Ms. Snehalata Y. Dhenge, Prof.V.S.Nandanwar / International Journal of Engineering Researchand Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 2, March -April 2013, pp.733-737733 | P a g eTo Study Speed Control and Four Quadrant Operation of BLDCMotorMs. Snehalata Y. Dhenge, Prof. V.S. Nandanwar(Department of Electrical Engg. PCE, Nagpur, India)(Department of Electrical Engg. PCE, Nagpur, India)ABSTRACTBrushless DC motor drives are becomingmore popular in industrial, Traction applications.This make the control of BLDC motor in all fourquadrant very vital. This paper deals with thecontrol of three phase BLDC motor. The motor iscontrolled in all the four quadrants without anyloss of power in fact energy is conserved duringthe regenerative period. In this paper, The BLDCmotor drive system along with the control systemfor speed and current has been present usingMATLAB.Keywords: BLDC Motor, PI Controller, HysteresisCurrent Controller, Four quadrant operation.I. INTRODUCTIONBrushless DC Motor has a rotor withpermanent magnets and stator with windings. It isessentially a Dc motor turn inside out. The brushesand commutator have been eliminated and thewindings are connected to the electronics. Thecontrol Electronics replace the function ofcommutator and energize the proper windings. Themotor has less inertia, therefore easy to start and stop.BLDC motor are permanently cleaner, faster, moreefficient, less noisy and more reliable .The brushless DC motor is driven by rectangular ortrapezoidal voltage strokes coupled with rotorposition. The voltage strokes must be properlyaligned, between the phase a, so that the anglebetween the stator flux and rotor flux is kept close to90 degree, to get maximum developed torque. BLDCmotor either incorporates either internal or externalposition sensors to sense the actual rotor position orits position can also be detected without sensors.BLDC motor are used in Aerospace, Consumer,Medical ,Industrial Automation equipment andInstrumentation.In addition, the ratio of torque delivered tothe size of the motor is higher, making it useful inapplications where space and weight are criticalfactors. BLDC motor require an inverter and positionsensors that exposes rotor position for appropriatealternation of current. the rotation of the BLDCmotor is built on the feedback of rotor position that isgained from hall sensors .BLDC motor generallyutilizes three hall sensors for deciding thecommutation sequence. In BLDC motor the powerlosses are in stator where heat can be easily shiftedthrough the frame or cooling system are utilized inmassive machines. BLDC motors have many benefitsare better speed torque characteristics, high dynamicresponse, high efficiency, long operating life,noiseless operation, higher speed ranges. Till now80% of the controllers are PI controllers because theyare facile and easy to comprehend.As the name implies, BLDC motors do not usebrushes for commutation; instead they areelectronically commutated. Brushless DC motorshave been used in various industrial and domesticapplications. Due to overweighing merits of thismotor, there is continuing trend to propose improvedcontrol schemes to enhance the performance of themotor. BLDC Motor considered in these models isstar connected with neutral grounding, but severalapplications require isolated neutral. Keeping meritsof these developments in view, in this paper themotor with windings placed in the slots that areaxially cut along the inner periphery or around statorsalient poles. The rotor is made of permanentmagnets and can vary from two to eight pole pairswith alternate north (N) and south (S) poles. In orderto rotate a BLDC motor, the stator windings shouldbe energized in a sequence. . It is essential to knowthe rotor position in order to understand as to whichwinding must be energized. In the brushless DCmotor, polarity reversal is performed by powertransistors switching in synchronization with therotor position. This paper is organized as follows:section II describes the three phase BLDC motor andcontrollers. In section III, the realization of fourquadrant control operation of the BLDC motor. Thecomplete drive system is reviewed in section IV.II . BLDC MOTOR And CONTROLLERSBrushless Direct Current (BLDC) motorsare one of the motor types rapidly gaining popularity.BLDC motors are used in industries such asAppliances, Automotive, Aerospace, Consumer,Medical, Industrial Automation Equipment andInstrumentation. As the name implies, BLDC motorsdo not use brushes for commutation; instead, they areelectronically commutated. BLDC motors have manyadvantages over brushed DC motors and inductionmotors. A few of these are:• Better speed versus torque characteristics• High dynamic response• High efficiency
Ms. Snehalata Y. Dhenge, Prof.V.S.Nandanwar / International Journal of Engineering Researchand Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 2, March -April 2013, pp.733-737734 | P a g e• Long operating life• Noiseless operation• Higher speed rangesBLDC motors are a type of synchronous motor. Thismeans the magnetic field generated by the stator andBrushless DC Motors are driven by DC voltagethe magnetic field generated by the rotor rotate at thesame frequency. BLDC motors do not experience the“slip” that is normally seen in induction motors.Brushless DC motors have been used in variousindustrial and domestic applications. Due tooverweighing merits of this motor, there iscontinuing trend to propose improved controlschemes to enhance the performance of the motor.For analysis of the BLDC motor drives system undervarious conditions, models such as d-q model anda,b,c phase variable models have been developed .Several simulation models were proposed based onnon-linear state-space equations. BLDC Motorconsidered in these models is star connected withneutral grounding, but several applications requireisolated neutral . Keeping merits of thesedevelopments in view, in this paper the motor ismodeled as star connected with isolated neutral andthe voltages supplied are line-line but currentcommutation is controlled by solid state switches.The commutation instants are determined by the rotorposition. The rotor shaft position is sensed by a HallEffect sensor, which provides signals. Whenever therotor magnetic poles pass near the Hall sensors, theygive a high or low signal, indicating either N or Spole is passing near the sensors. Based on thecombination of these three Hall sensor signals, theexact sequence of commutation can be determined.These signals are decoded by combinational logic toprovide the firing signals for 120° conduction oneach of the three phases. The rotor position decoderhas six outputs which control the upper and lowerphase leg MOSFETs.[2.1] Mathematical Model of the BrushlessDC MotorThe BDCM has three stator windings andpermanent magnets on the rotor. Since both themagnet and the stainless steel retaining sleeves havehigh resistivity, rotor-induced currents can beneglected and no damper windings are modeled.Hence the circuit equations of the three windings inphase variables are𝑉𝑎𝑉𝑏𝑉𝑐=𝑅 0 00 𝑅 00 0 𝑅𝑖 𝑎𝑖 𝑏𝑖 𝑐+ 𝑝𝐿 𝑎 𝐿 𝑏𝑎 𝐿 𝑐𝑎𝐿 𝑏𝑎 𝐿 𝐵 𝐿 𝑐𝑏𝐿 𝑐𝑎 𝐿𝑐𝑏 𝐿 𝑐𝑖 𝑎𝑖 𝑏𝑖 𝑐+𝑒 𝑎𝑒 𝑏𝑒𝑐(1 )Where it has been assumed that the stator resistancesof all the windings are equal. The back EMFs ea, eb,and ec, have trapezoidal shapes. Assuming furtherthat there is no change in the rotor reluctances withangle, thenLa = Lb = LcLab = Lca = LbcHence,𝑉𝑎𝑉𝑏𝑉𝑐=𝑅 0 00 𝑅 00 0 𝑅𝑖 𝑎𝑖 𝑏𝑖 𝑐+ 𝑝𝐿 𝑀 𝑀𝑀 𝐿 𝑀𝑀 𝑀 𝐿𝑖 𝑎𝑖 𝑏𝑖 𝑐+𝑒 𝑎𝑒 𝑏𝑒𝑐(2)But,Ia+ ib+ ic = 0(3)M ib + M ic = Mia(4)Hence,𝑉𝑎𝑉𝑏𝑉𝑐=𝑅 0 00 𝑅 00 0 𝑅𝑖 𝑎𝑖 𝑏𝑖 𝑐+ 𝑝𝐿 − 𝑀 0 00 𝐿 − 𝑀 00 0 𝐿 − 𝑀𝑖 𝑎𝑖 𝑏𝑖 𝑐+𝑒 𝑎𝑒 𝑏𝑒𝑐(5)In state-space form the equations are arranged asfollows:P𝑖 𝑎𝑖 𝑏𝑖 𝑐=1/𝐿 − 𝑀 0 00 1/𝐿 − 𝑀 00 0 1/𝐿 − 𝑀𝑉𝑎𝑉𝑏𝑉𝑐−𝑅000𝑅000𝑅 𝑖𝑎𝑖𝑏𝑖𝑐 − 𝑒𝑎𝑒𝑏𝑒𝑐 (6)And the Electromagnetic torque isTe =(eaia +ebib ecic)/wr (7)The equation of motion isPwr = (Te – TL – Bwr )/J(8)The currents ia, ib, and ic, needed to produce a steadytorque without torque pulsations are shown in Fig.With ac machines that have sinusoidal back EMFs, atransformation can be made from the phase variablesto d, q coordinates either in the stationary, rotor, orsynchronously rotating reference frames. Inductancesthat vary sinusoid ally in the a, b, c frame becomeconstants in the d, q reference frame. The back EMFbeing non-sinusoidal in the BDCM means that themutual inductance between the stator and rotor is nonsinusoidal, hence transformation to a d, q referenceframe cannot be easily accomplished. A possibility isto find a Fourier series of the back EMF, in whichcase the back EMF in the d, q reference frame wouldalso consist of many terms. This is considered toocumbersome, hence the a, b,c phase variable modelalready developed will be used without furthertransformation.
Ms. Snehalata Y. Dhenge, Prof.V.S.Nandanwar / International Journal of Engineering Researchand Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 2, March -April 2013, pp.733-737735 | P a g eFig. Back EMF and current waveform of BLDCmotor[2.2] PI CONTROLLERThe speed controllers are conventional PIcontroller and current controller are the Pcontrollers to achieve high performance.Conventional PI controller is used as a speedcontroller for recovering the actual motor speed tothe reference. The reference and the measured speedare the input signals to the PI controller. The KP andKI values of the controller are determined by trial anderror method for each set speed. The controller outputis limited to give the reference torque.80%of thecontroller are PI controllers because they are facileand easy to comprehend.[2.3] HYSTERESIS CURRENTCONTROLLERHysteresis controller limits the phasecurrents within the hysteresis band by switchingON/OFF the power devices. The switching pattern isgiven as:Ifi aerr>UL , S1 is on and S4 is off.Ifiaerr< LL , S1 is off and S4 is on.Ifiberr>UL , S3 is on and S6 is off.IfIberr< LL , S3 is off and S6 is on.IfIcerr>UL , S5 is on and S2 is off.IfIcerr< LL , S5 is off and S2 is on.Whereikerr= ikref- ikmesand UL, LL are the upper andlower limits of hysteresis band. Thus, by regulatingthe current desired quasi-square waveforms can beobtained. Small hysteresis band however imply ahigh switching frequency, which is practicallimitation the power device switching capabilityincreased switching also implies increased inverterlosses. The shape of the reference current ofHysteresis current controller is rectangular for BLDCMotor. Because of the nonzero inductance of thestator phase windings, the actual phase current unableto assume the desired rectangular form. Instead, thecurrent are trapezoidal due to the finite rise time. Thishas consequence on the torque production and thedrive performance.II. FOUR QUADRANT CONTROLOPERATIONThere are four possible modes or quadrantsof operation using a Brushless DC Motor. In an X-Yplot of speed versus torque, Quadrant I is forwardspeed and forward torque. The torque is propellingthe motor in the forward direction. Conversely,Quadrant III is reverse speed and reverse torque.Now the motor is “motoring” in the reverse direction,spinning backwards with the reverse torque.Quadrant II is where the motor is spinning in theforward direction, but torque is being applied inreverse. Torque is being used to “brake” the motor,and the motor is now generating power as a result.Finally, Quadrant IV is exactly the opposite. Themotor is spinning in the reverse direction, but thetorque is being applied in the forward direction.Again, torque is being applied to attempt to slow themotor and change its direction to forward again.Once again, power is being generated by the motor.The BLDC motor is initially made to rotate inclockwise direction, but when the speed reversalcommand is obtained, the control goes into the CWregeneration mode, which brings the rotor to thestandstill position. Instead of waiting for the absolutestandstill position, continuous energization of themain phase is attempted. This rapidly slows down therotor to a standstill position. Therefore, there is thenecessity for determining the instant when the rotorof the machine is ideally positioned for reversal.Hall-effect sensors are used to ascertain the rotorposition and from the Hall sensor outputs, it isdetermined whether the machine has reversed itsdirection. This is the ideal moment for energizing thestator phase so that the machine can start motoring inthe CCW direction.IV. SYSTEM CONFIGURATIONFig. shows the block diagram of the BLDCmotor drives system used in the paper. The rotorposition information supplied by the Hall Effectsensors of the BLDC motor. To control motorcurrent, a proportional controller is used to supplyproper switching pattern for inverter where three hallsensors are used. As shown in figure to control theBLDC drives system, PI controller and Hysteresiscurrent controller is used.
Ms. Snehalata Y. Dhenge, Prof.V.S.Nandanwar / International Journal of Engineering Researchand Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 2, March -April 2013, pp.733-737736 | P a g eFig. Model of BLDC Drive SystemSIMULATION RESULTSV. CONCLUSIONMOTOR SPECIFICATIONThe performance of the developed BLDCsystem model is examined using motor parameters aslisted in table In this paper, A control scheme isproposed for BLDC motor to change the directionfrom CW to CCW without going through thestandstill position. the time taken to achieve thisbraking is comparatively less. The generated voltageduring the regenerative mode can be returned back tothe supply mains which will result in considerablesaving of power. The modeling procedure presentedin this paper helps in simulation of various operatingconditions of BLDC drive system. The performanceevaluation results show that, such a modeling is veryuseful in studying the drive system before taking upthe dedicated controller design, accounting therelevant dynamic parameters of the motor.
Ms. Snehalata Y. Dhenge, Prof.V.S.Nandanwar / International Journal of Engineering Researchand Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 2, March -April 2013, pp.733-737737 | P a g eREFERENCESJournal Papers: P.Pillay and R.Krishnan, “Modeling, simulationand analysis of permanent-magnet motor drives,part-II: the brushless DC motor drives,” IEEETrans. on Industry Applications, vol. 25,pp.274-279, March/April 1989. Dr.B.Singh, Prof B P Singh and C. L. PuttaSwamy,“Modelling of Variable StructureControlled Permanent Magnet Brushless dcMotor”, IE(I)_Journal-EL, Vol 75, Febraury1995.[3 M.V.Ramesh, J.Amarnath, S.Kamakshaiah,B.Jawaharlal, Gorantla.S.Rao,”Speed TorqueCharacteristics of Brushless DC Motor ineither direction on load using ARMcontroller”Journal of Energy Technology andPolicy,2011 Sheeba Joice,C., Dr. S.R. paranjothi, Dr.Jawahar Senthil Kumar “PracticalImplementation of Four Quadrant Operation ofThree Phase BLDC motor using dsPIC” 2s andControl Engineering011 InternationalConference of Recent Advancement inElectrical, Electronic. S.K.Safi, P.P.Acarnley and A. G. Jack.“Analysis and simulation of the high-speedtorque performance of brushless DC motordrives,” Proc. Of IEE, vol 142, no.3, p.p.191-200, May 1995. C.Gencer and M,Gedikpinar “Modelling andsimulation of BLDCM using MATLAB”Journals of Applied Science 2006, Vinatha U, Swetha Pola, DrK.P.Vittal,Simulation of four quadrantoperation and speedcontrol of BLDC motorusing MATLAB,2008 Padmaraja Yedamale, “Brushless DC (BLDC)Motor Fundamentals”,AN885, MicrochipTechnology Inc., 2003.Books: Krishnan R motor “Drives Modeling, Analysisand Control”, Prentice Hall of India, First Edn,2002, Chapter 9, pp 513-615.. Gopal K Dubey “Fundamentals of ElectricalDrives”, Narosa Publishing House, New Delhi,Second Edn, 2001, Chapter 7, pp271-277. Bimal K Bose, “Modern Power Electronics andAC Drives”, Pearson Education Publications,New Delhi, 2002, Chapter 9, pp483 – 495V(v) 380 Kb(v/rad/sec) 0.13658P 4 J(kg-m2) 0.0022Rs(ohm) 0.7 Wrated 4000Lt(H) 0.00521 T(N-M) 2.73