DESIGN AND IMPLEMENT OF INTELLIGENT VARIABLE FREQUENCY DRIVE A thesis submitted to the Department of Electrical Engineering, University of Moratuwa in partial fulfilment of the requirements for the C degree of Master of Engineering by VALAHEW AGE CHAMILA CHANDRAKANTIII SUMATHIRATNA Supervised By: Dr. J.P. Karunadasa Department of Electrical Engineering University of Moratuwa Sri Lanka 2004 84141 Abstract Variable voltage variable frequency (VVYF) or V/f is the most common method of speed control of three phase induction motors. Majority of those operate in applications not requiring high accuracy position control or high accuracy speed control. A variety of v/f drives are available in market and the speed, acceleration time ,deceleration time are set manually .The key feature of the proposed v/f drive is it's ability to sense the external environment and take decisions intelligently. This is ideal when considering a production line. Automation of an induction motor for a particular production line can be done easily with this v/f drive. The brain of this drive is a Peripheral Interface Controller (PIC). It has 3 PWM outputs. PIC was programmed in assembly language .MPLAB software compiles assembly to hex codes. Three PWM signals generated from PIC are sent to three IGBT drivers which are capable of introducing interlock in order to drive one IGBT on the same leg. The signals are sent through four opto couplers to isolate the controller from disturbances from power side. A speed reference is provided by a potentiometer connected to analog channel. When a speed is input by potentiometer, interrupt service routine activates and the motor could be run at that speed. Numerous other applications are possible with this drive in industry, One is dispenser controller. Another application is flow contr Her and many more. However further research could develop the features of this controller particularly the closed loop feature. CONTENTS Declaration ............................................................................................................ I II .A.bstract .................................. ............................................................................... IV Ackno'W ledgernent. .............................. ................................................................... V Nomenclature ..................... .. .............. ................................................................... VI List of figures .................................................................................................... v'III List ofTables ........................................................................................................ IX CHAPTER 1 .J 1.1 Back ground ................................................................................................ l 1.2 Goals ............................................................................................................ 3 1.3 Achievement in brief.. ................................................................................. 4 CHAPTER 2 2.1 Research problem ........................................................................................ 5 '1 '1 Other related issues ..................................................................................... 5 2.3 Some r;;iateJ features of the Peripheral Int~rface Controller.. .................... 6 2.3. I 2.3.2 ..- .... "":" ~-.) . ..) 2.3.4 2.3.5 2.3.6 2.3.7 2.3.8 CHAPTER 3 Pin as3ign.::1cnt of PIC .................................... ...................... .......... 7 Ha\\'ard archi~cctun.! ................................................................ ..... I 0 .\-!emory or.;;-mizat.vn ............................................................. ...... i l Oscilbwr configu: tt1ons .............................................................. !2 I/0 ports ............... .. ........... .............. (~ ......................................... 13 Tirncr modules .............................................................................. 14 Capture comp:1rc ?\\ M moc!ulcs ................................................. 16 Analog to digital conwrtcr module ........................................... :.:· .. : 17 3.1 Hardware d~signing Proc~dure ......................................................... ..,., .... _, 18 ·,..~,_ ,; / iii 3.2 Comparison of characteristics of IGBT,MOSFET & BJT .. ...................... 22 3.3 Different package types or igbts .................................... .......... ................. 23 3.4 Calculations of the inverter ....................................................................... 24 3.-l.l Load current calculation of0.75 kw three phase ........................ 24 3.4.2 Selecting proper IGBT rating ....................................................... 24 3.4.3 Approximation of component characteristics .............................. 25 3.4.4 Calculations of IGBT .......... ..... .................................................... 27 3.4.5 Summary of calculation results ......................... ........ .. .............. 34 .1 3.5 Selection of heat ... inks .................. .. ............. .. ............................................ 35 3.6 IGBT gate. drivers .......................................................... ......... ....... .. .......... 36 3.7 Seh:ction of PIC ........................................................... ......... ....................... 40 3.7.1 Featuresofseketcd PICI6f777 ............................. ...... ................... 43 CHAPTER4 4.0 Sofr..var~ Developtnent ..... ................................................ .......................... 44 4.1 Asseml:!,r cod\!.:. vf the prOh'l'am ................................................................. 45 4.2 Results ..................... . ...... . .... . .... ... .................................... 50 4.3 ~vme pi1otJ3raphs cf the i:npiem'!nted •:If drive .......................... .. 52 4.4 ApplicatiOns and fit.-!her devetormenL. ....................................... 54 4. 5 ? ... '::~"c;r;:::r .. c.:~s ........................................ • f., ............................... 5::> >(' .-" ~,. .... ';. A .. ; .. / iv DECLARATION The work submitted in this thesis is the result of rrly own investigation, except where otherwise stated. lt has not already been accepted for any degree, and is also not being concurrently subll1itted for any other degree. c~Uv.( ~~ cc~ ( .......................... ~ ....... . 'N C C Sumathiratna I enc )r:;e the C.ecl3n~t:o'1 by the card idate . , '·; ~ ...... 1f;~ .......... . Dr. J P K~nmadasa ~·· ,. ....... ~ . ..,. ... ._, . /" v ACKNOWLEDGE~tENT I am high~y grateful to Dr. J P Karunadasa senior lecturer of Department and my supervisor, for the im·aJuable gllidance, assistance and cncouragemetJ.t gi,en to me throughout the course of this e\ent that contributed tmmer.sely to the successful completion of the research stuJy. I also \\ish to thank Prof. Rar.jith Perera the head of the department , Prof. J R Lucas tonner head of tne department, Dr . Lanka ud •watte Senior lecturer apd the Course Coordinator of ... the Master of Engineering Program in Electric~! engineering, Dr. Thrishantha 1\ianayakkara Senior Lecturer in the Department, for the vital advice and instructions given to me at crucial stages of the resea:-ch. I further thank Re~:earcher Mr. Kavindra Jayawardana and staff of Arther C Clarke Instimtc of Modem Technologies for their kinl corporation. Special regards shou!J go to :V!r. K H Kalug::unpitiy:1 thl'! Director GeneraL :Vlr. D D \Vijcsinghe the D·rector curriculum development and l\1r. U K D Sugathadasa Dirl'ctor information teclmoivgy of the ~mion:1l lnsrn.te of T•:cimica! Education of Sri Lanka, Ratma!m:a hr gi·;i!'3 me t!:c!r ft:!!~:..t c;>-operatio•:. 1 fi.:r.!te:- r~1:1ci<. ~:!::'. E S W ~-tJJanaynkc of Techni:::al C.:lkg~ L'f Ratmalana f•)r th~ viral advice a!ld instructions me thr,)Ughoul. I also "!mic stJtY ofNiTESif" Finally i wculd like to thanh: my husband Clw.ndima for encouragir.g me th:oughcut. Funher .. I thank my mother ,father and brother for encouragirg me and facing lot ofdiftlcultics with ny iittie sor., whe·.1 I wns bu.>y at my wvrr.. ~- ~ ---' :. .-.. " / v~i NOMENCLATURE CGATE gate charge Cgc gate to collector capacitance Cge gate to emitter capacitance l EoFF tum off energy EoN tum on energy Fs switching frequency l ave collector-to-emitter average current lc collcctcr current Inns drain-to-source rrns current PoFD forward power dissipation of diode PGATE pov. er dts~ipauon at g·1tc Psw switching losses ~ ' ; PTDF fvrv:ard po\vc:r dis::;tp..ltion of IGBT PToT total losses in IGBT RcE /},. V cE/~lc ... Ros-ON drain-to-source on-state resistance ~ ... - :. il .. ; / viii Rrmc Tc TJMAX Ton Tor: V CE(SA T.MA..X) V CE(SAT,TYP) V TO(MAX) VcEo VCE-SAT VFo VGATE junction to case thermal resistance case temperature maximum junction temperature tum on delay time tum off dc!ny time collector to emitter saturation voltage-rpaximum value -" collector to emitter saturation voltage-typical value maximum collector emitter voltage at zero current collector emitter voltage at zero current collector-to-emitter saturation voltage diode forward voltage at zero current gate voltage -~/ "' __..,. ~.,_ ... ·.- ~ .. ; / ix LIST OF FIGURES Fig l Block diagram of designed \', f drive 3 Fig2 Internal archttecture of PIC 1 I 13 i Fig3 Program memory of PIC Fig4 Internal circuitry ofOSCI & OSC2 pins 14 FigS Connecting the quartz oscillator 15 Fig6 PORTB & TRISB 16 Fig7 Prescalar ofTIMERO 17 FigS Hardware designing procedure 21 Fig9 Output characteristics of IGBT 24 FiglO Connections of IGBT drivers and opto couplers 34 Fig.l2 Pir. allocation oflGBT bridge gate dri\er 37 37 38 Figl3 Appearan~e of gate drive ~ ~~ .... ' Fig14 Internal capacitance ofiGBT FiglS Connections ofiGBT 38 Figl6 PIC16f777 pin diagram -· ..At' 49 ~ .. --Figl7 PWM output from IGBT :. ..... v / X Fig 18 Main routine 50 Fig 19 PWM out put of IGBT 51 Fig20 Filtered PW~1 out put 51 Fig21 External appearance of the designed v 'f drive 53 Fig 22 Inverter part of the designed v. f dnve 53 Fig 23 Close up of igbts in the im·ener 54 fig 24 Control board of the v/f drive .J 54 fig 25 Dispenser controller 55 Fig 26 Flow Controller 55 LIST OF TABLES Table 1 Comparison of characteristics of IGBT,MOSFET & BJT ")') Tabie 2 Commonly used IGBT p<1ckage typ.:s 23 Table 3 Summary of IGBT ca:cu;lation results for IGBT 34 ~ '.I' Table 4 commonly used heat sinks tor IGBT 35 Table 5 Main characteristics of gate drive circuits 36 ..... Table 6 Features of PIC 18 series 39 Table 7 Features of PIC 16 series ~ ........ 40 -:.~ .. / / xi Table 8 Features of PIC 16F9 series 40 Table 9 Features ofPIC 16F7 series 40 l ~ -~ ...... .,...,,_- :. ~ .. ,; / xli