Hybrid Pulse Width Modulation Method for VSI Fed Induction Motor Drive with Reduced Complexity

Transcription

1 Internatonal Journal of Engneerng Reearch and Development e-issn : 78-67X, p-issn : 78-8X, olume, Iue 6 Augut, PP. 4-5 Hybrd Pule Wdth Modulaton Method for SI Fed Inducton Motor Drve wth Reduced Complexty J.Bhavan, J.Amarnath, D.Subbarayudu Aocate profeor, EEE Department, Malla Reddy Engneerng college, Maammaguda, Hyderabad,Andhra Pradeh,Inda. J.Amarnath,Profeor, EEE Department,JNUH College of Engneerng,Hyderabad,Andhra Pradeh,Inda. D.ubba Rayudu,Profeor,EEE Department,Pulla Reddy Engneerng College, Kurnool,A.P. Abtract h paper preent a generalzed pule wdth modulaton GPWM algorthm for nducton motor drve. In the propoed approach, by varyng a contant k value from zero to one, varou DPWM algorthm can be generated along wth the SPWM algorthm. A the propoed approach ue ntantaneou phae voltage only for the calculaton of gatng tme of the nverter, the complexty burden nvolved very le when compared wth the clacal pace vector approach. hen, the rm tator flux rpple, whch a meaure of rpple n lne current charactertc have been plotted for all the DPWM and SPWM algorthm. From whch, t concluded that the SPWM algorthm gve uperor performance at low modulaton ndce, wherea the DPWM algorthm gve uperor performance at hgher modulaton ndce. Hence, to acheve the uperor waveform ualty at all modulaton ndce, a hybrd PWM HPWM algorthm ha been preented n th paper. o valdate the propoed algorthm, everal numercal mulaton tude have been carred out and reult have been preented and compared. Keyword DPWM, flux rpple, GPWM, HPWM, PWM, SPWM I. INRODUCION he varable peed drve SD are becomng popular n many ndutral applcaton due to ther numerou advantage. But, the SD reure ac voltage wth controllable magntude and freuency. o acheve the varable voltage and varable freuency ac upply, the pule wdth modulaton PWM algorthm are becomng popular. A large varety of PWM algorthm have been dcued n []. But, the mot popular PWM algorthm a nuodal PWM SPWM and pace vector PWM SPWM algorthm. he SPWM algorthm offer more degree of freedom when compared wth the SPWM algorthm. Hence, t attractng many reearcher. he SPWM algorthm explaned n detaled n []. hough the SPWM and SPWM algorthm gve good performance, thee gve more wtchng loe of the nverter due to the contnuou modulatng gnal. Hence, to reduce the wtchng loe of the nverter, the dcontnuou PWM DPWM algorthm are becomng popular. Alo, the clacal SPWM algorthm reure angle and ector nformaton to generate the actual gatng tme of the nverter. Hence, the complexty nvolved more. o reduce the complexty nvolved n the algorthm and for eaer mplementaton, nowaday, the carrer baed PWM algorthm are attractng many reearcher. he magntude tet baed approach preented to generate the carrer baed SPWM and varou DPWM algorthm wth reduced complexty n []. Alo, by dtrbutng the zero tate tme uneually, varou PWM algorthm have been generated n [4]. By addng a generalzed zero euence gnal to the voltage varou carrer baed PWM algorthm have been generated n [5]. However, the []-[5] gve the explanaton under the lnear modulaton regon only. o reduce the complexty n the clacal SPWM algorthm and to extend the operaton up to over modulaton regon, varou PWM algorthm have been generated n [6]-[8] by ung the concept of offet tme and duty cycle. By addng the utable offet tme to the magnary wtchng tme, whch are proportonal to the ntantaneou phae voltage, varou PWM algorthm have been generated under both lnear and over modulaton regon. hough, the SPWM and DPWM algorthm gve good performance, the SPWM algorthm gve more harmonc dtorton at hgher modulaton ndce when compared wth the DPWM algorthm and DPWM algorthm gve more harmonc dtorton at lower modulaton ndce. Hence, to reduce the harmonc dtorton at all modulaton ndce, a hybrd PWM algorthm approach ha been propoed n [9]-[]. h paper preent a mplfed approach for the generaton of SPWM and DPWM algorthm. hen, the rm tator flux rpple charactertc of all PWM algorthm preented wth reduced complexty. Baed on the flux rpple charactertc, mplfed hybrd PWM HPWM algorthm ha been preented wth reduced harmonc dtorton at all modulaton ndce. II. SWICHING SEQUENCES he propoed GPWM algorthm may be purued by the defnton of a duty cycle or modulatng gnal for phae n wth n = a, b and c, whch gven a the rato between pule wdth and modulaton perod. 4

2 * n Hybrd Pule Wdth Modulaton Method for SI Fed Inducton Motor Drve wth Reduced Complexty Pulewdth Modualtonperod * Once the modulatng gnal n calculated, the ON and OFF tme of the nverter-leg devce can be va dgtal counter and comparator. For example, the duty cycle or modulatng gnal of SPWM algorthm can be obtaned a follow [6]-[7]: * n n, n a, b and c where n the ntantaneou reference voltage of phae n and the -lnk voltage. In the mlar way, the modulatng gnal of the varou DPWM algorthm and SPWM algorthm can be obtaned by addng a utable zero euence voltage z to the ntantaneou phae voltage n. * n z n k where z k[mn n max n ] mn n 4 where k the parameter that take nto account the uneual null-tate harng, can be defned a follow: k.5 gnco t 5 where gnx, and when X potve, zero, and negatve, repectvely. A prevouly dcued, and k an addtonal parameter whoe value may be eual to the value of k or be fxed at.5. hu, the propoed approach elmnate the calculaton of both the hexagon ector, n whch the reference-voltage pace vector located, and the related phae. In all the other carrer-baed technue, t mut be taken that k k. he tandard SPWM algorthm can be obtaned by fxng the k value at.5. Smlarly, by fxng the k value at and, the DPWMMIN and DPWMMAX algorthm can be obtaned. By varyng the modulaton angle n 5, varou DPWM algorthm can be generated. he DPWM, DPWM, DPWM and DPWM can be obtaned for δ = π/6,, - π/6 and - π/ repectvely. he modulatng waveform of nuodal PWM SPWM, SPWM and all poble DPWM algorthm are gven n Fg.. In the DPWM method, any one of the phae clamped to the potve or negatve DC bu for utmot a total of over a fundamental cycle. Hence, the wtchng loe of the aocated nverter leg are elmnated. Moreover, wthn a amplng tme perod three wtchng wll occur n SPWM algorthm wherea two wtchng n all the above DPWM algorthm. Hence, to mantan contant average wtchng freuency of the nverter, the freuency of DPWM algorthm taken a.5 tme of the wtchng freuency of the SPWM algorthm. III. PROPOSED HYBRID PWM MEHOD he SPWM algorthm ue eual dtrbuton of zero tate tme among two zero tate. Wherea the propoed GPWM algorthm ue uneual dtrbuton of zero tate tme and t dtrbute the zero tate tme a kz,7 k z, where z the total zero tate tme. 4

3 Hybrd Pule Wdth Modulaton Method for SI Fed Inducton Motor Drve wth Reduced Complexty Fg. Modulatng waveform of varou PWM method at M =.7 In the pace vector approach, the appled voltage vector eual the reference voltage vector only n an average ene over the gven amplng nterval, and not n an ntantaneou fahon. he dfference between appled voltage vector and reference voltage vector the rpple voltage vector, whch depend on pace and modulaton ndex. he rpple voltage vector and trajectory of the tator flux rpple can be repreented n a complex plane a hown n Fg.. he correpondng d-ax and -ax component of the tator flux rpple vector are a hown n Fg., from whch t oberved that the applcaton of a zero voltage vector reult n a varaton of the -ax component of the flux rpple and the applcaton of any actve voltage vector reult n varaton of the both the d-ax and -ax component. he error volt-econd correpondng to the voltage rpple vector are gven by r n j co ref 6 o r n 6 7 o j co6 ref M r jref j j 8 M r77 jref 7 j 7 j7 9 44

4 Hybrd Pule Wdth Modulaton Method for SI Fed Inducton Motor Drve wth Reduced Complexty 45 Fg. oltage rpple vector and trajectory of the flux rpple Fg. -ax and d-ax component of the flux rpple vector From the wtchng tme expreon of the clacal SPWM algorthm, by ubttutng the value of n, co and 6 co o n 6-9, the followng expreon can be obtaned. 9.5 d r j M M j M 9.5 d r j M M j M hen the mean uare tator flux rpple over a amplng nterval can be calculated a d d rm dt dt By ung, the mean uare flux rpple can be ealy computed and graphcally repreented for all PWM method. he mean uare tator flux rpple charactertc obtaned from for varou PWM algorthm and for dfferent modulaton ndce are hown n Fg.4 Fg.7.

5 Hybrd Pule Wdth Modulaton Method for SI Fed Inducton Motor Drve wth Reduced Complexty Fg. 4 RMS flux rpple over a ubcycle agant the angle at M =.4 A: SPWM, CD: DPWM, BE: DPWM, DE: DPWMMAX, DPWM and BC: DPWMMIN, DPWM. Fg. 5 RMS flux rpple over a ubcycle agant the angle at M =.55 A: SPWM, CD: DPWM, BE: DPWM, DE: DPWMMAX, DPWM and BC: DPWMMIN, DPWM.. Fg. 6 RMS flux rpple over a ubcycle agant the angle at M =.75 A: SPWM, CD: DPWM, BE: DPWM, DE: DPWMMAX, DPWM and BC: DPWMMIN, DPWM.. 46

6 Hybrd Pule Wdth Modulaton Method for SI Fed Inducton Motor Drve wth Reduced Complexty Fg. 7 RMS flux rpple over a ubcycle agant the angle at M =.96 A: SPWM, CD: DPWM, BE: DPWM, DE: DPWMMAX, DPWM and BC: DPWMMIN, DPWM. From Fg. 4 Fg. 7, t can be oberved that replacng by 6 n the rm tator flux rpple expreon of SPWM doe not change t value. However, the rm rpple over a ubcycle not ymmetrc about the center of the ector for the other PWM euence. Moreover, t can be oberved that the DPWM algorthm gve le harmonc dtorton when compared wth the other DPWM algorthm. In order to mnmze the harmonc dtorton n the lne current, the rm current rpple or rm tator flux rpple over every amplng tme perod hould be reduced. he propoed hybrd PWM HPWM algorthm employ the bet PWM algorthm among the SPWM and DPWM algorthm to mnmze the rm current rpple n every amplng tme perod. In the propoed HPWM algorthm, n every amplng tme perod the rm tator flux rpple of SPWM and DPWM are compared wth each other and the PWM algorthm, whch ha le rm tator flux rpple appled to mnmze the HD. hu, the propoed HPWM algorthm ue the DPWM algorthm n conjuncton wth SPWM algorthm. I. SIMULAION RESULS AND DISCUSSION o verfy the propoed HPWM algorthm, numercal mulaton tude have been carred out on v/f controlled nducton motor drve and reult have been preented. Smulaton tude have been carred out at dfferent upply freuence dfferent modulaton ndce. he teady tate current waveform along wth the total harmonc dtorton HD value for SPWM and propoed HPWM algorthm baed drve are hown from Fg. 8 to Fg.. o a b Fg. 8 mulaton reult of SPWM baed drve f=45 Hz or M =.854 a current b Harmonc pectra of current 47

7 Hybrd Pule Wdth Modulaton Method for SI Fed Inducton Motor Drve wth Reduced Complexty a b Fg. 9 mulaton reult of SPWM baed drve at f=48 Hz or M =.87 a current b Harmonc pectra of current a b Fg. mulaton reult of SPWM baed drve a current f=5 Hz or M =.96 b Harmonc pectra of current 48

8 Hybrd Pule Wdth Modulaton Method for SI Fed Inducton Motor Drve wth Reduced Complexty a b Fg. mulaton reult of propoed HPWM baed drve at f=45 Hz or M =.854 a current b Harmonc pectra of current a b Fg. mulaton reult of propoed HPWM baed drve at f=48 Hz or M =.87 a current b Harmonc pectra of current 49

9 Hybrd Pule Wdth Modulaton Method for SI Fed Inducton Motor Drve wth Reduced Complexty a b Fg. mulaton reult of SPWM baed drve a current f=5 Hz or M =.96 b Harmonc pectra of current From the mulaton reult, t can be oberved that the propoed HPWM algorthm gve uperor waveform ualty when compared wth the SPWM algorthm. Alo, propoed PWM algorthm gve pread pectra and hence reduce the acoutcal noe of the nducton motor. hu, the propoed algorthm reduce both the harmonc dtorton and acoutcal noe.. CONCLUSIONS A mple and novel GPWM algorthm for SI fed nducton motor drve preented n th paper. he propoed algorthm generate a wde range of DPWM algorthm along wth SPWM algorthm by ung the ntantaneou phae voltage only. By utlzng the concept of tator flux rpple, the harmonc analy of varou PWM algorthm ha been carred out and the flux rpple charactertc are preented. By comparng thee charactertc, bet PWM algorthm ha been ued n the propoed HPWM algorthm. hu, the propoed HPWM algorthm gve reduced harmonc dtorton when compared wth the SPWM algorthm. he mulaton reult confrm the effectvene of the propoed PWM algorthm. REFERENCES [] Joachm Holtz, Pulewdth modulaton A urvey IEEE ran. Ind. Electron., vol. 9, no. 5, Dec 99, pp [] Henz Wll an Der Broeck, Han-Chrtoph Skudelny and Georg ktor Stanke, Analy and realzaton of a Pulewdth Modulator baed on oltage Space ector, IEEE ran. Ind. Applc., ol. 4, No., Jan/Feb 988, pp.4-5. [] Ahmet M. Hava, Ruel J. Krkman and homa A. Lpo, Smple analytcal and graphcal method for carrer-baed PWM-SI drve IEEE ran. Power Electron., vol. 4, no., Jan 999, pp [4]. Blako, Analy of a hybrd PWM baed on modfed pace-vector and trangle-comparon method, IEEE ran. Ind. Applcat., vol., pp , May/Jun, 997. [5] Olorunfem Ojo, he generalzed dcontnuou PWM cheme for three-phae voltage ource nverter IEEE ran. Ind. Electron., vol. 5, no. 6, Dec, 4, pp [6] Dae-Woong Chung, Joohn-Sheok Km, Seung-K Sul, Unfed oltage Modulaton echnue for Real-me hree-phae Power Converon IEEE ran. On Ind. Applcaton, vol. 4, no., pp 74-8, March/Aprl, 998, pp [7] Antono Catalott, Fabo Genduo, Angelo Ract, and Gueppe Rcco Galluzzo Generalzed PWM SI Control Algorthm Baed on a Unveral Duty-Cycle Expreon: heoretcal Analy, Smulaton Reult, and Expermental aldaton IEEE tranacton on Ind. Electron., vol. 54, NO., June 7, pp [8] Edon Roberto C. Da Slva, Euzel CpranoDo Santo, Jr., and Curno Bradao Jacobna, "Pulewdth modulaton tratege" IEEE Ind. Electron., Magazne, no., pp.7-45, June,. [9] H. Krhnamurthy, G, Narayanan,..Ranganathan, R. Ayyar, Degn of pace vector-baed hybrd PWM technue for reduced current rpple IEEEAPEC, ol., pp ,. [] G.Narayanan, D Zhao, H. Krhnamurthy and Rajapandan Ayyanar, Space vector baed hybrd technue for reduced current rpple IEEE ran. Ind. Applc., ol. 55, No.4, pp.64-66, Aprl 8. []. Brahmananda Reddy, J. Amarnath and D. Subbarayudu, Improvement of DC performance by ung hybrd pace vector Pulewdth modulaton algorthm Internatonal Revew of Electrcal Engneerng, ol.4, no., pp. 59-6, Jul-Aug, 7. [] N. Ravankar Reddy,. Brahmananda Reddy, J. Amarnath, and D. Subba Rayudu Hybrd PWM Algorthm for ector Controlled Inducton Motor Drve wthout Angle Etmaton for Reduced Current Rpple ICGS-ACSE journal, vol 9, ue, pp.4-49, Dec 9. 5