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[SOLVED]HFI parameters tuning on IPMSM

Question asked by Londero.Juan on May 21, 2016
Latest reply on May 28, 2016 by Londero.Juan
Hi!
I'm developing software to control a small, sensorless IPMSM at very low speeds (0-90RPM) using STM FOC SDK v4.2 on a STM32F4xx.
I've already got the motor (using a custom board), but I'm having trouble making it run.

I know I won't be able to control it using the lib in Speed Control Mode (due to the 6 RPM resolution), but I'm planning to control it in Torque Control Mode with an external loop. My efforts are right now in successfully getting a precise rotor position feedback.

I've seen the steps I should follow to tune the HFI algorithm, and it's quite clear I must first of all tune the B-EMF State Observer parameters. My first question comes here:
1) Does the HFI algorithm really need it, or is it just for changing to the STO estimator (assuming most applications do need high speed ranges) after the speed threshold? If that were the case, I wouldn't need it.

When I try to tune the STO, I always get a "start-up failure". I guess that means the STO does not get a proper speed feedback because of wrong parameters, which I'm not finding exactly easy to tune (especially at such low speeds!). The WB does not give G1, G2, F1, F2, etc automatically when generating files. It even leaves F1 and F2 as 0 (which causes an error when compiling).
2) Is this normal? I only read how to tune K1 and K2, but I don't know how they are related to F1, F2, G1, G2, etc...

3) I left that step for later today, and tried the next steps using the DAC and an oscilloscope. The Ia and the HFI Debug current signals are not as they should be (HFI Debug current is quite flat), and changing HFI amplitude would not help here. Is this because of my first question?
However, if I plot the Electrical Angle estimated by HFI, I do see some encouraging results (which I guess would be much better if the algorithm was correctly tuned).

Unfortunately I don't have the evaluation boards, so the motor profiler and the on-the-fly tuning features are almost impossible in my case. Any additional tuning tips will be very useful.

Thank you very much in advance!

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