Yaskawa iQpump Drive User Manual - Manual (Page 152)

6.7 Troubleshooting
152 YASKAWA TM.iQp.01 iQpump Drive User Manual
◆ If There is Mechanical Vibration
Use the following information when there is mechanical vibration.
■ The application is making unusual sounds.
The following causes are possible.
There may be resonance between the mechanical system's natural frequency and the carrier frequency.
This is characterized by the motor running with no noise generation, but the machinery vibrates with a high-pitched whine. To prevent
this type of resonance, adjust the carrier frequency with parameters C6-02 to C6-05.
There may be resonance between an applications characteristic frequency and the output frequency of the iQpump drive.
To prevent this from occurring, use the jump frequency functions in parameters d3-01 to d3-04, or have the driven motor and load
balanced to reduce vibration.
■
Oscillation and hunting are occurring with V/f control.
The gain adjustment may be insufficient. Reset the gain to a more effective level by raising the value of C4-02 (Torque Compensation
Primary Delay Time Parameter) and then lowering the setting of n1-02 (Hunting Prevention Gain).
■
Oscillation and hunting are occurring with PI control.
If there is oscillation or hunting during PI control, check the oscillation cycle and individually adjust P and I parameters.
• Disable integral (I) control
• Reduce the proportional gain (P) until hunting stops
• Reintroduce the integral function, starting with long integral time values, to eliminate the P offset
◆ If the Motor Rotates Even When iQpump Drive Output is Stopped
If the motor rotates even when the iQpump drive is stopped, the DC injection braking may be insufficient. If the motor continues
operating at low speed, without completely stopping after a stop has been executed, it means that the DC injection braking is not
decelerating the motor enough. Adjust the DC injection braking as follows:
• Increase the parameter b2-04 (DC Injection Braking (initial excitation) Time at Stop) setting.
• Increase the parameter b2-02 (DC Injection Braking Current) setting.
◆ If Zero Volts is Detected When a Motor is Started, or Stalls
Generation of 0 V (main circuit voltage) and stalling can occur if a motor is turning when it is started and the DC injection braking is
insufficient.
This can be prevented by slowing motor rotation by DC injection braking before starting. Increase parameter b2-03 (DC injection braking
time at start) setting.
◆ If the Accepted Speed Command Does Not Rise to the User Speed Command
Input
■
The Speed Command is within the jump frequency range.
When the jump frequency function is used, the output frequency cannot be set within the jump frequency range. Check to be sure that the
Jump Frequency (parameters d3-01 to d3-03) and Jump Frequency Width (parameter d3-04) settings are
suitable.
■
The frequency reference upper limit has been reached.
The output frequency upper limit is determined by the following formula:
• Freq Ref Upper Limit = Maximum Output Frequency (E1-04) × Frequency Reference Upper Limit (d2-01) / 100
• Check to be sure that the parameter E1-04 and d2-01 settings are suitable.