A frequency converter rectifies AC voltage from mains into DC voltage, after which this DC voltage is converted into a AC current with a variable amplitude

and frequency.

The motor is supplied with variable voltage / current and frequency, which enables infinitely variable speed control of three-phased, standard AC motors

and permanent magnet synchronous motors.

3.2.2 AutomationDrive FC 300 Controls

The frequency converter is capable of controlling either the speed or the torque on the motor shaft. Setting par. 1-00

the type of control.

Speed control:

There are two types of speed control:

•

Speed open loop control which does not require any feedback from motor (sensorless).

•

Speed closed loop PID control requires a speed feedback to an input. A properly optimised speed closed loop control will have higher accuracy

than a speed open loop control.

Selects which input to use as speed PID feedback in par. 7-00

Torque control (AutomationDrive FC 302 only):

The torque control function is used in applications where the torque on motor output shaft is controlling the application as tension control. Torque control

can be selected in par 1-00, either in VVC+ open loop [4] or Flux control closed loop with motor speed feedback [2]. Torque setting is done by setting

an analog, digital or bus controlled reference. The max speed limit factor is set in par 4-21. When running torque control it is recommended to make a

full AMA procedure as the correct motor data are of high importance for optimal performance.

•

Closed loop in Flux mode with encoder feedback offers superior performance in all four quadrants and at all motor speeds.

•

Open loop in VVC+ mode. The function is used in mechanical robust applications, but the accuracy is limited. Open loop torque function works

basically only in one speed direction. The torque is calculated on basic of current measurement internal in the frequency converter. See Appli-

cation Example Torque open Loop

Speed / torque reference:

The reference to these controls can either be a single refrence or be the sum of various references including relatively scaled references. The handling

of references is explained in detail later in this section.

Speed PID Feedback Source

MG.33.BC.02 - VLT

is a registered Danfoss trademark

3 Introduction to AutomationDrive FC 300

Configuration Mode

determines

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