5motor control & motor settings – Lenze i700 User Manual
Page 133
Lenze · i700 servo inverter · Reference manual · DMS 1.5 EN · 03/2014 · TD05
133
5
Motor control & motor settings
5.13
Parameterising filter elements in the setpoint path
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[5-8]
Use of the notch filter depending on the resonant frequency
• The notch filters are suitable for use with resonant frequencies equal to or higher than the limit
frequency of the speed controller.
• Resonant frequencies ≥ f
limit_speed_controller
= 70 Hz ... 110 Hz
• For resonant frequencies that are lower than the limit frequency of the speed controller, the use
of suitable speed profiles with an S-shaped ramp is recommended.
Setting the notch filters
Since the exact frequency response of the speed control path in most cases is not known
beforehand, an experimental procedure for setting the notch filters is described in the following.
How to set the notch filters:
1.
Setting and optimising the current controller
.
2. Adapt the speed controller reset time to the filter time constant of the speed filter and the
equivalent time constant of the current control loop:
• The following applies to axis A:
+ 500 μs)
• The following applies to axis B:
= 16 * (
+ 500 μs)
Note: The setting of the reset time includes the equivalent time constant of the current
control loop. The 500 μs indicated are typical in a power range of up to 50 kW. Above this
value, greater time constants may occur.
3. Slowly increase the proportional gain of the speed controller in
for
axis B) until the speed control loop starts to be unstable (acoustic determination or
measurement of the motor current).
4. Measure the oscillation frequency using an oscilloscope (observe current or speed).
5. Set the oscillation frequency determined as filter frequency in
axis B).
6. Set the filter width to 50 % of the filter frequency in
(or
for axis B).
• Example: filter frequency = 200 Hz filter width = 100 Hz.
7. Set the filter depth to 40 dB in
for axis B).
• If "0 dB" are set (default setting), the filter is not effective.
8. Further increase proportional gain of the speed controller in
for B)
until the speed control loop starts to be unstable again.
• If the oscillation frequency has changed now, readjust the filter frequency by trimming.
The use of a second filter is ineffective here.
• If the oscillation frequency remains the same, readjust the filter depth and/or the filter
width by trimming (the first reduces the amplitude, the second lets the phase rotate
faster).
• Repeat step 8 until the desired behaviour or the limit of a sensible speed controller gain
has been reached.
Usual and intended use of the notch filter
Use of the notch filter is only partially suitable
The notch filter should not be used
f
limit_speed_controller
1
2
f
2
f
limit_speed_controller
1
0