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

[der.ule]

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.

 

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

 

However I do not understand where does peaks are coming from

Any ideas will be greatly appreciated.

[MK.1]

why does your oscilloscope show a negative current value on a positive half-wave? sorry, didn't look there

[MK.1]

Please bring the oscillogram of the Hall sensors to the Back EMF Phase_U

[der.ule]

I'm not sure what I am suppose to do as I am not using an observer, but the hall sensors.

[MK.1]

I think your problem with the reverse rotation of the motor is due to the incorrect electrical angle of the shift of the Hall sensors. This can be easily checked with an oscilloscope. Draw a diagram.

[MK.1]

spin the motor by hand and watch BEMF

[der.ule]

Well I was sure I had done this measurement before (after all this is how I calculated my kV, but only with one phase), I could not find any of my old information, so I repeated the measurements today.

Three phases (P1: Yellow, P2: Cyan, P3: Magenta) and H1Three phases (P1: Yellow, P2: Cyan, P3: Magenta) and H2

Three phases (P1: Yellow, P2: Cyan, P3: Magenta) and H3

Three halls (H1: Blue, H2: Cyan, H3: Magenta) and phase 1 (U/L1/P1)

Three halls (H1: Blue, H2: Cyan, H3: Magenta) and phase 2 (V/L2/P2)

Three halls (H1: Blue, H2: Cyan, H3: Magenta) and phase 3 (W/L3/P3)

I used the motor calculator from ST to calculate the kV which turns out to be this time 2,53 Vrms/kRPM (I had a value closer to 4 last time, not sure if those resistors to form the virtual ground have an influence in my measurement)

 EDIT: I don't know why but my images did not appeared in the post the first time.

[MK.1]

Hi, calculate the correct angle, but first carefully read this post

https://community.st.com/s/question/0D53W00000GYrQNSA1/is-this-a-120-or-60-deg-displacement-angle-hall-motor

[der.ule]

Thanks a lot for the link!

Still I don't get it, reading the post that you linked and having the following measurement (where P1: yellow, H1: blue, H2, cyan and H3 magenta):

I understand that the "placement of electrical angle" should be ~75° (if I consider that each division is around 30°).

However this picture from the UM1052, tells me that the angle should be around 155° :dizzy_face:

 

[MK.1]

Hello, sorry for the long silence. Set the angle to 240 degrees.

[der.ule]

Nothing to be sorry about, I greatly appreciate the time you are taking helping me out, however, could you explain me how did you come up with 240° ?