Single-Phase Direct AC-AC Boost Converter

Transcription

1 [ownloaded from on Tuesday, Sepember, 4 a :43:4 (UTC) by Redisribuion subjec o AECE license or copyrigh.] Volume 4, Number 3, 4 Single-Phase irec AC-AC Boos Conerer Mihai LUCANU, Oidiu URSARU, Crisian AGHION, Nicolae LUCANU Gheorghe Asachi Technical Uniersiy of Iasi, Faculy of Elecronics, Telecommunicaions and Informaion Technology, Bld. Carol, No., 756, Iasi, Romania aghion@ei.uiasi.ro Absrac The paper presens a single-phase direc AC-AC boos conerer. The circui of he conerer is simple and i has good performances, irrespecie of he load naure. The adequae funcioning and high performance of he circui (he efficiency and waeform of he absorbed inpu curren) were esed boh by simulaion and experimenally. Index Terms choppers, conersion. circui simulaion, power I. INTROUCTION AC-AC conerers are currenly used in numerous fields, such as AC moor dries, adjusable AC sources, elecric ransformers, oupu olage waeform resorers ec. These conerers successfully replace alernaie olage ariaors using SCRs or TRIACs. Since operaion frequencies are higher (oer KHz), here is no noise, filers are smaller in size, he efficiency is higher and he curren aken from he grid is nearly sinusoidal. The firs AC-AC conerers (AC choppers) subjec o analysis were buck conerers []. References []-[4] presen improed PWM echniques, which increase he power facor and eliminae cerain harmonics. In [5], an IGBT chopper wih a 5kHz frequency was analyzed by simulaion. Reference [6] presens a hree-phase AC-AC conerer wih nine IGBTs and [7] suggess a mehod for ealuaing hree-phase AC-AC conerers. In [8] and [9], he proposed AC choppers are characerized by improed swiching and high efficiency, howeer he circuis are quie complex. References [] and [] presen AC choppers wih hree-leel conerers and opologies using commercial power modules. A high-performance single-phase AC conerer inoling wo inducances and four IGBTs is presened in []. The paper presens a single-phase direc AC-AC boos conerer using only wo IGBTs and one inducance (excep for he grid filer). The funcioning equaions presened are used for design purposes. The conerer can supply a bidirecional power flow. The funcioning frequency is khz, he efficiency is high and he inpu curren is nearly sinusoidal. This frequency was chosen since i goes beyond he range of acousic frequencies perceied by he human ear and in order o be able o use IGBT s. Cerainly, a higher swiching frequency of he conerer will deermine lower alues for he inducances and capaciors in he circui presened. The simulaion allowed us o es he adequae funcioning and o deduce he conrol characerisic of he AC-AC boos conerer. The circui funcions adequaely boh for resisie and inducie loads. One of our purposes was he correcion of he inpu curren waeform. Gien ha he supply olage is sinusoidal, he mos faorable sampling is uniform sampling, which we used in he paper, because he aerage alues of he olage (herefore of he curren) for arious sampling periods remain sinusoidal, which leads o he minimizaion of he harmonics for he curren supplied by he power source. The circui can be used when i is necessary o increase he load olage, especially for olage conersion from V o V, wih some conrol adjusmens when he inpu olage alues ary in he range ±%. II. CIRCUIT ANALYSIS Figure presens he circui of he single-phase AC-AC boos conerer comprising he Lf and Cf filer, he L inducor, he C capacior conneced in parallel wih he load impedance and wo AC swiches, each made up of four diodes and one IGBT. The load impedance Z has he olage and he curren i. In fac, wihou he grid filer, he circui is a classic boos conerer, excep ha he ransisor and he diode are replaced by wo bidirecional curren swiches. im L f i L L + (-) _ (+) + (-) _ (+) Cf 3 S 8 Rs Cs Rs C s 4 S C i R + (-) _ (+) Figure. Single-Phase irec AC-AC Boos Conerer Figure presens he waeform of he olage and he generaion of he conrol signals of IGBTs S and S. If he curren hrough he L inducor is i > for ime inerals [, T], i will flow hrough L,, S,, and for ime inerals [T, T] i will flow hrough L, 5, S, 6 and he L, R load. If i < for ime inerals [, T], he i curren will flow hrough 3, S, 4, L and for ime inerals [T, T], i will flow hrough he load circui 8, S, 7, L. The supply of he R, L load is insured by capacior C. igial Objec Idenifier.436/AECE AECE

2 [ownloaded from on Tuesday, Sepember, 4 a :43:4 (UTC) by Redisribuion subjec o AECE license or copyrigh.] Volume 4, Number 3, 4 ' L (ok ) (5) ok ' ' ',,( )T i k I KM L Since i is a boos conerer, he conrol characerisic corresponding o a T swiching period can be approximaed by he equaion: (6) k k V k π ω Tm VH Vcom VL r T T and he aerage alue of he i curren for a T period is (-)T S S IK Figure. The waeform of he olage and he generaion of he conrol signal for IGBTs PWM conrol is used, where he swiching duraions of he wo swiches are consan for all T swiching periods, similarly o he C conerers, and f= /T is he swiching frequency. The load impedance is: () Z R L, f m, f m Tm The equaions characerizing he funcioning of he conerer are deduced under he following simplifying hypoheses: he passie componens are ideal, he power deices are ideal swiches, he olage on he Cf capacior and olage on he load are sinusoidal and remain consan for a T period, and he load is purely resisie (L=). For an inducie load, he equaions do no change significanly. () For he ineral [, T], when S is ON and S is OFF: dik L d ik I km L L For he ineral [T, T], when S is OFF and S is ON: 8 I S K ( ) R I S K ( ) R (8) and he following alues for he maximum repeiie currens i I SKM I S KM I K k (9) ( ) R L f The maximum olages collecor-emier for he wo IGBTs are: VS KM VS KM k () Taking ino accoun he fac ha olages hae a sinusoidal ariaion, hese are he final curren and olage requiremens. The aerage curren hrough he S swich is: I Sar V ( ) R () I S ar V R () and he maximum repeiie currens are: (3) I S M I S M V ( ) R V L f (3) The olage sress of he IGBTs is: VS M VS M If we apply he ik equaion for =T, we obain: ik I km I km L T i I I km km k L f (7) ( ) R Similarly, we obain he following aerage alues of he currens for he bidirecional swiches, corresponding o a T period: V sin T V sin k cons, k k T k V sin k cons. (4) V (4) The normalized curren ripple resuls from equaions (4) and (7) R ik Ik L f (5) This equaion is used in he design process for he calculaion of he L inducance.

3 [ownloaded from on Tuesday, Sepember, 4 a :43:4 (UTC) by Redisribuion subjec o AECE license or copyrigh.] Volume 4, Number 3, 4 The normalized ripple of he oupu olage can be calculaed wih he equaion: (6) RCf This equaion lies a he basis of he calculaion of he C capaciy conneced in parallel wih he load. The calculaion of he filer LfCf componens [3] [7] requires he following daa: Line frequency fline Minimal RMS olage Vmin Maximum RMS load curren Imax Lowes swiching frequency fswmin V (7) Z min I max The filer cuoff frequency fcu is deermined from he aenuaion needed a he carrier frequency (plus a margin of 6 db), while a he same ime proiding minimal aenuaion a he line frequency. f cu f Line (8) The Lf and Cf alues of he filer are calculaed as follows: Z (9) Lf, Cf f cu f cu Z Figure 4 presens he same waeforms for = V =37.37V =54.96V V V -V -39V 4.A i =.4 A m i =.838A A -4.A 6.ms 8.ms Time.ms 3.4ms Figure 4. Waeforms of he olage, olage, im curren and i curren, for =.48 Figure 5 presens he same waeforms for =.56. The waeforms of he load olage and curren are nearly sinusoidal. 4V 5V = V = V V - 5 V -458V III. SIMULATION RESULTS AN EXPERIMENTAL RESULTS The adequae funcioning of he circui was esed by simulaion and experimenal prooype. The load used in he simulaions and in he prooype is he same - a resisie load: R=39 ohm; The componens of he simulaed circui hae he following alues: he grid filer is made up of Lf=3mH, Cf=6uF, he boos inducance is L=5 mh, and R=39Ω for load. The ampliude of he grid olage is 55V and he swiching frequency is f=khz. The simulaions ook ino accoun he following alues of he duy cycle: =.4,.48, and.56. The paper presens only some of he waeforms obained, namely he mos represenaie ones. Thus, Figure 3 shows he waeforms of he grid olage and of he load olage, as well as he waeforms of he im curren supplied by he grid and he i load curren for =.4. 33V 4. A i m= 3.4 A i =. A A -4. A 5. m s 6. m s 8. m s T im e. m s.5 m s Figure 5. Waeforms of he olage, olage, im curren and i curren, for =.56 The laboraory prooype presened in Figure 6 was buil and esed wih he following parameers: inpu olage Vm = V and fm = 5Hz. The componens of he power supply filer are: Lf=3mH, Cf=6µF and he swiching frequency is f = khz. =69.V =54.96V V V -V -333V.A im=.784a i =.69A A -.A 5m s 6m s 7m s 8m s Time 9m s ms Figure 3. Waeforms of he olage, olage, im curren and i curren, for =.4 Figure 6. Experimenal seup 9

4 [ownloaded from on Tuesday, Sepember, 4 a :43:4 (UTC) by Redisribuion subjec o AECE license or copyrigh.] The sofware was designed o be implemened on he PIC6F684 microconroller, made by he MICROCHIP Company. I was chosen because i is cheap, easy o program and use. Figure 7 presens he flowchar of he sofware rouine wrien in C programming language [8] for he PIC6F684 microconroller, which works a 8MHz. START Volume 4, Number 3, 4 Figure 8(a) shows he waeforms of he o olage and of he olage and Figure 8(b) shows he waeforms of he io curren and of he im curren for a duy facor = V +V Microconroller iniializaion AC - V Pors PWM -4 V a Main Sofware Rouine read AC inpu updae PWM alues according o AC inpu + 4. A +. A im i Figure 7. Flowchar of he sofware implemened on he microconroller A he beginning, he program ariables are iniialized, as well as some inernal blocks of he microconroller (AC: Analog o igial Conerer, Pors: Inpu/Oupus Pors, PWM: Pulse Widh Modulaion). The program implemened on he microconroller is aimed a obaining wo KHz PWM signals, which are complemenary o each oher, a he oupu pins PA (pin 5) and PB (pin 6) wih no dead-ime [9]. Since he experimenal par was designed wih he purpose of proing he concep of he power circui, we chose he direc mehod of changing he duy cycle in accordance wih he readings of an analogical olage a pin AN (pin ), where a poeniomeer was insalled. epending on he analogical olage read a his pin, he duy-cycle of he PWM signals from pins PA and PB is modified in order o ge differen PWM alues necessary for esing he power circui []. Using he microconroller for he sole purpose of obaining wo PWM signals (wih no dead-ime) wih fixed duy-cycle alues is a raher complicaed mehod; for he sake of simpliciy, we could use a common oscillaor wih wo complemenary oupus. Neerheless, we should menion ha when we need closed-loop funcioning in order o mainain consan he oupu olage, he use of he microconroller is an adanage. The PWM signals generaed by he microconroller are applied o he wo ransisors S and S in Figure, by means of wo HCPL38 opocouplers. They are mean o separae he power circui from he conrol circui, insuring hus he galanic isolaion beween hem as a safey measure in case of malfuncion. As presened in Figure 6, he pracical circui is made up of wo boards; one of hem includes he microconroller, he LC, he driers and he low-olage supply circui, and he oher one conains he power circui analyzed, whose schemaic is presened in Figure. -. A -4. A b Figure 8. a)waeforms of he o olage, olage; b) Waeforms of he io curren, and im curren for =.4 Figure 9(a), 9(b) and Figure (a), (b) respeciely, show he same waeforms for =.48 and = V + V - V 4V a + 4. A +. A im i -. A -4. A b Figure 9. a)waeforms of he o olage, olage; b) Waeforms of he io curren, and im curren for =.48

5 [ownloaded from on Tuesday, Sepember, 4 a :43:4 (UTC) by Redisribuion subjec o AECE license or copyrigh.] Volume 4, Number 3, 4 TH %(im) 7,% 6,% +6V +3V 5,75% 4,9% 5,% 3,84% 4,% -3V 3,% -6V,%,8%,%,98%,% a,%.4 source curren-prooype im +4.A.56 source curren-simulaion Figure. TH analysis for he curren supplied by he power source im i +.A.48 The inpu power facor PF can be deermined direcly from he TH of he inpu curren as follows: -.A -4.A PF %THi b Figure. a)waeforms of he o olage, olage; b) Waeforms of he io curren, and im curren for =.56 Figure shows he ariaions of he efficiency depending on he duy cycle, also based on he simulaion resuls. We noice hus ha he efficiency is high for all he alues of. cos () where φ is he angle beween he fundamenal componen of he inpu curren and he fundamenal componen of he inpu olage. Figure 3 compares (prooype s. simulaion) he PF analyses of he curren supplied power source [] PF,967,89 Efficiency cure in simulaions and prooype (%) 84,%,75,796,88,8 simulaions 8,% 8,% 8% 78,% 79,5% 8,6%.5 79% 78,% 76,% 76,% 74,% prooype 7,% 7,%.4 68,% Figure Variaion of he efficiency depending on he duy cycle. THi I 3 I I 4.56 simulaion Figure 3. PF analysis for he curren power source im For calculaing he TH, oal harmonic disorion of he inpu curren, he following equaion was used: I.48 prooype () where I is he RMS alue of he fundamenal inpu curren, I is he RMS alue of he firs harmonic of he inpu curren a a swiching frequency of khz, ec. Figure compares (prooype s. simulaion) he TH analyses of he curren supplied by he power source. IV. CONCLUSION The paper presens a circui of direc AC-AC boos conerer conaining, beside he grid filer, wo bidirecional curren swiches, each made up of one IGBT, four diodes and a boos inducance. Swiches were conrolled by uniform sampling, wih he same duy cycle in all he swiching periods. The resuling conrol circui is simple and he energy flow can be bidirecional. The adequae funcioning of he circui was esed by simulaion, as well as on a laboraory prooype The resuls allowed he idenificaion of he conrol characerisic and of he funcioning efficiencies.

6 [ownloaded from on Tuesday, Sepember, 4 a :43:4 (UTC) by Redisribuion subjec o AECE license or copyrigh.] The waeforms obained for he load olage and curren are ery good. The supplied curren is sinusoidal, herefore he circui can be used paricularly for conering he RMS olage from V o V. Volume 4, Number 3, 4 [9] [] [] REFERENCES [] [] [3] [4] [5] [6] [7] [8] G. N. Reenkar,. S. Trasi, Symmerical Pulse Widh Modulaed A. C. Chopper, IEEE Trans. on Ind. Elecron. Conr. Insrum., ol.ieci4, 977, pp G. Chose, M. Park, An Improed PWM Technique for A.C. Chopper, IEEE Trans. on Power Elecronics, ol 4, 989, pp Jang, G. Choe, Asymmerical PWM Mehod for A.C. Chopper wih Improed Inpu Power Facor, IEEE PESC Conf. Rec, 99, pp Jang o-hyum, Ghy-Ha Choe, M. Ehsany, Asymmerical PWM Technique wih Harmonic Eliminaion and Power Facor Conrol in A.C. Chopper, IEEE Trans. on Power Elecron., ol., Nr., March 995, pp M. Lucanu, O.Ursaru, C. Aghion, Single Phase A.C. Choppers wih I.G.B.T s, Proceedings of he Inernaional Symposium on Signal, Circuis and Sysems SCS 3, July -, 3, pp L. Congwei, W. Bin, N. R. Zargari, X. eei, and W. Jiacheng, A noel hree-phase hree leg AC/AC conerer using nine IGBT s, IEEE Trans. on Power Elecron., ol. 4, Nr. 5, May 9, pp R. Lai, F. Wang, R. Burgos, Y. Pei,. Boroyeich, B.Wang, T. A. Lipo, V.. Immanuel, K. J. Karimi, A Sysemaic opology ealuaion mehodology for high-densiy hree-phase PWM AC-AC conerers, IEEE Trans. on Power Elecron., ol. 4, Nr. 7, July 9, pp M. Lucanu, O.Ursaru, C. Aghion, Single Phase A.C. Choppers wih Inducie Load and Improed Efficiency, Proceedings of he Inernaional Symposium on Signal, Circuis and Sysems, ISSCS 5, ol., July 4-5 5, pp [] [3] [4] [5] [6] [7] [8] [9] [] [] J. H. Kim, B.. Min, B. H. Kwon, S. C. Won, A PWM buck-boos AC chopper soling he commuaion problem, IEEE Trans. on Ind. Elecron., ol 45, No , pp L. Li, Y. Yang, Q. Zhong, Noel family of single-sage hree leel A.C. Choppers, IEEE Trans. on Power Elecron., ol. 6, Nr., pp Thiago B. Soliero, Clois A. Pery, Joao C. dos S. Fagundes, Yo Barbi, irec AC-AC conerers using commercial power modules applied o olage resorers, IEEE Trans. on Ind. Elecron., ol 58, No., pp C. Aghion, M. Lucanu, O.Ursaru, N. Lucanu, irec AC-AC Sepown Single-Phase Conerer wih Improed Performances, Elecronics and Elecrical Engineering, ol.8, no., pp B. Mammano, B. Carsen, Undersanding and opimizing elecromagneic compaibiliy in swich-mode power supplies, TI power seminar series 3. J. Harper, Elecromagneic compaibiliy design for power supplies, Fairchild Semiconducor power seminar series 4/5 R. L. Ozenbaugh, EMI filer design, CRC, No C. Basso, Swich-Mode Power Supplies SPICE Simulaions and Pracical esigns, McGraw-Hill, 8 A. Hesener, Elecromagneic Inerference (EMI) in Power Supplies, Fairchild Semiconducor Power Seminar - Programming languages C, Inernaional Sandard, ISO/IEC 9899:TC A. Valachi, M. Timis, M. anubianu, Some Conribuions o Synhesis and Implemenaion of Mulifuncional Regisers, h WSEAS In.Conf. on Auomaic Conrol, Modelling & Simulaion (acmos'9), Isanbul, Turkey, May 3 - June, 9, p K. B. Bose,Microcompuer Conrol of Power Elecronics and rie, IEEE Press. New York, 987. I. V. Pleea, M., Pleea,., Alexa, N., Lucanu, "Simulaions and Analysis and Operaing Regime as Recifier wih Power Facor Correcion of Two - Quadran Conerer wih RNSIC," Adances in Elecrical and Compuer Engineering, Volume, Number 3, Year, pp