M.Sc. Thesis by Alper KURDOGLU ( ) Date of submission : 21 September Date of defence examination: 11 October 2007

Transcription

1 İSTANBUL TECHNICAL UNIVERSITY INSTITUTE OF SCIENCE AND TECHNOLOGY BRUSHLESS DC MOTOR SPEED CONTROL CIRCUIT DESIGN M.Sc. Thesis by Alper KURDOGLU ( ) Dte of submission : 21 September 2007 Dte of defence exmintion: 11 October 2007 Supervisor (Chirmn): Asst. Prof. Dr. Özgür ÜSTÜN Members of the Exmining Committee Prof.Dr. Oruç BİLGİÇ (Y.T.Ü.) Prof.Dr. Metin GÖKAŞAN (İ.T.Ü.) DECEMBER 2007 i

2 İSTANBUL TEKNİK ÜNİVERSİTESİ FEN BİLİMLERİ ENSTİTÜSÜ BRUSHLESS DC MOTOR SPEED CONTROL CIRCUIT DESIGN YÜKSEK LİSANS TEZİ Alper KURDOĞLU ( ) Tezin Enstitüye Verildiği Trih : 21 Eylül 2007 Tezin Svunulduğu Trih : 11 Ekim 2007 Tez Dnışmnı : Diğer Jüri Üyeleri Yrd.Doç.Dr. Özgür ÜSTÜN Prof.Dr. Oruç Bilgiç (Y.T.Ü.) Prof.Dr. Metin GÖKAŞAN (İ.T.Ü.) ARALIK 2007 ii

3 PREFACE This study hs focused to Closed Loop Speed Control Appliction of BLDC Motor. I hve tried to design control circuit bsed upon MC33035 microcontroller produced by the MOTOROLA nd gve the theory of opertion regrding the ppliction. I m sincerely grteful to my instructor Asst. Prof. Dr. Özgür ÜSTÜN who mde mny contributions to this Project. I hve lerned mny things bout the PCB design nd Power Electronics from him. I would lso like to thnk my deprtment mnger MSc. Civil Engineer Ali Levent Kuzum for his helps nd sensibility in my difficult thesis process. His goodwill ws very motivting in my stressfull dys. My vluble thnks go to my fmily for their limitless tolernce. Their pproch ws very helpful nd vluble to me. Lstly, I like to thnk my friend Cn Gökçe for introducing nd providing me the Altium Designer Softwre which ws very useful in the process of designing the PCB circuit. SEPTEMBER 2007 ALPER KURDOĞLU iii

4 CONTENTS ABBREVIATIONS TABLE LIST FIGURE LIST SYMBOL LIST ÖZET SUMMARY vi vii viii ix xi xii 1. INTRODUCTION Brushless DC Motor Drives BLDC MOTORS Generl Chrcteristics Construction Sttor Structure Rotor Structure Hll Sensors Mthemticl Model of Brushless DC Motor Torque Eqution of Brushless DC Motor Fundementls of BLDC Motor Opertion BLDC MOTOR CONTROL Torque-Speed Qudrnt Concept One Qudrnt Control Two Qudrnts Control Four Qudrnts Control Closed Loop Speed Control Theory Digitl Control nd Commuttion CLOSED LOOP SPEED CONTROL DRIVER Driver Construction MC IC Rotor Position Decoder Error Amplifier Oscilltor Pulse Width Modultor MC33039 Electronic Tchometer MSK3003 Power Module Assembyling the Circuit Timing Components 32 iv

5 Drive Circuits N-Chnnel Gte Drive Circuit P-Chnnel Gte Drive Circuit Control Fetures Open Loop Speed Control Closed Loop Speed Control Commuttion Rotor Position Decoder Commuttion Process Fult Mngement Over Current Detection Overcurrent Sensing Current Limiting Undervoltge Lockout Therml Shutdown Brking PRINTED CIRCUIT BOARD (PCB) DESIGN Creting the PCB Project on Altium Designer Creting nd Drwing the Schemtic Document-Circuit Locting the Component nd Loding the Librries Creting New PCB Document nd Component Lyout EXPERIMENTAL WORK The Speed Control of the Motor Speed Feedbck CONCLUSION 61 BIBLIOGRAPHY 63 RESUMEE 64 APPENDIX 65 v

6 ABBREVIATIONS BLDC EMF EPROM PWM PI PID MOSFET LED AMP IC PCB GND PWR FWD REV : Brushless DC Motor : Electromotor Force : Ersble Progrmmble red-only memory : Pulse Wide Modultion : Proportionl Integrl : Proportionl Integrl Derivtive : Metl-Oxide-Semiconductor Field-Effect Trnsistor : Light-Emitting Diode : Amplifictor : Integrted Circuit : Printed Circuit Bord :Ground :Power :Forwrd :Reverse vi

7 LIST OF TABLES Pge Number Tblo 2.1 Commuttion Intervls Depending on Rotor Position for One 7 Electricl Rottion Tble 4.1 MC33035 Pin Descriptions 21 Tble 4.2 Switching sequence nd resulting ir-gp field direction 33 Tble 6.1 Speed Control Experiment Result 60 vii

8 FIGURE LIST Pge Number Figure 2.1 Figure 2.2 Figure 2.3 Figure 2.4 Figure 2.5 Figure 2.6 Figure 3.1 Figure 3.2 Figure 3.3 Figure 3.4 Figure 3.5 Figure 4.1 Figure 4.2 Figure 4.3 Figure 4.4 Figure 4.5 Figure 4.6 Figure 4.7 Figure 4.8 Figure 4.9 Figure 4.10 Figure 4.11 Figure 4.12 Figure 5.1 Figure 5.2 Figure 5.3 Figure 5.4 Figure 5.5 Figure 5.6 Figure 5.7 Figure 6.1 Figure 6.2 Figure 6.3 Figure 6.4 Figure 6.5 Figure 6.6 Figure 6.7 Figure 6.8 Figure 6.9 Figure 6.10 Figure 6.11 : Trpezoidl Bck EMF... : Sinusoidl Bck EMF... : Roto Mgnet Cross Section... : BLDC Motor Trnsfer Section.... : Conduction equivlent circuit for the invertl... : Conduction equivlent circuit for the invertl... : Single Qudrnt DC Motor Drive Circuit... : Six steps drive system for BLDC motor... : Speed Controller... : Voltge Strokes Applied to the 3-Phse BLDC Motor... : 3-Phse BLDC Power Stge... : MC33035 Pin Connections... : MC33035 Representtive Block Digrm... : Error Amplifier... : Pulse Width Modultor Timing Digrm... : MC33039 block digrm... : MSK3003 circuit scheme... :Timing Digrm of A Three Phse, Six Step Motor Appliction :Closed Loop Brushless DC Motor Control : The Functionl Block Digrm of the System. : Principle Commuttion Circuit of A Brushless D.C. motor. : Four-poles permnent mgnet... : Three Phse, Six Step, Full Wve Commuttion Wveforms... : Schemtic Form of the Closed Speed Control Circuit... : The Best Lyout Pln Discovered After Mny Times of Trils. : The Best Lyout Pln Output. : PCB Formt with the Lyers Connections. : Five jumping connections... : Finl PCB redy for the mnufcturing.. : The Mnufctured PCB... : Voltge wveform in %50 PWM... : Voltge wveform in %100 PWM... : Current Wveform... : The Brushless Motor loded with DC Genertor... : The Improved Test Setup : The Close View of the Line Voltge t Low PWM... : The Close View of the line Voltge t High PWM... : The Frequency Ouput of the Motor Speed. : Accelerting of motor from stndstill to mximum speed.. : The wveform of MC33039 output for slightly loded motor : The wveform of MC33039 output for slightly loded motor viii

9 SYMBOL LIST e (k) : Input error in step k w(k) : Desired vlue in step k m(k) = Mesured vlue in step k u(k) = Controller output in step k u p (k) = Proportionl output portion in step k u I (k) = Integrl output portion in step k u I (k -1) = Integrl output portion in step k -1 T I = Integrl T = Smpling time time constnt K C = Controller gin τ ind B R B S = Torque induced on the rotor = Rotor Mgnetic Field = Sttor Mgnetic Field U DCB = DC U DCB = DC bus voltge CT = Timing cpcitor RT = Timing Resistor i = A phse current i = B phse current i b c R R R = C phse current b c = A phse sttor winding resistnce = B phse sttor winding resistnce = C phse sttor winding resistnce L = A phse sttor winding inductnce L = B phse sttor winding inductnce b L = C phse sttor winding inductnce c E = Induced voltge on the phse sttor winding ix

10 E = Induced voltge on the b phse sttor winding b E c = Induced voltge on the c phse sttor winding ω = Angulr velocity M= Torqute M = Motor torque M m y = Lod torque k = Motor constnt k = Motor constnt for A phse kb = Motor constnt for B phse kc = Motor constnt for C phse θ = Rotor position ngle J = Moment of Inerti x

11 FIRÇASIZ DOĞRU AKIM MOTORU HIZ KONTROL DEVRESİ TASARIMI ÖZET Günümüzde fırçsız doğru kım motorlrı gün geçtikçe önem kznmkt ve yygınlşmktdır. Fırçlı doğru kım motorlrıyl krşılştırıldığınd fırçsız doğru kım motorlrınd komütsyon işlemi meknik olrk fırçlrl değil elektronik olrk ypılmktdır ve bu kullnışlılıklrını rttırır. Fırçsız doğru kım motorlrınd rotorun mnyetik ypısı trfındn üretilen mnyetik ln motorun verimliliğini rttırır bu yüzde fırçsız doğru kım motorlrının çok geniş bir kullnım lnı vrdır. Bu tez çlışmsı 3 fzlı bir fırçsız doğru kım motorunun kplı çevrim hız kontrolünü ypn bir sürücü devrenin ypılmsı ve devrenin çlışm ilkesinin çıklnmsını hedef lmıştır. Ykın zmn kdr fırçsız doğru kım motorlrının vntjlrındn yrrlnmk isteyen motor üreticileri önemli bir sorunl krşılşmışlrdır. Bu sorun Hll sensörlerden gelen digitl sinylleri çözümleyecek ve bunun ynınd bir motorun sorunsuz çlışmsı için gerekli bzı fonksiyonlrı yerine getirecek bir tümdevrenin yokluğuydu. Bu fonksiyonlrı frklı komponentleri kullnrk gerçekleştirmek lterntif bir çözüm gibi görünse de devrenin lnın büyümesi ve mliyetin rtmsı tüm bu işlemleri tek bir tsrımd çözecek bir entegreyi gerekli kılmıştır. MOTOROLA firmsının üretmiş olduğu MC33035 tümdevresi bütün bu ihtiyçlr cevp verebilecek, istenilen fonksiyonlrı sğlybilecek bir entegredir. İçerisinde ihtiv ettiği decoder ypısıyl hll sensörlerden gelen sinylleri çözümleyerek motor komütsyon verebilmektedir. Anck kplı çevrim hız kontrolünü gerçekleştirememektedir. Bu sorun d yine MOTOROLA firmsının ürettiği MC33039 elektronik tkometreyle çözümlenebilir. Devrenin uygulm şmsı devre şemsının ALTIUM DESIGNER bilgisyr progrmıyl oluşturulmsı ve yine ynı progrml PCB şemsının oluşturulmsıyl bşlmıştır. PCB devre bsıldıktn sonr devre kompnentleri PCB devreye lehimlenmek suretiyle yerleştirilmiştir. Dh sonr bu devre özel bir kontrolör yrdımıyl minytür bir fırçsız DA motorunun hız denetiminde kullnılmıştır. Deneysel sonuçlr lınmış ve krşılştırmlr ypılmışır. xi

12 BRUSHLESS DC MOTOR SPEED CONTROL CIRCUIT DESIGN SUMMARY BLDC motors re very populr in wide rry of pplictions. Compred to DC motor, the BLDC motor uses n electric commuttor, replcing the mechnicl commuttor nd mking it more relible thn the DC motor. In BLDC motors, rotor mgnets generte the rotor s mgnetic flux, llowing BLDC motors to chieve higher efficiency. Therefore, BLDC motors my be used in high-end white goods (refrigertors, wshing mchines, dishwshers, etc.), high-end pumps, fns, nd other pplinces tht require high relibility nd efficiency. This thsesis describes the design of 3-phse brushless DC (BLDC) motor drive bsed on MOTOROLA s MC33035 microprocessor. Until recently, motor control designers who wished to tke dvntge of the brushless DC motor s unique ttributes were fced with difficult tsk. There were no control ICs designed to decode dt coming from Hll effect sensors, let lone perform ll the ncillry functions. Using discrete components to include these functions ws n lterntive, but discretes often consumed fr too much circuit bord re, especilly if the control unit ws to be plced inside the motor housing. The MC33035 is high performnce second genertion monolithic brushless DC motor controller contining ll of the ctive functions required to implement full fetured open loop, three or four phse motor control system. This device consists of rotor position decoder for proper commuttion sequencing, lso. But it hs not n bility to perform closed loop speed control. In this point the ppliction design solves the problem using Closed Loop Brushless Motor Adpter MOTOROLA MC The MC33039 is high performnce closed loop speed control dpter specificlly designed for use in brushless DC motor control systems. Implementtion will llow precise speed regultion without the need for mgnetic or opticl tchometer. xii

13 The ppliction prt of the thesis consist of the designing the circuit with Altium Designer softwre nd obtining the PCB formt. After tht this circuit hs been used for the speed control of miniture BLDC motor by mens of specil controller. Hs been obtined experimentl results nd some comprisons hs been performed. xiii

14 1. INTRODUCTION This project merges the theory, design, construction nd testing of two qudrnt djustble DC speed driver for brushless DC motor. The proposed drive system will consist of two ICs MC33035 (ror decoding nd control purposes) nd MC33039 (speed signl determining IC) produced by the MOTOROLA nd power podule MSK3003 produced by the MS Kennedy. 1.1 Brushless DC (BLDC) Motor Drives Nowdys, the speed control of dc motor is ccomplished by terminl voltge control. Most of the modern servomotors re brushless type motors (brushless c or brushless dc). A conventionl DC motor cn operte in four different qudrnts by chnging the polrity of voltge nd direction of current. These four modes re: forwrd motoring (positive voltge nd current), forwrd regenertion (positive voltge, negtive current), reverse motoring (negtive voltge nd current) nd reverse regenertion (negtive voltge nd positive current). The term regenertion (lso known s regenertive brking) mens operting the motor s genertor. This brkes the motor by converting its mechnicl energy into electricl energy nd sending it bck to the btteries. As mentioned bove, it is designed two qudrnt opertion in this ppliction. In brushless dc motors, this cn be ccomplished by PWM control of terminl voltge nd inserting the direction informtion to motor drive decoder. [1] A Brushless DC motor driver is more complicted thn brushed DC motor driver. Becuse the motor cnnot commutte the windings, so the control circuit nd softwre must control the current flow correctly to keep the motor turning smoothly. There re two bsic types of Brushless DC motors; sensor nd sensorless. It is criticl to know the position of the rotor to energize the correct winding of the motor therefore some method of detecting the motor position is required. A sensor motor directly reports the controller by Hll Effect sensors. Driving sensor motor requires 1

15 look-up tble. Hll sensors send logic signls to IC, then IC electroniclly commuttes the motor. A sensorless motor requires tht the induced voltge in the un-driven winding be sensed nd used to determine the current speed of the motor. Then, the next commuttion pttern cn be determined by time dely from the previous pttern. Sensorless motors re simpler to build due to the lck of the sensors, but they re more complicted to drive. A sensorless motor performs very well in pplictions tht do not require the motor to strt nd stop. A sensor motor would be better choice in pplictions tht must periodiclly stop the motor. However, the improvements in Hll Effect sensor technology llow the higher tempertures nd smll volumes. [2] In designed system, specil IC (MC33039) is gthering the dt from sensors nd giving the ctul speed informtion s frequency output. A low pss filter cn be used to obtin the nlog speed informtion signl. 2

16 2. BLDC MOTORS A brushless DC motor (BLDC) is n AC synchronous electric motor tht looks very similr to DC motor. Sometimes the difference of BLDC motors is explined s being n electroniclly controlled commuttion system, insted of mechnicl commuttion but this is misleding, becuse s physiclly the two motors re completely different. 2.1 Generl Chrcteristics Brushless Direct Current (BLDC) motors re one of the motor types rpidly gining populrity. BLDC motors re used in industries such s Applinces, Automotive, Aerospce, Consumer, Medicl, Industril Automtion Equipment nd Instrumenttion. As the nme implies, BLDC motors do not use brushes for commuttion; insted, they re electroniclly commutted. BLDC motors hve mny dvntges over brushed DC motors nd induction motors. Some of these re: Better speed versus torque chrcteristics High dynmic response High efficiency Long operting life Noiseless opertion Higher speed rnges In ddition, the rtio of torque delivered to the size of the motor is higher, mking it useful in pplictions where spce nd weight re importnt. 3

17 2.2 Construction BLDC motors re typiclly of synchronous motor s mentioned before. This mens tht the mgnetic fields generted by the sttor nd the rotor rotte t the sme frequency. There re 2-phse nd 3-phse BLDC motor configurtions. 3-phse motors re the most populr nd widely used Sttor Structure Trditionlly, BLDC sttor resembles sttor of induction motor, however the windings re distributed in different wy. Most BLDC motors hve three sttor windings connected in str form. There re two types of sttor windings vrints: trpezoidl nd sinusoidl motors. This difference comes from the bsis of the interconnection of the coils in the sttor windings nd these two windings form give the different types of bck Electromotive Force (EMF). As their nmes indicte, the trpezoidl motor gives bck EMF in trpezoidl form nd the sinusoidl motor give bck EMF in sinusoidl, s shown in Figure 2.1 nd Figure 2.2. In ddition to the bck EMF, in different types of motor the phse current lso hs trpezoidl nd sinusoidl vritions. This mkes the torque output of sinusoidl motor smoother thn tht of trpezoidl motor. However, this comes with n extr cost, cuse the sinusoidl motors hve extr winding interconnections becuse of the coils distribution on the sttor periphery. Figure 2.1: Trpezoidl Bck EMF 4

18 Figure 2.2: Sinusoidl Bck EMF Rotor Structure The rotor is mde of permnent mgnet nd cn vry from two poles to eight poles. Ferrite mgnets re trditionlly used to mke permnent mgnets. The ferrite mgnets re less expensive but they hve the disdvntge of low flux density for given volume. In contrst, the lloy mteril hs high mgnetic density per volume nd enbles the rotor to compress further for the sme torque. Figure 2.3 shows cross sections of different rrngements of mgnets in rotor. Figure 2.3: Roto Mgnet Cross Section 5

19 2.2.3 Hll Sensors Unlike brushed DC motor, the commuttion of BLDC motor is controlled electroniclly. To rotte the BLDC motor, the sttor windings should be energized in sequence. It is importnt to know the rotor position in order to understnd which winding will be energized. Rotor position is sensed using Hll effect sensors embedded into the sttor. Most BLDC motors hve three Hll sensors embedded into the sttor on the non-driving end of the motor. Whenever the rotor mgnetic poles pss ner the Hll sensors, they give high or low signl. Bsed on the combintion of these three Hll sensor signls, the exct sequence of commuttion cn be determined. Figure 2.4: BLDC Motor Trnsfer Section Figure 2.4 shows trnsverse section of BLDC motor with rotor tht hs N nd S permnent mgnets. Hll sensors re embedded into the sttionry prt of the motor. Embedding the Hll sensors into the sttor is complex process becuse ny mislignment in these Hll sensors, with respect to the rotor mgnets, will generte n error in determintion of the rotor position. The Hll sensors re normlly mounted on PC bord nd fixed to the enclosure cp on the non-driving end. This enbles users to djust the complete ssembly of Hll sensors, to lign with the rotor mgnets, in order to chieve the best performnce. The Hll sensors cn be mounted t 60 or 120 shifted ech others. 6

20 2.3 Mthemticl Model of Brushless DC Motor In this section, mthemticl model of brushless motor is improved. This mthemticl model is independent of pole number, winding form, rotor shpe nd electronic switches. In the model, it is considered tht the motor works in unsturted re nd electronic switches re idel. System model is 4th order nd vribles re three phse currents nd motor speed. As depending on the rotor position, differentil equtions re obtined for every rotor position. To improve the mthemticl model, for every rotor position, commuttion nd conduction differentil equtions re obtined. As defining the commuttion nd conduction equivlent circuit, differentil equitions for the mthemticl model of the sytem re derived. In the Tble 2.1, commuttion intervls re given ccording to the rotor position for one electricl rottion. Tble 2.1: Commuttion Intervls Depending on Rotor Position for One Electricl Rottion Rotor Position Pir of Switch on Conduction Eqution Number π 6 π θ < 2 < e S1-S6 (2.1) π 2 5π θ < 6 < e S1-S2 (2.2) 5π 7π < θ e < 6 6 S3-S2 (2.3) 7

21 7π 3π < θ e < 6 2 S3-S4 (2.4) 3π 11π < θ e < 2 6 S5-S4 (2.5) 11π π < θ e < 6 6 S5-S6 (2.6) Here the pssing from S5-S6 conduction step to S1-S6 step will be nlysed s improving the mthemticl model of the system. Figure 2.5 nd 2.6 show the conduction (red rrow) nd commuttion (blue rrow) times respectively when the π π rotor is positioned on < θ e < intervl. As is seen in the figure, fter finishing 6 2 the conduction of the C phse, A phse conduction is strted. The commuttion circuit in this rotor position corresponds to the turning off C phse current equivlent circuit. This equivlent circuit is vlid until the C phse current becomes zero. + - Vd S1 S3 S5 b c R A L A E R B R c L B L C E b E c S4 S6 S2 Figure 2.5: Conduction equivlent circuit for the π π < θ e < invertl 6 2 8

22 + Vd - S1 S3 S5 b c R A L A E R B R c i b i c L B L C i E b E c S4 S6 S2 Figure 2.6: Conduction equivlent circuit for the π π < θ e < invertl 6 2 The required differentil equtions re obtined by the help of conduction nd commuttion equtions nd str node point eqution. According to the str node point eqution, sum of the three phse currents is zero [12]. i + ib + ic = 0, R = RA = RB = RC, L = LA = LB = LC (2.7) dic dib 0 = Ric + ( L + M ) + Ec Eb Rib ( L + M ) (2.8) dt dt V di dib = Ri + ( L + M ) + E Eb Rib ( L + M (2.9) dt dt d ) From the 2.7 eqution, replcing the C phse current on the 2.8 eqution di dt di 1 2 [ 2 Rib + Ri Ec + Eb ] (2.10) dt ( L + M ) b =. is obtined. Derivtive expression of the A phse current is replced on 2.9 eqution, di b dt 1 = [ Vd 3Rib + E + Ec 2Eb ] (2.11) 3( L + M ) is obtined. This eqution consis of the, B phse current derivtive expression, is replced on 2.10 eqution 9

23 di dt 1 = [ 2V d 3. Ri + Eb + Ec 2E ] (2.12) 3( L + M ) is obtined. From the str node point eqution, di dt dib + dt dic + dt = 0 (2.13) di c dt 1 = [ Vd 3Ric + E + Eb 2Ec ] (2.14) 3( L + M ) C phse current derivtive eqution is obtined. After the C phse current becomes zero, the Figure 2.5 circuit will be vlid. While conduction of S1-S6 switches, C phse current re zero thus str node point eqution is given by the 2.15 eqution. + i b i = 0 (2.15) As considering the Fig. 2.6 circuit, if the A phse current is wrote s depending on the B phse current, di b dt 1 = 2 2 ( ) [ V ] d Rib + E Eb L + M (2.16) di dt = 1 d 2( L + M ) 2 [ V Ri + E E ] b (2.17) equtions re obtined nd 3.17 equtions re defined s the phse current π π equtions of brushless DC motor system, for the < θ e < electricl rotor position 6 2 intervl. 10

24 To complete the mthemticl model of the system in this step, it is needed to write the differentil equtions for mechnicl side. Mechnicl differentil equtions re sme for ll the conduction steps nd given s follow, M dω M y = J Bω (2.18) dt m + dω 1 = [ M m M y ( Bm + BY )]ω (2.19) dt ( J + J ) m y Instnt torque vlue of brushless DC Motor is given by 2.20 eqution. M ( t) = k i + k i + k b b i c c (2.20) Electricl nd mechnicl equtions for the other conduction steps cn be obtined by using the sme method. For the π 5π < θ e < rotor position intervl, the commuttion equtions: 2 6 di dt 1 = [ Vd 3Ri + ω ( kb + kc 2k )] (2.21) 3( L + M ) di b dt 1 = [ Vd 3Rib + ω ( k + kc 2kb )] (2.22) 3( L + M ) di c dt 1 = [ 2V d 3Ric + ω ( k + kb 2kc )] (2.23) 3( L + M ) d ω = 1 dt J [ k i + k i + k i M ] b b c c y (2.24) 11

25 For the π 5π < θ e < rotor position intervl, the conduction equtions: 2 6 di dt 1 = [ Vd 2Ri + ω ( kc k )] ( 2.25) 2( L + M ) i b = 0 (2.26) di c dt 1 = [ Vd 2Ric + ω ( k kc )] (2.27) 2( L + M ) d ω = 1 dt J [ k i + k i M ] c c y (2.28) For the 5π 7π < θ e < rotor position intervl, the commuttion equtions: 6 6 di dt 1 = [ Vd 3Ri + ω ( kb + kc 2k )] (2.29) 3( L + M ) di b dt 1 = [ 2V d 3Rib + ω ( k + kc 2kb )] (2.30) 3( L + M ) di c dt 1 = [ Vd 3Ric + ω ( k + kb 2kc )] (2.31) 3( L + M ) d ω = 1 dt J [ k i + k i + k i M ] b b c c y (2.32) For 5π 7π < θ e < rotor position intervl, the conduction equtions: 6 6 i = 0 (2.33) dib 1 = [ Vd 2Rib + ω ( kc kb )] (2.34) dt 2( L + M ) 12

26 di c dt 1 = [ Vd 2Ric + ω ( kb kc )] (2.35) 2( L + M ) d ω = 1 dt J [ k i + k i M ] b b c c y (2.36) For 5π 3π < θ e < rotor position intervl, the commuttion equtions: 6 2 di dt 1 = [ 2V d 3Ri + ω ( kb + kc 2k )] (2.37) 3( L + M ) di b dt 1 = [ Vd 3Rib + ω ( k + kc 2kb )] (2.38) 3( L + M ) di c dt 1 = [ Vd 3Ric + ω ( k + kb 2kc )] (2.39) 3( L + M ) d ω = 1 dt J [ k i + k i + k i M ] b b c c y (2.40) For 5π 3π < θ e < rotor position intervl, the conduction equtions: 6 2 di dt 1 = [ Vd 2Ri + ω ( kb k )] (2.41) 2( L + M ) di b dt 1 = [ Vd 2Rib + ω ( k kb )] (2.42) 2( L + M ) i = 0 (2.43) c d ω = 1 dt J [ k i + k i M ] b b y (2.44) 13

27 For 3π 11π < θ e < rotor position intervl, the commuttion equtions: 2 6 di dt 1 = [ Vd 3Ri + ω ( kb + kc 2k )] (2.45) 3( L + M ) di b dt 1 = [ Vd 3Rib + ω ( k + kc 2kb )] (2.46) 3( L + M ) di c dt 1 = [ 2V d 3Ric + ω ( k + kb 2kc )] (2.47) 3( L + M ) d ω = 1 dt J [ k i + k i + k i M ] b b c c y (2.48) For 3π 11π < θ e < rotor position intervl, the conduction equtions: 2 6 di dt 1 = [ Vd 2Ri + ω ( kc k )] (2.49) 2( L + M ) i = 0 (2.50) b di c dt 1 = [ Vd 2Ric + ω ( kb kc )] (2.51) 2( L + M ) d ω = 1 dt J [ k i + k i M ] c c y (2.52) For 11π π < θ e < rotor position intervl, the commuttion equtions: 6 6 di 1 = [ Vd 3Ri + ω ( kb + kc 2k )] (2.53) dt 3( L + M ) 14

28 di b dt 1 = [ 2V d 3Rib + ω ( k + kc 2kb )] (2.54) 3( L + M ) di c dt 1 = [ Vd 3Ric + ω ( k + kb 2kc )] (2.55) 3( L + M ) d ω = 1 dt J [ k i + k i + k i M ] b b c c y (2.56) For 11π π < θ e < rotor position intervl, the conduction equtions: 6 6 i = 0 (2.57) di b dt 1 = [ Vd 2Rib + ω ( kc kb )] (2.58) 2( L + M ) di c dt 1 = [ Vd 2Ric + ω ( kb kc )] (2.59) 2( L + M ) d ω = 1 dt J [ k i + k i M ] b b c c y (2.60) To complete the mthemticl model of the system, it is needed to express induced voltge on every phse for every conduction step. If str point is considered reference point, the instnt vlue of the induced voltge is the function of motor constnt, ngulr rotor velocity nd rotor position. Motor constnt depends on rotor position in brushless dc motor. In this concept, induced voltge on the phse windings for the unit velocity is improved in ccordnce with generl mthemticl model expression. Motor constnt chnge for A phse: 0 < θ e < α kθ k e = (2.61) α 15

29 0 < θ e < ( α + β ) k = k (2.62) ( α β ) < θ < ( π + α) + e k( θ e π ) k = (2.63) α ( π + α) < θ e < ( π + α + β ) = k (2.64) k ( π α + β ) < θ < 2π + e k( θ e 2π ) k = (2.65) α Motor constnt chnge for B phse: 2π 0 < θ e < α k b = k (2.66) 3 2π 5π α < θ e < α β 3 3 2π k( θ e ) k = 3 b (2.67) α 5π 5π α β < θ < α 3 3 e k k b = (2.68) 5π 8π α < θ e < α β 3 3 5π k( θ e ) k = 3 b (2.69) α 8π α β < θ e < 2π k b = k (2.70) 3 Motor constnt chnge for C phse: π 0 < θ e < α k c = k (2.71) 3 π α < θ e < 3 4π α β 3 π k( θ e ) k = 3 c (2.72) α 16

30 4π 4π α β < θ < α 3 3 e k c k = (2.73) 4π 7π α < θ e < α β 3 3 4π k( θ e ) k = 3 c (2.74) α 7π α β < θ e < 2π k c = k (2.75) Torque Eqution of Brushless DC Motor To explin the torque genertion of brushless DC motors, it is necessry to understnd the chrcteristics of movement voltges induced on sttor windings [12]. Mgnetic Flux induced on just one coil is given by: ψ = m ( πrl ) B,( π / 2 θ π / 2) (2.76) The Movement Voltge induced on the coil: e dψ dt dψ dθ dθ dt πrlb ω π / 2 m r = =. = = 2Bmlrωr (2.77) d θ = ω, r e pθ r r dt θ = (2.78) re obtined. Totl EMF induced on sttor windings given by the following eqution: E = 2NB lrω (2.79) m r nd the Torque generted by brushless DC motor is given nlyticl s follow, M E i + E i + E i b b c c totl = (2.80) ωr 17

31 M totl dω r M y = J + Bωr (2.81) dt 2.5 Fundementl of BLDC Motor Opertion To simplify the explntion of how to operte three-phse BLDC motor, we my consider tht BLDC motor hs only three coils. To mke the motor rotte, for ech commuttion sequence one of the three windings energized by positive power (current enters into the winding), the second winding is negtive (current exits the winding) nd the third one is non-energized condition. Torque is produced becuse of the interction between the mgnetic field generted by the sttor coils nd the permnent mgnets of the rotor. The mgnetic field ttrcts nd rejects the permnent mgnets of the rotor. In order to keep the motor running, the mgnetic field produced by the sttor windings sequence should chnge thus the rotor rottes to ctch up with the sttor mgnetic field. By chnging the current flow in the coils, the polrity of the mgnetic fields chnge t the right moment nd the motor rottes. Idelly, the pek torque occurs when the ngle of these two fields re t

32 3. BLDC MOTOR CONTROL 3.1 Torque-Speed Qudrnts Concept DC motor controls cn be clssified by the qudrnts of opertion referring to the torque versus speed plot. In this respect, there re four qudrnts control. (See the Fig 3.1) Second Qudrnt Negtive Speed, Positive Torque, Reverse Brking II III Third Qudrnt Negtive Speed, Negtive Torque, Reverse-Accelerting First Qudrnt Positive Speed, Positive Torque, Forwrd- Accelerting I IV Fourth Qudrnt Positive Speed, Negtive Torque, Forwrd-Brking Figure 3.1: Torque/Speed Qudrnt of Opertion One-Qudrnt Control Single - qudrnt controls only operte in the first qudrnt with positive speed nd positive torque. A single qudrnt drive usully consists of single trnsistor nd single clmp diode. This type of control cn only move the motor in one direction nd cnnot generte ny brking forces. [3] 19

33 3.1.2 Two-Qudrnt Control The most widely used control method for BLDC motors is the 2 Qudrnt Speed (Voltge) control. In the two-qudrnt control you cn not generte ny brking forces. The motor cn only operte in qudrnt I (forwrd ccelerting) nd qudrnt III (reverse ccelerting). In order to reverse the directions of the rotor, the motor must cost down to zero before reversing directions. If the verge pplied voltge is less thn the bck EMF of the motor, the motor current will decrese to zero nd the motor will cost. If there is no friction, the motor my spin forever. Mny lods, such s fns or pumps, re mostly frictionl. Two qudrnt control cn be esly used in these systems. In six steps drive system, to implement 2 qudrnt speed control it is sufficient to implement PWM only the bottom power switches in the power inverter (See Fig. 3.2). In this cse, 0-100% PWM duty cycle djusts the verge voltge pplied to the motor nd cretes controlled minimum to mximum Speed rnge. As the verge pplied voltge increses, motor current increses to ccelerte the motor. As motor speed increses its bck EMF voltge increses proportionlly, but opposes to the pplied voltge. In 2-Qudrnt Voltge control pplictions, the top power switches re opened nd closed t the commuttion frequency which is proportionl to (n x P)/60, where n is motor speed in rpm nd P is the number of pole pirs. As n exmple, 6000min 1, 16 pole (8 pole-pir) motor will hve commuttion frequency of (6000 x 8)/60 = 800 Hz mximum. The bottom switches must operte t the PWM switching frequency (typiclly 20kHz). Since both switching losses nd power switch gte drive requirements increse with switching frequency, not hving to PWM on the top switches results in Higher Operting Efficiency. The top gte drive circuitry is lso simpler thn the bottom gte drive circuitry. 2-Qudrnt operting BLDC motor cn be reversed by reversing the Electronic Commuttor switching sequence. However, this cnnot be done quickly becuse the motor current is not directly controlled (the motor voltge is controlled). In 2- Qudrnt control configurtion, the motor must cost to decrese speed. The ctions like controlled decelertion (dynmic brking), hrd reversl rottion s required by typicl servo ppliction, cn be chieved by operting the BLDC motor with 4- Qudrnt BLDC controller. 20

34 S1 S3 S5 b c R A L A E S4 S6 S2 Figure 3.2: Six-Step Drive System for BLDC Motor Four-Qudrnt Control 4-Qudrnt Squrewve BLDC controller is operted with n internl current (Torque) control loop. In 4-Qudrnt Power Inverter, both the top nd bottom power switches re simultneously Pulse-Width-Modulted. During the PWM OFF cycle, the current in the power inverter freewheel bckwrds-through the nti-prllel connected power diodes, nd the DC bus cpcitor. The current flows in the sme shunt, but in the opposite direction to the current during the PWM ON cycle. Thus, continuous feedbck signl proportionl to current (Torque) is obtined by sensing the shunt voltge with current sense mplifier tht lso detects the bsolute vlue of the current signl. This signl is then subtrcted from n externl current reference (Torque or current commnd signl) nd the resultnt current loop error signl is mplified nd used to control the PWM modultor. Hence, the motor current (Torque) is controlled directly. The Power losses in the 4-Qudrnt control re higher thn in the 2-Qudrnt since ll power switches re Pulse - Width-Modulted s discussed bove. In 4-Qudrnt controllers, Dynmic Brking resistor nd trnsistor (usully connected in series cross the DC bus) is used to bsorb the kinetic energy relesed by the motor during rpid decelertion nd hrd reversing. The relesed kinetic energy ppers s reverse current flowing out from the Power Inverter into the DC bus cpcitor, through the flybck diodes connected in nti-prllel with ech Inverter power switch. This reverse (brking) current chrges the bus cpcitor, incresing the verge DC bus voltge. A Dynmic Brking control circuit must sense this excess 21

35 DC bus voltge nd properly switch the Dynmic Brking trnsistor cross the DC bus in order to bound the DC bus voltge to sfe operting levels. When the brking trnsistor Turns-ON, power is dissipted in the brking resistor proportionl to brking resistnce times the squre of the RMS brking current. The excess kinetic energy is converted to het dissipted by the brking resistor while, the DC bus is simultneously mintined t sfe DC operting level [4]. 3.2 Closed Loop Speed Control Theory Commuttion provide the proper rotor rottion of the BLDC motor, while the motor speed only depends on the mplitude of the pplied voltge. The mplitude of the pplied voltge is djusted using the PWM technique. The required speed is controlled by speed controller, which is performed proportionl-integrl (PI) controller. To generte voltge proportionl to desired speed, the difference between the ctul nd required speeds is fed to input of the PI controller nd setted the duty cycle of the PWM pulses (See Fig. 3.3.) Figure 3.3: Speed Controller The speed controller clcultes the PI lgorithm given in the eqution below: t 1 u ( t) = K C[ e( t) + ç e( t) dt] (3.1) T I 0 22

36 After trnsforming the eqution into discrete time domin using n integrl pproximtion with the Bckwrd Euler method, it is obtined the following equtions for the numericl PI controller clcultion: u( k) = u u p ( k) = K u ( k) = u I p ( k) + u I C. e( k) ( k I 1) + ( k) K C T T I. e( k) (3.2) Where: e(k) = Input error in step k w(k) = Desired vlue in step k m(k) = Mesured vlue in step k u(k) = Controller output in step k u u u T = Integrl time constnt T = Smpling time K p I I I (k) (k) (k -1) C = Proportionl output portion in step k = Integrl output portion in step k = Integrl output portion in step k -1 = Controller gin 3.3 Digitl Control The BLDC motor is driven by rectngulr voltge pulses ccording to the given rotor position (see Figure 3.4). Rotor flux generted by the rotor mgnet intersect with the generted sttor flux thus creted torque tht defines the speed of the motor. Rotor flux is generted by rotor mgnet nd defines the torque nd thus the speed of the motor s mentioned before. The voltge pulses must be properly pplied to the phses of the three-phse winding system so tht the ngle between the sttor flux nd the rotor flux is kept s close to 90 s possible, to get the mximum generted torque. Therefore, the motor requires electronic control for proper opertion. 23

37 Figure 3.4: Voltge Strokes Applied to the 3-Phse BLDC Motor. For the 3-phse BLDC motors, stndrd 3-phse power stge is used (see Figure 3.5). The power stge consist of six power trnsistors. In both modes, the 3-phse power stge energizes two motor phses simultneously. The third phse is nonenergised. Thus, it is obtined six possible voltge vectors tht re pplied to the BLDC motor using pulse width modultion (PWM) technique. Q1 Q3 Q5 PWM_Q1 PWM_Q3 PWM_Q5 V DCB b c PWM_Q4 PWM_Q6 PWM_Q2 GND Q4 Q6 Q2 Phse A Phse B Phse C Figure 3.5: 3-Phse BLDC Power Stge. 24

38 4. CLOSED LOOP SPEED CONTROL DRIVER 4.1 Driver Construction The min difficulty for control BLDC motors is to decode dt coming from Hll effect sensors nd perform some importnt functions like forwrd/reverse selection, overcurrent shutdown, undervoltge lockout, overtemperture shutdown. It is possible to use discrete components to perform these functions but it mens too much circuit bord re, especilly if the control unit is to be plced inside the motor. Another problem is insufficient performnce of the existing power trnsistors. Power bipolrs cn not be fvored becuse they cn not be driven directly from control IC nd here power MOSFETs my be the best choice since they re esy to drive, efficient nd cheper. As explined in the following sections with the detils, three min devices undirlies our control circuit. MC33035 is the brin IC of the circuit nd control ll the opertion. MC33039 is the closed loop speed control IC (electronic tchometer) give the speed informtion of the rotor nd lstly MSK3003 is three phse bridge inverter electronicly comutte the motor nd mke the control esier MC IC The MC33035 is brushless DC motor controller IC cn perform ll of the ctive functions mentioned bove. This IC hs rotor position decoder to provide proper commuttion, swtooth oscilltor, three open collector top drivers nd three totem pole bottom drivers suited for driving power MOSFETs (See Fig. 4.1 nd Fig. 4.2). MC33035 hs the following fetures: 10 to 30 V Opertion Undervoltge Lockout 25

39 6.25 V Reference Cpble of Supplying Sensor Power Fully Accessible Error Amplifier for Closed Loop Servo Applictions High Current Drivers Cn Control Externl 3 Phse MOSFET Bridge Cycle By Cycle Current Limiting Pinned Out Current Sense Reference Internl Therml Shutdown Selectble 60 /300 or 120 /240 Sensor Phsings Cn Efficiently Control Brush DC Motors with Externl MOSFET H Bridge Figure 4.1: MC33035 Pin Connections [6] 26

40 Figure 4.2: MC33035 Representtive Block Digrm [6] 27

41 PIN SYMBOL DESCRIPTION 1,2,24 B A, C T Tble 4.1: MC33035 Pin Descriptions, These three open collector Top drive outputs re designed to T T drive the externl upper power switch trnsistors. 3 Fwd/Rev The Forwrd/Reverse Input is used to chnge the direction of motor rottion. 4, 5, 6 S S, S A, These three Sensor Inputs control the commuttion sequence. B C 7 Output Enble A logic high t this input cuses the motor to run, while low cuses it to cost. 8 Reference Output This output provides chrging current for the oscilltor timing cpcitor C T nd reference for the error mplifier. It my lso serve to furnish sensor power. 9 Current Sense A 100mV signl, with respect to Pin 15, t this input termintes Noninverting input output switch conductioın during given oscilltor cycle. This pin normlly connects to the top side of the current sense resistor. 10 Oscilltor The Oscilltor frequency is progrmmed by the vlues selected 11 Error Amp Noninverting Input 12 Error Amp Inverting Input 13 Error Amp Out/PWM 14 Input Fult Output for the timing components, R, C. T This input is normlly connected to the speed set potentiometer. This input is normlly connected to the Error Amp Output in open loop pplictions. This pin is vilble for compenstion in closed loop pplictions. This open collector output is ctive low during one or more of the following conditions: Invlid Sensor Input code, Enble Input t logic 0, Current Sense Input greter thn 100 mv (Pin 9 with respect to Pin 15), Undervoltge Lockout ctivtion, nd Therml Shutdown. T 15 Current Sense Inverting Input Reference pin for internl 100 mv threshold. This pin is normlly connected to the bottom side of the current sense resistor. 16 Gnd This pin supplies ground for the control circuit nd should be referenced bck to the power source ground. 17 V This pin is the positive supply of the control IC. The controller CC is functionl over minimum VCC rnge of 10 to 30 V , 20, 21 V C B The high stte (VOH) of the Bottom Drive Outputs is set by the voltge pplied to this pin. The controller is opertionl over minimum VC rnge of 10 to 30 V., BB A These three totem pole Bottom Drive Outputs re designed for B direct drive of the externl bottom power switch trnsistors. C, Select The electricl stte of this pin configures the control circuit opertion for either 60 (high stte) or 120 (low stte) sensor electricl phsing inputs. 23 Brke A logic low stte t this input llows the motor to run, while high stte does not llow motor opertion nd if operting cuses rpid decelertion. 28

42 Rotor Position Decoder The min duty of the rotor position decoder is to decode signls coming from Hll Effect Sensors nd to provide proper sequencing for the top nd bottom drive outputs. Here the inputs re TTL (Trnsistor-Trnsistor Logic) comptible, with their thresholds typiclly t 2.2 V. Tht mens V correspond to logic 0 nd 2.2-5V correspond to logic 1. Detils of rotor position decoder will be discussed in commuttion process Error Amplifier An importnt structure is high performnce internl error mplifier is designed s unity gin voltge follower tht is porssible to ccess to both inputs nd output (Pins 11, 12, 13). This structure enbles open nd closed loop speed control. In the following figure, error mplifier output is connected to the PWM input. Figure 4.3: Error Amplifier [5] Oscilltor Duty of the oscilltor is to set the both R-S flip flop nd thus control the conduction of the top nd bottom drive outputs. The frequency of the oscilltor is setted by the timing components R T (R 2 ) nd C T (C 2 ) (See Fig. 4.8). Cpcitor C T is chrged from the MC33035 Reference Output (Pin 8) through resistor R T nd dischrged by n internl trnsistor. 29

43 Pulse Width Modultor It s good nd energy efficient method to control the speed of the motor s vrying pulse widths of the pplied voltge to ech sttor windings during the commuttion. Here s C T (C 2 ) dischrges, the swtooth oscilltor djusts both ltches nd control the top nd bottom drive outputs. When positive rising voltge of C T becomes higher thn the error mplifier output, the PWM comprtor cut off the bottom drive output trnsmission s reseting the upper ltch. Pulse width modultion is performed only t the bottom drive outputs. The pulse width modultor timing digrm is shown in Figure 4.4. Figure 4.4: Pulse Width Modultor Timing Digrm [5] MC33039 ElectronicTchometer The MC33039 is n electronic tchometer cn perform closed loop speed control of brushless DC motor s coorporting with MC This prt consists of three input buffers, three digitl edge detectors, progrmmble monostble nd n internl shunt regultor. This device cn be used in mny closed-loop speed control pplictions. Refer to Figure 4.5 for the block digrm. 30

44 Figure 4.5: MC33039 Block Digrm [7] MSK3003 Power Module The MSK3003 is three phse bridge power module consisting of P-Chnnel MOSFETs for the top trnsistors nd N-Chnnel MOSFETs for the bottom trnsistors. The MSK3003 cn be used directly with mny brushless motor drive IC's without dditionl circuits. Refer to Figure 4.6 for the MSK3003 circuit schemtic. Figure 4.6: MSK3003 Circuit Scheme 31

45 4.2 Assembyling the Circuit Timing Components The brushless DC motor used in this project hs one pir of pole on its permnent mgnet nd there is one electricl degree for every mechnicl degree. Ech Hll effect sensor genertes one pulse nd the three sensors generte three pulses for every mechnicl revolution. MC33039 genertes one pulse for every rising nd flling edge nd totlly genertes 6 pulses. In Fig 4.8 R 1 nd C 1 re the MC33039 timing components nd the vlues of C 1 nd R 1 set the f out pulse width which tkes the mximum vlue for given mximum speed. Figure 4.7 shows the MC33039 timing digrm. The timing components re selected ccording to the desired mximum motor RPM. R 2 nd C 2 on Figure 4.8 re the timing components for the MC Cpcitor C 2 (C T ) is chrged from the Reference Output (Pin 8) through resistor R 2 (R T ) nd dischrged by n internl trnsistor s mentioned before in chpter The vlues of the timing components set the frequency of the internl rmp oscilltor Drive Circuits MC33035 hs six output drivers. Three top drive outputs open collector NPN trnsistors (Pins 1, 2, 24) drive the P-Chnnel MOSFETs. Three totem pole bottom drive outputs (Pins 19, 20, 21) cn drive directly N Chnnel MOSFETs. Bottom drive outputs re supplied from from V C (Pin 18) s being independent source of V CC. While V CC is grether thn 20V, MOSFETs gtes might dmge, therefore zener diode must be connected to Pin

46 Figure 4.7: Timing Digrm of A Typicl Three Phse, Six Step Motor Appliction [6] 33

47 N-Chnnel Gte Drive Circuit If tht considered our system supplied from 24V (18 to 30V), MC33035 cn be powered directly from system voltge since the IC hs 40 V rting. Here with the electrolytic cpcitor (C 8 ), smll filter cpcitor (C 7-0.1µF) is plced close the IC to minimize locl spiking cross the DC bus. To minimize the power losses in the IC, three lower output trnsistors re driven with seperte supply (V C -Pin18) from the MC The required current to drive the MOSFETs is just the current to chrge nd dischrge the gte-to-source nd drin-togte cpcitors of ech MOSFET. C 4 filter cpcitor supplies the turn-on current while refrehsed through resistor R 7 becuse the MOSFETs drw very smll verge current nd high current vlues re required to chrge their input cpcitnces. Dropping resistor (R 7 ) gets 3 V when the min supply tkes the lowest vlue 18 V in the 24 V system. For chrging the cpcitor it s good selection to use 1 kω resistor, it will lso supply t lest 1 ma current to the zener to provide good regultion. At high supply voltges the resistor will see voltge of 15 V, current of 15 ma, nd it mens to power dissiption bout 0.25 W. Therefore, 0.5 W resistor will be good choice. Tht s lso good power rting for the zener. Also three Schottky diodes D 1, D 2, D 3 re plced between the Gtes of the N-Chnnel MOSFETs nd the ground to prevent the rupture if the substrte current exceeds 50mA. If the gte drive impednce of the three lower devices is low it my be the problem tht gte drive loop my cuse ringing during gte voltge trnsitions. Such ringing is mplified by the MOSFETs nd my occures high levels of noise t the drin. It my be the solution to insert the series resistnce to gte drive s reducing the circuit s Q. Any gte drive resistor vlue lower thn 62 Ω my occur oscilltions in this circuit. (See Fig.4.8) P-Chnnel Gte Drive Circuit At lest 7-8 V my be cceptble on gtes for stndrd MOSFETs. R5 nd R6 re selected to provide tht the P chnnel gte drives tke 10 V vlue even if the supply voltge gets lowest vlue (18 V). R5, 12 nd 13 control turn-on speed s providing keep chrged of the P-chnnel input cpcitnces. Similrly, R6, R14 nd R15 control turn-off speed. Since P-chnnels MOSFETs work t the sme frequency with 34

48 the motor comuttion frequeny (lower thn the PWM frequency), it s not required the low impednce for P-Chnnel gte drives. Figure 4.8: Closed Loop Brushless DC Motor Control Using The MC33035, MC33039, MSK3003 [6] 4.3 Control Fetures The MC33035 is not cpble of closed loop speed control. The IC cn not monitor the motor speed nd genertes signl proportionl to the motor RPM, generlly performed by tchometer. If the motor speed signl is provided, MC33035 cn mnge closed loop speed control ppliction Open Loop Speed Control It s not required to know motor speed dt to perform open loop control. It is enough to give signl proportionl to desired motor speed into the error mplifier s non inverting input (Pin 11). Then output of the error mplifier is compred to the output 35

49 of the oscilltor to obtin PWM signl proportionl to desired motor speed until the control loop is terminted by n overcurrent or fult condition Closed Loop Speed Control For closed loop motor speed control, the MC33035 requires n input voltge proportionl to the motor speed. This input voltge is generted by the MC Figure 4.8 shows the ppliction tht 6.25 V reference from the MC33035 (Pin 8) is supplied to the MC33039 used to generte the feedbck voltge proportionl to the motor speed without need tchometer. The both MC33035 nd MC33039 use the sme Hll sensor signls. Altough MC33035 use them to decode rotor position, MC33039 use Hll sensor signls to detect the speed of the rotor. With every rising nd flling edge of the Hll sensor signls, MC33039 genertes n output pulse which its mplitude nd time durtion re setted by the vlues of the resistor R 1 nd the cpcitor C 1. These output pulses relesed from MC33039 ( Pin 5) re integrted by the error mplifier of the MC33035 nd generted DC voltge level proportionl to motor speed. After generting signl proportionl to motor speed, this signl set the PWM reference level t Pin 13 of the MC33035 nd closes the lst mjor link of the feedbck loop nd the signl is fed into the inverting input (Pin 12) of the MC33035 s comprtor. Here the MC33039 s output is low pss filtered by the R 4, C 3. The signl proportionl to desired motor speed drives the non inverting input (Pin 11) nd the rtio of the input nd feedbck resistors R 3 nd R 4 control the gin. Here feedbck cpcitor C 3 combines the low pss filtering nd generting the error signl. MC33035 expnds the output pulse width to the drive trnsistors if the motor speed becomes lower thn the desired speed, inversly the duty cycle decreses if the motor speed is greter thn the desired speed. If the desired speed is so much lower thn the motor speed, the duty cycle fll to zero nd the motor would cost to desired speed. 36

50 MC33039 Tcho IC Hll Sensor Signls Hll Effect Sensors BRUSHLESS DC MOTOR Actul Speed Signl Reference Speed Signl MC33035 Controller + Decoder Gte Signls POWER MODULE Energizing Signls (voltge) POWER SOURCE Figure 4.9: The Functionl Block Digrm of the System 37

51 4.4 Commuttion Rotor Position Decoder Corresponding to three sensor inputs, eight possible input code combintions vilble nd two of them re invlid inputs codes tht re there re six vlid input codes. The decoder cn define the rotor position using the six vlid input codes. The direction of motor rottion cn be chnged by the Forwrd/Reverse input (Pin 3) s giving reverse voltge to the sttor winding. The commuttion sequence is reversed when the input chnges from high to low with given sensor input code the ctive top nd bottom drive outputs re exchnged (AT to AB, BT to BB, CT to CB). Consequently the motor chnges directionl rottion. The Output Enble pin (Pin 7) controls the on/off stte of the motor. 25 ma current source provide sequencing of the top nd bottom drive outputs when the pin left disconnected. When grounded, the motor cost s turning off the top drive outputs nd forcing low the bottom drives nd the Fult output ctivtes. Brking is performed by setting the Brke Input (Pin 23) in high stte. Thus the top drive outputs turn off nd the bottom drives turn on s shorting the motor windings nd generting bck EMF. The brke input hs unconditionl priority over ll other inputs Commuttion Process The comuttion decoder of the MC33035 receives signls from the position sensors regrding the position of the rotor nd trnsltes them into the switching signls s supplying to the firing circuit consist of the electronic switches. In six step drive system, two switches re ctivted simultniously to energise two of the sttor phse nd rotting field is estblished in the ir-gp by the interction of the currents on the two coils. 38

52 Figure 4.10: An Illustrtion of the Principle Commuttion Circuit of A Brushless D.C. motor. [11] The generl principle of three-phse brushless dc motor drive is illustrted in Fig On the Fig 4.10, switches T 5 nd T 2, T 3 nd T 2, T 3 nd T 6, etc. re ctivted sequentilly to move the field round the ir-gp in the fwd (clockwise) direction. The switching sequence nd the direction of the resulting ir-gp field re shown in Tble 4.2. For reverse (nticlockwise) rottion, the switching sequence is reversed. In generl, 3-to 6 line decoder is needed for system with three position sensors nd six-switch inverter bridge. The three inputs line is connnected to the output of the sensors nd the six outputs re connected to the switches firing circuits. The sensors my be mounted with 30, 60 or 120 mechnicl degrees spcing. The decoder design discussed here for the cse of 60 nd 120 degrees spcing. 39

53 Tble 4.2: Switching Sequence nd Resulting Air-Gp Field Direction [11] Figure 4.11: Four - Poles Permnent Mgnet Rotor nd Three Sensors Spcing t 60 Degrees [11] 40

54 Schemtic of the four poles permnent mgnet rotor nd the position sensors is shown in Fig Ech sensor generte high (logic 1) pulse when it is pssed by South pole nd low (logic 0) when it is pssed by North pole. For the initil position shown in Fig 4.11, the first sensor (H 1 ) opertes t opertes fter 0 60 nd the third (H 3 ) releses fter 0 0 the second (H 2 ) 0 30 of rottion in the clockwise (forwrd) direction. Tble 4.3 is the comuttion truth tble nd shows the sensor ouput code for forwrd nd reverse rottion. There re six different commuttion logic combintions per one electricl revolution nd the logic codes for both directions re the sme, but the code sequence is reversed. The decoder truth tble is redily derived with the id of Tble 4.2, Fig.4.11 nd In order to enble rottion to both directions, code corresponding to the desired direction of rottion (F/R select) is dded s n input to the commuttion decoder. Here codes 1 nd 0 re chosen for forwrd (clockwise) nd bckwrd rottion respectively, but this is rbitrry. Other inputs to the commuttion decoder re sensors output codes, Output Enble code (Pin 7), brke input (Pin 23), Curren Sense input nd tble is given with the Tble sensor phse selection. The commuttion decoder truth The Boolen functions of the semiconductor switches re s follows: T1 = ( F. H1. H 2)( R. H1. H 2) T 2 =( F. H1. H 2)( R. H1. H 2) (4.1) T3 = ( F. H 2. H3)( R. H 2. H3) T 4 = ( F. H 2. H3)( R. H 2. H3) T5 =( F. H 3. H1)( R. H3. H1) (4.2) T 6 = ( F. H3. H1)( R. H 3. H1.) 41

55 Figure 4.12: Three Phse, Six Step, Full Wve Commuttion Wveforms [6] 42

56 Tble 4.3: Three Phse Six Step Commuttion Truth Tble Sensor Electricl Phsing Top Drives Bottom Drives Fult Active 60 0 S A S B S C S A S B Current S F/R Enble Brke Sense T C A B T C T A B B B C B Switches T5, T2 T3, T2 T3, T6 T1, T6 T1, T4 T5, T4 T1, T6 T1, T4 T5, T4 43

57 T5, T2 T3, T2 T3, T X X 0 X X X 0 X X X 1 X X X 1 X V V V V V V X 1 1 X V V V V V V X 0 1 X V V V V V V X 0 0 X V V V V V V X T2,T4,T6 T2,T4,T6 T2,T4,T6 T2,T4,T6 44

58 4.5 Fult Mngement The duty of the open collector Fult Output (Pin 14) is lerting the IC in the event of the system mlfunction. It pulls the Fult Output Pin low s supplying mximum 16 ma current when the system hs ny fult condition nd cn directly drive LED for visul indiction thus lert the IC for problemis. Here R11 (See Fig. 4.8) tkes the 2.2 k vlues in 24 V system to supply 1 ma to the LED. Upon fult detection, it is suitble to terminte ny further pulsing to the output trnsistors. This is possible by connecting the Fult Output to the Enble pin (Pin 7). Thus the motor strt up cırrent is limitted or ltched the system off. It is possible to crete time delyed ltched shutdown for overcurrent condition s inserting of RC (R 10 nd C 6, see Fig. 4.8) network between the Fult Output (Pin 14) nd the enble input (Pin 7). Here is the ltch cn be delyed by inserting C 6 (47µF). The dely is setted by the time constnt of R 10 nd C 6 before the system ltches. The Fult Output is ctive low when one or more of the following conditions occur: 1) Invlid Sensor Input code 2) Output Enble t logic [0] 3) Current Sense Input greter thn 100 mv 4) Undervoltge Lockout 5) Therml Shutdown Over Current Detection An over current condition my occur while continuous opertion of the motor tht is severely results in overheting nd eventul filure. If the pulse width is incresed bruptly to quickly ccelerte the motor, very high currents my flow. This will cuse n undesirble jerk on the motor nd the mechnicl system. Worse, it could exceed the current rting of the power devices Overcurrent Sensing The excessive lod currents re detected by the comprtor of MC A signl relted with ll the N-chnnel sources is fed into comprtor from the current sensing resistor (R 21 ). Here the trip threshold is 100 mv. The comprtor then feeds 45

59 the RS Flip Flop nd if n overcurrent condition is detected, the output drivers turn off the power trnsistors the reminder of the oscilltor cycle. In here, R 21 is the current sensing resistor 0.05 Ω nd hs 1W power rting nd the sense voltge is reduced by voltge divider. The voltge divider vlues re, 100Ω (R 8 in Figure 4.8) for the upper resistor nd 33Ω (R 9 ) for the lower one tht set the trip currnet to 8A. To preserve the overcurrent comprtor from noise or currents such s reverse recovery spikes of freewheeling diyotes replcing smll cpcitor (C 5 ). It is esy to see tht the DC gin of the network is set by the resistive divider, but the time constnt my not be obvious t glnce. The trnsfer function for the resistive divider network nd the cpcitor is clculted s follow: In the s domin nlysis cpcitnce C is replced by n dmitnce sc, or equivlently n impednce 1/sC, V T ( s) = V 0 i = R 8 R 9 + ( R // Z 9 C 5 // Z C 5 ) = R R9. s. C5 +1 R9 R8 + R. s. C = R. R 8 9 R9. s. C + R R 9 (4.3) R8 + R9. t C. R. R R R T ( t) = L { T ( s) } = L =. e (4.4) R. R. s. C + R + R C. R. R where V i is the voltge cross the current sense resistor nd V o is the voltge ppering t the input of the comprtor. In this cse τ is 2.4 µs Current Limiting Limiting the rte of ccelertion is firly simple tsk for n IC. However, simple rte limit moy not protect the MOSFETs under n overvurrent condition. This destructive condition cn be best prevented with the use of cycle by cycle current limiting. Cycle by cycle current limiting is ccomplished by monitoring the sttor current. While the current is building up n output switch conducts ech time, nd upon sensing n over current condition, immeditely turned off the switch nd holded it off for the remining durtion of the oscilltor rmp up period. The sttor current is converted to voltge by inserting grounded sense resistor R S (R 21 ) (See Figure 4.8) in series with the three bottom switch trnsistors (Q 4, Q 5, Q 6 ). The sense voltge, 46

60 which is proportionl to lod current, is fed into comprtor (Pin 9) on bord the MC Then this voltge is monitored by the current sense input (Pin 9 nd Pin 15) nd compred to the internl 100 mv reference. If the 100 mv current sense threshold is exceeded, the comprtor resets the lower sense ltch (RS Flip Flop) nd the output drivers turn off the power trnsistors on the reminder of the oscilltor cycle. The Fult output ctivtes during n over current condition. The vlue for the current sense resistor is: 0.1V R S = (4.4) I STATOR ( MAX ) Undervoltge Lockout The MC33035 provides undervoltge lockouts s terminting the conduction of the drive output trnsistors if ny of three conditions occur. The first one is indequte voltge to operte the IC. The second one is indequte voltge to drive the power MOSFET gtes. The third one is the condition tht MC33035 cn not continue its onbord 6.25 V reference. If one or more of the comprtors detects n undervoltge condition mentioned bove, the Fult Output is ctivted, the top drives re turned off nd the bottom drive outputs re held in low stte Therml Shutdown If the mximum opertion temperture is exceeded, typiclly t C, the Internl therml shutdown feture is ctivted. Then the IC cts s though the Output Enble ws grounded. 4.6 Brking Brke mode is the different mode opertion tht cuses high currents. Upon ppliction of the brke signl, ll three bottom trnsistors re turned on, shorted the motor windings. Since the current circultes between the windings through the three N chnnels does not pper in the sense resistor nd the MC33035 cn not detect the high currents in the brke mode. To prevent the rupture, the MOSFETs must be designed to resist very lrge currents if the brke is used. Motor speed, motor winding resistnce, frictionl loding nd motor inerti effects the time for the current to decy. 47

61 5. PRINTED CIRCUIT BOARD (PCB) DESIGN For prepring the PCB circuit design in this thesis, Altium Designer softwre is used. 5.1 Creting the PCB Project on Altium Designer A project in Altium Designer consists of links to ll documents nd setups relted to the design. Once the project is compiled, design verifiction, synchroniztion nd comprison cn tke plce. Any chnges to the originl schemtics or PCB, for exmple, re updted in the project when compiled. 5.2 Creting nd Drwing the Schemtic Document - Circuit After opening the schemtic document, the project nme is given to the new schemtic document then it is utomticlly dded (linked) to the project. The schemtic sheet is now listed under Source Documents beneth the project nme in the Projects tb. As the nme thesis is ssigned to the project nd schemtic document (See Figure 5.1). 5.3 Locting the Component nd Loding the Librries After crting the schemtic document, it is redy to drw the circuit. To mnge the thousnds of schemtic symbols included with Altium Designer, the Schemtic Editor provides powerful librry serch fetures. After ll the components of the circuit is locted to the schemtic document following figure is obtined. 48

62 Figure 5.1: Schemtic Form of the Closed Loop Speed Control Circuit 5.4 Creting New PCB nd Component Lyout Components lyout is very importnt. Inconvenient component locliztions result incompleted routine process. After components re plced on the bord, Altium Designer utomticlly route the bord. If some components re plced t irrelevnt positions, uto routing ction cn not be completed or completed with very much contentions nd disconnected routes. In this context, fter hs been tried lyout combintions plenty of times, the best lyout pln is found s is seen in the Figure

63 Figure 5.2: The Best Lyout Pln Discovered After Mny Times of Trils. Figure 5.3: The Best Lyout Pln Output 50

64 After uto-routing nd djusted ll of the lyers by mnul, the following PCB formt is obtined (See Figure 5.6). Figure 5.4: PCB Formt with the Lyers Connections Altough the utomtic routing is performed severl times, filed to complete 5 connections. Cuse not possible to use the top lyers, there is only wy to complete the disconnections tht using the jumpers. Five jumpers re connected s is seen in the Figure

65 Figure 5.5: Five jumping connections Next ction is to fill the spces on bord regrding the ground nd the power routes. Then the PCB Circuit hd the finl form s is seen in the Figure 5.8 nd

66 Figure 5.6: Finl PCB redy for the mnufcturing Figure 5.7: The Mnufctured PCB 53

67 6. EXPERIMENTAL WORK The designed circuit is used for driving miniture BLDC motor. First, the circuit is operted in openn-loop control mode which llows certin PWM vlue in ny loding condition. The voltge nd current wve forms re in below figures. The Motor prmeters : 24V, 22W, rpm. Figure 6.1: Voltge Wveform in 50% PWM Figure 6.2: Voltge Wveform in 100% PWM 54

68 Figure 6.3: Current Wveform 6.1 The Speed Control of the Motor To perform the speed control to the motor under loded condition, system is improved tht genertor is coupled to shft of the brushless motor s is seen in Fig.6.4. Figure 6.4: The Brushless Motor Loded with DC Genertor 55

69 The motor loding system shown in fig. 6.4 hs problem. It is difficult to provide proper coupling between motor shft nd genertor shft. without precise djustment, the genertor lods the motor excessively. To overcome this problem, n improved test setup is built to lod the motor properly. In this setup, n liminium disc is coupled to the motor shft nd horizontl djustble mgnet is plced in front of the motor. Thus simple eddy current brking system is builted. By djusting the irgp between the mgnet nd the liminium disc, the motor could be loded s required. The improved test setup is shown in Figure 6.5. Figure 6.5: The Improved Test Setup (With Eddy Current Brking System) After the test setup improvement, vrious exprmentl work he been done by using designed controller. A close view of the line voltge of motor windings t low PWM is shown in Fig

70 Figure 6.6: The Close View of the Line Voltge of the Motor Windings t Low PWM (Discontinuous Terminl Current Mode) After loding the motor closeview of high PWM is shown in the following figure: Figure 6.7: The Close View of the Line Voltge of Motor Windings t High PWM. (Continuous Terminl Current Mode) 57

71 6.2. Speed Feedbck The speed feedbck of the control circuit is proveided by MC33039 tcho IC. The signl outputs from Hll sensors re entered to the MC And this IC produces the speed vlue s speed-depending pulse trin. A resistor nd cpcitor re used to determine the pulse frequency ccording to the motor speed. Clculting of R 1 nd C 1 for MC33039 pulse frequency: -1 n mx = 14000min (no lod speed) n mx = 234s -1 recommended number of pulses during period = 234x12=2808 per second C = 22nF = 0.36ms 1 f out = ms Time intervl of MC33039 output is determined by the following prmeters: C R T 1 = 22nF = 24kΩ 1 out = 0. 5 ms The frequency output of the motor speed cn be seen in Figure 6. Figure 6.8: The Frequency Output of the Motor Speed. 58

72 Figure 6.9: Accelerting of motor from stndstill to mximum speed. (Scling Fctor = 4407 min -1 /V) The output of MC33039 is obtined from the Hll effect sensors by using certin procedures. In the Figure 7.1, the frequency output of the motor speed is shown. The frequency of pulses is incresed by ccelerting the motor. A low pss filter is used for proper nlog speed signl. In Fig.7.2, the speed wveform of ccelerting the motor is shown s voltge wveform. The speed response of the controller for slightly loded motor ( I bus = 0. 13A ) is shown in the following figure: Figure 6.10: The ctul motor speed nd the commnd speed s voltge vlues. The noisy wveform is of MC33039 filtered output (ctul motor speed) for slightly loded motor 59

73 The speed response of the controller for highly loded motor ( I bus = 1. 02A ) is shown in the figure. Figure 6.11: The ctul motor speed nd the commnd speed s voltge vlues. The noisy wveform is of MC33039 filtered output (ctul motor speed) for highly loded motor. The speed control experiment results for given reference speed re given in Tble 6.1. It cn be esily seen tht the the speed error hs difference rnge of n= 190 min -1 which corresponds the reltive speed regultion of 1.8%. This shows tht n effective speed control cn be chieved by using this circuit. Tble 6.1. Speed Control Experiment Results. Actul Speed (min -1 ) Terminl Current (A) Clculted ElectromgneticTorque (Nm)

74 7. CONCLUSION Conventionl dc motors re highly efficient nd their chrcteristics mke them suitble for use s servomotors. However, their only drwbck is tht they need commuttor nd brushes which re subject to wer nd require mintennce. When the functions of commuttor nd brushes were implemented by solid-stte switches, mintennce-free motors were relised. These motors re now known s brushless dc motors. There re two types for controling brushless dc motors; sensor nd sensorless control. Sensored control type is required less complicted control circuit thn sensorless control type. Sensored control is preferred in pplictions tht motor strt nd stop periodiclly. This study is focused to sensored control of brushless dc motor. A BLDCM speed control driver is designed, mnufctured, nlyzed nd tested for brushless motor hving the prmeters of 24 V, 22W, rpm (nominl speed). Control circuit hs three mjor prts: MC33035, MC33039 nd MSK3003. MC33035 is the brin of the circuit tht receive the signls from hll effect sensors for detecting the rotor position nd electroniclly commutte the motor by mens of MSK3003 power module pck. MC33039 is kind of electronic tchometer. MC33035 tkes the speed informtion of the motor from MC33039 nd compres them with desired speed dt. Thus closed loop speed control is implemented. In the ppliction prt of the study, brushless dc motor is firstly loded by dc genertor but this wy hs problem tht very difficult to provide proper coupling between the motor shft nd genertor shft, thus precise djustment to lod the motor cn not be chived. Therefore the brushless motor is loded by eddy current brking system tht is n liminium disc is coupled to the motor shft nd horizntl djustble mgnet is plced in front of the motor. By djusting the irgp between the mgnet nd the liminium disc, the motor could be loded s required properly. 61

75 After the test setup is builted, severl experimentl works re performed. In Figure 6.5 the motor is run t different lod conditions nd the speed of the motor is mesured for every lod condition thus the following results re obtined: The motor rpm is t 0,09A lod current The motor rpm is t 0,27A lod current The motor rpm is t 0,859A lod current The motor rpm is t 1,219A lod current The motor rpm is t 0.72lod current After observing the bove experiment results, it is clerly seen tht the motor speed chnge very slightly t different lod conditions nd this result proves the system implement PWM opertion very well. In Fig.6.6 nd 6.7, line voltge of the motor winding grphs re obtined t high nd low PWM for the motor is loded nd unloded respectively. In Fig.7.1 the motor speed frequency output is obtined nd observed tht frequency of pulses is incresed by ccelerting the motor. In the figure 7.2, voltge wveform is obtined while the motor is ccelerting. Fig 7.3 nd 7.4 re noisy wveforms of MC33039 for silghtly nd highly loded motor conditions. These grps show the speed response of the controller for two different conditions. In conclusion, n overviewing of experimentl works results tht the mnufctured control circuit drive the motor t nerly constnt speed in spite of different lod conditions nd the speed response of the system t different lod conditions is very good. These observtions show tht the control circuit perfom closed loop speed control pplictions s properly.. 62

76 BIBLIOGRAPHY [1] Hendershot, J.R. nd Miller, T.J.E., Design of Brushless Permnent- Mgnet Motors, Mgn Pysics Pub., Hillsboro-OH [2] Giers, J.F Axil flux permnent mgnet brushless mchines, Dordrecht, Boston. [3] Krishnn, R., Electric motor drives : modeling, nlysis, nd control, Prentice Hll, Upper Sddle River-N.J. [4] Dvid L. Firszt, Introduction to BLDC Motor Drive Power Stge Design - Prt 1, Hitchi Americ, Ltd., NY [5] Guen, K. nd Alberkrck, J., Three Piece Solution for Brushless Motor Controller Design, ON Semiconductor Publictions, 2-9. [6] Guen, K. nd Alberkrck, J., MC33035 Brushless DC Motor Controller, ON Semiconductor Publictions, [7] Guen, K. nd Alberkrck, J., MC33039, NCV33039 Closed Loop Brushless Motor Adpter, ON Semiconductor Publictions, 1-2. [8] Sedr, S. nd Smith, K., Microelectronic Circuits, Oxford University Press, New York. [9] Spiegel, M.R., Theory nd Problems of Lplce Trnsformers. McGrw- Hill Book Compny, New York. [10] Miller, T.J.E., Brushless Permnent Mgnet nd Reluctnce Motor Drives. Oxford University Pres, New York. [11] Hmdi, E.S., Design of Smll Electricl Mchinesles, John Wiley & Sons Ltd. Bffins Lne, Chichester. [12] Yılmz, M., Fırçsız doğru kım motorunun lgılyıcısız kontrolünde dlgcık tekniğinin uygulnmsı, PhD Thesis, İ.T.Ü. Fen Bilimleri Enstitüsü, İstnbul. [13] Elevich, L.N., Phse BLDC Motor Control with Hll Sensors Using 56800/E Digitl Signl Controllers, Freescle Semiconductor Appliction Note, 2-8. [14] Chpmn, J.S., Electric Mchinery Fundementls, McGrw-Hill Book Compny, London. 63

77 [15] Mohn, N., Advnced electric drives : nlysis, control nd modeling using Simulink, Mnpere, Minnepolis. 64

78 RESUMEE Alper Kurdoglu hs been borned in Istnbul, He hs received his bchelor of Electricl Engineering degree from Istnbul Technicl University, Turkey in From 2003 to 2006, he worked s Avionic Engineer t MNG Technig Aircrft Mintnence Compny. He currently works t Generl Directorte of Sttes Hydrolic Works in Istnbul since 2006, December. 65

79 APPENDIX 66