Unidimensional modulation technique for cascaded multilevel converters

Unidimensional Modula ion Technique o Cascaded Mul ile el Con e e s J. I. Leon, Membe ,IEEE, S. Vazquez, Membe ,IEEE, S. Kou o, Membe ,IEEE, L. G. F anquelo, Fellow Membe ,IEEE, J. M. Ca asco, Membe ,IEEE and J. Rod iguez, Membe ,IEEE Abs ac —This pape p esen s a simple and low compu a ional cos modula ion echnique o mul ile el cascaded H-b idge con e e s. The echnique is based on geome ical conside a ions conside ing an unidimensional con ol egion o de e mine he swi ching sequence and he co esponding swi ching imes. In addi ion, a simple s a egy o con ol he dc ol age a io be ween he H-b idges o he mul ile el cascaded con e e is p esen ed. Examples o he wo-cell opology a e shown bu he p oposed echnique can be applied o de elop modula ion me hods o a highe numbe o H-b idges. Expe imen al esul s a e p esen ed o alida e he p oposed echnique. I. INTRODUCTION THE de elopmen o new simple and e icien modula ion echniques o mul ile el con e e s is a ocus o esea ch in he las 25 yea s. Pulse wid h modula ion (PWM) and space ec o modula ion (SVM) a e he mos common ways o ob ain he modula ed ol age o a mul ile el con e e gene a ing he e e ence ol age a e aged o e a swi ching pe iod [1]–[3]. The la ge numbe o ou pu ol age le els is an impo an cons ain leading o complex ha dwa e sys ems using mul iple iangle ca ie s (in PWM echniques) o a high compu a ional bu den (in SVM echniques). Among he exis ing mul ile el con e e opologies, he cascaded H-b idge con e e (CHB) is one o he mos in e es ing ones due o i s high modula i y, aul ole an capabili y, educed numbe o powe de ices and high e iciency [4]–[6]. In Fig. 1, a single-phase wo-cell CHB is shown. The ou pu phase ol age Vab is ob ained as he addi ion o he ou pu ol age o each H-b idge (also called cell) o he con e e . In gene al, he dc ol age a io o he wo-cell CHB con e e can be de ined as k:1 (being ka eal posi i e numbe ) meaning ha he ol age o he uppe cell VC1is k imes highe han he ol age o he lowe cell VC2. In his pape , a simple and in ui i e modula ion me hod o CHB is p esen ed. This modula ion echnique is based on geome ical conside a ions leading o he de e mina ion o he swi ching sequence and he swi ching imes by e y simple calcula ions. In addi ion, he Manusc ip ecei ed Augus 22, 2008. Accep ed o publica ion Feb u- a y 14, 2009. Copy igh c °2009 IEEE. Pe sonal use o his ma e ial is pe mi ed. Howe e , pe mission o use his ma e ial o any o he pu - poses mus be ob ained om he IEEE by sending a eques o pubs- [email p o ec ed]. J. I. Leon, S. Vazquez, L. G. F anquelo and J. M. Ca asco a e wi h he Elec onic Enginee ing Depa men , Uni e si y o Se ille (Spain), (e-mail: [email p o ec ed]). S. Kou o is wi h Depa men o Elec ical and Compu e Enginee ing, Rye son Uni e si y, To on o (Canada) (e-mail: sami [email p o ec ed]). J. Rod iguez is wi h he Elec onic Enginee - ing Depa men , Uni e sidad T´ ecnica Fede ico San a Ma ´ ıa (Chile), (e-mail: [email p o ec ed]). b S3 C1 C2 a VC1 VC2 Vab S3 S4 S4 S1 S1 S2 S2 uppe cell lowe cell Iab Fig. 1. Two-cell cascaded H-b idge con e e . ab V 3 3 a) b) ab V Fig. 2. 1D con ol egion o he wo-cell CHB (whe e VC2=E ol s) wi h dc ol age a io equal o a) 1:1 b) 2:1. The edundan swi ching s a es a e chosen educing he swi ching losses. p oposed me hod conside s di ec ly he edundan swi ching s a es in o de o educe he swi ching losses. This pape is an upda ed e sion o [7] including new expe imen al esul s and in oducing imp o emen s in he implemen a ion o he p oposed modula ion echnique. II. 1D CONTROL REGION As was in oduced in [8], [9], a possible way o ep esen he swi ching s a es o mul ile el con e e s is o plo he possible ou pu ol ages o he con e e using a one dimensional (1D) con ol egion. Fo example, he con ol egion o he wo-cell CHB wi h dc ol age a io 1:1 and 2:1 a e shown in Fig. 2. Each cell o he con e e can ob ain h ee di e en ou pu ol ages, −VCi,0and VCi, de ined as H-b idge s a es 0, 1 and 2 espec i ely. In his igu e, a s a e XY co esponds o he uppe H-b idge ha ing s a e X and he lowe H-b idge ha ing s a e Y. III. GEOMETRICAL MODULATION TECHNIQUE The p oposed modula ion s a egy gene a es he e e ence ol age (V∗ ab) as a linea combina ion o he wo nea es swi ch- ing s a es o he con ol egion. The e o e, his calcula ion is educed o a geome ical sea ch o V∗ ab in he con ol egion. The swi ching sequence is o med by wo swi ching s a es XY called uppe 1-lowe 1and uppe 2-lowe 2wi h swi ching imes 1and 2 espec i ely. The swi ching imes a e also de e mined using e y simple ma hema ical exp essions. I he wo nea es swi ching s a es o he con ol egion ha e edundancies, hose ha educe he numbe o commu a ions a e selec ed. Fo example, in he case o CHBs wi h dc ol age a ios di e en o 1:1, he edundan swi ching s a es a e chosen educing he swi ching o he high dc ol age cell. The ansi ions be ween he di e en edundancies a e illus a ed wi h a ows in Fig. 2. In addi ion, he o de o he swi ching s a es in he swi ching sequence is chosen acco ding o he p emises p esen ed in [10], [11] in o de o imp o e he ha monic pe o mance o he ou pu wa e o ms. The p oposed modula ion s a egy is based on he ollowing s eps: 1) No maliza ion o he e e ence phase ol age V∗ ab using he dc ol age o he lowe ol age cell (E ol s) using exp ession a=V∗ ab E.(1) 2) De e mina ion o ai ac o as loo (a)whe e ope a o loo (x) ounds he elemen s o x o he nea es in ege owa ds minus in ini y. 3) De e mina ion o he swi ching imes pe uni o he wo swi ching s a es applying 1=a−ai 2= 1 − 1.(2) 4) Geome ical sea ch o he e e ence phase ol age V∗ ab in he 1D con ol egion using ac o ai. As an example, he low diag am o he p oposed geome i- cal modula ion echnique o he wo-cell CHB wi h dc ol age a io 1:1 and 2:1 a e shown in Fig. 3. The low diag am o he dc ol age a io 3:1 case was shown in he p e ious e sion o his pape [7]. As can be obse ed, he esul ing low diag ams a e simple and consequen ly he compu a ional cos is e y low. The p oposed echnique can be ex ended o CHB wi h mo e han wo powe cells. The analysis o ex end his modula ion echnique o con e e wi h mo e powe cells ises p opo ionally in complexi y, since he numbe o cases o be s udied inc eases. Howe e , his s udy can be done o line and i can be no iced ha he online calcula ions needed o execu e he co esponding modula ion echnique do no inc ease signi ican ly. IV. DC VOLTAGE RATIO CONTROL An in e es ing applica ion o he CHB is he g id connec ion wi hou use o he inpu ans o me ha p o ides he isola ed dc sou ces o also as ac i e il e . Howe e , he dc ol ages con ol is a challenge in hese applica ions [12]–[15]. A simple s a egy o con ol he dc ol age a io o he wo-cell CHB is in oduced wi h he p oposed geome ical modula ion o be applied o exis ing ec i ie o g id connec ion con ol s a egies. The con olle used in his pape o manage he sum o he dc ol ages o he wo-cell CHB was in oduced in [16]. Howe e , he o al dc ol age is sha ed and con olled be ween he cells o he CHB applying he p oposed modula ion wi h simple addi ional dc ol age a io conside a ions. The ou pu o he con olle is he e e ence phase ol age V∗ ab which is he inpu o he p oposed geome ical modula ion echnique. The echnique o con ol he dc ol age a io be ween he cells is based on he elimina ion o he swi ching s a es which end o unbalance he dc ol age a io [17]. In Table I, he swi ching s a es o be elimina ed o he 1D con ol egion a e summa ized depending on he ac ual dc ol age a io and he sign o he phase cu en Iab. These swi ching s a es a e elimina ed om he 1D con ol egion shown in Fig. 2, leading o new low diag ams o de elop he geome ical modula ion echnique. Fo ins ance, he dc ol age a io 2:1 has been s udied in his pape . The low diag ams o ca y ou he modula ion achie ing he con ol o he dc ol age a io 2:1 a e in oduced in Fig. 4. The 1:1 case and he 3:1 case we e p esen ed in he p e ious e sion o his pape [7]. V. EXPERIMENTAL RESULTS Fi s ly, he p oposed geome ical modula ion echnique o he wo-cell CHB wo king as an in e e is applied gene a ing a pu e 50 Hz sinusoidal e e ence wi h modula ion index equal o 0.9. The swi ching equency is 2 kHz and he CHB is connec ed o a RL load (R=20 Ω,L=15 mH). The ob ained esul s a e shown in Fig. 5 o dc ol age a ios equal o 1:1 (VC1=VC2=90 V), 2:1 (VC1=200 V, VC2=100 V) and 3:1 (VC1=270 V, VC2=90 V). No e ha o dc ol age a ios 2:1 and 3:1, he commu a ions and consequen ly he swi ching losses o he high powe cell a e educed. I can be no iced ha in he 1:1 case (Fig. 5 a) bo h cells equally sha e (in a e age) he powe demanded by he load due o he na u e o he p oposed modula ion and con ol s a egy. In o he cases such as 2:1 and 3:1, as he same cu en lows h ough all he cells and each cell con ibu es wi h a ol age p opo ional o i s dc-link ol age, he H-b idges sha e he powe in a a io simila o he dc ol age a io o he cells o he CHB (Fig. 5 b and Fig. 5 c). This phenomenon could be seen as a d awback in e ms o swi ch usage and loss o modula i y. Howe e , he bene i s a e a s ong educ ion in he swi ching losses and an imp o emen o he powe quali y wi h same numbe o powe semiconduc o s. Secondly, he applica ion o he p oposed me hod o a CHB con olled ec i ie connec ed o he g id h ough an TABLE I SWITCHING STATES TO BE AVOIDED TO CONTROL THE DC VOLTAGE RATIO k:1 Vol age Fo bidden s a es Fo bidden s a es unbalance wi h Iab >0wi h Iab <0 VC1> kVC220,21,10 02,12,01 VC1< kVC202,12,01 20,21,10 ai < 0 ab * / ai= loo (a) 1=a-ai 2=1- 1 uppe 1=0 =0 =ai YES NO a=VE uppe 2 lowe 1 lowe 2+2 =ai+3 uppe 1 = uppe 2 lowe 1 lowe 22 =2 =ai+1 =ai ai > 0 YES NO ai > -2 YES NO uppe 1 uppe 2 =1 =1 uppe 1=2 =2 =ai uppe 2 lowe 1 lowe 2-1 =ai =ai lowe 1 lowe 2+1 =ai+2 uppe 1 uppe 2 =0 =0 =ai lowe 1 lowe 2+3 =ai+4 a) b) ab * / ai= loo (a) 1=a-ai 2=1- 1 a=VE Fig. 3. Flow diag am o he p oposed geome ical modula ion echnique (whe e VC2=E ol s) o he wo-cell CHB wi h dc ol age a io equal o a) 1:1 b) 2:1 ai < -1 ai= loo (a) YES NO ai = -1 YES NO ai = 0 NO YES uppe 1 = uppe 2 lowe 1 lowe 22 =1 =1 =0 uppe 1=0 =0 =ai uppe 2 lowe 1 lowe 2+3 =ai+4 1=a-ai 2=1- 1 1=a+1 2=1- 1 1=a 2=1- 1 uppe 1 = uppe 2 lowe 1 lowe 21 =2 =1 =1 2=1- 1 uppe 1 = uppe 2 lowe 1 lowe 22 =2 =2 =1 1=a-1 2 ai > 0 ai= loo (a) YES NO ai = 0 YES NO ai = -1 NO YES uppe 1 = uppe 2 lowe 1 lowe 21 =0 =2 =1 uppe 1=2 =2 =ai uppe 2 lowe 1 lowe 2-1 =ai 1=a-ai 2=1- 1 1=a 2=1- 1 1=a+1 2=1- 1 uppe 1 = uppe 2 lowe 1 lowe 20 =1 =1 =1 2=1- 1 uppe 1 = uppe 2 lowe 1 lowe 20 =0 =1 =0 1=a+3 2 a) b) ab * / a=VEab * / a=VE Fig. 4. Flow diag am o he geome ical modula ion echnique (whe e VC2=E ol s) o a dc ol age a io con ol equal o 2:1 when he elimina ed swi ching s a es a e a) 20, 21 and 10 b) 02, 12 and 01. induc ance (L=3 mH) is es ed. The swi ching equency is 2.5 kHz. Expe imen al esul s a e p esen ed achie ing dc ol age a ios 1:1, 2:1 and 3:1 in Fig. 6. In he expe imen s, a load s ep om no load o connec ing unbalanced esis i e loads (R1=20 Ωand R2=10 Ω o uppe and lowe cells espec i ely) o he dc ol ages o he CHB is shown. As conclusion, a high quali y dynamic beha io o he dc ol age a io con ol s a egy is achie ed. I is clea ha he p oposed geome ical modula ion wi h he dc ol age a io s a egy achie es an accu a e dc ol age con ol o each cell, despi e ha he ex e nal ec i ie con olle is only in cha ge o he o al dc ol age con ol. I he capaci o ol ages a e no pe ec ly con olled a possible solu ion o minimize he ela ed dis o ion in he ou pu wa e o ms is o apply a eed- o wa d modula ion (a) (b) (c) Fig. 5. Expe imen al esul s o in e e ope a ion wi h dc ol age a io: a) 1:1, b) 2:1 and c) 3:1. In all he igu es om bo om o op: Channel 1: Ou pu ol age o uppe cell; Channel 2: Ou pu ol age o lowe cell; Channel 3: Phase ol age Vab; Channel 4: Phase cu en Iab echnique [17]. As can be obse ed om Fig. 7, he elimina ion he un- balancing swi ching s a es leads o a sligh dis o ion in he phase ol age Vab when he desi ed dc ol age a io is no 1:1. This is he ade-o o achie e asymme ic dc ol age a ios. In o de o analyze his phenomenon, he o al ha monic dis o ion (THD) o Vab is s udied depending on he alue o he modula ion index o dc ol age a ios 1:1, 2:1 and 3:1. The swi ching equency is 2 kHz and he o al ac i e powe p o ided by he wo-cell CHB is 6 kW. The con e e is connec ed o esis i e loads in such a way ha he powe a io be ween he cells coincides wi h he dc ol age a io. The ob ained esul s a e shown in Fig. 8 whe e he THD is calcula ed conside ing ha monic o de up o 49 h. In his igu e, he modula ion index is de ined as he a io be ween he (a) (b) (c) Fig. 6. Expe imen al esul s o he p oposed geome ical modula ion echnique wi h con ol o he dc ol age a io: a) 1:1 (V∗ C1=V∗ C2= 40 V), b) 2:1 (V∗ C1= 2V∗ C2= 50 V) and c) 3:1 (V∗ C1= 3V∗ C2= 60 V). G id ol age Vs= 50 V ms. In all he igu es om bo om o op: Channels 1-2: Vol age o he cells VC1and VC2, Channel 3: G id ol age Vs, Channel 4: Phase cu en Iab ampli ude o he undamen al componen o he phase ol age and maximum possible ou pu dc ol age o he con e e . F om his esul , i can be seen ha he dc ol age a io 2:1 is he bes one in o de o ob ain a be e pe o mance in e ms o THD. Ra io 1:1 has no addi ional dis o ion since he elim- ina ed swi ching s a es ha e edundan allowed s a es keeping he i e ou pu ol age le els. In a io 2:1, he e is a be e THD compa ed o 1:1 despi e o he elimina ed swi ching s a es (some o hem ha e no edundancy) because 2:1 has se en ou pu le els, compensa ing he dis o ion in oduced by he dc ol age a io algo i hm. On he o he hand, a io 3:1 p esen s highe THD since he e a e no edundancies a ailable o all swi ching s a es leading o a highe dis o ion when hey a e elimina ed. The possible nine ou pu le els ha can −100 0 100 −100 0 100 0 0.01 0.02 0.03 0.04 0.05 −100 0 100 Time (s) V ab (V) a) b) c) Fig. 7. Phase ol age Vab using he p oposed geome ical modula ion echnique wi h con ol o he dc ol age a io. Dc ol age a io a) 1:1 b) 2:1 c) 3:1 0.6 0.7 0.8 0.9 1 15 20 25 30 35 40 45 Modula ion index Vab THD(%) a io 1:1 a io 2:1 a io 3:1 Fig. 8. To al ha monic dis o ion e sus modula ion index o he ob ained phase ol age Vab depending on he desi ed dc ol age a io. be gene a ed using a io 3:1 do no compensa e his dis o ion. VI. CONCLUSIONS A simple and low compu a ional cos modula ion me hod o mul ile el cascaded con e e s has been p esen ed. The modula ion me hod de e mines he swi ching sequence and he swi ching imes based on geome ical conside a ions using an unidimensional con ol egion. The e e ence phase ol age V∗ ab is gene a ed using a linea combina ion o he wo nea es swi ching s a es in he con ol egion educing he swi ching losses. Se e al examples using a wo-cell CHB ha e been in oduced depending on he dc ol age a io o he con e e . Expe imen al esul s a e shown in o de o alida e he p o- posed s a egies. The same me hod can be applied o CHB wi h a highe numbe o cells ex ending he con ol egion and de eloping simila low diag ams o de e mine he swi ching sequence and he swi ching imes. In addi ion, a simple s a egy o con ol he dc ol age a io o each cell o he wo-cell CHB has been in oduced. This echnique is based on he elimina ion o he inapp op ia e swi ching s a es om he 1D con ol egion. Once hese swi ching s a es a e elimina ed, new low diag ams a e used o ca y ou he geome y-based modula ion using educed e sions o he 1D con ol egions. The phase ol age Vab quali y achie ed by he p oposed modula ion s a egy is simila o o he well-known PWM ech- niques such us le el-shi ed PWM o hyb id PWM echniques. Howe e , using he p oposed modula ion echnique wi h dc ol age a io 1:1, an equal usage o he powe semiconduc o s unde all possible alues o he modula ion index is ob ained. In addi ion, o o he dc ol age a ios, he commu a ions o he highe ol age H-b idge ha e been educed leading o a educ ion o he commu a ion losses o he sys em making he p oposed echnique e y a ac i e imp o ing he o e all e iciency o he con e e . On he o he hand, when he CHB is ope a ing as a ec i ie , he p oposed modula ion s a egy has been modi ied in o de o con ol he dc ol age a io using he edundan swi ching s a e concep wha canno di ec ly conside ed by o he PWM echniques. Expe imen al esul s a e p esen ed o show he ope a ion o he p oposed modula ion echnique wi h he dc ol age a io con ol o a wo-cell CHB. The esul s show ha he p oposed modula ion echnique wi h he dc ol age con ol achie e high quali y esul s wi h e y low compu a ional cos . ACKNOWLEDGMENT The au ho s g a e ully acknowledge inancial suppo p o- ided by he Spanish Minis y o Science and Technology unde p ojec TEC2006-03863, by he Chilean Na ional Fund o Scien i ic and Technological De elopmen (FONDECYT), unde g an no. 1080582 and by he Uni e sidad T´ ecnica Fede ico San a Ma ´ ıa. REFERENCES [1] D. G. Holmes and T. A. Lipo, “Pulse Wid h Modula ion o Powe Con e e s - P inciples and P ac ice,” IEEE P ess, 2003. [2] R. Nade i and A. Rahma i, “Phase-Shi ed Ca ie PWM Technique o Gene al Cascaded In e e s,” IEEE T ans. Powe Elec on., ol. 23, no. 3, pp. 1257–1269, May 2008. [3] Y. Wenxi, H. Haibing and L. Zhengyu, “Compa isons o Space-Vec o Modula ion and Ca ie -Based Modula ion o Mul ile el In e e ,” IEEE T ans. Powe Elec on., ol. 23, no. 1, pp. 45–51, Jan. 2008. [4] J. Rod iguez, S. Be ne , Bin Wu, J. O. Pon and S. 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Cla e, “A Comple e Ha monic Elimina ion App oach o DC Link Vol age Balancing o a Cascaded Mul ile el Rec i ie ,” IEEE T ans. Ind. Elec on., ol. 54, no. 6, pp. 2946–2953, Dec. 2007. [13] J. A. Ba ena, L. Ma oyo, M. A. R. Vidal and J. R. T. Ap aiz, “Indi idual Vol age Balancing S a egy o PWM Cascaded H-B idge Con e e -Based STATCOM,” IEEE T ans. Ind. Elec on., ol. 55, no. 1, pp. 21–29, Jan. 2008. [14] H. Iman-Eini, J. L. Schanen, S. Fa hangi and S. Wang, “Design o Cascaded H-B idge Rec i ie o Medium Vol age Applica ions,” in IEEE Powe Elec onics Specialis s Con e ence (PESC 2007), pp. 653–658, 17-21 June 2007, O lando (USA). [15] Jian Wang and Yongdong Li, “PWM ec i ie in powe cell o cascaded H-b idge mul ile el con e e ,” in In e na ional Con e ence on Elec ical Machines and Sys ems (ICEMS 2007), pp. 18–21, 8-11 Oc . 2007, Seoul (Ko ea). [16] S. Vazquez, J. I. Leon, J. M. Ca asco, E. Gal an, J. A. Sanchez and E. Dominguez, “Con olle Design o a Single-Phase Two-Cell Mul ile el Cascade H-B idge Con e e ,” IEEE In e na ional Symposium on Indus ial Elec onics (ISIE’08), pp. 1–6, 30 June – 2 July 2008, Camb idge (UK). [17] J. I. Leon, S. Vazquez, A. J. Wa son, L. G. F anquelo, P. W. Wheele and J. M. Ca asco, “Feed- o wa d Space Vec o Modula ion o Single- Phase Mul ile el Cascade Con e e s wi h any dc ol age a io,” IEEE T ans. Ind. Elec on., ol. 56, no. 2, pp. 315–325, Feb. 2009. Jose I. Leon (S’04, M’07) was bo n in C´ adiz, Spain, in 1976. He ecei ed he B.S. and M.S. and PhD deg ees in elecommunica ions enginee ing om he Uni e si y o Se ille (US), Spain, in 1999, 2001 and 2006 espec i ely. In 2002, he joined he Powe Elec onics G oup, US, wo king in R&D p ojec s. Cu en ly, he is an Associa e P o esso wi h he Depa men o Elec onic Enginee ing, US. His esea ch in e es s include elec onic powe sys ems, modeling, modula ion and con ol o powe con e - e s and indus ial d i es. Se gio Vazquez (S’04) was bo n in Se ille, Spain, in 1974. He ecei ed he B.S. and M.S. deg ees in indus ial enginee ing om he Uni e si y o Se ille (US) in 2003 and 2006, espec i ely. In 2002, he was wi h he Powe Elec onics G oup, US, wo king in R&D p ojec s. He is cu en ly an Assis an P o esso wi h he Depa men o Elec onic Enginee ing in he US. His esea ch in e es s include elec onic powe sys ems, modeling, modula ion and con ol o powe elec onic con e e s and powe quali y in enewable gene a ion plan s. Sami Kou o (S’04, M’08) was bo n in Valdi ia, Chile, in 1978. He ecei ed he M.Sc. and Ph.D. deg ees in elec onics enginee ing om he Uni- e sidad T´ ecnica Fede ico San a Ma ´ ıa (UTFSM), Valpa a´ ıso, Chile, in 2004 and 2008 espec i ely. F om 2004 o 2008 he was a Resea ch Assis an , and om 2008 o 2009 Associa ed Resea che a he Elec onics Enginee ing Depa men o UTFSM. Cu en ly he is a Pos Doc o al Fellow a Rye son Uni e si y, To on o, Canada. In 2004 he was dis- inguished as he younges esea che o Chile in being g an ed wi h a go e nmen al unded esea ch p ojec (FONDECYT) as P incipal Resea che . His esea ch in e es s include powe con e e s, adjus able speed d i es, and enewable ene gy con e sion. Leopoldo G. F anquelo (M’84, SM’96, F’05) was bo n in M´ alaga, Spain. He ecei ed he M.Sc. and Ph.D. deg ees in elec ical enginee ing om he Uni e si y de Se ille (US), Se ille, Spain in 1977 and 1980 espec i ely. His cu en esea ch in e es lies on modula ion echniques o mul ile el in e - e s and i s applica ion o powe elec onic sys ems o enewable ene gy sys ems. He was he Vice- P esiden o he Indus ial Elec onics Socie y (IES) Spanish Chap e (2002 - 2003), membe a La ge o he IES AdCom (2002 - 2003). He was he Vice- P esiden o Con e ences o he IES (2004 - 2007), in which he has also been a Dis inguished Lec u e since 2006. He has been an Associa ed Edi o o he IEEE T ansac ions on Indus ial Elec onics since 2007. Since Janua y 2008 he is P esiden Elec o IEEE Indus ial Elec onics Socie y. Juan M. Ca asco (M’97) was bo n in San Roque, Spain. He ecei ed he M.Eng. and D .Eng. deg ees in indus ial enginee ing om he Uni e si y o Se ille (US), Se ille, Spain, in 1989 and 1992, espec i ely. F om 1990 o 1995, he was an As- sis an P o esso wi h he Depa men o Elec onic Enginee ing in he US whe e he is cu en ly an Associa e P o esso . He has been wo king o se e al yea s in he powe elec onic ield whe e he was in ol ed in he indus ial applica ion o he design and de elopmen o powe con e e s applied o enewable ene gy echnologies. His cu en esea ch in e es s a e in dis ibu ed powe gene a ion and he in eg a ion o enewable ene gy sou ces. Jose Rod iguez (M’81, SM’94) ecei ed he Engi- nee and he D .-Ing deg ees om he Uni e sidad T´ ecnica Fede ico San a Ma ia in Chile and he Uni e si y o E langen in Ge many in 1977 and 1985 espec i ely, bo h in Elec ical Enginee ing. He wo ks as P o esso since 1977 a Uni e sidad T´ ecnica Fede ico San a Ma ´ ıa in Valpa a´ ıso, Chile. F om 2001 o 2004 he was appoin ed as Di ec o o he Elec onics Enginee ing Depa men . F om 2004 o 2005 he se ed as Vice-Rec o o academic a ai s, and in 2005 he was elec ed Rec o o he same uni e si y, posi ion he holds ill oday. Du ing his sabba ical lea e in 1996, he was esponsible o he mining di ision o he Siemens Co po a ion in Chile. He has a la ge consul ing expe ience in he mining indus y, especially in he applica ion o la ge d i es like cyclocon e e - ed synch onous mo o s o SAG mills, high powe con eyo s, con olled ac d i es o sho els and powe quali y issues. His main esea ch in e es s include mul ile el in e e s, new con e e opologies and adjus able speed d i es. P o esso Rod ´ ıguez has di ec ed o e 40 R&D p ojec s in he ield o Indus ial Elec onics, he has coau ho ed o e 250 jou nal and con e ence pape s, and con ibu ed wi h one book chap e . His esea ch g oup has been ecognized as one o he wo cen e s o excellence in Enginee ing in Chile h ough he yea s 2005 o 2008. P o esso Rod iguez is IEEE Senio Membe since 1999, and is an ac i e associa e edi o o he IEEE Powe Elec onics and Indus ial Elec onics Socie ies since 2002. He has se ed as Gues Edi o o he IEEE T ansac ions on Indus ial Elec onics in i e oppo uni ies (Special Sec ion on: Ma ix Con e e s (2002), Mul ile el In e e s (2002), Mode n Rec i ie s (2005), High Powe D i es (2007) and P edic i e Con ol o Powe Elec onics D i es (2008). View publica ion s a sView publica ion s a s