Industrial Engineer · phase 11 of 16
Scalar / V/Hz Control
Control method that commands motor voltage mainly as a function of output frequency without independently regulating flux and torque vectors.
The Explain card
- Plain English
- Scalar control is the simplest drive mode. The drive sets voltage as a fixed function of frequency, follows the volts per hertz curve, and does no modelling of the motor at all.
- Example
- A cooling tower fan runs on V/Hz control. The drive ramps frequency to the setpoint, sets the matching voltage, and the motor finds its own speed a little below synchronous.
- Why it matters
- It needs almost no motor data and works with several motors on one drive, which vector modes cannot do. Low speed torque is weak, speed drifts with load, and it responds slowly, so it belongs on loads that do not care.
- Hook
- The curve, and nothing else.
Where it sits in the deck
Phase 11: VFD Control Modes and Tuning
How a drive decides what to send the motor, from plain volts per hertz up to closed loop vector control, and how each mode is tuned.
