We have observed some issues during our testing under the following circumstances:
Starting up small motors with large inertia loads
Starting up certain motors with low-speed reference
Instability in the current loop
These are some solutions that may work for some motors:
Starting small motors with large inertia loads using the classic startup method may be difficult with the transition from forced commutation to closed-loop commutation. Use the Weathervane startup method in these circumstances.
Certain motors with low-speed references fail to start. This may be due to either an issue in the startup method or the behavior of the sensorless estimator during the transition to closed-loop commutation. Workarounds for this issue include: using the Weathervane startup method, ensuring that the speed command is not at the low end of its range, or reducing the DC link voltage if possible.
If instability in the current loop is observed, an increase of 5° or 10° in the current loop phase margin may help.
If you need to work with Microchip Support staff directly, you can submit a technical support case. Keep in mind that many questions can be answered through our self-help resources, so this may not be your speediest option.
