VFD - A variable frequency drive or Variable speed drive VSD is an electronic power unit which provides infinitely adjustable control of the speed of 3 phase AC motors by converting fixed mains voltage and frequency into variable quantities.
Provides infinitely adjustable control
Has to be a 3 phase motor
Converts frequency and voltage
Components of a VFD
Rectifier - Converts the alternating current (AC) input power to direct current (DC) power
DC link- Stores the DC power to be used by the converter. These are the capacitors that are typically in the back of VFD.
Converter - The IGBT (Inverse Gate Bipolar Transistor ) inverter is the heart of the converter component.It under direction of the control circuit provides the PWM (Pulse width Modulation) output of the motor,a controlled frequency and voltaage.
Control Circuit - This is where the programming takes place and controls all the working of the VFD the brains of the operation.