Siemens A1 사용자 설명서
International English
Simple Applications
MICROMASTER Applications Handbook
27
5.8.7 Slip
Compensation
The motor speed is reduced depending on the load, due to the slip as described
earlier. Slip can cause a speed regulation by as much as 10% with small motors.
The inverter can compensate for this by increasing the output frequency slightly as
the load increases. The inverter measures the current and increases the output
frequency to compensate for the expected slip. This can give speed holding of
better than 1%.
earlier. Slip can cause a speed regulation by as much as 10% with small motors.
The inverter can compensate for this by increasing the output frequency slightly as
the load increases. The inverter measures the current and increases the output
frequency to compensate for the expected slip. This can give speed holding of
better than 1%.
Slip compensation has no effect during Sensorless Vector Operation, as
compensation is inherent.
compensation is inherent.
Slip compensation is a positive feedback effect (increasing load increases output
frequency), and too much compensation may cause slight instability. It is set up on
a trial and error basis.
frequency), and too much compensation may cause slight instability. It is set up on
a trial and error basis.
T
or
que/Cur
rent
Speed
Load Change
Speed Change without
Slip Compensation
Figure 5-6
Slip Compensation
5.8.8
Pulse Frequency selection
The switching, or pulse width modulation frequency does not change with output
frequency. See section 1.2. The switching frequency of the inverter can be
selected between 2 and 16 kHz. A high switching frequency has higher losses and
produces more Electromagnetic Interference (EMI). A lower switching frequency
may produce audible noise. The switching frequency can be changed to suit the
application, but some derating (as described in the Reference Manual), may be
necessary on certain units.
frequency. See section 1.2. The switching frequency of the inverter can be
selected between 2 and 16 kHz. A high switching frequency has higher losses and
produces more Electromagnetic Interference (EMI). A lower switching frequency
may produce audible noise. The switching frequency can be changed to suit the
application, but some derating (as described in the Reference Manual), may be
necessary on certain units.
The acoustic noise generated has a frequency of twice the switching frequency,
except at light loads, where there is some fundamental frequency content.
Therefore a switching frequency of 8 kHz will often be inaudible.
except at light loads, where there is some fundamental frequency content.
Therefore a switching frequency of 8 kHz will often be inaudible.