Danfoss VLT FC 102 Programming Manual page 216

Programming Guide | VLT® HVAC Drive FC 102
Drive 1
Setpoint
Calculation
Drive 2
Setpoint
External Setpoint
Calculation
Drive 3
Setpoint
Calculation
Figure 59: Concept of 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 drive 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 drive reduces its output to this motor by 50% of the 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.
Use speed trim if the application requires the following features:
Accurate speed (the actual shaft speed matches the reference speed).
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Precise speed adjustment down to 0 RPM.
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Enabling PID droop
To enable speed PID droop:
Run the drive in 1 of the following modes:
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Flux closed loop (parameter 1-01 Motor Control Principle, [3] Flux w/ motor feedb).
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Flux sensorless (parameter 1-01 Motor Control Principle, [2] Flux sensorless).
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Run the drive in speed mode (parameter 1-00 Configuration Mode, option [0] Speed open loop or [1] Speed closed loop).
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Ensure that parameter 1-62 Slip Compensation contains the default value (0%).
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Ensure that all drives in the torque sharing system use the same speed reference and start and stop signal.
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Ensure that all drives in the torque sharing system use the same parameter settings.
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Adjust the value in parameter 7-01 Speed PID Droop.
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216 | © 2024.10
Speed
Ramp -
PID
Droop
Speed
-
Ramp
PID
Droop
Speed
Ramp -
PID
Droop
Parameter Descriptions
Torque
M1
PID
Torque
M2
PID
Torque
M3
PID
AU430028034214en-001901 / 130R0310