Avoid EMC noise on serial communication
This terminal is connected to ground via an internal RC
link. Use twisted-pair cables to reduce interference
between conductors. The recommended method is shown
in
.
PE
FC
PE
FC
130BB923.12
PE
PE
69
68
61
69
68
61
1
2
<10 mm
1
Minimum 16 mm
2
(6 AWG)
2
Equalising cable
Illustration 2.10 Twisted-pair Cables
Alternatively, the connection to terminal 61 can be
omitted.
PE
FC
PE
FC
130BB924.12
PE
PE
69
69
68
68
1
2
<10 mm
1
Minimum 16 mm
2
(6 AWG)
2
Equalising cable
Illustration 2.11 Twisted-pair Cables without Terminal 61
2.3 Control Structures
2.3.1 Control Principle
A frequency converter rectifies AC voltage from mains into
DC voltage, after which this DC voltage is converted into
an AC current with a variable amplitude and frequency.
The motor is supplied with variable voltage/current and
frequency, enabling infinitely variable speed control of 3-
phased, standard AC motors and permanent magnet
synchronous motors.
2.3.2 Control Modes
The frequency converter is capable of controlling either
the speed or the torque on the motor shaft. Setting
1-00 Configuration Mode
determines the type of control.
Speed control
There are 2 types of speed control:
•
Speed open loop control, which does not require
any feedback from the motor (sensorless).
•
Speed closed loop PID control, which requires a
speed feedback to an input. A properly optimised
speed closed loop control has higher accuracy
than a speed open loop control.
Select which input to use as speed PID feedback in
7-00 Speed PID Feedback Source
.
Torque control
The torque control function is used in applications where
the torque on motor output shaft is controlling the
application as tension control. Torque control can be
selected in
1-00 Configuration Mode
. Torque setting is done
by setting an analog, digital, or bus controlled reference.
When running torque control, it is recommended to run a
full AMA procedure, because correct motor data is
important in achieving optimal performance.
•
Closed loop in VVC
+
mode. This function is used
in applications with low to medium dynamic
variation of shaft, and offers excellent
performance in all 4 quadrants and at all motor
speeds. The speed feedback signal is mandatory.
It is recommended to use MCB102 option card.
Ensure the encoder resolution is at least 1024
PPR, and the shield cable of the encoder is well
grounded, because the accuracy of the speed
feedback signal is important. Tune
7-06 Speed PID
Lowpass Filter Time
to get the best speed
feedback signal.
•
Open loop in VVC
+
mode. The function is used in
mechanically robust applications, but the
accuracy is limited. Open loop torque function
works for 2 directions. The torque is calculated on
the basis of the internal current measurement in
the frequency converter.
Speed/torque reference
The reference to these controls can be either a single
reference or the sum of various references including
relatively scaled references. Reference handling is
explained in detail in
chapter 2.4 Reference Handling
Product Overview
Design Guide
18
Danfoss A/S © 09/2014 All rights reserved.
MG06B402
2
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