What is Variable-frequency drive?
[[File:Small variable-frequency drive.jpg|thumb|Variable-frequency drive]] A '''variable-frequency drive''' ('''VFD''') is a device used to control the [[speed]] and [[torque]] of an [[Alternating current|AC]] [[Electric motor|motor]] by changing the motor input [[frequency]] and [[voltage]]. ==Applications== VFDs are used for many things that range from small appliances to large mining motors and [[compressor]]s. {{science-stub}} [[Category:Electricity]] [[Category:Control engineering]]