How do you find the performance of the allegro ACS sensors in general? I have only used resistive current sense in the past but allegro now have some nice 100V high current SMD models and their existing models were upgraded with more bandwidth. It's almost impossible to find any performance comparison between the different current sensing options around or information about if you should prioritize bandwidth, rise time or other characteristics when selecting them for motor control.Lebowski said:I actually want to sense changes in phase inductances (to deduce position) while powered, i do not want something where i have to alternate between powering and sensing. The video a few posts back was sensing and powering at the same time.
Lizardmech comment about enough resolution ('Dynamic Range') is correct and is the reason for the analog pre-processing.
This kinda worked but was horribly unreliable and audible noisy to boot
Lebowski said:my idea for getting full 360 info has worked, now I get reliable info about whether the phase is 0-179 or 180-359. So all combined I now get full 360 degree info (smooth, not just 6 levels) about the rotor position, sensorless at standstill. Processing time is around 10 to 20 msec for the first reliable output after a cold start, after that it should be able to keep up until it shifts to backemf based sensorless. The short processing time makes that the controller can switch off the output stage while waiting for the traffic lights, and switch on only at throttle up. And independent of whether you rolled backwards or forwards, and without needing to accurately sample motor voltages (doesn't need motor voltages...)
There is still a big mistery in there somewhere that I need to look at... a case of a polarity being different from what I expected. If I just dumbly take this into its stride it will work, I'm just curious why it is different and I want to understand this.
Next step is to add phase current.... I have kept this in mind and it should be OK, but you never know...
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