Industrial Engineer · phase 8 of 16
VFD
Variable Frequency Drive, an electronic motor controller that varies output frequency and voltage to control AC motor operation.
The Explain card
- Plain English
- A VFD takes fixed frequency power from the wall and makes new power at whatever frequency and voltage the motor should see. Change the frequency and an AC motor changes speed.
- Example
- A 60 hertz fan motor runs flat out across the line. Behind a drive it runs at 30 hertz for half speed and draws roughly an eighth of the power, because fan power falls with the cube of speed.
- Why it matters
- Drives are the single biggest energy saving in most plants and the single biggest source of electrical noise. They also soft start motors, protect them, and report on them, so a modern motor circuit almost always has one.
- Hook
- Rectify it, store it, chop it back out at the speed you want.
Where it sits in the deck
Phase 8: VFD Drive Hardware and Power Path
Inside the drive: rectifier, DC bus and inverter, the three stages every variable frequency drive uses to rebuild the waveform a motor sees.
