Siemens SINUMERIK 840Di sl Commissioning Manual page 516

Drive Optimization with HMI Advanced
14.4 Frequency response measurements
Measurement: Reference and interference frequency response
The response range should be as wide as possible and without resonance. It may be
necessary to use bandstop or low-pass filters. Pay special attention to resonances within the
speed controller limit frequency range (stability limit approx. 200-500 Hz).
Alternatively, the interference frequency response can be recorded in order to assess how
well the control suppresses interference.
Measuring parameters
● Amplitude
● Bandwidth
● Averaging
● Settling time
● Offset
516
This parameter determines the magnitude of the test signal amplitude. This should give
rise to only a very low speed of a few (approximately 1 to 2) rev/min at the motor end.
The bandwidth parameter is used to set the analyzed frequency range. The larger this
value, the finer the frequency resolution and the longer the measurement time. The
maximum value is specified by the position controller cycle (T
[Hz] = 1 / (2 * T
position controller
Example:
Position controller cycle: 2 ms
Bandwidth = 1 / (2 * 2*10
max
The accuracy of the measurement and measurement duration increase with this value. A
value of 20 is normally suitable.
This value represents the delay between recording of the measured data and injection of
the test setpoint and offset. A value of between 0.2 and 1 s is recommended. Do not set
too low a value for the settling times or the frequency response and phase diagrams will
be distorted.
The measurement requires a slight speed offset of a few motor revolutions per minute.
The offset must be set to a higher value than the amplitude.
– The offset is run up via an acceleration ramp.
– The acceleration value is defined for one
Axis: MD 32300 $MA_MAX_AX_ACCEL
spindle: MD 35200 $MA_GEAR_STEP_SPEEDCTRL_ACCEL
MD 35210 $MA_GEAR_STEP_POSCTRL_ACCEL
– The following applies: Acceleration value = 0, no ramp
Acceleration value > 0, ramp is active
– The actual measuring function becomes active only when the offset value is reached.
[sec])
) = 250 Hz
-3
Commissioning Manual, 05/2008, 6FC5397–4CP10–4BA0
): Bandwidth
position controller max
Manual