Question:
Is the chopping frequency of the controllers 9300 in noise-optimizsed operation (C0018 = 0) switched from 16 kHz to 8 kHz, depending on the heatsink temperature?
Answer:
No, the chopping frequency is changed over independent of the heatsink temperature (device temperature).
The chopping frequency in the mode (C0018 = 0) 'Noise-optimized operation with automatic change to 8 kHZ' is changed automatically only in dependence on the required motor current. If a current above the reduced maximum value for 16 kHz is necessary e.g. for an acceleration, the controller changes automatically to 8 kHz with higher maximum current. A chopping frequency of 8 kHz causes less switching losses in the power stages which allows for a higher motor current without overloading the controller.
Current derating below 5 Hz field frequency depending on the heatsink temperature:
When the controller 9326 to 9332 are operated with 8 kHz, they automatically decrease the maximum current (current derating) only in dependence on the heatsink temperature. For a chopping frequency of 16 kHz, however, there is only a maximum current characteristic with a defined reduction, independent of the heatsink temperature (see also Operating Instructions 9300, section 'Device protection by current derating'). The controllers 9321 to 9325 do not use the automatic current derating below 5 Hz field frequency.
Note:
For all controllers of the 9300 series, a power derating must be considered if the ambient temperature rises above 40°C (see Operating Instructions 9300, section 'Ratings').
