1.0 -1.0
Half Voltage, 30 Hz PWM Waveform
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Voltage Source VFD
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10), 3+).%03 &'#()*+ !"#$% ,!0,+ 3+.%!4!+3 ,-.-'/01%)2+ 4++,5).6 3+2$1)%03 !"/+3%+3 :0%03
Volts / Hz Ratio
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Voltage Variable Frequency
F? >? B? C? &? @? A? ? ? A? @? &? C? B? >? (03*+#09+3 %037$+
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SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Region of continuous operation 200% Torque (Typical) Region of intermittent operation
100%
Continuous torque capability
Rectifier and Filter
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Power Factor
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
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.
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Diode Rectifier
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Insulated Gate Bipolar Transistors
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
100 % Output Voltage Field Weakening Region
Amount of Boost 60Hz Output Frequency
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 IGBT’s per output phase switch the positive and negative sides of the DC Bus utilising pulse width modulation ! IGBT’s will have a characteristic rise time depending on its generation and current rating ! Rise time is the time it takes the IGBT pulse when switched on to reach DC bus voltage level
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Load Torque Proportional To The Square of Speed
Inverter
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
PWM Waveform
1.0 -1.0
Full Voltage, 60 Hz PWM Waveform
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Torque Curve
A?? G? E?
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PWM Power Diagram
Input Line
Capacitor
AC Motor Rectifier Inverter
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC VARIABLE SPEED DRIVES POWER QUALITY PRODUCTS
Variable Frequency Drives Basic VFD Theory
SALES & SERVICE FOR ABB AC VARIABLE SPEED DRIVES SOFT STARTERRS DC 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 the speed. (Press1 / Press2) = (RPM1)2 / (RPM2)2 ! HP is proportional to the cube of the speed. (HP1 / HP2) = (RPM1 )3/ (RPM2)3
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) .
Convert AC Input Power to DC
AC input power is rectified to DC through a six pulse diode 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