Torque Prod Duct Ion With AC Drives and Motors-Understanding the Technology

8/8/2019 Torque Prod Duct Ion With AC Drives and Motors-Understanding the Technology

1/62


2/62

Spring Update CD, May 2001

After 25 years of AC DriveAfter 25 years of AC Driveacceptance, drive manufacturersacceptance, drive manufacturers

offer the industry many types of offer the industry many types of control methods.control methods.

Well review some motor & driveWell review some motor & drivebasics and then discuss thebasics and then discuss thetechnologies offered in AC Drivestechnologies offered in AC Drivesalong with the selection process.along with the selection process.

Presentation AbstractPresentation Abstract

Presentation AbstractPresentation Abstract


3/62


REVIE WING MOTO R REVIE WING MOTO R FU N DAMEN TALSFU N DAMEN TALS

AC & DC Motor Basics AC & DC Motor Basics

AC & DC Motor Basics AC & DC Motor Basics


4/62


Motor nameplate HP is achieved at Base RPM:Motor nameplate HP is achieved at Base RPM:

HP = Torque * Speed / 5252HP = Torque * Speed / 5252Torque

RP MBase Speed

100%Constant TorqueConstant TorqueR angeR ange Constant Horsepower Constant Horsepower R angeR ange

Motor BasicsMotor Basics

Motor BasicsMotor Basics

N ameplate H P is onlyN ameplate H P is only

achieved at baseachieved at basespeed, N OT B E FO RE!speed, N OT B E FO RE!


5/62


3 phase stator winding circuit w/ connections T1, T2 & T 33 phase stator winding circuit w/ connections T1, T2 & T 3

Motor BasicsMotor Basics -- AC Motor Construction AC Motor Construction

Motor BasicsMotor Basics -- AC Motor Construction AC Motor Construction

Motor FrameMotor FrameAssemblyAssembly

R otor & ShaftR otor & ShaftAssemblyAssembly

Stator WindingStator WindingAssemblyAssembly


6/62


R otating Magnetic Field of a 2 P ole AC Induction Motor R otating Magnetic Field of a 2 P ole AC Induction Motor

Motor RP M is equal to:

120 * Frequency

# Motor P oles

2 P ole Motor 2 P ole Motor

N ote that FrequencyN ote that Frequency

is the only variable tois the only variable toaffect motor speedaffect motor speed

Motor BasicsMotor Basics -- AC Motor Operation AC Motor Operation

Motor BasicsMotor Basics -- AC Motor Operation AC Motor Operation


7/62


ArmatureArmatureAssemblyAssembly

Distinct Armature & Field Circuits are mechanically separatedDistinct Armature & Field Circuits are mechanically separated

N OT E : The Armature & FieldN OT E : The Armature & FieldCircuits are mechanicallyCircuits are mechanically

fixed at 90fixed at 90 at all timesat all times

Field P olesField P oles

AssembliesAssemblies

Commutator &Commutator &Brush AssemblyBrush Assembly

Motor BasicsMotor Basics -- DC Motor ConstructionDC Motor ConstructionMotor BasicsMotor Basics -- DC Motor ConstructionDC Motor Construction


8/62


R otating Magnetic Field of a 2 P ole AC Induction Motor R otating Magnetic Field of a 2 P ole AC Induction Motor

Motor RP M is equal to:

Both Armature TerminalBoth Armature TerminalVoltage & Field StrengthVoltage & Field Strengthaffect DC Motor speedaffect DC Motor speed

Simple ModelSimple Model

Voltage - ( Voltage Drop )

Field FluxArmSS N NV

V

To create motor torqueTo create motor torqueat the shaft, we increaseat the shaft, we increase

Armature Current Armature Current

Motor BasicMotor Basic -- DC Motor OperationDC Motor OperationMotor BasicMotor Basic -- DC Motor OperationDC Motor Operation


9/62


K ey P oints of UnderstandingK ey P oints of Understanding

Mechanical differences must be overcome mathematicallyMechanical differences must be overcome mathematically

AC Induction Motors have one circuit to connectAC Induction Motors have one circuit to connect

Connection to T1, T2 & T3

for the stator Connection to T1, T2 & T3

for the stator DC Motors have 2 separate circuits to connectDC Motors have 2 separate circuits to connect

Connection to F1 & F2 for the FieldConnection to F1 & F2 for the Field

Connection to A1 & A2 for the ArmatureConnection to A1 & A2 for the Armature

To make AC Motors perform like DC MotorsTo make AC Motors perform like DC MotorsTreat the AC motor like a 2 circuit machineTreat the AC motor like a 2 circuit machine

Motor BasicsMotor Basics -- AC & DC Summary AC & DC SummaryMotor BasicsMotor Basics -- AC & DC Summary AC & DC Summary


10/62


P WM AC D RIVE P WM AC D RIVE FU N DAMEN TALSFU N DAMEN TALS

AC Drive Basics AC Drive Basics AC Drive Basics AC Drive Basics


11/62


Diode rectifier converts AC line voltage to fixed voltage DC.DC voltage is filtered to reduce current ripple from rectification.Inverter changes fixed voltage DC to adjustable PWM AC voltage.

Diode rectifier converts AC line voltage to fixed voltage DC.DC voltage is filtered to reduce current ripple from rectification.Inverter changes fixed voltage DC to adjustable PWM AC voltage.

Motor Motor AC LineAC Line

IG BTIG BTInverter Inverter

DiodeDiodeR ectifier R ectifier

DC BusDC BusFilter Filter

Drive BasicsDrive Basics -- PWM AC Drive ConstructionPWM AC Drive ConstructionDrive BasicsDrive Basics -- PWM AC Drive ConstructionPWM AC Drive Construction


12/62


P WM waveform is a series of repetitiveP WM waveform is a series of repetitive Voltage pulsesVoltage pulses

1

3

+ DC Bus+ DC Bus

-- DC BusDC Bus

VVLLLL @ Drive@ Drive500 Volts / Div.500 Volts / Div.

P hase CurrentP hase Current10 Amps / Div.10 Amps / Div.

M2.00 Qs Ch1 1.18 V

AC Drive Basics AC Drive Basics -- PWM AC WaveformsPWM AC Waveforms AC Drive Basics AC Drive Basics -- PWM AC WaveformsPWM AC Waveforms


13/62


Motor speed is controlled by ramping Voltage & FrequencyMotor speed is controlled by ramping Voltage & Frequency

OutputOutputFrequencyFrequencyBase FrequencyBase Frequency

6060

OutputOutput

VoltageVoltage

Hz3 0

460460

23 0

115

15 90

R atio @ 460 VAC= 7.67 V /Hz

0

Operation at Base SpeedOperation at Base Speed

AC Drive Basics AC Drive Basics -- V/Hz OperationV/Hz Operation AC Drive Basics AC Drive Basics -- V/Hz OperationV/Hz Operation

At 100% of the motors base speed, the V/Hz ratio is At 100% of the motors base speed, the V/Hz ratio isdetermined: HP = 100% of motor nameplatedetermined: HP = 100% of motor nameplate


14/62


At 50% of base speed, Voltage & Frequency decrease by 1/2At 50% of base speed, Voltage & Frequency decrease by 1/2


60

OutputOutput

VoltageVoltage

Hz3 03 0

460

23 023 0

115

15 90

R atio @ 460 VAC= 7.67 V /Hz

0


At 50% of the motors base speed, the V/Hz ratio is At 50% of the motors base speed, the V/Hz ratio ismaintained: HP = 50% of motor nameplatemaintained: HP = 50% of motor nameplate

Operation at 50% Base SpeedOperation at 50% Base Speed


15/62


At 25% of the motors base speed, the V/Hz ratio is At 25% of the motors base speed, the V/Hz ratio ismaintained: HP = 25% of motor nameplatemaintained: HP = 25% of motor nameplate


60

OutputOutput

VoltageVoltage

Hz3 0

460

23 0

115115

1515 90

R atio @ 460 VAC= 7.67 V /Hz

0

At 25% base speed, Voltage & Frequency decreases by 3 /4sAt 25% base speed, Voltage & Frequency decreases by 3 /4s


Operation at 25% Base SpeedOperation at 25% Base Speed


16/62


To increase starting torque, V/Hz Drives use Voltage BoostTo increase starting torque, V/Hz Drives use Voltage Boostto over to over- -flux the motor to increase starting torqueflux the motor to increase starting torque

Offsetting the voltage ratio increases motor starting torqueOffsetting the voltage ratio increases motor starting torque


60

OutputOutput

VoltageVoltage

Hz3 0

460

248

13 8

15 90

R atio @ 460 VAC= 7.67 V /Hz +

% BOOST

0VoltageVoltageBoostBoost



17/62


Voltage Boost over prolonged operatingVoltage Boost over prolonged operatingperiods may result in overheating of theperiods may result in overheating of themotors insulation system and result inmotors insulation system and result indamage or premature failure.damage or premature failure.

Unable to perform like DC, the industry looks to Vector ControlUnable to perform like DC, the industry looks to Vector Control

CAUTION: Motor Insulation Life isdecreased by 50% for every 10 C abovethe insulations temperature capacity

CAUTION: Motor Insulation Life isdecreased by 50% for every 10 C abovethe insulations temperature capacity



18/62


If we can deIf we can de- -couple and Regulatecouple and Regulate Current, theCurrent, thecomponent that creates torque at the motor component that creates torque at the motor , we, wecan regulate motor torque, not just motor speed!can regulate motor torque, not just motor speed!

Current R egulation allows Torque ControlCurrent R egulation allows Torque Control

This is the premise for

Vector Control

This is the premise for

Vector Control

AC Drive Basics AC Drive Basics -- Vector OperationVector Operation AC Drive Basics AC Drive Basics -- Vector OperationVector Operation


19/62


AC VE CTO R DRIVE AC VE CTO R DRIVE FU N DAMEN TALSFU N DAMEN TALS

AC Drive Basics AC Drive Basics AC Drive Basics AC Drive Basics


20/62


21/62


Magnetizing Current is the current required to excite theMagnetizing Current is the current required to excite themotor laminations and copper winding w/o doing work.motor laminations and copper winding w/o doing work.

Magnetizing Current is: NO LOAD AMP draw lessMagnetizing Current is: NO LOAD AMP draw lessfriction and windagefriction and windage

Establishes the motors FluxEstablishes the motors Flux

(FLA(FLA -- Mag. Amps) = 100% Torque CurrentMag. Amps) = 100% Torque CurrentWrong data will reduce motor torque productionWrong data will reduce motor torque production

Magnetizing Current will range from 3 5% to 50% of FLA valueMagnetizing Current will range from 3 5% to 50% of FLA value

AC Drive Basics AC Drive Basics -- Motor ModelingMotor Modeling AC Drive Basics AC Drive Basics -- Motor ModelingMotor Modeling

AC Drive P arameters: Magnetizing CurrentAC Drive P arameters: Magnetizing Current


22/62


Torque is produced, as well as regulated even at 0 RPMTorque is produced, as well as regulated even at 0 RPM

Magnetizing Current is the equivalent of Field CurrentMagnetizing Current is the equivalent of Field Current

Magnetizing Current = Motor No Load AmpsMagnetizing Current = Motor No Load Amps

a fixed value from 0 RPM to Motor Base RPMa fixed value from 0 RPM to Motor Base RPM


TorqueCurrent

Magnetizing Current

100%

90 r


23/62


The motor FLA valueThe motor FLA value maymay set the scaling for:set the scaling for:

Motor OverloadMotor OverloadDrive OverloadDrive Overload

Torque Current AvailableTorque Current Available

(FLA * %OL)(FLA * %OL) -- Mag. Amps = Max. Available Torque CurrentMag. Amps = Max. Available Torque Current

Wrong data affects available torque current and mayWrong data affects available torque current and mayallow damage to the motor.allow damage to the motor. Since every Vector algorithm is unique, check w/ manufacturer Since every Vector algorithm is unique, check w/ manufacturer


AC Drive P arameters: Full Load AmpsAC Drive P arameters: Full Load Amps


24/62


Voltage & Base Hz valuesVoltage & Base Hz values will will::

Establish the motor V/Hz ratio for the drive outputEstablish the motor V/Hz ratio for the drive outputWrong data will cause motor heating and possiblyWrong data will cause motor heating and possiblyreduce motor torque as well as shorten insulation life.reduce motor torque as well as shorten insulation life.

N eeded to assure proper motor operation w/o over N eeded to assure proper motor operation w/o over- -heatingheating


AC Drive P arameters: Voltage & Base HzAC Drive P arameters: Voltage & Base Hz


25/62


Base Hz & RPM valuesBase Hz & RPM values willwill set the scaling for:set the scaling for:

Calculation of motor slipCalculation of motor slipIdentifies expected motor RPM at FrequencyIdentifies expected motor RPM at Frequency

Allows for speed error detection & correction Allows for speed error detection & correction

Establishing the point of field weakeningEstablishing the point of field weakening

Wrong data here can cause excessive current drawWrong data here can cause excessive current draw

AC Drives regulate speed based upon motor slipAC Drives regulate speed based upon motor slip


AC Drive P arameters: Base HZ & RP MAC Drive P arameters: Base HZ & RP M


26/62


The Horsepower valueThe Horsepower value maymay be used to:be used to:

Estimate the expected motor impedanceEstimate the expected motor impedanceEstimate the expected motor inductanceEstimate the expected motor inductance

Calculate the torque loop gainsCalculate the torque loop gains

Wrong data here can cause poor speed and torqueWrong data here can cause poor speed and torqueregulationregulation

Horsepower information gets us in the BallparkHorsepower information gets us in the Ballpark


AC Drive P arameters: HorsepowerAC Drive P arameters: Horsepower


27/62


Flux Vector Drives act very much like DC DrivesFlux Vector Drives act very much like DC Drives

Field Weakening Field Weakening occurs whenever we exceed Motor Base RP Moccurs whenever we exceed Motor Base RP M

Magnetizing Current is decreased above Motor Base RPMMagnetizing Current is decreased above Motor Base RPM


TorqueCurrent

Magnetizing Current

100%

90r

TorqueCurrent

Magnetizing Current

100%

90r

90r


28/62


Torque at the motor shaft based upon loadTorque at the motor shaft based upon load

Torque Current increases or decreases dependent upon loadTorque Current increases or decreases dependent upon load

Torque Current = Motor Load at the ShaftTorque Current = Motor Load at the Shaft

a variable value during speed regulated operationsa variable value during speed regulated operations


TorqueCurrent

Magnetizing Current

100%

90 r

TorqueCurrent

Magnetizing Current

10%

90 r


29/62


Torque at the motor shaft based upon Torque ReferenceTorque at the motor shaft based upon Torque Reference

Torque Current can be commanded as a reference valueTorque Current can be commanded as a reference value

Torque Current = Reference settingTorque Current = Reference setting

a fixed value during torque regulated operationsa fixed value during torque regulated operations


TorqueCurrent

Magnetizing Current

100%

90 r

TorqueCurrent

Magnetizing Current

10%

90 r


30/62


Torque production suffers if 90Torque production suffers if 90 is not maintainedis not maintained

Motor torque is optimized O N LY when 90Motor torque is optimized O N LY when 90 rr is maintainedis maintained

Improper tuning, incorrect motor parameters, problemsImproper tuning, incorrect motor parameters, problemswith motor speed feedback or undersized drivewith motor speed feedback or undersized driveapplications will result in poor load (torque) regulation.applications will result in poor load (torque) regulation.


TorqueCurrent

Magnetizing Current

100%

90 r

OptimizedOptimizedTorqueTorqueProductionProduction

TorqueCurrent

Magnetizing Current

? r

Poor TorquePoor TorqueProduction &Production &RegulationRegulation

ie: Impact Loadie: Impact Load


31/62


Load Type: Forward Speed & Reverse TorqueLoad Type: Forward Speed & Reverse Torque

Time to find motor rpm & position is limited by inertia & speedTime to find motor rpm & position is limited by inertia & speed

How a load becomes appliedHow a load becomes appliedto the drive system can beto the drive system can becritical to system success.critical to system success.

A load where there is Forward A load where there is Forward

Velocity & Reverse Torque isVelocity & Reverse Torque isthe most difficult load tothe most difficult load tohandle.handle.


? r

If the Nip Rolls are engaged duringIf the Nip Rolls are engaged duringweb travel, a condition withweb travel, a condition withforward velocity and reverseforward velocity and reversetorque can occur.torque can occur.

Use either V/Hz or a closed loopUse either V/Hz or a closed loopsystem if inertia or speed is high.system if inertia or speed is high.


32/62


Motor Current is = Vector Sum of Torque & MagnetizingMotor Current is = Vector Sum of Torque & Magnetizing

This is where the termThis is where the term VECTOR DRIVE VECTOR DRIVE is derived is derived

Motor Current is whats measured with a clampMotor Current is whats measured with a clamp- -on meter on meter


100%

Magnetizing Current

TorqueCurrent

Magnetizing Current

100%

Motor Current

90 r

TorqueCurrent

Motor Current

90 r

A+

B = CA+

B = C


33/62


Flux Vector Drives regulate current & torque using rotor Flux Vector Drives regulate current & torque using rotor speed & position to optimize torque at the motor shaftspeed & position to optimize torque at the motor shaftalong w/ current feedback from the motor.along w/ current feedback from the motor.

E ncoders provide rotor speed & position informationE ncoders provide rotor speed & position information

L1L2L3

Current

Feedback

Motor

EMicro P

AC Drive Basics AC Drive Basics -- Flux Vector OperationFlux Vector Operation AC Drive Basics AC Drive Basics -- Flux Vector OperationFlux Vector Operation


34/62


As motor temperature reaches nominal operating values, As motor temperature reaches nominal operating values,torque linearity and accuracy improves in FVC operationtorque linearity and accuracy improves in FVC operation

Torqueaccuracy of 5%

or better !

AC Drive Basics AC Drive Basics -- Rotor Temperature & TorqueRotor Temperature & Torque AC Drive Basics AC Drive Basics -- Rotor Temperature & TorqueRotor Temperature & Torque

% Torque

Inch - Lbs

-800

-600

-400

-200

0

200

400

600

-200 -150 -100 -50 0 50 100 150 200 30 deg

80 deg

Ideal Value

HOTMotor

COLDMotor


35/62


Field Oriented Control uses the same basic technology asField Oriented Control uses the same basic technology asFlux Vector Control, but adds Voltage Feedback toFlux Vector Control, but adds Voltage Feedback tooptimize / adapt to changes in motor temperature.optimize / adapt to changes in motor temperature.

The drive continuously adapts to motor temperature changeThe drive continuously adapts to motor temperature change

L1L2L3

Voltage

Feedback

Motor

EMicro P

AC Drive Basics AC Drive Basics -- Field Oriented ControlField Oriented Control AC Drive Basics AC Drive Basics -- Field Oriented ControlField Oriented Control


36/62


K ey P oints of UnderstandingK ey P oints of Understanding

Motor information, measured or programmed is key to successMotor information, measured or programmed is key to success

Errors in Encoder Feedback affect the MicroErrors in Encoder Feedback affect the Micro- -Processor Processor

Speed instability will occur Speed instability will occur

Encoder Feedback Signals must be NOISE FREEEncoder Feedback Signals must be NOISE FREE

Select an appropriate encoder for Vector Motor useSelect an appropriate encoder for Vector Motor use

Proper grounding is very importantProper grounding is very important

Motor Data programmed in the drive must be accurateMotor Data programmed in the drive must be accurate

AC Drive Basics AC Drive Basics -- SummarySummary AC Drive Basics AC Drive Basics -- SummarySummary


37/62


Those with aThose with a V/Hz CoreV/Hz Core

All Sensorless Vector Drives areAll Sensorless Vector Drives are N OTN OT the same !the same !

There are actually 2 types of drives advertised asThere are actually 2 types of drives advertised asSensorless Vector;Sensorless Vector;

Those with aThose with a V ector CoreV ector Core

AC Drive Basics AC Drive Basics -- Sensorless Vector OperationSensorless Vector Operation AC Drive Basics AC Drive Basics -- Sensorless Vector OperationSensorless Vector Operation


38/62


S VC withS VC with V/Hz Core Technology V/Hz Core Technology

V /Hz Core S VC Drives can operate multiple motorsV /Hz Core S VC Drives can operate multiple motors

Use sophisticated Current Limiting algorithms toUse sophisticated Current Limiting algorithms toimprove constant torque & starting torque operationimprove constant torque & starting torque operation

Typically needs less motor information for setup addingTypically needs less motor information for setup addingsome simplicitysome simplicity

Can operate multiple motors from one driveCan operate multiple motors from one drive

ONLY regulates V/Hz output, clamps CURRENTONLY regulates V/Hz output, clamps CURRENTCan only operate as a Speed Regulator, NOT TORQUECan only operate as a Speed Regulator, NOT TORQUE



39/62


S VC withS VC with V ector Core Technology V ector Core Technology

Vector Core S VC Drives can operate only one motor at a timeVector Core S VC Drives can operate only one motor at a time

De-couples Torque & Magnetizing Currents to maintain90 r alignment

Typically needs more motor information for setup addingsome complexity

Can operate only one motor per drive due to theinformation required to regulate current

Regulates SPEED and Regulates TORQUE



40/62


S VC Drives w/ a Vector CoreS VC Drives w/ a Vector Core estimatesestimates rotor speed &rotor speed &positionposition

A Speed E stimator calculates rotor speed & positionA Speed E stimator calculates rotor speed & position

L1L2L3

Motor

CurrentSensors

Micro P

( F VC + Speed E stimator )



41/62


POSITIONPOSITION SPEEDSPEED TORQUETORQUE MOTORMOTOR

Position ReferencePosition Referenceis optional in mostis optional in mostVector Controls,Vector Controls,internal in someinternal in some

Speed Reference isSpeed Reference istypical of how wetypical of how wecontrol motor control motor operationoperation

Torque Reference can madeTorque Reference can madedirectly, bypassing the speeddirectly, bypassing the speedloop as a reference for loop as a reference for applications such as Winders &applications such as Winders &Test StandsTest Stands

There are 3 Basic Control Loops in High P erformanceThere are 3 Basic Control Loops in High P erformanceDrives:Drives:

Bandwidth ratio between loops ranges from 3 :1 to 10:1Bandwidth ratio between loops ranges from 3 :1 to 10:1

1,000 rad/sec100 rad/sec10 rad/sec

AC Drive Basics AC Drive Basics -- Control LoopsControl Loops AC Drive Basics AC Drive Basics -- Control LoopsControl Loops


42/62


SpeedR eference

FluxFluxCommandCommand

TorqueCommand G ate

Signals

AC Line

CurrentFeedback

R otor Speed& P osition

++

--

TorqueTorqueLoopLoop

SpeedSpeedLoopLoop

FieldFieldController Controller

P WMP WMInverter Inverter

SpeedSpeedFeedbackFeedback

ACMotor

E

Typical R egulator Control Diagram for F VCTypical R egulator Control Diagram for F VC

AC Drive Basics AC Drive Basics -- Regulator DiagramRegulator Diagram AC Drive Basics AC Drive Basics -- Regulator DiagramRegulator Diagram


43/62


INVER TERINVER TERDUTYDUTYMOTO R SMOTO R S

AC Motor Basics AC Motor Basics -- Inverter DutyInverter Duty AC Motor Basics AC Motor Basics -- Inverter DutyInverter Duty


44/62


Some motor frames are sized soSome motor frames are sized sothat just the surface area is suitablethat just the surface area is suitableto dissipate motor heat w/o the needto dissipate motor heat w/o the need

of a fan or blower of a fan or blower

Blowers may be added toBlowers may be added tomotors to allow operation atmotors to allow operation atlow speed including 0 RPMlow speed including 0 RPMwith 100% Torque continuouswith 100% Torque continuous



45/62


Types of AC Motors

Definite purpose laminated frameDefinite purpose laminated framedesigns provide higher power designs provide higher power densities & improved torque todensities & improved torque toinertia performance.inertia performance.

Definite purpose laminated frameDefinite purpose laminated framedesigns provide higher power designs provide higher power densities & improved torque todensities & improved torque toinertia performance.inertia performance.

TT--Frame Construction Motors allowFrame Construction Motors allowcommonality in footprint & shaftcommonality in footprint & shaftheight.height.

TT--Frame Construction Motors allowFrame Construction Motors allowcommonality in footprint & shaftcommonality in footprint & shaftheight.height.


Match Motor typeto meet your

needs!


46/62


R otor Designs Vary by motor type:

Definite purpose single squirrelDefinite purpose single squirrelcage rotor design for Variablecage rotor design for VariableFrequency Drive useFrequency Drive use

Standard Industrial AC Motor doubleStandard Industrial AC Motor doublesquirrel cage R otor Design for squirrel cage R otor Design for improved across the line startingimproved across the line startingtorque.torque.


Rotor designaffects torqueproduction!

Rotor designaffects torqueproduction!


47/62


E quivalent Circuit Diagram of an AC Induction Motor E quivalent Circuit Diagram of an AC Induction Motor

Resistan ce

Stator

Indu ctan ce

Stator

Indu ctan ce

Rotor

Resistan ce

Rotor

Indu ctan ce Magnetizing

ACIn put

Vo ltage

-

+

Current Working

AC Motor Basics AC Motor Basics -- Equivalent Circuit DiagramEquivalent Circuit Diagram AC Motor Basics AC Motor Basics -- Equivalent Circuit DiagramEquivalent Circuit Diagram

Rotor heating

affects torqueproduction!


48/62


P eak Torque capacity is dependent upon the motor BDT %P eak Torque capacity is dependent upon the motor BDT %

AC Motor Basics AC Motor Basics -- Drive Operating RegionDrive Operating Region AC Motor Basics AC Motor Basics -- Drive Operating RegionDrive Operating Region

NE MA Design B Motor NE MA Design B Motor

Full Load Torque

Breakdown Torque R ule of Thumb:R ule of Thumb:

Approximately 80% of BDT Approximately 80% of BDT(ft(ft--lbs) is usable for PEAKlbs) is usable for PEAKTorque needs when currentTorque needs when currentis available.is available.

Therefore, currentTherefore, currentheadroom from the driveheadroom from the drivecan improve recovery fromcan improve recovery fromsudden load changes.sudden load changes.


49/62


Breakdown Torque identifies P eak Torque capabilitiesBreakdown Torque identifies P eak Torque capabilities

AC Motor Basics AC Motor Basics -- Drive Operating RegionDrive Operating Region AC Motor Basics AC Motor Basics -- Drive Operating RegionDrive Operating Region

NE MA Design B Motors vary in Breakdown Torque capacityNE MA Design B Motors vary in Breakdown Torque capacity


50/62


Inverter Duty Motors operate at 1/10th Base RP MInverter Duty Motors operate at 1/10th Base RP M

Speed / Torque Curve of an AC Drive & Inverter Duty Motor Speed / Torque Curve of an AC Drive & Inverter Duty Motor

%TORQ

UE

0

10

20

3 0

40

50

60

70

80

90

100

0 6 12 18 24 3 0 3 6 42 48 54 60 66 72 78 84 90

TorqueTorque

TorqueTorque

HZ

Acceptable Regionfor Continuous Operation

AC Motor Basics AC Motor Basics -- Operating RangeOperating Range AC Motor Basics AC Motor Basics -- Operating RangeOperating Range


51/62


CHp Operation above Base RP M is typically limited to 150%CHp Operation above Base RP M is typically limited to 150%

Speed / Torque Curve of an AC Drive & Inverter Duty Motor Speed / Torque Curve of an AC Drive & Inverter Duty Motor

%TORQ

UE

0

10

20

3 0

40

50

60

70

80

90

100

0 6 12 18 24 3 0 3 6 42 48 54 60 66 72 78 84 90

TorqueTorque

TorqueTorque

HZ

Torque abovebase RPM =

100%% Above Base RPM



52/62


Vector Duty Motors operate at 0 RP M w/ 100% Torque Cont.Vector Duty Motors operate at 0 RP M w/ 100% Torque Cont.

Speed / Torque Curve of a Vector Drive & Vector Duty Motor Speed / Torque Curve of a Vector Drive & Vector Duty Motor

%TORQ

UE

0

10

20

3 0

40

50

60

70

80

90

100

0 6 12 18 24 3 0 3 6 42 48 54 60 66 72 78 84 90

TorqueTorque

TorqueTorque

HZ

Acceptable Regionfor Continuous Operation



53/62


Some Vector Duty Motors can provide CHp ( 2 * Base RP M )Some Vector Duty Motors can provide CHp ( 2 * Base RP M )

Speed / Torque Curve of a Vector Drive & Vector Duty Motor Speed / Torque Curve of a Vector Drive & Vector Duty Motor

HZ

%TORQ

UE

0 6 12 18 24 3 0 3 6 42 48 54 60 66 72 78 84 90

TorqueTorque

TorqueTorque

010

20

3 0

40

50

60

70

80

90

100

96 102 108 114 120

Vector Duty Motors may haveCHP Ranges of

2 * Base Speed or moredepending on their design


Special motor & driveSpecial motor & drivedesigns can allowdesigns can allow

operation up to 8 *operation up to 8 *Base RPMBase RPM


54/62


COM P ARINGCOM P ARINGAC D RIVE AC D RIVE PER FO R MAN CEPER FO R MAN CE

AC Drive Performance AC Drive Performance AC Drive Performance AC Drive Performance


55/62


Control SelectionControl SelectionControl SelectionControl Selection

Starting in torotating loads

/ z S C F C

etter Good est

FVC operation is best since the position and velocity of theFVC operation is best since the position and velocity of therotor is known and restarting is immediate.rotor is known and restarting is immediate.

V /Hz being a soft speed regulator is very forgiving for V /Hz being a soft speed regulator is very forgiving for restarting into loads with high inertia.restarting into loads with high inertia.

S VC may be more difficult to implement due to limitations byS VC may be more difficult to implement due to limitations bymanufacturer. P rocessor & algorithm dependent.manufacturer. P rocessor & algorithm dependent.


56/62


V /Hz operation inheriently controls multiple motors.V /Hz operation inheriently controls multiple motors.S VC or F VC operation with multiple motors is only possibleS VC or F VC operation with multiple motors is only possiblewhen motor shafts are mechanically locked together andwhen motor shafts are mechanically locked together andassumptions are made about total motor current values.assumptions are made about total motor current values.


ulti- otor peration fro

one drive/ z S C F C

estot

eco endedot

eco ended


57/62


V /Hz is typically good for up to 10:1 Constant Torque.V /Hz is typically good for up to 10:1 Constant Torque.

S VC is typically good for up to 40:1 Constant Torque.S VC is typically good for up to 40:1 Constant Torque.

FVC is typically good for up to 1,000:1 which includesFVC is typically good for up to 1,000:1 which includescontinuous operation at Zero Speed.continuous operation at Zero Speed.


ConstantTorque Range V/Hz SVC FVC

ood Better Best


58/62


V /Hz has no quantifiable response time or bandwidth.V /Hz has no quantifiable response time or bandwidth.

Typical S VC specifications may state 100 R adians/second.Typical S VC specifications may state 100 R adians/second.

Typical F VC specifications may state 1,000 R adian/second.Typical F VC specifications may state 1,000 R adian/second.


yna icesponse / z S C F C

Good etter esto

tuningdjustable

Gains for tuningdjustable

Gains for tuning


59/62


Both AC & DC Drives have specific areas of merit to consider Both AC & DC Drives have specific areas of merit to consider

Feature Flux ector - benefits rive - li itations

o er Factor 92% to 96% at all speedsloads

88% to 33% dependent onspeed load

Torque roduction 1,000 radian/sec 300 radian/secperation at tall losed Loop Flux ector at

tall continuousoperation at tall li ited by

brushes co utator

otor ost otor cost is lessexpensive due to si plicity

otor cost is higher due tolabor co plexity parts

igh peedpplications

Lo er rotor ass allo shigh speed operation

echanically li ited in speeddue to construction

rive electionrive electionrive electionrive election


60/62


Both AC & DC Drives have specific areas of merit to consider Both AC & DC Drives have specific areas of merit to consider

Feature Flux Vector - limitations DC Drive - benefits

Line Regeneration 60% to 100% premium over drive cost to do

5% to 25% premium over drivecost to do

Motor Lead Length Limitation of lead length canaffect operation & reliability

No concerns of lead lengthother than voltage drop

Drive Only Cost More expensive due tocontroller complexity

Less expensive due tocontroller simplicity

Shock Load Applications

Less inertia at motor requiresmore tuning and setup time

Armature inertia helps todampen shock loads

Drive SelectionDrive SelectionDrive SelectionDrive Selection


61/62


PerformanceFeatures

DC Drivew/ Encoder

DC Drivew/ Tach

DC Drivew/o Fdbk

FluxVector

SensorlessVector

OperatingSpeed Range

0 RPM toBase RPM

90 RPM toBase RPM

90 RPM toBase RPM

0 RPM toBase RPM

45 RPM toBase RPM

CT SpeedRegulationw/o loadchange

1,000 : 10.01%

70 : 11.0%

20 : 13.0%

1,000 : 10.01%

40 : 10.5%

CT SpeedRegulationw/ 100% loadchange

100 : 10.05%

30 : 13.0%

10 : 15.0%

100 : 10.05%

20 : 11.0%

Digital DC Drives & AC Vector Drives performance similarlyDigital DC Drives & AC Vector Drives performance similarly

Drive SelectionDrive Selection -- Speed RangeSpeed RangeDrive SelectionDrive Selection -- Speed RangeSpeed Range


62/62

Any Q uestions?

Thank You!Thank You!Thank You!Thank You!

Date post:	10-Apr-2018
Category:	Documents
Upload:	cpopescu48
View:	217 times
Download:	0 times

Torque Prod Duct Ion With AC Drives and Motors-Understanding the Technology

Documents