Control Structures; Control Principle - Danfoss VLT AQUA Drive FC 202 Design Manual

Introduction

2.9 Control Structures

2.9.1 Control Principle

2 2
A frequency converter rectifies AC voltage from mains into DC voltage, after which this DC voltage is converted into AC
power 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-phase
power
input
DC bus
Illustration 2.7 Control Principle
The control terminals provide for wiring feedback, reference, and other input signals to the following:
•
frequency converter
•
output of frequency converter status and fault conditions
•
relays to operate auxiliary equipment
•
serial communication interface
Control terminals are programmable for various functions by selecting parameter options described in the main or quick
menus. Most control wiring is customer supplied unless factory ordered. A 24 V DC power supply is also provided for use
with the frequency converter control inputs and outputs.
Table 2.7 describes the functions of the control terminals. Many of these terminals have multiple functions determined by
parameter settings. Some options provide more terminals. See chapter 5.1 Mechanical Installation for terminal locations.
18
Design Guide
91 (R/L1)
92 (S/L2)
93 (T/L3)
95
PE
88 (-)
89 (+)
Danfoss A/S © Rev. 06/2014 All rights reserved.
(U/T1) 96
(V/T2) 97
(W/T3) 98
(PE) 99
Motor
(R+) 82 Brake
resistor
(R-) 81
MG20Z202