Control Principle; Fc 300 Controls - Danfoss FC 300 Design Manual

FC 300 Design Guide

3.2.1. Control Principle

An adjustable frequency drive rectifies AC voltage from line into DC voltage, after which this DC
voltage is converted into an AC current with a variable amplitude and frequency.
The motor is supplied with variable voltage / current and frequency, which enables infinitely var-
iable speed control of three-phased, standard AC motors and permanent magnet synchronous
motors.

3.2.2. FC 300 Controls

The adjustable frequency drive is capable of controlling either the speed or the torque on the
motor shaft. Setting par. 1-00 determines the type of control.
Speed control:
There are two types of speed control:
•
•
Selects which input to use as speed PID feedback in par. 7-00.
Torque control (FC 302 only):
Torque control is part of the motor control and correct settings of motor parameters are very
important. The accuracy and settling time of the torque control are determined using
motor feedback
•
Speed / torque reference:
The reference to these controls can either be a single reference or the sum of various references
including relatively scaled references. The handling of references is explained in detail later in this
section.
Speed open-loop control which does not require any feedback (sensorless).
Speed closed-loop control in the form of PID control that requires speed feedback to an
input. Properly optimized speed closed-loop control will have higher accuracy than speed
open-loop control.
Motor Control Principle
(par. 1-01
Flux with encoder feedback offers superior performance in all four quadrants and at all
motor speeds.
MG.33.B9.22 - VLT ® is a registered Danfoss trademark.
3. Introduction to FC 300
).
3
Flux with
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