How do variable frequency drives work?


Quick Answer

A variable frequency drive, or VFD, is an adjustable-speed drive used to control an electric motor by varying the frequency and voltage supplied to the motor. The speed of the motor is controlled by either increasing or decreasing the voltage of the VFD.

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Full Answer

In a variable frequency drive, electricity is forced through a converter. The converter is made of six diodes which allow current flow in one direction. The diodes open and close based on how much current is flowing through them. A VFD has two converters that convert AC to DC and DC to AC. One converter is called a diode bridge converter and the other, an inverter.

A VFD is different from other drives because it allows users to generate any necessary frequency. This is accomplished by closing one or more of the switches on the drive.

Variable frequency drives all have essentially the same parts that make them work. Each has a cooling fan, a DC bus, AC power output, heat sink and other components.

VFDs are popular because they reduce energy consumption and cut down on energy costs. Because electric motor systems use so much electricity, installing a VFD can cut costs by up to 70 percent. Installing a VFD can help to reduce maintenance and downtime and help equipment last longer.

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