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 17 page image

Control PrincipleA frequency converter rectifies AC voltage from mains into DC voltage, after which this DC voltage isconverted into a AC current with a variable amplitude and frequency.The motor is supplied with variable voltage / current and frequency, which enables infinitely variablespeed control of three-phased, standard AC motors and permanent magnet synchronous motors.FC 300 ControlsThe frequency converter is capable of controlling either the speed or the torque on the motor shaft. Set-ting par. 1-00 determines the type of control.Speed control:There are two types of speed control:ï Speed open loop control which does not require any feedback (sensorless).ï Speed closed loop control in the form of a PID control that requires a speed feedback to an input.A properly optimised speed closed loop control will have higher accuracy than a speed open loopcontrol.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 from Flux with motor feedback (par.1-01 Motor Control Principle).ï Flux with encoder feedback offers superior performance in all four quadrants and at all motorspeeds.Speed / torque reference:The reference to these controls can either be a single refrence or be the sum of various references in-cluding relatively scaled references. The handling of references is explained in detail later in this section.FC 301 vs. FC 302 Control PrincipleFC 301 is a general purpose frequency converter for variable speed applications. The control principle isbased on Voltage Vector Control (VVC plus ).FC 301 can handle asynchronous motors only.The current sensing principle in FC 301 is based on current measurement in the DC link or motor phase.The ground fault protection on the motor side is solved by a de-saturation circuit in the IGBTs connectedto the control board.Short circuit behaviour on FC 301 depends on the current transducer in the positive DC link and thedesaturation protection with feedback from the 3 lower IGBT's and the brake.FC 300 Design GuideIntroduction to FC 300MG.33.B7.02 - VLT is a registered Danfoss trademark 17