MODELLING AND SIMULATION OF TWO-LEVEL SPACE VECTOR PWM INVERTER USING PHOTOVOLTAIC CELLS AS DC SOURCE

Transcription

1 INTERNATIONAL JOURNAL OF ELECTRONICS; MECHANICAL nd MECHATRONICS ENGINEERING ol. Num.4 pp.(3-37) MODELLING AND SIMULATION OF TWO-LEEL SPACE ECTOR PWM INERTER USING PHOTOOLTAIC CELLS AS DC SOURCE Ayse KOCALMIS BILHAN Erhn AKBAL Deprtment of Eletril nd Eletroni Engineering, 39, Elzig, Firt University, Tel: , Deprtment of Informtis 39, Elzig, Firt University E-mil: Astrt- A spe vetor PWM method for two level inverter is proposed in this pper. A two level inverter using spe vetor modultion strtegy hs een modeled nd simulted with pssive R-L lod. Photovolti ells re used s DC soure for input of two-level inverter. Simultion results re presented for vrious opertion onditions to verify the system model. In this pper, MATLAB/Simulink pkge progrm hs een used for modeling nd simultion of P ells nd two-level spe vetor pulse width modultion (SPWM) inverter. Keywords: Two -level inverter, spe vetor pwm, photovolti ell. INTRODUCTION Renewle energy soure eome one of the most widely studied eletri power pplitions sine fossil fuels re deresing nd oil pries nd glol wrming re inresing. Hydrogen energy, wind turines nd photovolti ells re the most populr renewle soures. A photovolti system hs dvntges suh s eing stti nd quite sine it hs no moving prts. So tht, it hs little opertion nd mintenne osts. The output hrteristi of photovolti ells depends on prmeters s temperture, the solr insoltion nd output voltge []. Inverters re power eletronis devies whih onverter DC power to AC power []. In mny power eletroni pplitions, it is desired to ontrol output frequeny nd voltge level. AC voltge n e produed t desired output frequeny nd voltge level y using inverters. Reently, developments in power eletronis nd semiondutor tehnology hve led improvements in power eletroni systems [3]. Inverters n e lssified to two min topology s voltge soure inverters (SI) nd urrent soure inverters (CSI). When lod hs high impedne ginst to hrmoni urrent, SI must e used there, while the lod with smll impednes ginst to hrmoni urrent requires CSIs to e used. In this work, three phse two-level inverter hs een simulted in order to onvert DC output power of solr pnels [4-5]. Six swithes re used to onstitute two-level inverter where eh phses re ommutted y only two swithes [6].A shemti drwing of three phse six step inverter is shown in Fig. Where the S, S3 nd S5 swithes stnd for upper swithes while S, S4 nd S6 swithes re down swithes. Three-phse output voltge wveforms re generted y vrious swithing omintion of the swithes in six step inverter resulting t output phse voltge wveforms s +DC/ nd -DC/ [7]. In reent yers, vrious pulse width modultion (PWM) tehniques hve een developed eside inverters. The totl hrmoni distortion of output voltge n e ontrolled y PWM tehniques. Also lod urrent wveforms n e ontrolled too.

2 Ayse KOCALMIS BILHAN, Erhn AKBAL +. SPACE ECTOR PWM (SPWM) S S 3 S 5 Two level inverters swithing sttes re shown in Fig. 3. DC S 4 S 6 S - LOAD Figure. Two-level inverter The most known PWM tehnique is Sinusoidl PWM (SPWM) tehnique [8-9]. In this tehnique, swithing pulses re generted y ompring sinusoidl wveform with referene tringle wveform. The omprison wveforms nd swithing signls hve een shown in Fig.. Figure. Two level sinusoidl PWM (SPWM) However it is diffiult to regulrly smpling of sinusoidl wveform for digitl pplition. For this reson, interest in other PWM tehniques hs een inresed. Seletive Hrmoni Elimintion PWM (SHEPWM), minimum urrent ripple PWM, third hrmoni injetion PWM (THIPWM) re some lterntives of the PWM tehniques. However spe vetor PWM (SPWM) tehnique is reently showing populrity for inverter pplitions. Figure 3. Swithing sttes of two level inverter In two level inverters, there re 3= 8 possile sttes []. Two of them re ( nd ) zero voltge vetors nd others re tive voltge vetors. "" swithing stte represents +DC/ nd "" swithing stte represents- DC/ []. The priniple of SPWM method is tht the ommnd voltge vetor is pproximtely lulted y using three djent vetors. The durtion of eh voltge vetors otined y vetor lultions []; T. T. T. T s. ref T T T T s () where,, nd re vetors tht define the tringle region in whih ref is loted. T, T nd T re the orresponding vetor durtions nd T S is the smpling time. In two-level inverter, spe vetor digrm is divided into 6 setors (A- -F). A typil spe vetor digrm of two-level inverter hs een shown in Fig. 4. SPWM for two-level inverters n e implemented y onsidering the following steps; Setor identifition, Clulte the swithing times, T, T, T Find the swithing sttes. 3

3 Ayse KOCALMIS BILHAN, Erhn AKBAL 3 Setor B 4 Setor C 7 Setor A w ref θ Setor D Setor F Setor E 5 6 Figure 4. Spe vetor digrm of two-level inverter Orthogonl oordintes to represent the 3- phse voltge in the phsor digrm. A threephse-voltge vetor n e expressed s; ref d q 3 n nd θ ngle is lulted y; rtn( q d ) j j s s ne ne () (3) where, n, n nd n re three phse voltges nd ref (referene voltge vetor) rottes t ngulr speed of w =.π.f... Setor Identifition Setor determintion ording to θ ngle hs een shown in Tle. Tle I. Setor Determintion (θ) Setor where ref is pled θ< 6 Setor A 6 θ< Setor B θ< 8 Setor C 8 θ< 4 Setor D 4 θ< 3 Setor E 3 θ< 36 Setor F. Clulting the Swithing Times ref is lulted y using two tive voltge vetor nd one zero voltge vetor. If ref is loted in Setor A, ref is synthesized y, nd. Aording to this pproh T, T nd T n e lulted s; T = (4) T = (5) T = T S - T - T If T, T nd T swithing times for ll setor n e generlized, they n e lulted y; T k = (6) T k+ = (7) T = T S - T - T where k = (Setor A-..-Setor F) nd θ 6. 33

4 Ayse KOCALMIS BILHAN, Erhn AKBAL.3. Finding Swithing Sttes Swithing sttes for Setor A hs een shown in Figure 5. PWM A PWM B PWM C T / T k T k+ T T k+ T k T / Figure 5. Swithing sttes of Setor A All swithing sttes hs een given in Tle. Tle II. Swithing sttes for Two level inverter Setors Swithing Sttes Setor A 7 7 Setor B MODELLING AND SIMULATION OF TWO-LEEL INERTER MATLAB/Simulink pked progrm is used to model nd simulte the two-level inverter. Fig. 5 shows Simulink model of the whole drive system inluding R-L lod. Clultion lok in Fig. 5 lultes θ ording to the demnd inverter output frequeny nd modultion index. Then, the setor in whih the vetor flls into ording to rules given in Tle is found y using the vlue of θ in Setor Determintion lok. SPWM lok lultes the swithing times ording to Eq. 6 nd Eq. 7 nd it genertes SPWM signls s explined in Tle. Inverter lok represents the two level inverter model using idel swithes. Three phses R-L lod is modeled s shown in Fig. 5. P Pnel genertes DC voltge input of twolevel inverter nd its model hs een given in Fig. 6. Two photovolti ells re used for otining DC soure of two-level inverter. Eh ell produes for 5W. Setor C Setor D Setor E Setor F *pi*f w lok Setor Determintion Setor Setor T T n Continuous powergui Clultion T T n m m T T n n SPWM + + n 3-Phse R-L Lod - P Pnel - n Inverter voltge Figure 5. Simultion lok of whole system. 34

5 Ayse KOCALMIS BILHAN, Erhn AKBAL P P module (I) pv nv + Simultion results hve een given for vrious operting using khz swithing frequeny nd pssive lod. Photovolti ells re used for DC voltge supply of two-level inverter. P module (I) pv 5 nv P Figure 6. Struture of P Pnel - 4. SIMULATION RESULTS Simultion results hve een tken for vrious operting onditions feeding pssive lod for R=Ω nd L=.H. Swithing frequeny of khz ws used in the model. DC link voltge of the two-level inverter ws tken s from photovolti ells. Simultion results shown in Fig. 7 through Fig. 9 hve een otined for modultion index of. nd output frequeny of Hz. Fig. 7 illustrtes output line voltge of the inverter ( ) whih is pplied to n R-L lod. As n e seen the output voltge wveform hs two levels. Corresponding single phse line urrent nd three-phse line urrents re shown in Fig. 8 nd Fig. 9, respetively. Although khz of swithing frequeny is used the urrent wveforms hve sinusoidl shpe. The line voltge wveform nd its frequeny spetr re demonstrted in Fig.. As n e seen the output voltge wveform hs min hrmoni t Hz. The other hrmonis re round swithing frequeny. The simultion hs een repeted for n output frequeny of 5Hz nd modultion index of.8. The results for the line output voltge nd single phse nd three phse urrent wveforms re given in Fig., Fig. nd Fig. 3, respetively. The line voltge wveform nd its frequeny spetr re demonstrted in Fig.4 for 5 Hz output frequeny. As n e seen the output voltge wveform hs min hrmoni t 5Hz. The other hrmonis re round swithing frequeny. i i, i, i Figure 7. The line output voltge wveform for f o =Hz nd m= Figure 8. Single phse line output urrent wveform (i ) for f o =Hz nd m= Figure 9. Three-phse line output urrent wveforms for f o =Hz nd m=. 5. CONCLUSION In this pper two-level inverter hs een modelled nd simulted using Simulink/MATLAB pkge progrm. 35

6 Ayse KOCALMIS BILHAN, Erhn AKBAL () i, i, i Frequeny (Hz) () Figure. The line output voltge wveform nd its spetrum for f o =Hz nd m= Figure 3. Three-phse line output urrent wveforms for f o =5Hz nd m= () i Figure. The line output voltge wveform for f o =5Hz nd m= Figure. Single phse line output urrent wveform (i ) for f o =5Hz nd m= Frequeny (Hz) () Figure 4. ()-The line output voltge wveform ()-its spetrum for f o =5Hz nd m=.8 The proposed ontrol lgorithm n e esily pplied in the two-level inverter It hs een shown tht high qulity wveforms t the output of the two-inverter n e otined even with khz of low swithing frequeny. Photovolti ell is one of the most known renewle soures. It hs very width pplition re. In this work, it hs een shown tht photovolti ells n e used s DC soure for inverters nd it hs effiient working re for power eletroni pplitions. 36

7 Ayse KOCALMIS BILHAN, Erhn AKBAL 6. REFERENCES [] H. - L. Tsi, C.-S. Tu, Y. - J. Su, Development of generlized photovolti model using MATLAB /SIMULINK, Proeeding of the World Congress on Engineering nd Computer Siene, ISBN: (Conferene Pper) [] B., K., Bose, Modern power eletronis nd AC drives, Prentie Hll In., (Book). [3] N., Mohn, Power eletronis-onverters, pplition nd design, JohnWiley & Sons In., 3, (Book) [4] W., D., Hrt, Introdution to power eletronis upper sddle river, N. J. Prene Hll, 997, (Book) [5] Y., Tdros, S., Slm, R., Höf, Three level IGBT inverter rrier sed pwm method, 99, (Book) [6] E. Deniz, Uzy vetor dre genişlik modülsyonu kullnn üç seviyeli H-köprü evirii tnlı D-sttkom un tsrımı ve gerçekleştirilmesi, Phd Thesis, Firt University,. [7] R. Cordero, J., O., P., Pinto, J., Solres, New simplifition of S-PWM sed on onditionl rottion of the referene vetor, Power Eletroni Conferene (IPEC),, (Conferene Pper) [8] Z., Qing, L., Zhihui, C., Jin, A novel 3- phse SPWM tehnique: instntneously floting the neutrl point, Power Eletronis nd Drive Systems Conferene, pp ,, 997. [9] I. Çolk, E. Klı, R. Byındır, S., Sğıroglu, The Design nd Anlysis of 5-Level Csded oltge Soure Inverter with Low THD, 9nd Power Engineering Energy nd Eletril Drives Conferene, Ankr, pp , 8- Mrh. (Conferene Pper) [] S., Mondl, J.,O.,P., Pinto, nd B., K., Bose, A neurl-network-sed spe vetor pwm ontroller for threel-level voltge-fed inverter indution motor drive, Industry Applition Conferene [] A., Kolmis, Uzy vektör PWM kontrollü çok seviyeli inverterin modellenmesi ve enzetimi, Mster Thesis, F. U., 5. [] D., Rthn Kumr, P., Lkshmn, T., Srinivsn, A new softwre implementtion of spe vetor PWM, Proeeding of Southest Conferene, pp. 3-36, 8- April. (Conferene Pper) 37