Industrial Engineer · phase 11 of 16 · noun
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.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
During conveyor commissioning, the technician selected Scalar control on the VFD and entered the motor nameplate frequency and voltage.
How it is built
- scal- root ladder or flight of steps
- -ar suffix relating to
Where it came from
- Origin
- Latin scalaris, meaning relating to a ladder, from scala, meaning ladder or staircase
- Entered the language
- 1650s
- What changed
- It began as a stair-related adjective, became a mathematical noun for a quantity with magnitude, and later became an engineering label used in motor-control terminology.
How it is spelled
- Pattern
- It keeps the Latin-derived ending -ar found in relational words.
Spelled like
- linear
- angular
- circular
Broken into chunks
-
scal
- scale
- scalable
- scaling
-
ar
- linear
- angular
- circular
What it sits beside
Same subject
- variable frequency drive
- induction motor
- vector control
- motor nameplate
Same shape
- linear
- angular
- circular
VFD control modes
- Scalar control
- sensorless vector control
- closed-loop vector control
Scalar control names
- V/Hz control
- V/f control
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.
