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BLDC switching sequence from PWM to GND

adromo95
Associate II

Hi all,

I am working on BLDC motor control using Hall sensors. At the moment, the motor seems to be running fine, however, I have noticed something strange in one of the sequences (this can be seen in the attached image taken from an oscilloscope). When switching from PWM stage to floating, I do not see these spikes and waveforms that can be seen in the switching from GND to floating. Thus, I am a bit concerned as this floating stage is used for sensorless rotor position estimation through BEMF zero crossing.

Could it be that one of the switching sequences is not working as expected? Looking at other BLDC phase signals from internet, it seems that those oscillations during the floating stage occur in both cases. Does anybody know how to infer the correct sequence for a BLDC motor? (I am using BLDC RS Pro 24V and it does not contain any information on how to program the sequence. Looking at ST and other manuals about BLDC do not match the sequence I am applying to rotate it.)

Thank you in advance.


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