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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Frequency Drives
Basic VFD Theory
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ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
What is a VFD
( Variable Frequency Drive)
! Electrical / electronic piece ofequipment that varies the speed of a3 phase or AC motor.
! Also called .
! VSD ( Variable speed drive)
! ASD ( Adjustable speed drive)
!AFD ( Adjustable frequency drive)
! Inverter
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Basic VFD Operation
! Convert AC power to DC power.
!Filter DC power.
! Invert DC power to variable voltage
and variable frequency AC power.
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Voltage Source VFD
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Input
Line Capacitor
InverterRectifier
AC Motor
PWM Power Diagram
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Convert AC Input Power to DC
AC input power is rectified to DC through a six pulsediode bridge
DC voltage is equal to AC input voltage * 1.414 (root
2)!230 * 1.414 = 325
!460 * 1.414 = 650
!600 * 1.414 = 850
DC power is filtered and stored through a capacitor
bank called the DC bus
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Diode Rectifier
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Rectifier and Filter
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Power Factor
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Invert DC Power to Variable Voltage
and Frequency AC Power
! 2 IGBTs per output phase switch the positive and negativesides of the DC Bus utilising pulse width modulation
! IGBTs will have a characteristic rise time depending on itsgeneration and current rating
! Rise time is the time it takes the IGBT pulse when switched onto reach DC bus voltage level
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Insulated Gate Bipolar Transistors
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Inverter
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Full Voltage, 60 Hz PWM Waveform
Half Voltage, 30 Hz PWM Waveform
1.0
-1.0
1.0
-1.0
PWM Waveform
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Pulse Width Modulation
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Modulation of Waveform
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
PWM Carrier Frequency
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS
DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Volts / Hz Ratio
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Voltage Variable Frequency
100
%
Amount
of Boost
Field Weakening
Region
Ou
tputVoltage
60HzOutput
Frequency
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
VFD Summary
! VFD Varies the speed of an AC Motor
! Maximum output voltage = input
voltage
! V/Hz ratio is controlled throughout the
range up to 60 Hz.
! Torque decreases after 60Hz.
! Output wave form is Pulse Width
Modulated (PWM) .
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Application Types
! Variable Torque
! Constant Torque
! Constant Horsepower
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Torque Curve
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Torque
Affinity Laws:
! Flow is proportional to speed.
(Flow1/ Flow2) = (RPM1)/(RPM2)
! Pressure is proportional to the square of thespeed.
(Press1/ Press2) = (RPM1)2/ (RPM2)
2
! HP is proportional to the cube of the speed.
(HP1/ HP2) = (RPM1 )3/ (RPM2)
3
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Load Torque Proportional
To The Square of Speed
60 100
200%
100%
63%
Torque
(Typical
)
Continuous torque
capability
Speed in Hertz
Region of continuousoperation
Region of intermittent
operation
Peak torque
capability
Load torqueRequirement
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Torque - Flow
Flow is proportional to speed.
(Flow1/ Flow2) = (RPM1) / (RPM2)
Flow RPM Second Second
Gallons/min RPM Flow
10000 1800 900 5000.00
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Torque - Pressure
Pressure is proportional to the
square of the speed.
(Press1/ Press2) = (RPM1)2/ (RPM2)2
Pressure RPM Second Second
Lb/sq. in RPM Pressure (lb/sq. in)
1000 1800 3600 4000
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Torque Horsepower
HP is proportional to the cube of the speed.
(HP1/ HP2) = (RPM1)3/ (RPM2)
3
Horsepower RPM Second SecondRPM Horsepower
10 3450 3000 6.58
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Torque Applications
Irrigation Water Pumps
Down-hole Water Pumps
Submersible Water Pumps
Domestic Water Pumps
Centrifugal Sewage
Treatment Pumps
Centrifugal Fans
Blowers
Air Handling Units
Chillers
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ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Constant Torque
! Torque remains constant up to the motor basespeed.
! HP is proportional to the speed.
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Constant Torque Curve
/0
1%)2+
;
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Constant Torque Applications
Conveyors
Compressors
Positive Displacement Pumps
Crushers
Mixers
Elevators
Escalators
Etc.
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Constant Torque Load
60 100
200%
100%
63%
Torq
ue
(Typ
ical)
Continuous torquecapability
Speed in Hertz
Region of continuouso eration
Region of intermittenoperation
Load torquerequirement
Region of intermittentoperation
Peak torquecapability
60 100
200%
100%
63%
Torq
ue
(Typ
ical)
Continuous torquecapability
Speed in Hertz
egion of continuousperation
Region of intermittentoperation
Load torquerequirement
Region of intermittentoperation
Peak torquecapability
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Torque De-rating Due to
Motor Cooling
6 0 1 0 0
2 0 0 %
1 0 0 %
6 3 %
Fie ld w eaken ing reg ion
Peak torque capab i li ty
prov ided tha t the AC
dr ive has adeq uateover load capabi l i tyT
or
que
(Ty
pical)
C o n t i n u o u s t o r q u e
cap abi l i ty l imited
by m otor coo l ing
S p e e d i n H e r t z6 0 1 0 0
2 0 0 %
1 0 0 %
6 3 %
Fie ld w eaken in g reg ion
Peak torque capab i li ty
prov ided tha t the AC
dr ive has adeq uateover load capabi l i tyT
or
que
(Ty
pical)
C o n t i n u o u s t o r q u e
cap abi l i ty l imited
by m otor coo l ing
S p e e d i n H e r t z
T C B l & Ab 60
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SALES & SERVICE FOR
ABB AC VARIABLE SPEED DRIVES SOFT STARTERRSDC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Torque Curve Below & Above 60
Hz, Constant Torque V/F Ratio
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