ps basics of an ac drive
DESCRIPTION
Basic of AC DrivesTRANSCRIPT
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Review of How Motor Works• Motor converts Electrical Energy to Rotating Mechanical
Energy• Coils placement in motor creates rotating, magnetic field in
stator• Rotating magnetic field cuts rotor bar and induces current in
rotor• Rotor current creates magnetic field on rotor• Attraction of rotor to stator creates torque and, hence,
horsepower
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AC Motor ReviewIn an AC Motor, speed varies by:
Motor Speed (rpm) = 120 x Frequency - SlipMotor Speed (rpm) = 120 x Frequency - Slip
# of Poles# of Poles
Since you can not change the number of poles in an AC motor,the frequency is changed to vary the speed.
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Varying the Speed of an AC Motor
60 Hz30 Hz
1800(rpm)
900(rpm)
1800 = 60 x 120(rpm) 4
900 = 30 x 120(rpm) 4
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AC Motor Review
In an AC motor, Torque Varies by:
T = K x ( )2 x I LineE
F
Where:K is a constantE is applied voltageF is input frequency I Line is motor current
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AC Motor Review
Torque/Current RelationshipWhat you really need to know…...
• Current is roughly proportional to load torque
• The higher the load torque the higher the current
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AC Motor Review
Horsepower of an AC motor can be determined by:
HP = Torque x Speed 5252
Where:Torque is in lb-ftSpeed is in RPM5252 is a constant
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Motor nameplate Horsepower is achieved at Base RPM:Motor nameplate Horsepower is achieved at Base RPM:
HP = Torque * Speed / 5252HP = Torque * Speed / 5252
Torque
RPMBase Speed
100%
Horsep
ower
Constant Torque Constant Torque RangeRange
Constant Horsepower Constant Horsepower RangeRange
Note that motor nameplate Note that motor nameplate horsepower is only horsepower is only achieved at and above achieved at and above base speed, NOT BEFORE.base speed, NOT BEFORE.
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Operation Above Base Speed
HP
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AC Motor Review
IMPEDANCE
IMPEDANCE: Resistance of AC Current flowing through the windings of an AC Motor
NOTE: Impedance decreases as frequency decreases
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Volts/Hertz Relationship
• I = Current• V = Voltage• Z = Impedance
I = V Z
To reduce motor speed effectively:• Maintain constant relationship between current & torque• A constant relationship between voltage and frequency must be maintained
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Volt/Hertz Relationship
60 Hz30 Hz
230 V
460 V
The AC variable speed drive controls voltage & frequencysimultaneously to maintain constant volts-per-hertz relationshipkeeping current flow constant.
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AC DriveDC Bus
•Rectifier
- Converts AC line voltage to Pulsating DC voltage
• Inverter
- Changes fixed DC to adjustable AC
- Alters the Frequency of PWM waveform
• Intermediate Circuit (DC BUS)
- Filters the pulsating DC to fixed DC voltage
V
TT
V V V
T
AC Power Supply
Rectifier Inverter
M
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Sine Weighted PWM
Bus Voltage Level
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Sine Weighted PWM
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PWM WAVEFORM
PWM waveform is a series PWM waveform is a series of repetitive of repetitive voltage pulsesvoltage pulses
1
3
+ DC Bus+ DC Bus
- DC Bus- DC Bus
VVLLLL @ Drive @ Drive
500 Volts / Div.500 Volts / Div.
Phase CurrentPhase Current10 Amps / Div.10 Amps / Div.
M2.00s Ch1 1.18V
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Drive and Motor CompatibilityDrive and Motor CompatibilityDrive and Motor CompatibilityDrive and Motor Compatibility
VLL @ Drive500 Volts / Div.
VLL @ Motor500 Volts / Div.
Voltage Wave @Drive Output
Voltage Wave @ Motor Conduit Box
Potentially Damaging Voltage Peaks
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How to Specify -- NEMA StandardsHow to Specify -- NEMA StandardsMG1-1993, Part 31.40.4.2MG1-1993, Part 31.40.4.2
How to Specify -- NEMA StandardsHow to Specify -- NEMA StandardsMG1-1993, Part 31.40.4.2MG1-1993, Part 31.40.4.2
10%
90%
Vpeak
t
Steady-state voltage100%
Voltage
V
dV
dt
V
t
Rise timeTime
Maximum of 1600 Volt Peaks
Minimum Rise Time of .1 Microseconds
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GV3000/SEV/Hz OperationV/Hz Operation
At Base RPM or 60Hz, the Motor sees line input voltageAt Base RPM or 60Hz, the Motor sees line input voltage
OutputOutputFrequencyFrequencyBase FrequencyBase Frequency
6060
Output Output VoltageVoltage
Hz30
460460
230
115
15 90
Ratio @ 460VAC
= 7.67 V/Hz
0
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GV3000/SEV/Hz Operation V/Hz Operation
OutputOutputFrequencyFrequencyBase FrequencyBase Frequency
60
Output Output VoltageVoltage
Hz30
460
230
115115
1515 90
Ratio @ 460VAC
= 7.67 V/Hz
0
At 25% of Base RPM or 15 Hz, Voltage & Frequency is 25%At 25% of Base RPM or 15 Hz, Voltage & Frequency is 25%
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VECTOR DRIVE
Torque - ProducingCurrent (23.5 Amps)
MagnetizingCurrent
(8.5 Amps)
25.0AmpsFull
Load
Vector calculates Torque-Producing Current by knowing actual amps and magnetizing current.
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GV3000/SEVector Control - Torque can be produced, as well as regulated even at “0” RPM
Motor Current is the Vector Sum of Torque & MagnetizingMotor Current is the Vector Sum of Torque & Magnetizing
Motor Current is the VECTOR SUM of Magnetizing Motor Current is the VECTOR SUM of Magnetizing & Torque Current,& Torque Current,
this is where the term VECTOR DRIVE is derivedthis is where the term VECTOR DRIVE is derived
Motor Current is the VECTOR SUM of Magnetizing Motor Current is the VECTOR SUM of Magnetizing & Torque Current,& Torque Current,
this is where the term VECTOR DRIVE is derivedthis is where the term VECTOR DRIVE is derivedTorque Current
Magnetizing Current
100%
Motor Current
90
Torque Current
Magnetizing Current
10%
Motor Current
90
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GV3000/GV3000/SESEFlux Vector DriveFlux Vector Drive - - simple diagram reviewsimple diagram review
A Vector Drive always regulates current
Encoder feedback provides rotor speed & position information for calculations Encoder feedback provides rotor speed & position information for calculations
L1L2
L3
Micro P
“LEM”Current Sensors
Motor
E
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GV3000/GV3000/SESESensorless Vector Control Sensorless Vector Control - - simple diagram reviewsimple diagram review
SVC estimates rotor speed & position to the stator field
A “Speed Estimator” calculates rotor speed & position to maintain 90° to the fieldA “Speed Estimator” calculates rotor speed & position to maintain 90° to the field
L1L2
L3 Motor
Micro P
( FVC + Speed Estimator )
“LEM”Current Sensors
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• 150% Overload• Operation to 0 RPM
• 120:1 Speed Range• Speed Regulation
• 40:1, 0.5% Steady State• 20:1, 1.0% Dynamic
• Dynamic Response• 100+ radian Speed Loop• 1000 radian Torque Loop• Tunable Speed PI gains
• 150% Overload• Operation @ 0 RPM
• 1000:1 Speed Range• Speed Regulation
• 100:1, 0.01% Steady State• 100:1, 0.5% Dynamic
• Dynamic Response• 100+ radian Speed Loop• 1000 radian Torque Loop• Tunable Speed & Torque PI gains
Sensorless Vector Flux Vector
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INVERTER DUTY MOTORS
AC Drives regulate Motor Speed based on designed slipAC Drives regulate Motor Speed based on designed slip
NEMA Design ‘B” Motor w/ 3% Slip - Across the Line StartNEMA Design ‘B” Motor w/ 3% Slip - Across the Line Start
Operating Regionon AC Drives
Operating Regionon AC Drives
200%200%BDTBDT
FLTFLT100%100%
Base RPMBase RPM
SlipSlip
PUT
LRT
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INVERTER DUTY MOTORS
Some motor frames are sized so that Some motor frames are sized so that just the surface area is suitable to just the surface area is suitable to
dissipate motor heat w/o the need of a dissipate motor heat w/o the need of a fan or blowerfan or blower
Some motor frames are sized so that Some motor frames are sized so that just the surface area is suitable to just the surface area is suitable to
dissipate motor heat w/o the need of a dissipate motor heat w/o the need of a fan or blowerfan or blower
Blowers may be added to Blowers may be added to motors to allow operation at low motors to allow operation at low speed including “0” RPM with speed including “0” RPM with
100% Torque continuous100% Torque continuous
Blowers may be added to Blowers may be added to motors to allow operation at low motors to allow operation at low speed including “0” RPM with speed including “0” RPM with
100% Torque continuous100% Torque continuous
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VXS Motors• Based on Reliance XEX Motor Designs
• TENV, TEFC-XT and TEBC Enclosures• Ideal for;
• Positive Displacement Pumps and Blowers• Extruders and Mixers• Steel and Converting Process lines
• Standard Features;• Encoder Mounting Provisions
• Motor Shaft Tapped for Stub @ ODE • Accessory Face @ ODE
• Motor Winding Thermostats, 1/Phase• 10:1 to 1000:1 CT speed ranges w/o derating
GV3000/SE with“Inverter & Vector Duty” AC Motors
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RPM-AC Motors• Laminated Steel, DC-style construction
• DPFV, TENV, & TEBC enclosures• Ideal for;
• Extruder applications• Web processing & mill applications• Retrofitting existing DC Drive & Motor systems
• Standard Features;• High torque to inertia ratios• Encoder Mounting Provisions• Motor Winding Thermostats, 1/Phase• Infinite CT speed range, 0 RPM continuous• CHp Range of 2:1 on TENV & TEBC Frames• Base Speeds from 650 RPM to 3600 RPM
GV3000/SE with“Inverter & Vector Duty” AC Motors
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Speed Range
• Speed Range - Designed operating range of an inverter duty motor
• Example• 1800 rpm motor• 10:1 Speed Range = 180 -1800 (rpm)
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CONSTANT TORQUE REGION
Inverter Duty Motors operate at 1/4th Base RPMInverter Duty Motors operate at 1/4th Base RPM
Speed / Torque Curve of an AC Drive & Inverter Duty MotorSpeed / Torque Curve of an AC Drive & Inverter Duty Motor
% TORQUE
0
10
20
30
40
50
60
70
80
90
100
0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90
TorqueTorque
TorqueTorque
HZ
Acceptable Regionfor Continuous Operation
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CONSTANT HP REGION
CHp Operation above Base CHp Operation above Base
RPM is typically limited to 150%RPM is typically limited to 150%
Speed / Torque Curve of an AC Drive & Inverter Duty MotorSpeed / Torque Curve of an AC Drive & Inverter Duty Motor
% TORQUE
0
10
20
30
40
50
60
70
80
90
100
0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90
TorqueTorque
TorqueTorque
HZ
Torque above base RPM =
100%% Base RPM
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CONSTANT TORQUE REGION
Vector Duty Motors operate at Vector Duty Motors operate at
““0” RPM w/ 100% Torque Cont.0” RPM w/ 100% Torque Cont.
Speed / Torque Curve of a Vector Drive & Vector Duty MotorSpeed / Torque Curve of a Vector Drive & Vector Duty Motor
% TORQUE
0
10
20
30
40
50
60
70
80
90
100
0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90
TorqueTorque
TorqueTorque
HZ
Acceptable Regionfor Continuous Operation
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CONSTANT HP REGION
Some Vector Duty Motors can Some Vector Duty Motors can
provide CHp ( 2 * Base RPM )provide CHp ( 2 * Base RPM )
Speed / Torque Curve of a Vector Drive & Vector Duty MotorSpeed / Torque Curve of a Vector Drive & Vector Duty Motor
HZ
% TORQUE
0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90
TorqueTorque
TorqueTorque
0
10
20
30
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 & drive Special motor & drive designs can allow operation designs can allow operation
up to 8 * Base RPMup to 8 * Base RPM
Special motor & drive Special motor & drive designs can allow operation designs can allow operation
up to 8 * Base RPMup to 8 * Base RPM
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Drive Terminology• V/Hz• DC Boost• Accel / Decel• Frequency• Voltage• HP• Speed• Skip & Bandwith• Braking• DB• Regen• Injection• Coast• Ramp
• Restart• Preset• Jog• Current Limit• Analog / Digital• Power Factor• Harmonics• Ride - Thru• Speed Range• Speed Regulation• Frequency Regulation• Cogging• Efficiency
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Accel/Decel
• Acceleration Rate - Deceleration Rate
• Rate of change of motor speed.
Example:0 Speed - 1750 rpm 30 seconds
TIME
Frequency
100 %
30 sec
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Full Voltage Bypass
GV3000/SE M
InputDisconnect
Switch
DriveBranchFusing
BypassDisconnect
Switch
BypassOption
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Speed Regulation
How Much Will the Speed Change
Between No Load and Full Load?
Expressed as a Percentage
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Speed Regulation
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DC Voltage Boost
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Voltage BoostVoltage Boost over prolonged operating periods may result in Voltage Boost over prolonged operating periods may result in overheating of the motor’s insulation system and result in overheating of the motor’s insulation system and result in premature failure.premature failure.
Unable to perform like DC, Unable to perform like DC,
the industry looks to Vector Controlthe industry looks to Vector Control
CAUTION: Motor Insulation Life is decreased by 50% for
every 10°C above the insulation’s temperature
capacity
CAUTION: Motor Insulation Life is decreased by 50% for
every 10°C above the insulation’s temperature
capacity
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Critical Frequency
An Output Frequency of a Controller that
Produces a Load Speed at Which Severe
Vibration Occurs.
A Frequency at which Continuous Operation
is Undesirable
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Skip Bandwith
0
10
20
30
40
50
60
0 1 2 3 4 5 6 7 8 9 10
Command Freq.
Output Freq
Skip Band
Skip Freq
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AC Drive Inputs
Analog Inputs:• 0-10 VDC• ± 10 VDC• 4-20 mA
Digital Inputs:• Start• Stop• Reset• Forward/Reverse• Run/Jog• Preset Speeds
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• For Trip Free Deceleration if low to medium inertia loads
GV3000/GV3000/SESE
Trip Free Deceleration when enabled
High Bus Avoidance ( SVC & FVC )
SPEED
TIME
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Snubber/Dynamic BrakingDC Bus
AC Power Supply
Rectifier Inverter
M
Braking Resistor
7th IGBT
• Snubber/Dynamic Braking
- Addition of Snubber Resitor Kit
- Dissipates excess energy to regulate
braking
- Regulator monitors DC bus voltage
- Signal sent to 7th IGBT
- Handles short term regenerative loads
- Less expensive than AC line regeneratiion braking
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AC Regenerative Braking
AC Power Supply
• Severe Regenerative Braking
- Addition of AC Line Regeneration Module
- Monitors DC bus voltage
- Sends Excess voltage back to AC line
- Handles long term regenerative loads
Drive 1AC Line Regeneration
Module
Drive 2 Drive 2
- Run Multiple Drives off 1 Module
- Drives powered through DC bus instead
of through the Rectifier bridge
- Share regenerative energy between
motoring and regenerating drives
- Send energy back to AC Line instead of
dissipating as heat
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Auto - Restart
How will the drive react after being shut down
by a fault condition? Will the drive resume
Running after the Fault condition is Cleared?
(Sometime restricted to certain Faults)
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Preset Speeds
A Pre-Programmed Command Frequency
That can be activated via Mode
Select or Input Device
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Current Limit
The ability of a drive to react to the increased current caused by momentarilyincreasing the load on the motor (Shock Loading) without tripping the drive on Overcurrent.
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Power Loss Ride-Through
The Ability of a Controller to
sustain itself through a loss of
Input Line Voltage for a specific
period of time.
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Operating Range ForVariable Frequency AC Drives