5.4 Details of Function Codes
5-236
P gain
Definition of P gain = 1.0 is that the torque command is 100% (torque output of 100% of each inverter
capacity) when the speed deviation (speed command - actual speed) is 100% (equivalent to the maximum
speed set value).
Adjust the P gain according to inertia moment of the system connected to the motor shaft. Larger inertia
moment needs larger P gain to keep the flat response in whole operations.
Specifying a larger P gain improves the quickness of control response, but may cause a motor speed
overshooting or hunting. Moreover, mechanical resonance or vibration sound on the machine or motor could
occur due to excessively amplified noises. If it happens, decreasing P gain will reduce the amplitude of the
resonance/vibration. A too small P gain results in a slow inverter response and a speed fluctuation in low
frequency, which may prolong the time required for stabilizing the motor speed.
Integral time
Specifying a shorter integral time shortens the time needed to compensate the speed deviation, resulting in
quick response. Set a short integral time if quick arrival to the target speed is necessary and a slight
overshooting in the control is allowed; specify a long time if any overshooting is not allowed and taking
longer time is allowed.
If a mechanical resonance occurs and the motor or gears sound abnormally, setting a longer integral time
can transfer the resonance point to the low frequency zone and suppress the resonance in the high
frequency zone.
Output Filter (d06)
d06 sets the time constant for the primary delay of the speed controller output filter.
- Data setting range: 0.000 to 0.100 (s)
Use d06 when even adjusting the P gain or integral time cannot suppress mechanical resonance such as
hunting or vibration. Generally, setting a larger value to the time constant of the output filter decreases the
amplitude of resonance; however, a too large time constant may make the system unstable.
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