Lab Based Analysis of Speed Control of DC Motor by Using Different Semiconductor Power Converters

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1 Open Access Librry Journl Lb Bsed Anlysis of Speed Control of DC Motor by Using Different Seiconductor Power Converters Abdul Khlique Junejo, Ghull Mustf Bhutto, Munwr Ayz Meon, hsn Ali Buriro Deprtent of lectricl ngineering, Quid--Aw University of ngineering Sciences nd Technology, Nwbshh, Pkistn il: Received 3 June 215; ccepted 16 July 215; published 22 July 215 Copyright 215 by uthors nd OALib. This work is licensed under the Cretive Coons Attribution Interntionl License (CC BY). Abstrct The flexible control of DC otor hs been donted in the extensive use of DC otor in the er of industry, s the incresing usge of seiconductor power converter units. The speed control of DC otor is very sophisticted nd specific. The speed of DC otor hs been controlled by controlling the rture voltge by using thyristors. The rture voltge is controlled by using the different types of AC to DC seiconductor converters such s hlf wve converter, sei converter nd full wve converter by using thyristor-diodes. This pper shows the experientl coprtive nlysis of the DC otor speed control by using the different power converter topologies perfored t the Quid--Aw University of ngineering Sciences nd Technology, Nwbshh lb. Keywords AC/DC Convertors, DC Motor, Torque Speed Chrcteristics Subject Ares: lectric ngineering 1. Introduction The DC otors re widely used becuse of their siplicity in their control ction. The srtness of the DC otor is its control up to the wide rnge. Dc Mchine cn be controlled by rture voltge control, rture voltge controlled by AC-DC converters [1]. There re severl ethods of speed control of the DC otor nd the rture voltge control is one of the ethods ong these ethods. AC-DC converter drives effects on the linerity of the torque-speed chrcteristics [2]. The rture voltge control of DC otor is perfored by using vrious topologicl networks of power seiconductor converters such s controlled nd uncontrolled rectifiers by using diodes nd the thyristor [3]. The disdvntge of power converters is the discontinuity in current. Due How to cite this pper: Junejo, A.K., Bhutto, G.M., Meon, M.A. nd Buriro,.A. (215) Lb Bsed Anlysis of Speed Control of DC Motor by Using Different Seiconductor Power Converters. Open Access Librry Journl, 2: e153.

2 A. K. Junejo et l. to this property of the power converters, non-linerity will occur in the torque of DC otors. The non-linerity in the torque is unvoidble for lrge lods on otors. Nowdys, ltest techniques re pplied to control the discontinuity of current [4]. Different topology og power converter y be fbricted in single chip fro seiconductor teril for speed control of DC Mchine [5]. Speed control of DC otor y be by using chopper which cn give us better results of speed-torque chrcteristics [6]. Speed control of DC otor cn be controlled by using P, PID nd Fuzzy technique with power converters for better results [7]. An experientl setup is crried out in the lectricl ngineering Deprtent of Quid--Aw University of Sciences nd technology (QUST) lbortory. The Continuity nd the linerity hve been observed on DC otor by using seiconductor converters hlf wve converter, sei converter nd full wve converter shown in following figures. A single phse hlf wve thyristor bsed converter which is used to control the DC otor is shown in Figure 1. A single phse hlf wve controller is used for the DC otor up to its rting of.5 kw. The verge output voltge of single phse converter cn be clculted fro eqution. It is hlf qudrnt drive converter. V Vo = ( 1+ COSθ) for < θ < π 2π Single phse sei wve thyristor bsed converter is shown in Figure 2. This converter is used for the DC otor up to the rting of 15 kw. The verge output voltge of single phse sei converter cn be clculted fro eqution. It is one qudrnt drive controller. V Vo = ( 1+ COSθ) for < θ < π π T R L Vt = V sin (wt) FD M T Lf Rf Figure 1. Single phse hlf wve converter drive. T1 T2 R L Vt = V sin(wt) FD M T Lf Rf D11 D12 Figure 2. Single phse sei converter drive. OALibJ DOI:1.4236/olib July 215 Volue 2 e153

3 A. K. Junejo et l. A single phse full wve thyristor bsed converter is shown in Figure 3. This converter is used for the DC otor up to the rting of 15 kw. The verge output voltge of single phse full wve converter cn be clculted fro eqution. It is two qudrnt drive converter. 2V Vo = ( 1+ COSθ) for < θ < π π The rture voltge converters y be hlf, sei nd full converter nd works on positive nd negtive voltge fro first qudrnt to fourth qudrnt. 2. Modelling of DC Motor When DC supply is pplied to the rture of the dc otor with its field excited by dc supply, torque is developed in the rture due to the contct between the xil current crrying conductors on the rotor nd rdil gnetic flux is produced by the sttor. If V is the pplied voltge pplied to the rture terinl of the otor, nd is the internlly developed rottionl e..f. The resistnce nd inductnce of the coplete rture re represented by R nd L s shown in Figure 4 [8]. Under driving conditions, the rottionl e..f. lwys opposes the pplied voltge V, nd for this reson it is referred to s bck ef for current to be forced in to otor, V ust be greter thn, the rture circuit voltge eqution being given by di v= + IR + L (1) d t The lst ter in qution (1) denotes the inductive voltge drop due to rture self-inductnce. This voltge is proportionl to rte of chnge of current, so under stedy stte conditions (i.e. when the current is constnt), the ter will be zero nd cn be overlooked. Under stedy stte-condition, the rture current I is constnt nd qution (1) siplifies to T1 T2 R L Vt = V sin(wt) M T Lf Rf T3 T4 Figure 3. Single phse full wve converter drive. R L v M T Rf Lf Figure 4. quivlent circuit digr of DC otor. OALibJ DOI:1.4236/olib July 215 Volue 2 e153

4 A. K. Junejo et l. The otor bck ef is given by b V= + IR (2) NZ P = Volts 6 A where is flux per pole in webers Z is nuber of rture conductors. N is speed in rp. A is nuber of prllel pths in rture. Here Z, P, A re fixed for prticulr chine fter wounded. Therefore for given DC chine where 6 ω, substitute in qution (4) 2π The torque developed by rture is given by where, Fro expression (2) b ZP = N volt 6A b = K N (5) b ZP 6 = ω volts 6A 2π ZP ZP = ω = I 2πA 2πA b b = K ω (6) ZI P T = N 2π A Substituting qution (1) in qution (9), we get Substituting qution (9) in qution (11), we get Rerrnging the bove equtions, we get T ( 2π ) K = ZP A (8) T = K I = T (9) T I V = R V = K R = K R V K ω V ω = K ( K ) 2 The bove expression gives the reltionship between speed nd torque for DC otors. Speed-current rel- R T (3) (4) (7) (1) (11) (12) (13) OALibJ DOI:1.4236/olib July 215 Volue 2 e153

5 A. K. Junejo et l. tionship cn be obtined if low T K in the expression (13) is replced with I (Fro qution (9)) s given be- V ω = K RI ( K ) Figure 5 shows the speed toque chrcteristics nd speed current chrcteristics of DC otor when the rture nd field voltge re kept constnt. As seen fro in the bove eqution prt 2 the speed torque chrcteristics nd speed current chrcteristic of seprtely excited or DC otor is given below, V ω = T = ω V ( K ) RI ω = = k K ω ω 2 where ω the no lod is speed nd ω is the speed drop. The no lod speed is dded where the torque nd current re equl to zero. The speed drop is function of lod torque. Fro the bove expression speed of seprtely excited DC otor or otor cn be controlled by controlling the following quntities. ) Resistnce dded to rture circuit. When resistnce is inserted in rture circuit, the speed drop ω increses nd otor speed decreses. b) Terinl voltge (Arture voltge). Reducing the rture voltge V of the otor reduces the otor speed. c) Field Flux (or field voltge). Reducing field voltge V of the otor reduces the flux, nd the otor speed increses. Controlling Speed by regulting rture voltge A coon ethod of controlling speed is to djust the rture voltge. This ethod is very efficient, stble nd is siple to ipleent. The circuit digr shown in Figure 1 gives the bsic concept of this ethod. The only controlled vrible is the rture voltge of the otor, which is represented s odifible voltge source. Bsed on qution (9). When rture voltge is reduced no lod speed is lso reduced, the rture voltge does not ffect the speed drop ω. The slope of speed torque nd field flux, the rture voltge does not ffect the speed drop R ω. The slope of speed torque chrcteristics is, which is independent of the rture voltge. 2 ( K ) Therefor chrcteristics re shown s Figure 5. It is observed tht the field voltge is Unchnged when the rture voltge vries [8]. V1 > V2 > V3 (14) (15) (16) Angulr Speed (rd/sec) V1 V2 V3 Lod Torque (N.) Figure 5. Speed-Torque chrcteristic of DC otor. OALibJ DOI:1.4236/olib July 215 Volue 2 e153

6 A. K. Junejo et l. 3. Lb Results nd Discussions The speed control nlysis of the DC otor by using different power converters such s hlf wve, sei converter nd full wve converter. This nlysis is purely bsed on the experientl nlysis of power converters by pplying different torques on the DC otor in QUST University Nwbshh Sindh Pkistn lbortory. The pplied torque chnging fro to 2 N (echnicl) lod, to nlyze the speed of the DC otor by using the different power converters, the odel picture of DC otor with ptching digr shown in Figure 6. The results of the speed-torque chrcteristics of DC otor on the single phse hlf wve converter, sei converter nd full wve converter shown in following Figure 7, Figure 9 nd Figure 11. It hs been observed in grphs tht the liner nd nonlinerity of rture current due to power converters. This non linerity in rture current effects on DC otor torque, whenever torque increses the speed of DC otor decreses s shown in following figures. It hs been lso observed tht when torque of DC otor incresing the rture voltge decreses s shown in Tbles 1-3. Arture current-voltge wve fors shown in Figure 8, Figure 1 nd Figure 12, it is clerly shown in wve for of rture current tht discontinuous of rture current cuse high nonliner torque on DC otor. In Figure 7, speed-torque chrcteristics of DC otor shown by using the Tble 1, when torque on DC otor increses the speed of DC otor decreses, lso in Figure 8 wve fors of rturevoltge nd rture current is shown it is cler view of discontinuous in rture current due to this discontinuous of rture current will effect on linerity of DC otor torque. In Figure 9, speed-torque chrcteristics of DC otor shown by using the Tble 2, when torque on DC otor increses the speed of DC otor decreses, lso in Figure 1 wve fors of rture voltge nd rture current is shown it is cler view of discontinuous in rture current due to this discontinuous of rture cur- Figure 6. DC otor with ptched controlled pnel Hlf wve converter Speed Torque (N.) Figure 7. Speed-Torque chrcteristics of single phse hlf wve converter. OALibJ DOI:1.4236/olib July 215 Volue 2 e153

7 A. K. Junejo et l. Figure 8. Arture current nd rture voltge t full lod torque t hlf wve converter Sei Converter Speed Torque (N.) Figure 9. Speed-Torque chrcteristics of single phse sei converter. Tble 1. Speed nd rture voltge on different torque vlues by using hlf wve converter. S. NO. Hlf Wve Torque (N.) Arture Voltge OALibJ DOI:1.4236/olib July 215 Volue 2 e153

8 A. K. Junejo et l. Figure 1. Arture current nd rture voltge t full lod torque t sei converter. Tble 2. Speed nd rture voltge on different torque vlues by using sei wve converter. S. No. Sei Wve Torque (N.) Arture Voltge rent will effect on linerity of DC otor torque but coprtively it is observed tht in sei converter hs less discontinuous current nd sller non-linerity. In Figure 11, speed-torque chrcteristics of DC otor shown by using the Tble 3, when torque on DC otor increses the speed of DC otor decreses, lso in Figure 12 wve fors of rture voltge nd rture current is shown it is cler view of discontinuous in rture current due to this discontinuous of rture current will effect on linerity of DC otor torque. It is coprtively shown in Figure 13 by using the Tble 4 in which clerly shown tht which power converter is better thn other. 4. Conclusion This pper dels with the experientl nd coprtive nlysis of AC/DC power seiconductor converters (i.e. hlf wve converter, sei converter nd full wve converter) with study of speed-torque chrcteristic of the DC otor for rture current nd torque ode. This study is perfored in the lbortory of the Quid--Aw OALibJ DOI:1.4236/olib July 215 Volue 2 e153

9 A. K. Junejo et l Full wve converter Speed Torque (N.) Figure 11. Speed-Torque chrcteristics of single phse full wve converter. Figure 12. Arture current nd rture voltge t full lod torque t full wve converter. Tble 3. Speed nd rture voltge on different torque vlues by using full wve converter. S. No. Full Wve Torque (N.) Arture Voltge OALibJ DOI:1.4236/olib July 215 Volue 2 e153

10 A. K. Junejo et l Hlf wve converter Speed Full wve converter Speed sei wve converter Speed" Torque Figure 13. Speed-Torque chrcteristics of hlf, sei nd full converters. Tble 4. Coprtive dt of speed-torque on different power converters. S.No. Hlf Wve Full Wve Sei Torque University of ngineering Sciences nd Technology, Nwbshh, Sindh, Pkistn. The DC otor hs been tken for experientl test on vrious torque (echnicl lod) pplied on DC otor rnging fro to 2 N; it hs been observed tht discontinuous in rture current due to ech converter. This inferior property of power converters will effect on DC otor torque, which is not cceptble for hevy lod. It is concluded tht the sei power converter hs less non linerity in the torque due to sll discontinuity of the rture current s copring with hlf wve nd full wve power converters. References [1] nny, M.A. (21) ffects of Single Phse AC/DC Converter Drive on the Torque-Speed Chrcteristic of DC Motor. Proceedings of the 14th Interntionl Middle st Power Systes Conference (MPCON 1), Ciro University, gypt, Deceber 21, Pper ID: 284. [2] Chpn, S.J. (1998) lectric Mchinery Fundentls. WCB/McGrw-Hill, New York. Dniels, W.M. nd Shffer, A.R. (1998) Re-Inventing the lectricl Mchines Curriculu. I Trnsctions on duction, 41, [3] Mohn, N. (2) lectric Drives: An Integrtive Approch. University of Minnesot Printing Services. [4] Nedeljkovic, M. nd Stojiljkovic, Z. (23) Fst Current Control for Thyristor Rectifiers. I Proceedings lectric OALibJ DOI:1.4236/olib July 215 Volue 2 e153

11 A. K. Junejo et l. Power Applictions, 15, [5] Consoli, A., Cccito, M., Test, A. nd Gennro, F. (24) Single Chip Integrtion for Motor Drive Converters with Power Fctor Cpbility. I Trnsctions on Power lectronics, 19, [6] Vdplli, V.R. (215) Speed Control of D.C. Motor Using Chopper. Interntionl Journl of lectricl nd lectronics Reserch, 3, [7] Ahed, A. (213) Coprtive Study of Speed Control of D.C. Motor Using PI, PID, nd Fuzzy Controller. Interntionl Journl of Advnced Reserch in Coputer nd Couniction ngineering, 2. [8] Gupt, R. (212) Thyristor Bsed Speed Control Techniques of DC Motor: A Coprtive Anlysis. Interntionl Journl of Scientific nd Reserch Publictions, 2, OALibJ DOI:1.4236/olib July 215 Volue 2 e153