Csr BLaaDC Drive

8/13/2019 Csr BLaaDC Drive

1/24

Dr.(Mrs.)C.S.Rajeshwari

,


2/24

Objectives

Introduction

Constructionand

operating

principle

Controlstrategy

Mathematicalmodel

Bldc motorapplications

Manufacturersofbldc motorintheWorld

Conclusion


3/24

Introduction

Developmentinpowerelectronicshas

calledBLDC

motor.

Thesedrivearecosteffective,energyefficientandreliable.

BLDC

motor

has

become

alternative

to

.

Brushless

Direct

Current

(BLDC)

motors

areoneofthemotortypesrapidlygainingo ularit .


4/24

Advantages &DisadvantagesofBrushlessDCMotors

Due to replacement of mechanical commutator by Electronic Commutator

Absence of sparking,

Has longer operating life and

ess ma n enance

Highly reliable

100,000 rpm.

Since armature winding is on stator, cooling is better. Hence higher specific

ou pu s can e o a ne

High efficiecy(75%), much quiter(due to absence of brushes) less length of motor

etc

Reduced radio interference causes small filter design

Pollution free since produce no brush /commutator particles/Gases as

ypro uc s o opera on

Can operate under submerged condition in fluids/combustible gases as they may

be hermatically sealed

Disadvantages:High Cost and low Starting Torque


5/24

A BLDC motor is a Synchronous motor with a

permanent magnet rotor using semiconductor

currents such that the a constant maximum

speed.

Unlike conventional DC motor the function of

electronic commutator in BLDC motor.


6/24

Therotorfluxdensitydistributionproducedby

thepermanentmagnetsisrepresentedbythe

greenspace

vector

Br.

Apowerprocessingunitsuppliesthreephase

currentstothestatorwindingsinsucha

mannerthat

the

resultant

stator

current

space

vectorIsis 90o aheadoftherotorfluxvector.

Themmf distributionproducedbythestator

currentsflowing

in

the

stationary

three

phase

windingsisequivalenttothatproducedbyIs

flowinginasinglesinusoidallydistributed

rotatingwinding

whose

magnetic

axis

lines

up

withIsasillustratedinthisanimation.


7/24

CONSTRUCTIONAND

OPERATINGPRINCIPLE

A brushless dc motor has a rotor with permanent

magnets and a stator with windings. The control

energize the proper winding.

The magnetic field generated by the stator and

the rotor are rotates at the same frequency.

The function of the magnet is the same in both

motor.


8/24

Ina

BLDC

motor,

t e

position

o

t e

rotor

is

sensedandcontinuall fedbacktothe

commutation

electronics

to

provide

for

appropriateswitching.

coupledwiththegivenrotorposition.


9/24

Disassembledviewofabrushlessdc

motor


10/24


11/24

BrushlessDCmotoralongwithelectroniccontroller

connected to a current regulated Voltage

source inverter comprising of 6 SCRs.

protect these from reactance voltage.

Rotor carries a commutating disc with0

Light sensitive or hall effect sensors are

fixed 120 0apaprt receiving light from fixed

.

receiving light and logic 0 when dark

The 3 fixed sensors and rotating

commu a ng sc ro a ng a ong w ro or

produce the required sensor code from

which electronic circuitary generates gating

be in synchronism with the rotors

mechanical position.

e s a or an ro or ge s oc e w eac

other and remain in synchronism at anyspeed


12/24

BrushLessDC(3Phase2poleTrapezoidalPMAC)MotorDrives

windingsdisplacedby1200 andeachwindingspansoneachsideby600

WhenrevolvinginCCWdirection

upto 1200,

rotationfrom

the

position

,linkswithsouthpoleandallbottomconductorsofphaseAwilllinkwith

theNorth

pole.

SoVoltageinducedinPhaseAis,

Beyond1200 someconductorsattop

link with N ole and others S ole.

Sameiswithbottomconductors.

Voltageinduced inphaseAlinearlyreversesinnext60 rotation


13/24

TorqueinBLDCmotorSince air gap flux is constant , the voltageinduced is proportional to speed of rotor.

During each 60 interval current enters onephase and comes out of another

phase.Therefore power supplied to themotor in each such interval

E = Ke m=

d

d= 2 E Id

e m d

Torque = T = P/ m

e d

= 2 KTIdorque s proport ona to

Id


14/24

RegenerativeBrakinginBLDC

When speed reverses, polarityo in uce vo tage reverse.

Reversin hase currents reversethe source current Id

inverter and from inverter to dcsource,


15/24

fed with current pulses.

each 1200 duration and

where induced voltageis constant andmaximum

Polarit of currentpulses is same as that ofinduced voltage


16/24

T1T6,T1T2,T3T2,T3T4,T5T4,T5T6


17/24

Duringoto60,iA=IdandiB=Id

CurrentiA enters

through

phase

A

and

leavesthroughphaseB

WhenT1T6areon,terminalsAandBareconnectedto+ve andve erminals ofthedc source Vd.

CurrentflowsfromVd,T1Ph.A,Ph.B and, A

positive

WhenT1andT6areturnedoffcurrentflowsfromPh.A ,Ph.B,diodeD3,vd and

diodeD4

SincethecurrentshastoflowagainstvoltageVd,rateofchangeofcurrent iwillbenegative

T1T6,T1T2,T3T2,T3T4,T5T4,T5T6


18/24

LowCostBLDCMotor

Low cost BLDC motopr

em lo s onl 3 transistors

and 3 diode converter to

su l onl ositivecurrents or voltages to 3

motor hases


19/24


20/24

Hall Effect devices which generally provide optimum size

and the best environmental capabilities versus cost.


21/24

Backemf detectiontechniqueisusedfor

sensorless

operation

of

BLDC

motor.


22/24

BLDCMOTORAPPLICATIONS Used

in

turn

table

drives

in

record

players,Tape drive

for

vrdio recorders,

spindledrivesinharddiskdrivs forcomputers

Lowcostlowpowerdrivesincomputerperipherals,Instrumentsandcontrol

systems

Usedinbiomedicallikecryogeniccoolersandartificialheartpumps

Usedfordrivingcoolingfansforelectroniccircuitsandheatsinks

Railways

Fan

110

V

DC. SolarbasedIrrigation/Pumpingmotor.

a e e o ar rac ng ower upp y.

EngineCoolingapplicationinAutomobiles.

AutomotiveReturnlessFuelpump.

ExternalRotorfanapplicationswherelowacousticnoiseisimportant

ElectricWheelchairwithDSPbasedcontroller.

ControlofRobotarmandTrackingapplication.


23/24

Inconclusion,BLDCmotorshaveadvantagesoverbrushedDCmotorsand

inductionmotors.

Theyhavebetterspeedversustorquecharacteristics,highdynamicresponse,

hi hefficienc lon o eratin life noiselesso eration hi hers eedran es

ruggedconstruction

and

so

on.

, ,

wherespaceandweightarecriticalfactors.

Withtheseadvantages,BLDCmotorsfindwidespreadapplicationsin

automotive,appliance,aerospace,consumer,medical,instrumentationand

automationindustries.


24/24

ThankYou

Csr BLaaDC Drive

Documents

Transcript of Csr BLaaDC Drive