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AC IM Scalar Drives

In scalar drives normally only the frequency and the magnitude of the voltage fed to the motor are controlled (current feedback not mandatory).
For 3Φ Induction Motors in particular, scalar drives typically control the voltage-to-frequency (V/F) ratio in open or closed speed loop (motor speed feedback mandatory only in the latter case). If motor speed information is known, slip regulation can be additionally implemented resulting in an optimized motor efficiency.
In spite of its simplicity (it can be executed by both 8 and 32 bit microcontrollers), V/f control is more than sufficient for most applications.

Design Support


Technical Documentation

Application Notes

Description Version Size
AN1904: ST7MC three-phase AC induction motor control software library
3.3 1,146 KB
AN4363: How to select the right Triac
1.2 337 KB

Design Notes & Tips

Description Version Size
DN0005: A three phase induction motor drive using a V/F control
2.0 528 KB
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