A Variable Frequency Drive (VFD), also known as an adjustable-frequency drive, variable-speed drive, AC drive, micro drive, or inverter drive, is a type of motor controller that varies the frequency and voltage supplied to an electric motor, primarily a three-phase induction motor. This variation allows the motor's speed and torque to be controlled, providing improved process control, energy savings, and extended lifespan of the mechanical systems.
Here's a simplified overview of how a VFD works:
Rectifier Stage: The VFD first converts the input AC voltage into DC voltage. This stage is known as rectification.
Intermediate DC Link Stage: The rectified DC voltage is smoothed in a DC link section of the VFD.
Inverter Stage: The smoothed DC voltage is then converted back into AC voltage at the desired frequency. This stage is known as inversion. By varying the output frequency, the motor speed can be precisely controlled.
Power Control, on the other hand, is a broad term that can refer to various methods and devices used to manage and control the flow of electrical power in a system. This can involve anything from circuit breakers and fuses that protect systems from overload, to advanced digital systems that monitor and adjust power usage for efficiency and safety.
In the context of a VFD, power control might refer to the ability of the VFD to control the power delivered to the motor, optimizing it for the demands of the load and the operating conditions. This can lead to significant energy savings, especially in applications where the motor doesn't need to operate at full speed all the time.