Danfoss FC 300 Design Manual

Also see for FC 300: Operating instructions Instruction manual Design guide Design guide Design guide

Contents

Danfoss FC 300 Design Manual Manual pdf 21 page image

3.2.1. Control PrincipleAn adjustable frequency drive rectifies AC voltage from line into DC voltage, after which this DCvoltage 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 synchronousmotors.3.2.2. FC 300 ControlsThe adjustable frequency drive is capable of controlling either the speed or the torque on themotor shaft. Setting par. 1-00 determines the type of control.Speed control:There are two types of speed control:• 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 aninput. Properly optimized speed closed-loop control will have higher accuracy than speedopen-loop 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 veryimportant. The accuracy and settling time of the torque control are determined usingFlux withmotor feedback (par. 1-01Motor Control Principle).• Flux with encoder feedback offers superior performance in all four quadrants and at allmotor speeds.Speed / torque reference:The reference to these controls can either be a single reference or the sum of various referencesincluding relatively scaled references. The handling of references is explained in detail later in thissection.FC 300 Design Guide 3. Introduction to FC 300MG.33.B9.22 - VLT® is a registered Danfoss trademark. 213