A Variable Frequency Drive (VFD) controls the speed of an AC motor by adjusting input frequency and voltage, while also providing motor protection. It works by converting AC to DC and then back to three-phase AC, allowing it to be called an inverter. VFDs can drive multiple motors at the same RPM and are widely used in various applications, including pumps and automated equipment.

1. WHAT IS VFD?
VFD (Variable Frequency drive) is a device that can control the speed
of an AC drive or induction motor by reducing/increasing the input
frequency and voltage of the motor. And can also provide protection
to the motor.
N= (120f/p)
N= Synchronous speed
F= Frequency
P= Number of poles

2. Why VFD is also called inverter?
When DC is converted to AC by inverter and AC to DC is Converter. DC to
AC = Inverter AC to DC = Converter VFD to complete its operation first
converts AC to DC and then converts DC to 3 phase AC. Therefore it will not
be wrong to call VFD as Inverter.
If you want to drive a 3 phase motor with your home's single
phase line, a VFD can do that too.

3. Advantage of VFD:

4. Disadvantage of VFD:

5. Multiple motors with one VFD:
• All motors will run at same RPM.
• Total cable length for motors should be less than 500 meters.
• Total load (KW) must be 20% less than VFD power rating.

6. Where are the AC induction motor used:
• AC motors are a great power source for a number of reasons such as
in pumps, food and beverage machines, automated conveyer equipment,
packaging operations, washing machines, electric knife sharpeners, office
equipment, ovens, and water heaters etc.