4-256
While tuning ASR P and I gain the system may overshoot and an over voltage condition can occur. A
braking unit (braking resistor) can be used to avoid an over voltage condition.
1
1
2
2
t
Motor
Speed
1
: 20-01 setting is too short(oscillation occurs)
2
: 20-01 setting is too long(slow response)
Figure 4.4.98 The response of ASR integral time
Both low-speed ASR gain and the high-speed gain can be set to the same values and only require to be
adjusted in case of system instability.
In case tuning of the ASR P and I gain 20-00~20-03 does not improve the system response, reduce the
low-pass filter time constant 20-13~20-14 to increase the bandwidth of the feedback system and re-tune
the ASR gain.
Tune low-speed low-pass filter time constant 20-14, make sure the reference frequency is below
parameter 20-15 value.
Tune high-speed low-pass filter time constant 20-13 at frequency reference, make sure the reference
frequency is above parameter 20-16 value.
Increasing the low-pass filter time constant can limit the bandwidth of the speed feedback system and
may reduce the system response. Increasing the low-pass time reduces the speed feedback signal
interference but may results in sluggish system response when the load suddenly changes. Adjust the
low-pass filter time if the load stays fairly constant during normal operation. The low bandwidth of the
speed feedback must be supported by the low gain of ASR to ensure the stable operation.
Decreasing the low-pass filter time constant may increase the bandwidth of the speed feedback and the
system response. Decreasing the low-pass time may increase the speed feedback interference
resulting in system instability when the load suddenly changes. Decrease the low-pass filter time is a
quick system response is required for rapidly changing loads. The high bandwidth of the speed
feedback allows for a relative high ASR gain.
In case tuning 20-00 ~ 20-03 and the low-pass filter time constant 20-13 do not improve the system
response time, tuning the PI gain 20-09 ~ 20-12 of the speed estimator may be required.
Setting a high gain for the speed estimator (high proportion (P) gain and small integral (I) time)
increases the bandwidth of the speed feedback, but may cause speed feedback interference resulting
in system instability.
Setting a low gain for the speed estimator (small proportion (P) gain and high integral (I) time)
decreases the bandwidth of the speed feedback, may improve speed feedback interference resulting in
a more stable system.
The default values for the ASR can be used in most applications, no adjustment is required. Adjusting
the low-pass filter time and speed estimator gains requires a good understanding of the overall system.
Parameter 20-15 sets the gain switch frequency at low-speed and parameter 20-16 sets the gain switch
frequency at high-speed.
Operating at a speed below 20-15 will result in a larger excitation current for low-speed operation
accuracy. When the frequency reference rises above 20-16, the inverter will output the rated excitation
current at the no-load voltage (02-19).
For general purpose applications parameter 20-15 should be set to a value of 5 ~ 50% of the motor
base frequency.
If this value is too high, the inverter output may saturate. Parameter 20-16 should be set to a value of
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