FUZZY LOGIC BASED FIELD ORIENTED CONTROL OF PERMANENT MAGNET SYNCHRONOUS MOTOR

Transcription

1 International Journal of Electrical, Electronic an Data Communication, ISSN: Volume-3, Iue-8, Aug FUZZY LOGIC BASED FIELD ORIENTED CONTROL OF PERMANENT MAGNET SYNCHRONOUS MOTOR 1 BINITA NANDA, 2 A.N THAKUR 1 M.Tech, Department of Electrical an Electronic Engineering, NIT Jamhepur 2 Profeor, Department of Electrical an Electronic Engineering, NIT Jamhepur 1 bini.n.pgrace@gmail.com, 2 anthakur.ee@nitjr.ac.in Abtract- The preent reearch i inicating that the Permanent magnet motor rive coul become eriou competitor to the inuction motor rive for ervo application. Further, with the evolution of permanent magnet material an control technology, the Permanent Magnet Synchronou Motor (SM) ha become a pronounce choice for low an mi power application uch a computer peripheral equipment, robotic, ajutable pee rive an electric vehicle ue to it pecial feature like high power enity, high torque/inertia ratio, high operating efficiency, variable pee operation, reliability, an low cot etc. However, the main iavantage of SM i the non-uniform variance in the evelope torque. Vector controlle SM rive provie better ynamic repone an leer torque ripple. Thi paper propoe a Fuzzy logic control cheme for a SM rive riven by Fiel Oriente Control (FOC). The propoe cheme i evelope in MATLAB/SIMULINK environment. Simulation reult are generate for teting the performance valiity of the control law. Inex Term- Permanent Magnet Synchronou Motor, Fuzzy Logic Control, Vector Control, Fiel Oriente Control. I. INTRODUCTION The Permanent Magnet Synchronou motor (SM) i a rotating electrical machine where the tator prouce a inuoial flux enity itribution in the air gap an the rotor ha permanent magnet. From the lat three ecae AC machine rive are becoming more an more popular, epecially Inuction Motor Drive (IMD) an Permanent Magnet Synchronou Motor (SM), but with ome pecial feature, the SM rive are reay to meet ophiticate requirement uch a fat ynamic repone, high power factor, an wie operating pee range like high performance application, a a reult, a graual gain in the ue of SM rive will urely be witnee in the future market in low an mi power application [1]. Now in a permanent magnet ynchronou machine, the c fiel wining of the rotor i replace by a permanent magnet to prouce the air-gap magnetic fiel. Having the magnet on the rotor, ome electrical loe ue to fiel wining of the machine get reuce an the abence of the fiel loe improve the thermal characteritic of the machine hence it efficiency. Alo lack of mechanical component uch a bruhe an lip ring make the motor lighter, high power to weight ratio which aure a higher efficiency an reliability. With the avantage ecribe above, permanent magnet ynchronou generator i an attractive olution for win turbine application alo. Like alway, machine alo have ome iavantage: at high temperature, the magnet get emagnetize, ifficultie to manufacture an high cot of material. The performance of thee motor in rive ytem epen up on the motor control an metho of control in power converter. The metho of motor control i very important in the rive ytem. Thi i becaue the operation of the SM uner effect of calar control i uffere from complicate coupling nonlinear ynamic performance. Thi problem can be olve by fiel oriente control (FOC). SM with FOC emulate the eparately excite DC motor. The control of an ac motor in fiel co-orinate (alo known a fiel oriente control or tranvektor control) a propoe by Blachke[2] for an inuction machine an later by Bayer et al. [3] for a ynchronou machine, lea to a ecoupling between the flux an the torque reulting in a goo ynamic torque an pee repone [4]. In thi metho of control, the tator current can be ecuple into flux an torque current component. They can be controlle eparately. Vector control (or Fiel Oriente Control) principle make the analyi an control of Permanent Magnet Synchronou Motor (SM) rive ytem impler an provie better ynamic repone. It i alo wiely applie in many area where ervo- like high performance play a econary role to reliability an energy aving. Thi paper preent the fiel oriente vector control cheme for permanent magnet ynchronou motor (SM) rive, which regulate the pee of the SM. The performance of the motor uffer from uncertaintie, parameter variation, an harmonic in both motor an inverter. They lea to problem in torque an ocillation in the pee come out a the econary problem from the torque problem. To olve thi problem, the torque mut be tuie. The motor torque i a um of: 1) Mutual torque, ue to the interaction of the rotor fiel an tator Fuzzy Logic Bae Fiel Oriente Control Of Permanent Magnet Synchronou Motor 27

2 International Journal of Electrical, Electronic an Data Communication, ISSN: current; 2) Reluctance torque, ue to rotor aliency; 3) Cogging torque, ue to the exitence of tator lot. Thee torque contain harmonic which lea to torque ripple. The mutual torque an reluctance torque have harmonic if the tator flux or rotor magnet are non- inuoial. The reluctance torque i exit only if the inuctance i a function in the rotor poition. The cogging torque arie ue to geometry an lot in the SM. The machine eign an control technique are ue to reuce the torque ripple. The firt metho i complicate an high cot o the other metho i preferable. Proportional integrator controller (PI), it i the mot common controller ue in a wie range in the inutrial application. The popularity of PI control can be attribute to it implicity. Due to it fixe proportional gain an integral time contant, the performance of the PI controller are affecte by parameter variation, loa iturbance an pee variation. Thee problem can be overcome by the Fuzzy logic controller, which o not require any mathematical moel an i bae on the linguitic rule obtaine from the experience of the ytem operator. SPWM an SVPWM can be ue for effective witching of the inverter an the propoe ytem can be imulate uing MATLAB/ Simulink environment. II. MATHEMATICAL MODEL OF SM The mathematical moel of a SM i imilar to that of woun rotor ynchronou motor. The rotor wining of ynchronou motor i replace with high reitivity permanent magnet material, hence inuce current in the rotor are negligible. The rotor type of SM are hown in Fig. 1. The permanent magnet on the rotor are hape in uch a way a to prouce inuoial back EMF in tator wining. The following equation repreent the SM moel where v an v q are the an q axi terminal voltage; i an iq are the an q axi current; r i the wining reitance; L an L are the an q axi elf inuctance; e i the angle between the rotor an axi. i the angular pee of the e rotor; J i the rotor moment of inertia; B i the amping coefficient; Tm i the evelope torque ant L i the loa torque. q Volume-3, Iue-8, Aug Fig. 1: The type of rotor in SM: (a) urface inet, (b) urface interior (burie) III. FOC SM DRIVE SYSTEM Scalar control i omewhat imple to implement, but the inherent coupling effect (both torque an flux are function of voltage or current an frequency) give luggih repone an the ytem i eaily prone to intability becaue of a higher orer ytem effect. The invention of the vector control in the beginning of 1970 an the emontration that an Inuction Motor can be controlle like a eparately excite c motor brought a renaiance in the high-performance control of AC rive. Becaue of c machine like performance, vector control i alo known a ecoupling, orthogonal or tranvektor control. In cae of SM, the main flux i prouce by permanent magnet on the rotor. The current through the tator coil prouce a flux calle the armature reaction flux, becaue the tator of the a ynchronou machine repreent the armature. Then the total tator flux i given a a vector um of both of thee fluxe. i the torque angle, the angle between the vector of tator current I an the irect axi which i aligne with the vector of the permanent magnet flux on the rotor. The armature reaction flux a L a I, where L a i efine a the tator inuctance can be reolve to -q frame a follow: Then the total flux in the -q frame i given a: A it can be een in Fig.2, the magnitue of the total tator flux epen on the location an magnitue of the tator current phaor. For example, the motor excite by the nominal flux uring no-loa teay Fuzzy Logic Bae Fiel Oriente Control Of Permanent Magnet Synchronou Motor 28

3 International Journal of Electrical, Electronic an Data Communication, ISSN: tate operation prouce a mall no loa tator current. Then the armature reaction fluxe in the -q frame are negligible. In thi cae the magnitue of the total tator flux an the flux prouce by the permanent magnet are coniere to be ame: q V jx I R I E R I Volume-3, Iue-8, Aug Fig. 3(A): Overexcite Moe q aq L I a a aq Fig.2: Phaor Diagram Illutrating Relation Between Stator Fluxe An Stator Current. In cae the vector of the tator current i locate in a manner that it -component i in the ame irection an in the ame ene a flux of, the total flux in -axi i given a a um of the permanent magnet flux an of the contribution of the armature reaction flux in the -axi ( a L I ). Flux repreent the total flux in the machine an the inuce voltage E generate by thi flux i higher than the inuce voltage E generate by the magnet, Fig. 3(a). On the contrary, if the vector of the tator current in -axi i in oppoite ene to the flux of Permanent Magnet, the total flux in -axi i given a ifference between the permanent magnet flux an the contribution of the armature flux in -axi. The inuce voltage E generate by the main flux i lower than the inuce voltage E generate by permanent magnet Fig. 3(b). I I a I q aq a r Fig. 3(B): Unerexcite Moe The vector control of SM allow eparate cloe loop control of both the flux an torque, hence achieving a imilar control tructure to that of a eparately excite DC machine. Electromagnetic torque expree in -q component of current i given a: For implification, if a mooth air gap i aume an if on the rotor only the permanent magnet repreent the ource excitation, the electromagnetic torque i expree a General expreion of torque can be written a: i aume to be contant. For a given value of tator current, the maximum torque can be 0 obtaine with an angle of = 90 a explaine in Fig.4. Thi moe of operation give the maximum torque per ampere of tator current an therefore a higher efficiency. Fig. 4: Phaor Diagram Of Vector Controlle Motor For Maximum Torque Per Stator Current. The torque requet i generate by the pee controller in epenence on the pee error. By keeping I current frozen at zero, the phaor of Fuzzy Logic Bae Fiel Oriente Control Of Permanent Magnet Synchronou Motor 29

4 International Journal of Electrical, Electronic an Data Communication, ISSN: tator current will be place jut in quarature axi. (Fig. 4) an the maximal riving torque will be achieve. Thi can be one by etting the emane current to zero. The -component of tator current i kept at zero all the time an the magnitue of the total tator flux an the flux of the Permanent Magnet are equal. Uing uch a control trategy avoi the motor to become uner or over-excite. The block iagram of propoe FOC with PI or Fuzzy logic bae controller (FLC) for the SM rive i hown in Fig.5. Volume-3, Iue-8, Aug The torque i ene from the motor an it i compare with the reference torque. The error ignal i given either to the PI or Fuzzy Logic Controller. The PI or FLC calculate reference torque, which i proportional to the quarature axi tator current component i qref. The, q projection of the tator phae current are then compare to their reference value iref an iqref an are correcte by mean of PI controller. The output of the current controller are pae through the invere Park tranform an a new tator voltage vector i impree to the motor uing pace vector pule with moulation (SPWM). IV. SPACE VECTOR PULSE WIDTH MODULATION (SPWM) Fig.5: Block Diagram Of SM Drive With FOC Uing Fuzzy Logic Controller. Single phae AC upply i given to the inverter through the rectifier. The inverter fee the SM which rive the loa. The 3 phae current i a, i b, i c are meaure. i c i calculate uing the relationhip: Space vector moulation i a one of the avance pule with moulation (PWM) technique ue for inverter witching. Uually there are eight poible witching tate in an inverter. In thee ix are active vector. Thi PWM technique approximate the reference voltage V ref by a combination of the eight witching pattern (V 0 to V 7 ) are ecribe in the Fig. 6 with the witching pattern an output voltage of a three-phae power inverter in Table 1. To implement the pace vector PWM, the voltage equation in the abc reference frame can be tranforme into the tationary α,β reference frame that conit of the horizontal (α) an vertical (β) axe, a a reult, ix non-zero vector an two zero vector are poible. The Clarke tranformation i applie to etermine the tator current projection in the two co-orinate (, ) tationary frame. The tranformation from the three phae ytem into the two imenion orthogonal ytem i given by the relation: The Park tranformation i then applie in orer to obtain thi projection in the, q- rotating frame. The relationhip between the two reference frame can be obtaine from the following equation. Fig. 6: Switching vector an ector The require pace vector Vref can be generate uing two neighboring active vector V1 anv 2 for Fuzzy Logic Bae Fiel Oriente Control Of Permanent Magnet Synchronou Motor 30

5 International Journal of Electrical, Electronic an Data Communication, ISSN: a time perio of t 1 an t 2 repectively along with null vector for a time perio of ( T -( t t )), where T i the witching perio. Table 1: Switching Pattern of SVM V. TORQUE CONTROLLER The eign of the torque controller i important from the point of view of imparting eire tranient an teay-tate characteritic to the torque-controlle SM rive ytem. Volume-3, Iue-8, Aug better than other in term of quick repone time, alo inenitivity to parameter an loa variation etc [6-8]. Thu, here a FLC i implemente a another pee controller for propoe vector control of ISM rive an alo to tuy the performance comparion of the propoe ISM rive with conventional PI controller bae rive in MATLAB/Simulink environment. The input to the FLC are Torque error (e) an change in torque error ( e ). The FLC initially convert the crip error an change in torque error into fuzzy variable an then are mappe into linguitic label. The input an output contain memberhip function with five linguitic variable; namely HN- High Negative, LN- Le Negative, ZE- Zero, HP-High Poitive, LP- Le Poitive an the rule for generating the controller i hown in the Table 2. The Fig. 7(a) how the pee error, Fig. 7(b) how the change in pee error an Fig. 7(c) how the torque limit of the FLC. A. PI CONTROLLER A proportional plu integral controller i ufficient for many inutrial application an hence, it i coniere in thi ection. The torque error between the electromagnetic torque an it reference, given by ( Tref Tm ), i procee through a proportional plu integral (PI) type controller. PI controller are ue wiely for motion control ytem. They conit of a proportional gain that prouce an output proportional to the input error an an integration gain to minimize the teay tate error zero for a tep change in the input. Two parameter are ue to eign thi controller. Thee parameter are proportional gain ( k p ) an integral gain ( k i ). Thi controller can be repreente a: Fig. 7(A) Spee Error Fig. 7(B) Change In Spee Error. B. FUZZY LOGIC CONTROLLER (FLC) The concept of "Fuzzy Logic" wa firt introuce by Lotfi A. Zaeh in 1965 with a novel propoal of Fuzzy Set Theory. Fuzzy logic ha been tuie ince the 1920 a infinite-value logic notably by Łukaiewicz an Tarki. Fuzzy logic theory i an artificial intelligence metho which ha been ha been employe to many fiel like control theory to artificial intelligence. Among the variou intelligent controller, fuzzy logic controller (FLC) i the implet, robut an Fig. 7(C) Torque Limit. Fuzzy Logic Bae Fiel Oriente Control Of Permanent Magnet Synchronou Motor 31

6 International Journal of Electrical, Electronic an Data Communication, ISSN: Table 3: Rule for FLC Volume-3, Iue-8, Aug A. PI CONTROLLER WITH SPACE VECTOR PULSE WIDTH MODULATION Fig. 8(A): i An i q Current V. Time V. RESULTS AND DISCUSSIONS A Fiel Oriente Controlle SM fe from DC upply via inverter with SVPWM uing PI an FLC torque controller i eigne an imulate uing MATLAB verion R2010a an the reult are compare. The parameter of SM ue in imulation are given below: Fig. 8(B): i a, i b An ic Current V.Time Fig. 8(C): Spee V. Time The torque ripple can be calculate by uing the relation: Torque ripple (%) = (Peak to peak Torque/ Average). The imulink moel of the SM FOC rive i evelope an the imulaton i carrie out for 0.05 ec.fig. 9(a) how the i ani q current where i i et to zero an q i i the require torque component. Fig. 8(b) how the three phae tator current.fig. 8(c) how the rotor pee in rpm an Fig. 8() how the evelope torque an the torque ripple. Fuzzy Logic Bae Fiel Oriente Control Of Permanent Magnet Synchronou Motor 32

7 International Journal of Electrical, Electronic an Data Communication, ISSN: CONCLUSION Volume-3, Iue-8, Aug Fuzzy logic controller bae Torque controller moel of SM motor rive have been analyze an imulate uing MATLAB 2010b an the reult have been preente to viualize the comparion between two control technique. The reult obtaine from PI torque controller emontrate fat an atifactory repone with loa perturbation. In future implementation, Hybri PI-Fuzzy controller can be ue in replacement to PI controller Fig. 8(D): Torque V. Time Inference: Rate Torque=8 Nm Torque ripple (%) = (Peak to peak Torque/ Average Torque) * 100 = ( )/8 *100 = 1.675% B. FUZZY CONTROLLER WITH SPACE VECTOR PULSE WIDTH MODULATION Fig. 9: Torque V. Time Uing FLC Fig. 9 how the evelope torque uing FLC where the torque ripple are reuce a compare to that obtaine uing PI controller. Inference: Rate Torque=8 Nm Torque ripple (%) = (Peak to peak Torque/ Average Torque)* 100 = ( )/8 *100 = 1.536% C. DISCUSSIONS It i clear that the variation in Torque i le in cae of Fuzzy logic controller an they can achieve a minimum torque ripple than other control technique. Thu by uing FLC bae controller, ripple are reuce to a greater extent. REFERENCES [1] T.M. Jahn, " Motion control with permanent magnet ac machine, " Proc. IEEE, vol. 82, no. 8, pp , Aug [2] F.Blachke, "The principle of fiel orientation a applie to the new TRANSVEKTOR cloe-loop control ytem for rotating fiel machine, " Siemen Review, vol. 39, no. 5, pp , May [3] K.H Bayer, H.Walmann, an M. Weibelzahl, " Fiel oriente cloe loop control of a ynchronou machine with the NEW Tranvektor control ytem,"siemen Review, vol. 39, no. 5, pp , [4] D.W. Novotny an T.A. Lipo, " Principle of vector control an fiel orientation, "IEEE-IAS, Introuction to Fiel Orientation an High Performance Drive, Tutorial Coure, pp , Oct [5] A. V. Sant an K. R. Rajagopal, " ynchronou motor pee control uing hybri fuzzy PI with novel witching function, " IEEE Tran. Mag., vol. 45, no. 10, pp , Oct [6] Q. Lili, Y. Zhaohua, Q. Vi, an Z. Bo, "Analyi an eign of a ecoupling control trategy for three-phae voltage-ource PWM converter," Tra. Of China Electrotechnical Society vol. 22, pp , Jul M. N. Uin an M. A. Rahman; " High Spee Control of ISM Drive Uing Improve Fuzzy Logic Algorithm, " IEEE Tran. In. Electron., vol. 54, no. 1, [7] Liye Song an Jihen Peng, " The tuy of fuzzy Pi controller of Permanent Magnet Synchronou Motor," Power Electronic an Motion Control Conference, IPEMC '09. IEEE 6th International, pp [8] Amit Vila Sant.; K. R. Rajagopal an Nimit K. Sheth, "Permanent Magnet Synchronou Motor Drive Uing Hybri PI Spee Controller With Inherent an non inherent witching," IEEE TRANSACTIONS ON MAGNETICS, VOL. 47, NO: 10, OCTOBER 2011, Page(): [9] M. Zerikat an S. Chekroun; "Deign an implementation of a hybri fuzzy controller for a high performance inuction motor, " in Proc. Worl Acaemy of Science, Engineering an Technology, Apr. 2007, vol. 20, pp [10] M. Nair Uin.; Ronal S. Rebeiro.; " Fuzzy Logic Bae Spee Controller an Aaptive Hyterei Current Controller Bae ISM Drive for Improve Dynamic Performance, " Electric Machine & Drive Conference (IEMDC), 2011 IEEE International, Page(): 1 6. [11] B.Ahavan, A. Kuppuwamy, G.Jayabakaran an Dr.V.Jagannathan, " Fiel oriente control of Permanent Magnet Synchronou Motor (SM) uing Fuzzy Logic Controller, Recent Avance in Intelligent Computational Sytem (RAICS), 2011 IEEE, Page(): [12] Boe B.K., Moern Power Electronic an AC Drive: Prentice Hall, [13] Krihnan R., Electric Motor Drive: Moeling, Analyi & Control, Prentice Hall Fuzzy Logic Bae Fiel Oriente Control Of Permanent Magnet Synchronou Motor 33