4-194
operation.
. Decreasing the low-pass filter time constant can increase the bandwidth of speed
feedback and the response capacity of the whole system. Thus it can easily
receive the interference signal of the speed feedback, but high capacity for the
momentary load impact will be caused. If the load changes rapidly and quick
response is required, it can be tuned by this way. The high bandwidth of the speed
feedback allows relative high ASR gain.
. If tuning 20-00 ~ 20-03 and low-pass filter time constant 20-13 can not obtain rapid
response, tuning the PI gain 20-09 ~ 20-12 of the speed estimate device will be
required.
. The high gain of speed estimate (relative great proportion (P) gain and relative
small integral (I) time) can accelerate the bandwidth of speed feedback, but it is
also easily interfered, leading to the instability of the system.
. The low gain of speed estimate (relative small proportion (P) gain and relative
great integral (I) time) can decelerate the bandwidth of speed feedback, but it
avoids the interference, leading to the stability of the system.
. In general, the set value of ASR has met most of the applications. Adjusting the
low pass filter time constant and the speed estimate are complex and risky in
practice. Therefore, it is not recommend that users adjust them frequently. If
getting a high-speed response and stable operation in SLV mode, SV mode can
be used.
. 20-15 defines the gain switch frequency of low-speed, while 20-16 defines the gain
switch frequency of high-speed.
. When the speed is lower than 20-15, the inverter will output a larger excitation
current to make low-speed operation more accurate. When the frequency
reference is greater than 20-16, the inverter will output the rated excitation current
under the no-load voltage (02-19).
. In general, 20-15 should be set at 5 ~ 50% of the motor basic frequency. If this set
value is too high, the inverter output may be saturated. 20-16 should be set to 4Hz
and higher than 20-08.
. For the operation with heavy load (greater than 100%), if it is stable at middle
speed but jitter at high speed, reduce the no-load voltage (02-19) or tune the FOC
parameters (18-05 ~ 18-06).
. 20-17 and 20-18 compensate speed feedback at low speed and high speed
respectively.
. Set 20-17 to adjust the no-load speed when it is lower than 2Hz. Tuning 20-17 is
similar to add an offset to torque-speed curve. When the no-load speed is lower
than the frequency reference, you can increase 20-17. When the no-load speed
is higher the frequency reference, you can decrease 20-17. The impact on the
torque-speed curve from 20-17 is shown as the following figure:
Decrease 20-17 Increase 20-17
Torque
Speed
Figure 4.3.115 The impact on the torque-speed curve from 20-17
. Set 20-18 to adjuset the no-load speed of the middle and high speed range. In
general, it is no need to tune. 20-18 is similar to 20-17, the torque-speed curve is
shown as below:
To Next Page
Loading...
