A variable frequency drive (VFD) is a type of motor controller that drives an electric motor by varying the frequency and voltage supplied to the motor. VFDs have been in use since the 1980s, and today, the combination of energy awareness, energy regulations, and new VFD technologies are driving an increasing demand for these energy-saving products.
The concept of a VFD is fairly straightforward. Frequency (hertz) is directly related to a motor’s speed (RPMs). The faster the frequency is, the faster the RPMs go. If an application does not require an electric motor to run at full speed, a VFD can be used to ramp down the frequency and voltage to meet the requirements of the electric motor’s load. As the application’s motor speed requirements change, the VFD can turn the motor speed up or down to meet the speed requirement.