Control Principle - Danfoss VLT AutomationDrive FC 300 Design Manual

Product Introduction
Speed/Torque Reference
The reference to these controls can either be a single reference or be the sum of various references including relatively
scaled references. For more information on reference handling, see 3.3 Reference Handling.

3.2.1 Control Principle

3 3
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 3.1 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 3.3 describes the functions of the control terminals. Many of
these terminals have multiple functions determined by parameter settings. Some options provide more terminals. See
6.2 Mechanical Installation for terminal locations.
Table 3.3 describes the functions of the control terminals. Many of these terminals have multiple functions determined by
parameter settings. Some options provide more terminals. See 6.2 Mechanical Installation for terminal locations.
20
®
VLT AutomationDrive FC 300 Design Guide 90-1200 kW
91 (R/L1)
92 (S/L2)
93 (T/L3)
95
PE
88 (-)
89 (+)
MG34S202 - Rev. 2013-08-19
(U/T1) 96
(V/T2) 97
(W/T3) 98
(PE) 99
Motor
(R+) 82 Brake
resistor
(R-) 81