Multilevel Inverter with Less Number of Isolated dc Bus Voltages

Transcription

1 Interntionl Journl of Engineering & ehnology IJE-IJENS ol: No: 8 Multileel Inerter with Less Numer of Isolted Bus oltges Mhrous E. Ahmed, Htim Ghzi M. Zini Fulty of Engineering, if Uniersity, KSA mehmed7@ieee.org rhgz@hotmil.om Astrt his pper proposes three-phse 7 leels oltge soure inerter employing spe etor modultion (SM) ontrol sheme nd with nturl us oltges lning. he proposed inerter is modulr type tht n inrese its leel y dding more ells to eh rm. A high frequeny trnsformer (HF) is proposed in this pper to generte the us oltge of the uxiliry ell from the min ell us oltge. As result of tht the numer of isolted us oltges required is redued y hlf. In ddition, nturl lning etween the min nd uxiliry ell us oltges of eh rm will e ttined due to the HF turns rtio whih result in simplifying the oerll ontrol of the whole system. In order to redue the size of the HF judiious modultion index (MI) will e hosen. he proposed system hs een simulted using indution motor lod. Anlyses nd simultion he een proided to lidte the proposed system. Index erm MLI, Isolted DC us soures, HF, SM, DC soures lning. I. INRODUCION In reent yers, there hs een gret interest in multileel inerters (MLIs) tehnology. Speil ttention hs een pid for sded H-ridge inerter [] []. Generlly, there re mny dntges in the pplitions of MLIs inerters oer onentionl two-leel inerters. he series onnetion of power onerter modules redues the oltge stress of eh onerter module (or inreses the oltge pility of the oerll onerter struture). Besides, the resolution of the stirse weform of the output oltge inreses with the numer of oltge steps of pitor oltge soures ille in the multileel inerter []. As result of the improed resolution in the oltge hrmoni ontent, filtering efforts nd the leel of the eletromgneti interferene (EM) generted y the swithing opertion of the onerter n e redued. Despite this importnt improement, these topologies he n importnt drwk: hey need mny isolted power supplies tht must e lned. hese lned isolted soures re generted from the P system for the onsidered sitution in this pper. his reson, ostly nd omplex topologies he to e implemented to get mny isolted supplies. Some solutions using sded multileel inerters with single power soure nd without trnsformers he een introdued reently [6] [7]. Howeer, these solutions use floting pitors with omplex lning systems nd mny mo re semiondutors in reltion to the numer of leels produed. he proposed MLI [8] is modulr type tht n inrese its leel y dding more ells to eh rm. he phse rm onsists of ells nd eh ell onsists of single isolted soure with two swithes. Swithes re onneted in suh wy tht one swith is in series with the isolted pitor nd the seond swith is onneted in prllel with the series soure nd the series swith. In order to inrese its resolution, isolted soure oltges with different lues re used in suh wy tht the soure oltge of ell equls hlf of the next ell soure oltge (, ). his MLI hs less omponents ompred to the existene MLI. he ojetie of this pper is to reple the us oltges of eh sded two ells (min nd uxiliry ells) using High Frequeny Link (HFL) with s mll size, whih llows using only one power supply (ttery pk, fuel ell or other) for single rm. he system hs inherent regultion of the oltges supplied mong the H-ridges, so the full numer of leels n e produed t ny mplitude of oltge, depending only on the single--supply regultion per rm, whih n e ontrolled with hopper. his proposed new topology does not need floting pitors or hey ulky trnsformers. II. PROPOSED MULI-LEEL INERER SYSEM Fig. shows the proposed struture of three-phse MLI inerter. It onsists of three rms from left to right for phses A, B nd C, respetiely. Eh rm onsists of ells, eh ell is omposed of one oltge soure nd two swithes, one swith is onneted in series with the oltge soure nd the other swith is onneted in prllel with oth the oltge soure nd the series swith s shown in Fig.. By doing this, eh ell n generte two sttes () nd the oltge soure ssoited with the onsidered ell. In order to inrese the leels of this proposed topology, the oltges re ssumed to e not onstnt ut their lues re ssumed to e inresed in geometri series mnner i.e. ( =, = ). Assume tht ell is the min ell with while ell is the uxiliry ell with. hus the numer of leels tht n e generted is (+(+) = 7). le I shows the swithing sttes nd the lod node oltge referred to the neutrl of the us oltge ( N ) for Arm A for two ells per rm inerter. It n e noted tht N hs four sttes (,,, ). he lod line-to-line oltges n e lulted s follows () N N herefore the lod line-to-line oltges n he (,,,,, -, - ). And the lod phse oltges n, n nd n n e lulted s in () 466-IJE-IJENS April IJENS

2 Interntionl Journl of Engineering & ehnology IJE-IJENS ol: No: 9 () n n n ABLE I SIMPLE SWICHING DESCRIPION OF HE PROPOSED MODEL oltge leel S S S S ( N) s s s s III. N N N SPACE ECOR MODULAION FOR HE PROPOSED MLI OPOLOGY he spe etor modultion ontrol lgorithm [9] [] will e employed to generte swithes pulse of the proposed MLI. By looking to Fig., the numer of leels tht n e generted is 7. Generlly eery swithing stte produes speifi three-phse oltges n, n, nd n referred to the neutrl of the us oltge whih n e defined s follows k n k n n () k Where k, k nd k [,,,..., 7], nd swithing sttes of inerter line-to-line oltges goerned y the following eqution. ( k k ) ( k k ) (4) ( k k ) Eqution (4) n e expressed in mtrix form s,, nd re l l( k k k k k k k k k, [, ) ] () Similrly, referene line-to-line oltge etor in stedy stte n e represented in etor form [os( t) os( t /) os( t /) ] l l (6) l l( k, k, k ) nd defined y eqution () nd (6) in d-q sttionry plne re represented y the following trnsformtion: 4 [ j j ( ll) d ( ll) q ] l l( k ) [ ]. k k e e ll( k, k, k ) (7) 4 j j ( ) d ( ) q [ e e ]. (8) Using the definition of etor norm, the length of the referene etor is. (9) l l Also, using the sme definition, the length of the lrgest ( oltge spe etor of l l k, k, k ) is: l l( k k k ( q ),, ) mx () Sine the mximum length of the referene etor tht n e synthesized equls the rdius of the lrgest irle tht n e insried in the outermost hexgon, the mximum length of the referene etor is: (,, ) os ( ) mx l l k k k mx 6 () he detiled SM ontrol sheme n e found in [8]. N Cell S S S S S S Cell- S S S S S S Fig.. he proposed 7 leel MLI In order to hoose the smllest size of the HF, the opertion of this inerter hs een simulted for different lues of MI to figure out the lod shring of the min inerter nd the uxiliry inerter ells. Assuming tht the min inerter DC oltge is 8 nd the uxiliry oltge is 4, results he een tulted in tle II. It n e onluded tht for MI round.8, the uxiliry ell ontriutes with ery smll lue of lod power nd the lod power is minly tken from the min inerter. his mens tht if the opertion of the MLI hs een fixed t MI round.9, the rting of the HF will e ery smll less thn 8% - whih dereses drstilly its ost. herefore the ontrol of the lod oltge is shifted to the front end - onerter to fix the inerter oltge. IM w 466-IJE-IJENS April IJENS

3 MI ABLE II RESULS OF HE MLI WIH WIDE RANGE OF MI Numer of output oltge leel Interntionl Journl of Engineering & ehnology IJE-IJENS ol: No: Rtio of ontriution of Aux nd Min ells: % Aux/Min ells ABLE III IM PARAMEERS Sttor oltge Frequeny Hz.9 7.9% Sttor resistne Sttor indutne rotor resistne rotor indutne power 8. mh mh W Fig. shows the HF tht onnets the min inerter unit with the uxiliry inerter unit. It omposed of HF with single phse H-ridge inerter opertes t high swithing frequeny to generte ipolr output oltge whih n e refleted using the HF together with single phse diode retifier to oltge with fixed rtio ompred to the input oltge. he trnsform is step down with / turns rtio whih is suitle for this speifi pplition nd MLI. he min tsk of this HF is to generte the soure of the uxiliry inerter unit from the min trnsformer unit soure. By this method, it n e gurnteed tht oltges of soures of the min nd uxiliry ells is nturlly lned. his lning is ery importnt euse it will result in simplify the ontrol system required y the whole system. Using HF will derese the isolted soures y hlf for this MLI whih mens soures insted of 6. In nother wy, normlly eh soures is generted from renewle soures P or fuel ell whih mens tht eh HF is used to reple P module whih will lso derese the ost of the whole system. S S 4 S S HF : Fig.. he upper MLI ell oltge is generted from the lower MLI ell I. SIMULAIONS RESULS Fig. 6 shows the integrtion of the oe desription of the system for single rm (phse). he proposed system hs een simulted using MALAB/SIMULINK to erify the performne of the proposed ontrol. A kw indution motor (IM) lod hs een used to study the performne of the proposed system. he IM prmeters he een proided in tle III. he dynmi response hs een erified due to sudden hnge in the torque t simultion time of.4s. An idel eletroni swithes nd diodes he een ssumed for simultion. Mutul indutne 6 mh Moment of inerti (J). kg.m Fig. nd Fig. 4 show the simultion results of the MLI line-to-line output oltge t fixed MI =.8 nd fixed swithing frequeny of khz. he MI hs een fixed s explined efore to redue the rting of the HF. he output oltges produe re 7 leels oltges weforms with rms lue of out nd its HD hs een found to e pproximtely %. Fig. 4 shows the three phse IM line urrents relted to step hnge in the lod torque t.s, the HD of the urrent hs een found to e pproximtely % nd this lue ttriutes for the swithing frequeny whih is khz nd the high indutne of the IM. Fig. nd Fig. 6 show the IM torque nd speed profiles due to this speifi loding ondition. hey gie the onentionl nd well-know profiles, the torque trks its referene with n eptle performne. On the other hnd, the speed uilds up with n eptle performne lso esides it dereses with smll mount fter loding t time.4s. Fig. 7 nd Fig. 8 show ontriution of the min nd uxiliry inerters ells oltges nd urrents, respetiely. Fig. 7 shows the oltges of the uxiliry nd min ells oltges. It indites tht the uxiliry oltges he more swithing ompred to the min ell oltges. he min ells oltge is nerly hs lod frequeny swithing. Besides the reltie lues etween the uxiliry ell oltge nd the min ell oltge is / whih omes from the HF. In the other hnd Fig. 8 shows the urrent ontriution of the uxiliry nd min ells of the proposed MLI. wo osertion n e done, ) the uxiliry ell urrent is more swithed thn the min ell urrent; ) the min ell urrent during loding ondition, fter.4s, is lmost unidiretionl while the uxiliry inerter urrent is idiretionl. Due to tht the erge lues will follow the design gien in tle II. his indites tht lod is tully supplied from the min inerter. herefore this will e refleted on the size of the HF to e ery smll whih is min tsk in this work. Fig. 9 illustrtes the HF input oltge nd output oltge. A ipolr PWM oltge t khz swithing frequeny he een employed. Fig. shows the us oltge of the min nd uxiliry inerters. he min inerter us is out 8 nd the uxiliry inerter us is out 4. By this wy, lned oltges he een inherently quired etween the min nd uxiliry ells whih results 466-IJE-IJENS April IJENS

4 Interntionl Journl of Engineering & ehnology IJE-IJENS ol: No: in reduing the ost of independent soures nd simplifying the ontrol lgorithm Fig.. Line-to-line output oltges of the proposed MLI system Fig. 7. Min nd Auxiliry inerter ells oltges Fig. 4. IM line urrents Fig. 8. Min nd Auxiliry inerter ells urrents em referene torque Fig. 9. High frequeny trnsformer input oltge Fig.. he IM torque Fig. 6. he IM speed profile le I shows the omprison etween the suggested inerter topology nd nother topology. Atully the omprison is done with respet to the generi form of proposed topology. Aording to the swith numer, leel numer nd leel to swith rtio. he omprison shows tht the proposed topology is etter thn the reent existene topology. ABLE I COMPARISON BEWEEN HE SUGGESED INERER SYSEM OPOLOGY AND HYBRID CASCADED HREE-SAGE ECOR DECOMPOSIION CONROL OPOLOGY []-[]. property No. Of swithing deies(three phse) opology nd ontrol desription he proposed MLI Hyrid sde -stge etor deomposition ontrol 8 No. Of leels 7 9 Leel/swith rtio.8. Min stge swithing frequeny khz Isolted DC soures IJE-IJENS April IJENS

5 . CONCLUSION his pper presents the nlysis, simultion nd the opertion of new topology of three-phse 7 leel inerter using spe etor modultion (SM) ontrol. he new in this pper is tht the proposed MLI used hs two min dntges; ) it hs lower numer of isolted us oltges, ) the us oltges of the min nd uxiliry ells re inherently lned due to using the HF. In this system HF is used per phse to generte the us oltge of the uxiliry inerter from the us of the min inerters. A fixed nd optimum MI is hosen to redue drstilly the HF whih is ery importnt in reduing the oerll system size. he dynmi performne of the system is tested due to sudden hnge in the lod oltge. Authors now re working towrd lidting the proposed system through experimentl testing. ACKNOWLEDGMEN he uthors would like to knowledge the if Uniersity projet. he reserh hs een rried out under the Projet no Interntionl Journl of Engineering & ehnology IJE-IJENS ol: No: ERENCE [] M. N. A. Kdir, S. Mekhilef, nd H. W. Ping, oltge etor Control of Hyrid hree-stge Eighteen-Leel Inerter y etor Deomposition, IEEE rns. Power Eletron., ol., pp.- 6,. [] S. Mekhilef, nd M. N. A. Kdir, Noel etor Control Method for hree-stge Hyrid Csded Multileel Inerter, IEEE rns. Ind. Eletron., ol. 8, pp. 6-6, April. [] S. Kouro, S. Bernl, H. Mirnd, C. A. Sil, nd J. Rodríguez, High-Performne orque nd Flux Control for Multileel Inerter Fed Indution Motors, IEEE rns. Power Eletron., ol., pp: 6, Noemer 7. [4] Brushk, L., Mertens, A., Comprison of Csded H-Bridge nd Modulr Multileel Conerters for BESS pplition, IEEE Energy Conersion Congress nd Exposition (ECCE), pp ,. [] H. Sephnd, J. Lio, M. Ferdowsi, Inestigtion on Cpitor oltge Regultion in Csded H-Bridge Multileel Conerters With Fundmentl Frequeny Swithing, IEEE rns. Ind. Eletron., ol. 8, pp.,. [6] D. Zhong, B. Ozpinei, L. M. olert, nd J. N. Chisson, DC- AC Csded H-Bridge Multileel Boost Inerter With No Indutors for Eletri/Hyrid Eletri ehile Applitions, IEEE rns. Ind. Appl., ol. 4, pp , 9. [7] S. zquez, J. I. Leon, L. G. Frnquelo, J. J. Pdill, nd J. M. Crrso, DC-oltge-Rtio Control Strtegy for Multileel Csded Conerters Fed With Single DC Soure, IEEE rns. Ind. Eletron.,, ol. 6, pp., 9. [8] M. M. Hsn, M. Ahmed, nd S. Mekhilef, Anlyses nd Simultion of hree-phse MLI with High lue of Resolution per Swith Employing SM Control Sheme, IEEE Interntionl Conferene on Power nd Energy, pp. 7, Deemer. [9] N. Celnoi nd D. Boroyeih, A Fst Spe-etor Modultion Algorithm for Multileel hree-phse Conerters, IEEE rns. Ind. Appl., ol. 7, pp , Mrh/April. [] M. M. Prts, R. Portillo, J. M. Crrso, L. G. Frnquelo, New Fst Spe-etor Modultion for Multileel Conerters Bsed on Geometril Considertion, IEEE Interntionl Conferene on Industril Eletronis, Control nd Instrumenttion, ol. 4, pp. 4-9, -8 Noemer. [] IEEE Stndrd for Interonneting Distriuted Resoures with Eletri Power Systems. [] M. N. A. Kdir, S. Mekhilef, Dul etor Control Strtegy for hree-stge Hyrid Csded Multileel Inerter, Journl of Power Eletronis, ol., pp.64,. Mhrous Ahmed ws orn in Sohg, Egypt. He reeied the B.S. nd M.S. degrees in eletril engineering from Assiut Uniersity, Assiut, Egypt, in 996 nd, respetiely, nd the Ph.D. degree in eletril engineering from Uniersity of Mly, Kul Lumpur, Mlysi, in 7. Sine 7, he hs een n ssistnt professor with the Aswn Fulty of Engineering, South lley Uniersity, Aswn, Egypt. In 8, he joined Aswn Power Eletronis pplitions reserh enter. Currently, he is n ssistnt professor t fulty of engineering, if Uniersity, KSA. His reserh interests re power eletronis nd rel time ontrol systems. Htim Ghzi Zini reeied the Bhelor's degree/higher diplom in 99 from Eletril & Computer Engineering, Fulty of Engineering, Umm Al-Qur Uniersity, Me, Sudi Ari. he Mster degree nd the Ph.D. from Florid Institute of ehnology, Melourne, FL, United Sttes in 998 nd, respetiely. In, he joined Fulty of Applied Computer Sienes, Umm Al Qur Uniersity, Mkkh, Sudi Ari s n ssistnt professor. In 7, 8, nd 9 he eome superisor Ciso Networking Ademy, Memer of the College Committee of Qulity Control nd Qulity Assurne, Memer of the College Higher Committee of Consulttion t ehnil Collge t Mkkh, Deprtment of Computer ehnology, Sudi Ari, respetiely. In June nd Jnury he eome ssistnt professor nd soite professor, respetiely, t if Uniersity, Deprtment of Eletril Engineering, Sudi Ari. His reserh interests inlude progrmming, omputtion lgorithms nd rel time ontrol systems. 466-IJE-IJENS April IJENS