5-133
5.2.8 d codes (Application Functions 2)
d01 to d04
d06
Speed Control 1 (Speed command filter, Speed detection filter, P (Gain) and I (Integral time))
Speed Control 1 (Output filter)
These function codes control the speed control sequence for normal operations. For application of each function code,
refer to the figure below and the subsequent descriptions.
Block diagram of the speed control sequence
Speed command filter (d01) Data setting range: 0.000 to 5.000 (s)
d01 specifies a time constant determining the first order delay of the speed command filter.
Modify this data when an excessive overshoot occurs against the speed command change.
Increasing the filter time constant stabilizes the speed command and reduces overshoot against the speed command
change, but it slows the response speed of the inverter.
Speed detection filter (d02) Data setting range: 0.000 to 0.100 (s)
Modify this data when the control target (machinery) is oscillatory due to deflection of a drive belt or other causes so
that ripples (oscillatory components) are superimposed on the detected speed, causing hunting (undesirable oscillation
of the system) and blocking the PI processor gain from increasing (resulting in a slow response speed of the inverter). In
addition, if the lower encoder (PG) resolution makes the system oscillatory, try to modify this data.
Increasing the time constant stabilizes the detected speed and raises the PI processor gain even with ripples
superimposed on the detected speed. However, the detected speed itself delays, resulting in a slower speed response,
larger overshoot, or hunting.
P gain (d03) Data setting range: 0.1 to 200.0 (times)
I integral time (d04)
Data setting range: 0.001 to 9.999 (s)
d03 and d04 specify the gain and integral time of the speed regulator (PI processor), respectively.
P gain
Definition of "P gain = 1.0" is that the torque command is 100% (100% torque output of each inverter capacity) when
the speed deviation (reference speed – actual speed) is 100% (equivalent to the maximum speed).
Determine the P gain according to moment of inertia of machinery loaded to the motor output shaft. Larger moment of
inertia 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 (undesirable oscillation of the system). 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 in speed. Specify 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) Data setting range: 0.000 to 0.100 (s)
d06 specifies the time constant for the first order delay of the speed controller output filter.
Use this function code when setting of the P gain and/or integral time cannot control mechanical resonance such as
hunting or vibration. Generally, setting a larger value to this time constant decreases the amplitude of resonance;
however, a too long time constant may make the system unstable.
To Next Page
Loading...
