YASKAWA GA700 Series Technical Manual page 671

• PID Feedback Loss [FbL]
Set these parameters for the PID feedback loss detection function.
The drive detects feedback loss when the feedback value is less than the value in b5-13 for longer than the time
in b5-14.
– b5-12 [Feedback Loss Detection Select]
– b5-13 [PID Feedback Loss Detection Lvl]
– b5-14 [PID Feedback Loss Detection Time]
• Excessive PID Feedback [FbH]
Set these parameters to set how the drive detects a feedback level that is too high.
The drive detects too much PID feedback when the feedback value is more than the value in b5-36 for longer
than the time in b5-37.
– b5-12 [Feedback Loss Detection Select]
– b5-36 [PID High Feedback Detection Lvl]
– b5-37 [PID High Feedback Detection Time]
Figure 12.37 shows the operation principle when the feedback value is too low, and the drive detects feedback
loss. The operation is the same when the drive detects too much feedback.
■
PID Sleep
PID sleep stops drive operation when the PID output or the frequency reference is less than b5-15 [PID Sleep
Function Start Level]. This function shuts off drive output after the motor decelerates to the set frequency.
The drive will automatically restart the motor when the PID output or the frequency reference is more than the b5-
15 value for the time set in b5-16 [PID Sleep Delay Time].
Figure 12.38 shows the PID Sleep function.
Note:
• The PID Sleep function is enabled when PID control is disabled.
• When the PID Sleep function is triggered, the drive will stop the motor as specified by b1-03 [Stopping Method Selection].
■
Fine-Tuning PID
Fine-tune the following parameter settings to have PID control eliminate problems with overshoot and oscillation.
• b5-02 [Proportional Gain (P)]
• b5-03 [Integral Time (I)]
• b5-05 [Derivative Time (D)]
• b5-08 [PID Primary Delay Time Constant]
YASKAWA SIEPC71061705H GA700 Series Technical Manual
Figure 12.37 Time Chart for PID Feedback Loss Detection Time
Figure 12.38 PID Sleep Time Chart
12.3 b: Application
12
671