Variable-frequency drives (VFDs) can have two control modes – V/F control and vector control.

Our variable-frequency drives include multiple monitoring modes. The most well-known of all is V/F control, which is also called scalar control.

This control mode is originally set on our inverters (factory settings).

It enables to:

• better manage the engine start
• adjust the motor rotation speed (between 30% to 100% of rated speed)

But it does not enable to:

• control the torque

The vector control of an induction motor can be done via two different ways:

1. Vector control with open-loop enables to:

• better manage the induction motor’s engine start (voltage peak less high)
• have a more important torque with low speed (up to 10% rated speed) but does not allow to set the torque
• better handle speed variations.

2. Vector control in closed-loop enables to:

• set the speed on the operating range motor
• set the torque

Control in closed-loop is done via an incremental encoder.