Internatonal Journal of Scentfc & Engneerng esearch, Volume 5, Issue 4, Aprl04 ISSN 9558 78 Analyss And Modelng Of New Mofed Multlevel Inverter Wth PMSM Apllcatons.Yazhn, M.Jagabar Sathk,Dr. K.aman AbstractThs paper presents a new mofed multlevel nverter wth PMSM based on PI control technque. The proposed multlevel nverter usng mnmum number of swtches and DC source. Where conventonal multlevel nverters requred more number of components, t seem to more complex control crcutry and bulky. For ths complextes we acheve to reduce the number of swtches n ths proposed multlevel nverter wll also reduce swtchng losses and conducton losses. The Total Harmoncs Dstorton and electromagnetc nterference wll be reduced n the proposed multlevel Inverter. The Proposed multlevel nverter output voltage level ncreased by usng mnmum number of swtches drven by the multcarrer modulaton technques.. Index Terms Cascaded H brdge,multlevel Inverter, multcarrer modulaton, PMSM, PI controller. NOMENCATUES Vdc, Vdc.Vdcn Input DC Voltages INTODUCTION V, out/v, out Vn, out Output Voltage of H Brdge Multlevel nverter has a very sgnfcant role n the area of Vo Ss Output Voltage of CascadedHBrdge Subsary Swtches HS, HS, HS& HS4 D,D,D& D4 H Brdge Swtches H Brdge Freewheelng Dode M Number of Output Voltage evel Ns Number of DC Sources N Swtches Number of IGBTs Sn nth Subsary swtch Kp, K Gan values d, q nductances of d and q axs Vds, Vqs stator voltage of d and q axs an,bn,cn hghpower meumvoltage control. The desred multstarcase output voltage s acqured by combnng several dc voltage sources. Currently, there occur three commercal topologes of multlevel voltagesource nverters are as follows:. Neutral pont clamped(npc). Flyng capactor(fc). Cascaded Hbrdge(CHB) For these topologes the voltage level s ncreased by ncreasng the number of swtches. Hence there wll be swtchng losses and voltage stresses n these topologes and the crcut wll become more complex. By usng the proposed topology number of swtches wll reduce sgnfcantly and hence the effcency wll mprove. [,]. The most attractve features of multlevel nverters are as follows:. They have very low harmonc storton. Three phase currents S(t) Swtchng functon s Stator resstance of PMSM. ωr ds, qs Speed of rotor Stator current n d and q axs v. Ψf flux lnkage. They can operate wth a lower swtchng frequency. Yazhn.. s currently pursung masters degree program n power electroncs and drve n J.J.college of engneerng and technology,trchy, Moble+9 9788958. Emal: yazhnrav9@gmal.com Jagabar Sathk. M. s currently workng as an Assstant Professor n the department of EEE at J.J College of Engneerng and Technology, Trchy, Moble +9 9500554. Emal: jagabarsathk@gmal.com educed Voltage Stress. educed swtchng loss, conducton loss and electromagnetc nterference. Permanent Magnet Synchronous Motor (PMSM) s wdely used for exact speed and torque control, better effcency, and hgher torque to nerta rato and hgh power densty [6,9]. The mplementaton of PMSM wth the voltage source nverter means for the converson of electrc energyfrom DC to AC. The man performance of the nverter s nfluenced by the PWM technque, the swtchng losses and conducton losses [4].PMSM has varous advantages over other machnes that are conventonally used for ac servo drves. PMSM drves are wdely used for hgh 04
Internatonal Journal of Scentfc & Engneerng esearch, Volume 5, Issue 4, Aprl04 ISSN 9558 79 performance servo applcatons lke robotcs and aerospace actuators. There s no need of supplyng magnetzng current through the stator for constant ar gap flux due to the presence of permanent magnet n the rotor of the PMSM. Because of the absence of magnetzng current, the PMSM wll work at a hgher power factor for the same output and wll be more effcent than the IM. To make PMSM hghly effcent there s no need of slp rngs for external exctaton gven to rotor and there wll be low mantenance and losses n the rotor. [,7,]. Table.. Varous swtchng sequence for seven level output. POPOSED MUTIEVE INVETE The new topology produces a sgnfcant reducton n the number of power devces and capactors requred to mplement a multlevel output. The new topology s used n the desgn of a sevenlevel nverter; only seven controlled swtches and three capactors are requred to mplement the sevenlevel nverter usng the proposed topology. In ths topology, three voltage splt capactors are used so, each phase needs just one dc voltage source. The two parts n the proposed topology are, the conventonal Hbrdge operates at hgh swtchng frequency and the subsary swtches whch operates n low swtchng frequency. Ths topology acheves a reducton of 4% of swtches than the conventonal converter. C S 4. MODEING OF THE POPOSED SYSTEM Fg.. Equvalent crcut of the proposed system V dc C S HS HS The State space equatons llustrate the dependency of the swtches, nput and output equatons. S(t) s Swtchng functon w.r.t tme. The state Space representaton of the above crcuts s, C. OPEATION S HS Fg.. Proposed seven level nverter HS4 For postve cycle the swtches HS and HS4 n the conventonal Hbrdge and the subsary swtch S, S and S turned ON to obtan the desred voltage levels Vdc, Vdc and Vdc corresponngly. For negatve cycle the swtches HS and HS n the conventonal Hbrdge and the subsary swtch S, S and S turned ON to obtan the desred voltage levels Vdc, Vdc and Vdc corresponngly. Ẋ AX BU ( 4 ) V V V dc dc dc t () t ( ) t ( ) From the above equatons the swtchng state of postve and negatve cycle expressons can be wrtten as, (). Postve Cycle: The state space equaton can be wrtten as sn no.oflevels t * n * ( 5 ) n nv dc 04
Internatonal Journal of Scentfc & Engneerng esearch, Volume 5, Issue 4, Aprl04 ISSN 9558 80 ().Negatve Cycle: The state space equaton can be wrtten as sn no.oflevels t * n * (6 ) n nv dc Where n= 0,,, 5. M The three phase current are expressed as, an bn cn *V dc * sn t / n* (7 ) *V dc * sn t / n* ( 8 ) *V dc * sn t / n* ( 9 ) d q 0 0an 0 bn (0) cn *V n* dc* sn t / () *V * cos t / n* dc () Modelng of PMSM: The modelng of PMSM s vtal for proper smulaton of the system. The dq model on the rotor reference frame s developed. Make the rotor daxs as zero n the reference frame and the rotor angle θr s combned wth the qaxs current to form the reference current Irabc. Stator mmf rotates at the same speed as that of the rotor. The mathematc model of PMSM s based on the followng assumptons [5,8,]. Neglectng the saturaton of armature;. Neglectng the wastages of eddy and magnetc hystercs;. There s no rotor damp resstance. Voltage equatons of PMSM are, vds s p d vqs r d V ds r q ds ( ) s p q qs s p d ds r q qs (4) dq V ds r d ds s qs qs (7 ) dd ds s ds V ds r q qs (8) dq qs s qs V qs r d ds (9 ). s vds q ds ds r qs ( 0) d d d. d vqs s qs r ds qs ( ) q q q Combned equaton of multlevel nverter and PMSM. s ds d. d qs r q q r sn ds d n d vds ( ) s qs cos vqs q n q 5. PI CONTOE PI regulators are also employed for motor control whereas a PI controller s used n a closed control loop whch controls poston, speed, torque, current or voltage of the system. Hence PI controller reacts to an error sgnal and tres to regulate the controlled quantty to attan the desred system response. Generally PMSM s a nonlnear system wth multple coupled states and parameter varatons [5,]. Hence t s ffcult to obtan a adequate hgh performance usng lnear control algorthms. PI control was wdely used for speed control where the fference between the reference speed and the actual speed are calculated and an error s produced, whch s fed to the PI controller [0]. The output produced by the proportonal gan wll be proportonal to the nput error and an ntegraton wll be taken to obtan the steady state error as zero. V qs (5) r d where p d, ds s p q qs dd V ds s ds ds r q qs (6 ) Fg.. PI controller For determnng the proportonal and ntegral constants of the controller, the Kp and K values are gven as, 04
Internatonal Journal of Scentfc & Engneerng esearch, Volume 5, Issue 4, Aprl04 ISSN 9558 f sd sq K p qs V qs q v d k r ds cos n V ds s q 6. MODUATION TECHNIQUE A common method of multcarrer PWM technque called Phase Dsposton (PD) method s appled to the multlevel nverter and can be drawnout to any number of voltage levels. Among the varous carrer based modulaton technque PD has better performance than others. In PD method all the carrer waveforms must be n phase wth the reference. Here number of levels wll be m then the carrer waveforms must be n the conton of (m). For example, the level s 5 then there are 4 carrer waveforms are arranged, so that all carrer waveforms are n phase. Hence for +Vdc when the reference s greater than both carrer waveforms. If the nverter s swtched to zero when the reference s greater than the lower carrer waveform but less than the upper carrer waveforms. For Vdc the reference wll be less than both carrer waveforms. 8 7. SIMUATION ESUTS The newly developed multlevel nverter topology has been smulated wth the help of MATAB/Smulnk009b. The smulaton was carred out usng speed control to study the performance of the motor drve. The closed loop speed control for PMSM drve s acheved by usng PI controller. Speed s taken as reference and the desred speed obtaned from the PMSM s compared wth t, an error s produced whch s fed to the PI controller. Output of the controller wll be the current q and d s assumed to be zero. By usng nverse park transformaton the dq0 values are transformed to three phase reference current Irabc whch s compared wth the feedback current Iabc. The reference and feedback current are compared and the output s fed to the multlevel nverter. Then the speed of the multlevel nverter s controlled usng the close loop control technque Output Current Waveform Output Voltage Waveform Speeed Waveform Fg. 4: Modulaton Waveform of Phase Dsposton PWM Fg. 5. Smulaton Output Waveforms 04
Internatonal Journal of Scentfc & Engneerng esearch, Volume 5, Issue 4, Aprl04 ISSN 9558 8. CONCUSION [] The proposed new mofed multlevel nverter fed PMSM usng reduced number of swtches was developed. The proposed topology shows that the swtchng devces and gate drver crcuts need not requred more numbers. The sze of the proposed multlevel nverter s smaller than the other multlevel nverters. The Conducton losses and swtchng losses are reduced. The overall cost wll be reduced by reducng the number of man swtches and control crcuts etc. The outputs are verfed by smulaton model developed usng the Matlab/Smulnk software. EFEENCES [] [] [] [4] [5] [6] [7] [8] [9] [0] [] Gobnath.K, Mahendran.S, Gnanambal.I, New Cascaded HBrdge Multlevel Inverter Wth Improved Effcency, Internatonal Journal of Advanced esearch n Electrcal, Electroncs and Instrumentaton Engneerng Vol., Issue 4, Aprl 0 Gerardo Cegla, Víctor Guzmán, Carlos Sánchez, Fernando Ibáñez, Julo Walter, and María I. Gménez, A New Smplfed Multlevel Inverter Topology for DC AC Converson, IEEE Transactons On Power Electroncs, Vol., No. 5, September 006 cha Pandey and S.P.Dubey, "Multlevel Inverter Fed Permanent magnet Synchronous Motor Drve wth Constant Torque Angle Control" Advance n Electronc and Electrc Engneerng. ISSN 97, Volume, Number 5 (0), pp. 550 YU Yanjun, CHAI Feng and CHENG Shukang, "Analyss of Modulaton Pattern and osses n Inverter for PMSM Drvers", IEEE Ve Dr hcle Power and Propulson Conference(VPPC), September 5, 008, Harbn, Chna 9784448497/08/$5.00 C 008 IEEE Mohd. Marufuzzaman, M.B.I. eazl, M.S.ahman,M.A. Mohd. Al, "Hardware Prototypng of an ntellgent current dq PI controller for FOC PMSM drve 6th Internatonal Conference on Electrcal and Computer Engneerng ICECE 00, 80 December 00. K Narasmhaah Achar, B Gururaj, D V Ashok Kumar, M Vjaya Kumar, A Novel MATAB/Smulnk Model of PMSM Drve usng Drect Torque Control wth SVM, Internatonal Conference on Emergng Technology Trends on Advanced Engneerng esearch (ICETT ) G. Sree akshm, Dr. S. Kamakshaah, Dr. G. Tulas am Das, Closed oop P Control Of Two & Three evel Dode Clamped Multlevel Inverter Fed Pmsm Usng Svpwm, Internatonal Conference on Advanced Engneerng & Technology, 0th March Chenna, ISBN: 978987007 Deepa.P S.Svaranjan A.Napolean, Certan Investgatons on Model Prectve Controller for PMSM Drve,Internatonal Journal of Electrcal, Electroncs and Computer Engneerng (): 4(0) S.V Dshore, Ms.JshaBhubesh, G.Devdas, Smulaton Of PMSM Vector Control System Based On Propeller oad Characterstc, Internatonal Journal of Engneerng esearch & Technology (IJET) Vol. Issue, January 0 ISSN: 7808 Madhumta Chakraborty, Comparatve Analyss of Speed Control of PMSM usng PIController and Fuzzy Controller, Internatonal Journal of Scentfc & Engneerng esearch, Volume 4, Issue 7, July0 0 ISSN 9558 0 Yogendra Sngh and Shryansh Jan, Comparatve Analyss of PI and PID Controller for PMSM wth New Slng Mode observer, Internatonal Journal of Electrcal, Electroncs and Computer Engneerng (): 4(0) 8 Zhang Yaou, Zhao Wansheng, Kang Xaomng, Control of the Permanent Magnet Synchronous Motor Usng Model eference Dynamc Inverson, Internatonal Journal of Advanced Scentfc and Techncal esearch Issue volume, JanuaryFebruary 0 BIBIOGAPHIES.Yazhn was born n Tamlnadu, Ina, on March 0, 99. She receved her B.E degree n Instrumentaton and Control Engneerng from A.V.C. College of Engneerng, Mayladuthura, n 0; currently she s dong M.E degree n Power Electroncs and drves from J.J. College of Engneerng and Technology, Trchy. Her current research nterests nclude smulaton of multlevel nverters, Ac Drves and Control System. M. M.Jagabar Sathk s Post graduated n 004 from Anna Unversty, Chenna. He s currently workng as an Assstant Professor n the department of EEE at J.J College of Engneerng and Technology, Trchy from January 0 onwards. Currently he s pursung Ph.D from Anna Unversty, Chenna and he has presented 4 papers n varous nternatonal conferences/journals. Hs current research nterests nclude Power Converters, AC Drves, FACTS and Optmzaton. K.aman s graduated n 004 from Bharathar Unversty, Combatore and post graduated n 006 at Anna Unversty, Chenna. He receved hs Ph.D from Anna Unversty Chenna. He s currently workng as an Assocate Professor n the department of EEE at K.S.angasamy College of Technology, Truchengode from January 006 onwards. He receved the 0 Young Teacher Award from the AICTE.He publshed more than 5 nternatonal/natonal conferences and journals. Hs research nterests nvolve power electroncs converters, modelng of nducton motor and optmzaton technques. He s gung UG, PG Students. He s an ISTE, IETE member 04