Danfoss VLT Decentral Drive FCD 302 Design Manual

Also see for vlt fcd 302: Installation guide Operating guide Operating instructions Programming guide Operating guide

Contents

Danfoss VLT Decentral Drive FCD 302 Design Manual Manual pdf 12 page image

2 Product Overview130BC963.10Illustration 2.1 Small UnitIllustration 2.2 Large Unit2.1 ControlA frequency converter rectifies AC voltage from mains intoDC voltage. This DC voltage is converted into an ACcurrent with a variable amplitude and frequency.The motor is supplied with variable voltage, current andfrequency, which enables infinitely variable speed controlof three-phased, standard AC motors and permanentmagnet synchronous motors.The FCD 302 frequency converter is designed for instal-lations of multiple smaller drives, especially on conveyorapplications, for example, in the food and beverageindustries and materials handling. In installations wheremultiple motors are spread around a facility such asbottling plants, food preparation and packaging plants andairport baggage handling installations, there may bedozens, perhaps hundreds, of drives, working together butspread over a large physical area. In these cases cablingcosts alone outweigh the cost of the individual drives andit makes sense to get the control closer to the motors.The frequency converter can control either the speed orthe torque on the motor shaft.Speed controlThere are two types of speed control:• Speed open loop control which does not requireany feedback from motor (sensorless).• Speed closed loop PID control, which requires aspeed feedback to an input. A properly optimisedspeed closed loop control is more accurate thana speed open loop control.Torque controlThe torque control function is used in applications wherethe torque on motor output shaft is controlling theapplication as tension control.• Closed loop in Flux mode with encoder feedbackcomprises motor control based on feedbacksignals from the system. It improves performancein all four quadrants and at all motor speeds.• Open loop in VVCplus mode. The function is usedin mechanical robust applications, but theaccuracy is limited. Open loop torque functionworks only in one speed direction. The torque iscalculated on basic of current measurementinternal in the frequency converter. Seeapplication example 4.5.1 Control Structure inVVCplus Advanced Vector Control.Speed/torque referenceThe reference to these controls can either be a singlereference or be the sum of various references includingrelatively scaled references. The handling of references isexplained in detail in 2.3 Reference Handling.2.1.1 Control PrincipleThe frequency converter is compatible with various motorcontrol principles such as U/f special motor mode, VVCplusor Flux Vector motor control.In addition, the frequency converter is operable withPermanent Magnet Synchronous Motors (Brushless servomotors) as well as normal squirrel cage asynchronousmotors.Product Overview VLT® Decentral Drive FCD 302MG04H102 - VLT® is a registered Danfoss trademark 112 2