What does a variable frequency drive do?
A variable frequency drive (VFD) is a type of motor controller that drives an electric motor by varying the frequency and voltage of its power supply. The VFD also has the capacity to control ramp-up and ramp-down of the motor during start or stop, respectively.
How frequency is varied in VFD?
Output voltage is varied by varying the gain of the inverter. Output frequency is adjusted by changing the number of pulses per half cycle or by varying the period for each time cycle.
What is a variable frequency drive VFD and what is its advantage?
Variable frequency drives (VFDs) can help even small organizations realize energy savings. Cost and size of VFDs have decreased; performance has improved. Other benefits of VFDs include less line disturbances, less maintenance, and longer motor life.
How do variable frequency drives save energy?
VFDs save energy by enabling electric motors to operate at less than full speed. The Laws of Affinity for centrifugal pumps and fans states. Reducing motor speed by 25% decreases energy consumption by nearly 60% while reducing motor speed by 50% decreases energy consumption by nearly 90%.
How does VFD reduce starting current?
VFDs deliver much higher frequency source power during startup to reduce current due to the increased inductive impedance. This can be advantageous if control is desired after full speed is reached. This control allows for continuing control as the load on the motor is changing.
How is variable frequency drive?
A variable frequency drive controls the speed of an AC motor by varying the frequency supplied to the motor. The first step in this process is to convert the AC supply voltage into DC by the use of a rectifier. DC power contains voltage ripples which are smoothed using filter capacitors.
When would you use a variable frequency drive?
You need a variable frequency drive if you have AC motors in your facility or use mechanical means for varying VFD output. You would need variable frequency drives even if the AC motors in your facility require a variable output.
Are VFDs more efficient?
In HVAC systems, VFD controlled fans have been shown to significantly reduce energy consumption by up to 70%.