Speed Pid Droop - Danfoss VLT AutomationDrive FC 302 Programming Manual

Parameter Descriptions
7-00 Speed PID Feedback Source
Option:
[9] Frequency
input 33
[11] MCB 15X
3 3
[12] MCB 102
Absolute
[13] 24V encoder
27/29
External Set-point
Illustration 3.47 Speed PID Droop
The value in parameter 7-01 Speed PID Droop ensures that
the load is shared equally between the motors. If the
torque on the motor is 100% of nominal motor torque, the
frequency converter reduces its output to this motor by
100% of the value in parameter 7-01 Speed PID Droop. If the
torque is 50% of nominal motor torque, the frequency
converter reduces its output to this motor by 50% of the
144
®
VLT
Function:
The option is only available for MCB 102
Encoder module option with version 4.00 and
newer and when parameter 17-00 Encoders
Connected is set to [1] Two Encoders.
Single signal generated from 24V High
Threshold Logic (HTL) encoder connected to
terminals 27 and 29. Configure the 24V
encoder interface in parameter group 5.7* 24V
Encoder Input.
Program terminals 27/29 to [0] No operation.
VLT 1
Set-point
Calculation
VLT 2
Set-point
Calculation
VLT 3
Set-point
Calculation
Danfoss A/S © 10/2018 All rights reserved.
AutomationDrive FC 301/302
7-00 Speed PID Feedback Source
Option:

3.8.2 Speed PID Droop

This feature implements precise torque sharing between
multiple motors on a common mechanical shaft.
Speed PID droop is useful for marine and mining
applications, where redundancy and higher dynamics are
required. Speed PID droop allows to reduce inertia by
utilizing multiple small motors instead of 1 big motor.
Illustration 3.47 shows the concept of the feature:
Speed
Ramp -
PID
Droop
Speed
-
Ramp
PID
Droop
Speed
-
Ramp
PID
Droop
value in parameter 7-01 Speed PID Droop. This ensures that
the motors share the load evenly.
A side effect of using speed PID droop is that the actual
shaft speed does not match the reference exactly. Speed
PID droop is not efficient in low-speed applications
because the adjustment range may be insufficient.
Function:
The option is named as 24V encoder in
software version 8.XX.
Torque
PID
Torque
PID
Torque
PID
M1
M2
M3
MG33MP02