How does a variable frequency drive (VFD) work?

A variable frequency drive (VFD) controls the speed and torque of an electric motor by changing both the frequency and voltage of the electrical power supplied to it. When the frequency of the power supply is altered, it affects the motor's speed because the speed of an AC motor is directly proportional to the frequency of the supply voltage. By varying the voltage alongside the frequency, the drive ensures that the motor operates efficiently across a range of speeds while maintaining optimal performance and preventing overheating. This combination allows for precise control over motor operations, making VFDs essential for applications where speed and energy efficiency are crucial.

It is important to note that merely altering the voltage alone does not provide control over motor speed, and neither does regulating current flow in a circuit or controlling temperature directly influence the motor's operation in the context of a VFD. Therefore, understanding that the dual adjustment of frequency and voltage is fundamental to the functioning of a VFD provides clarity on its role in motor control systems.