A variable frequency drive often called VFD is a kind of motor controller that has the ability to drive an electric motor by changing its power supply of frequency and voltage. It has the ability for controlling motor ramp-up and ramp-down during beginning or end, correspondingly. Although the drive controls the motor power supply's frequency and voltage, we often called it to speed control as it comes out as an adjustment of motor speed. https://cmindustrysupply.com/blog_detail.php?title=Why-do-we-need-a-Variable-Frequency-Drive&blog_id=57