A Variable Frequency Drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) motor by controlling the power frequency supplied to the motor.
An electric motor rotates its rotor according to the parameters achieved by the voltage and frequency of the electrical power supplied to the motor. Internationally, there are different mains voltages, such as 400 V (three-phase), 380 V (three-phase), etc., and frequencies of 50 or 60 Hertz. By varying the voltage and/or frequency, the performance of the motor, including the speed, varies. It is usually difficult to change the voltage or frequency without auxiliary equipment.
To vary the voltage and frequency effectively, a variable frequency drive is used. Normal power is supplied to the VFD and the output of the VFD is fed to the electric motor. The VFD has controls that can be adjusted to control the speed of the motor.
A VFD provides precise control of the speed and torque of an AC motor through pulse width modulation (PWM). In a VFD system, it is critical to choose the right cable for best performance, maximum energy efficiency and long life.