., vol. 7, o. 6, , Nov. 22. [4] A. Bht d F. D. T, A uified roch to chrcteriztio of PWM d qusi-pwm switchi coverters: Tooloicl costrits, clssifictio, d sythesis, IEEE Trs. Power Electro., vol. 6, o. 4, , Oct. 99. [5] Y. Zh d L. Su, A efficiet cotrol strtey for five-level iverter comrisi flyi-ccitor symmetric H-ride, IEEE Trs. Id. Electro., vol. 58, o. 9,. 4 49, Se. 2. All rihts reserved y 75