What is the definition of a VFD Drives? A variable frequency drive (VFD) is an electrical device used to control the speed of an electric motor by changing the frequency and voltage of the electrical power supply. The VFD is also known as a frequency converter or AC drive. It is widely used in industrial applications for controlling the speed of pumps, fans, and other equipment requiring variable speed operation. The main components of a VFD are the rectifier, inverter, and controller. The rectifier converts the AC input power to DC power. The inverter then converts the DC power into AC power, but with a variable frequency. The controller then adjusts the frequency and voltage of the output power, which in turn adjusts the speed of the motor. VFDs are also used to reduce energy consumption, reduce starting currents, and improve motor performance. With so many advantages and applications, VFDs are an essential component of modern industrial systems.