Danfoss VLT HVAC Drive FC 102 Design Manual page 209

Basic Operating Principles ...
11.2.7.1 Control Structure in VVC
P 1-00
Con g. mode
Ref.
+
Process

_
P 7-20 Process feedback
1 source
P 7-22 Process feedback
2 source
Illustration 11.8 Control Structure in VVC
In Illustration 11.8, the resulting reference from the reference handling system is received and fed through the ramp
limitation and speed limitation before being sent to the motor control. The output of the motor control is then limited by
the maximum frequency limit.
Parameter 1-01 Motor Control Principle is set to [1] VVC
If parameter 1-00 Configuration Mode is set to [1] Speed closed loop, the resulting reference is passed from the ramp
limitation and speed limitation into a speed PID control. The speed PID control parameters are located in parameter group
7-0* Speed PID Ctrl. The resulting reference from the speed PID control is sent to the motor control limited by the frequency
limit.
Select [3] Process in parameter 1-00 Configuration Mode to use the process PID control for closed-loop control of, for example,
speed or pressure in the controlled application. The process PID parameters are in parameter groups 7-2* Process Ctrl. Feedb
and 7-3* Process PID Ctrl.
11.2.7.2 Internal Current Control in VVC
When the motor torque exceeds the torque limits set in parameter 4-16 Torque Limit Motor Mode, parameter 4-17 Torque Limit
Generator Mode, and parameter 4-18 Current Limit, the integral current limit control is activated.
When the drive is at the current limit during motor operation or regenerative operation, it tries to get below the preset
torque limits as quickly as possible without losing control of the motor.
MG16C302
Design Guide
+
P 4-13
Motor speed
high limit (RPM)
P 1-00
P 4-14
Con g. mode
Motor speed
high limit (Hz)
P 3-**
High
Ramp
Low
P 4-11
Motor speed
low limit (RPM)
P 4-12
Motor speed
low limit (Hz)
+ Open Loop and Closed-loop Configurations
+ and parameter 1-00 Configuration Mode is set to [0] Speed open loop.
+
Mode
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P 4-19
Max. output freq.
+f max.
Motor
controller
-f max.
P 7-0*
Speed Motor
+

PID controller
_
P 7-00 Speed PID
feedback source
P 4-19
Max. output freq.
+f max.
-f max.
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