V/f

V/f control is for simple controlled operation of asynchronous motors without encoder feedback and motors with LSPM technologyGuided startup in preparation. provided by SEW-EURODRIVE. The procedure operates an asynchronous machine on a parameterizable voltage/frequency characteristic. To keep the magnetizing current on a constant level, the voltage (V) is adjusted in proportion to the frequency (f).

The actual slip is estimated and can be compensated.

V/f control is suitable for applications with a limited speed setting range, where no dynamic step changes in load occur and where there are small requirements regarding the control characteristics.

V/f control is suitable for group drives. A group drive is an electrical parallel connection of several identical or different motors at one inverter. The motors do not have a rigid mechanical connection.

The V/f mode is an encoder-less mode and calculates the actual speed value. The calculation is always based on the electrical values of the motor; information from a potentially existing encoder system is not used.

If an encoder is parameterized in the encoder assignment as "Actual speed source", the speed measured by this encoder is issued as the actual speed by the inverter. Otherwise, the model speed calculated by the V/f mode based on stator frequency and slip is issued as the actual speed.

The V/f mode does not have a higher-level speed controller; speed controller parameterization is not possible. An acceleration and torque precontrol is not possible either.