Speed Control of Brushless DC Motor Using Proportional Integral Controller

Transcription

1 Volume 3 Issue XII, December 2015 Inernaional Journal for Research in Applied Science & Engineering Speed Conrol of Brushless DC Moor Using Proporional Inegral Conroller Vikramarajan Jambulingam Elecrical and Elecronics Engineering, VIT Universiy, India. Absrac: Ease conrol and high power densiy are he wo main reasons for using brushless DC moor in wide range of indusrial applicaions. In general he brushless DC moors are conrolled using power Semiconducor bridge. So he roor posiion sensors are used in he inverer bridge for saring and o provide proper commuaion sequence o he power swiches. In building inverer bridge power swiches are used due o high reliabiliy and performance. In his paper he hree phase brushless DC moor model is designed wih proporional inegral conroller and esed in MATLAB sofware. The PI conroller is used o conrol he speed of he brushless DC moor. On he oher hand parameers like Back EMF, curren, speed and orque are evaluaed for he designed models of BLDC moor. Due o he easy implemenaion and simple conrol srucure he convecional PI conroller are used in indusries. Keywords: Brushless DC moor, PI conroller, PMBLDC. I. INTRODUCTION The replacemen for convenional DC moor is BLDC moor in many cases. The characerisic of DC moor is reained by BLDC moor excep brushes and commuaor. To provide large amoun of orque for a wide range of speed BLDC moor suis he mos wih high performance. Acually for applicaions ha require high power, high reliabiliy and high efficiency BLDC moor is he ideal choice. A small BLDC moor is used in hard disk drives and large BLDC moor is used in elecric vehicles. In BLDC moor physical commuaor is no necessary because he elecric curren powers he permanen magne ha causes roaion in moor. So curren commuaion akes place because of solid sae swiches. In his case commuaion happens elecronically. Mos commonly used BLDC moors are hree phases raher han wo phase BLDC moor. Due o he roor roaion volage is induced in he saor winding called back-emf of BLDC moor. So orque is primarily influenced by back-emf of BLDC moor. In case size of he moor and orque delivered raio is higher so he criical facors are space and weighs in cerain applicaion o make i useful. When pracical speaking he orque ripple exi mainly due o imperfecion emf, ripple curren and phase curren commuaion. Due o he magne size and shape of he BLDC moor he imperfecion emf is occurred. On he oher side hyseresis and PWM conrol generaes ripple in curren. The Bimbra [1] has explained he generalized machine heory. II. BLOCKING DIAGRAM OF PROPOSED METHOD Figure 1: Block diagram of BLDC moor s Speed conrol The block diagram of brushless dc moor wih is speed conroller is shown in [Figure.1].I consis of four main pars hey are IJRASET 2015: All Righs are Reserved 471

2 Volume 3 Issue XII, December 2015 Inernaional Journal for Research in Applied Science & Engineering BLDC moor, sensors, conroller and power converers. The power is ransformed from source o BLDC moor hrough converer. So he BLDC moor in urn convers elecrical energy in o mechanical energy. To he power converer gae signal is applied on he basis of roor posiion. III. WORKING PRINCIPLE OF BLDC MOTOR One afer anoher he BLDC moor s elecronic commuaor energizes he saor coils and generaes a roaing elecric field ha drags he roor around wih i. N elecrical roaions equaes o one mechanical roaion, where N is he number of magne pairs. To indicae he relaive posiion of saor and roor o he conroller hree phase effec sensors are embedded in he saor of he hree phase brushless DC moor. The hall sensor helps brushless DC moor o energize he winding in a correc sequence and a he correc ime.consrucionally he all sensor is mouned on he non driving side of he sysem [Figure.2]. Figure 2: Hall sensors are embedded in he saor of a BLDC moor The high or low signal is generaed during he roor magneic poles passes he hall sensors by combining he signals from he hree sensors. Due o he movemen of he winding hrough he associaed magneic field he poenial volage is generaed by he elecrical moors and i can be called as elecromoive force. As per Lenz s law he magneic field which opposes original change in flux will give rise in winding curren. In general his means elecromoive force ends o resis he roaion of he moor and referred as back elecromoive force. The Baldursson [2] has developed brushless DC moor modelling and conrol. Padmaraja [3] has developed he fundamenals of brushless DC moor. A new simulaion model is developed by Jeon [4].For complee MATLAB modelling Simulink user s guide is helpful [5]. IV. DESIGN OF PI SPEED CONTROLLER In indusrial sysem PI is a conrol loop feedback mechanism. Acually beween measured process variable and desired se poin error exis. So o correc ha error Proporional inegral conroller is used in indusries. The proporional mode and inegral mode are wo separae modes involved in proporional inegral mode calculaion. The reacion o he curren error is calculaed by Proporional mode and reacion o he recen error is calculaed by inegral mode. So he sum of hese wo modes oupu is considered as correcive acion o he conrol elemen and PI conroller is implemened as, oupu( ) K pe( ) K e( ) d e( ) =se reference value acual calculaed value. The basic model of permanen magne brushless DC moor is shown in figure.2. In ha model i consis of BLDC moor, posiion sensor, pulse widh modulaion curren conroller, volage source inverer, reference curren generaor and PI conroller. The speed error is processed o PI conroller afer comparing he speed of he BLDC moor wih is reference speed. e( ) ( ) ref m T ( ) T ( 1) K [ e( ) e( 1)] K e( ) K ref ref p p & K -gain of speed conroller I I 0 1 IJRASET 2015: All Righs are Reserved 472

3 Volume 3 Issue XII, December 2015 Inernaional Journal for Research in Applied Science & Engineering The reference orque is nohing bu oupu of he conroller. The hree phase reference curren,, a b c i i i is generaed by reference curren generaor wih he limis of peak curren magniude decided by he conroller and posiion sensor. The swiching commands are generaed o drive he inverer devices by comparing moor curren and is reference curren. KO [3] has implemened he conrol of BLDC moor using PI conroller. V. MATHEMATICAL MODELLING OF THE BLDC MOTOR dia dib dic Va ia Ra La M ab M ac ea Eq.(1) d d d dib dia dic Vb ib Rb Lb M ba M bc eb Eq.(2) d d d dic dib dia Vc icrc Lc M cb M ca ec Eq.(3) d d d Where, Ra, Rb, Rc - Saor resisance of phase a, b and c. La, Lb, Lc - Saor inducance of phase a, b and c. ia, ib, ic -Saor curren of phase a, b and c. Va, Vb, Vc -Volages of phase a, b and c. Ra Rb Rc R -Muual inducance beween phases La, Lb, Lc -Saor self inducance of phase a, b and c. In his case, La Lb Lc L M M M M M M M ab ac bc ba ca cb Assuming hree phase balanced sysem, all phase resisance are equal. R R R R a b c Le us rearrange he above equaions 1, 2 and 3. We ge, dia dib dic Va ia R L M M ea Eq.(4) d d d dib dia dic Vb ib R L M M eb Eq.(5) d d d dic dib dia Vc ic R L M M ec Eq.(6) d d d Le us neglec muual inducance in equaions 4, 5 and 6. We ge, dia Va iar L ea Eq.(7) d dib Vb ib R L eb Eq.(8) d dic Vc icr L ec Eq.(9) d IJRASET 2015: All Righs are Reserved 473

4 Volume 3 Issue XII, December 2015 Inernaional Journal for Research in Applied Science & Engineering VI. TORQUE GENERATION Theoreical moor consan K is he produc of orque and supply curren I. Ta Tb Tc K K K K ( moor ) ( a) ( b) ( c) imoor ia ib ic -Angle Ta, Tb, Tc -Toal orques d P * d 2 The generaed elecromagneic orque is given by, [ eaia ebib ecic ] Te in N-M T K { f ( ) i f ( ) i f ( ) i e a a b b c c d J B Te T1 d The relaion beween angular velociy and angular posiion is given by, d P * d 2 T1 -load orque -Moor ineria B-Damping Consan P-Number of poles VII. SIMULATION MODEL OF THE BLDC MOTOR TABLE I Volage (V dc ) 160 vols Damping consan (T load ) 0.02 N-M/rad/sec Resisance (R) 0.7 ohms Inducance (L) 2.72 mh Momen of ineria (J) Kg-m/sec 2 Number of poles 4 Number of phases 3 Table.1. Specificaion of BLDC moor IJRASET 2015: All Righs are Reserved 474

5 Volume 3 Issue XII, December 2015 Inernaional Journal for Research in Applied Science & Engineering Figure 3: MATLAB Simulink model of BLDC moor Figure 4: MATLAB Simulink Sub sysem model of BLDC moor IJRASET 2015: All Righs are Reserved 475

6 Volume 3 Issue XII, December 2015 Inernaional Journal for Research in Applied Science & Engineering Figure 5: MATLAB Simulink Sub sysem model of PI conroller A. Curren VIII. SIMULATION RESULTS Figure 6: Curren Phase A in amperes Figure 7: Curren Phase B in amperes IJRASET 2015: All Righs are Reserved 476

7 Volume 3 Issue XII, December 2015 Inernaional Journal for Research in Applied Science & Engineering B. Back EMF Figure 8: Curren Phase C in amperes Figure 9: Back EMF Phase A in Volages Figure 10: Back EMF Phase B in Volages IJRASET 2015: All Righs are Reserved 477

8 Volume 3 Issue XII, December 2015 Inernaional Journal for Research in Applied Science & Engineering C. Speed Figure 11: Back EMF Phase c in Volages D. Torque Figure 12: Speed in radian / second Figure 13: Torque in Newon meer IX. CONCLUSION The speed conrol of Proporional inegral conroller is shown in [Figure.12].The Proporional inegral conroller he moor reaches he reference speed wih a percenage overshoo of 6.23.Iniially he reference speed is se as 700rpm wih seconds a res. A he same ime he iniial phase back elecromoive force of he BLDC moor is zero. Therefore he phase curren a he ime of saring is ransien bu once he speed reaches is reference speed. Then he curren also reach is reference speed he conducion period of curren is 120 degree as shown in [Figure.6]. In general o provide mechanical work in indusry and generae elecric power in power plans elecrical machines are used. Due o high efficiency and good dynamic response he permanen magne brushless DC moor gains araciveness in he recen years. Because of low cos and high reliabiliy he brushless DC drives are preferred. In his mission speed conrol of permanen magne brushless DC moor is achieved using Proporional inegral conroller in MATLAB sofware and also esed successfully by evaluaing he parameers like back EMF, curren, orque and speed. IJRASET 2015: All Righs are Reserved 478

9 Volume 3 Issue XII, December 2015 Inernaional Journal for Research in Applied Science & Engineering REFERENCES [1] P. S. Bimbhra, Generalized Theory of Elecrical Machines, Khanna Publishers, Delhi, India, 2001, pp [2] Padmaraja Yedamale, Brushless DC (BLDC) Moor Fundamenals, Microchip Technology Inc [3] J.S.Ko, Robus Posiion Conrol of BLDC Moors Using Ineral-Proporional-Plus Fuzzy Logic Conroller, IEEE Trans. On IE, Vol, June 1994, pp [4] S. Baldursson, BLDC Moor Modelling and Conrol A MATLAB/Simulink Implemenaion, Maser Thesis, May, [5] Y.S. Jeon, H.S.Mok, G.H.Choe, D.K.Kim and J.S. Ryu, A New Simulaion Model of BLDC Moor wih Real Back EMF waveforms, IEEE CNF. On compuers in Power Elecronics, COMPEL 2000.pp , July [6] Sim power Sysems for use wih Simulink, user s guide, Mah Works Inc., Naick, MA, Mah Works, 2001, Inroducion o MATLAB, he Mah Works, Inc. BIOGRAPHY Mr.J.Vikramarajan received his Maser degree in Power Elecronics and Drives and Bachelor degree in Elecrical and Elecronics Engineering from VIT Universiy, India. He has published several inernaional research books and journals. His research ineress are elecrical machines, power elecronic applicaions, power qualiy, power elecronic converers and power elecronic conrollers for renewable energy sysems. IJRASET 2015: All Righs are Reserved 479