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Strange current waveform driving a BLDC motor using the IHM08M1 with the Nucleo F303

der.ule
Associate III

I keep investigating why I have problems driving my motor with negative speeds.

I captured the phase voltage directly on the motor leads (yellow, cyan and magenta channels) and the current on the DAC output (Ia or Ib) and I noticed this peaks on the current waveform.

0693W00000JODPSQA5.png 

Zooming in, the currents themselves don't look bad at all

0693W00000JODMoQAP.png 

However I do not understand where does peaks are coming from

0693W00000JODRdQAP.pngAny ideas will be greatly appreciated.

34 REPLIES 34
 
MK.1
Senior

The picture in the manual contradicts what is written.

Oh my .. ! I was totally blinded by the 120° of the Hall Sensor, that I did not stop an think about the whole picture, thanks a lot for that. I will test out next week and see how it goes.

After a lot of testing (different problem but same parameter search) and re-reading the thread that you linked before.

I believe that the correct angle should be around 120°.

I annotated the pic posted by @Dario CUCCHI​ for the case where the hall sequence is H1, H2 and H3 according to his text:

As you can see now measuring from the maximum of the B-emf induced on phase A to the first rising edge of signal H1 I get 120° as in the previous case: and this the value to be set in the "Placement electrical angle".

0693W00000QKGusQAH.png 

Following his instructions, I annotated my capture too and calculated an angle of around 120° as you can see.

0693W00000QKGvqQAH.pngstill, thanks a lot for your help and pointing me in the correct direction (several times) 👍

that's right, it's my carelessness)