A thorough understanding of how to match the VFD to the driven
load is the key to a successful application. When applied
properly, the variable frequency drive (VFD) is the most
effective motor controller in the industry today. Modern VFDs
are affordable and reliable, have flexibility of control, and
offer significant electrical energy savings through greatly
reduced electric bills. They are used in a wide variety of
applications for various reasons. For example, they are the most
effective energy savers in pump and fan applications; they
enhance process operations, particularly where flow control is
involved. VFDs provide soft-start capabilities, which decrease
electrical stresses and line voltage sags associated with full
voltage motor start-ups, especially when driving high-inertia
loads. To obtain a clear understanding of the proper and most
effective application of VFDs, you first should gain a working
knowledge of VFD basic theory as well as a strong familiarity
with practical know-how. Basic VFD Theory