Showing results for 
Search instead for 
Did you mean: 

How to profile a motor with Rs<1Ohm, Ls<1mH ?

Senior II

According to here: 

The STM32 MC motor profiler has the following limitation: it cannot profile motors with Rs < 1 Ω or Ls < 1 mH.

That wording is a bit different from saying "is not optimized for" I saw elsewhere earlier.

I have a bunch of quite different PMSM motors - candidates for different purposes, and every single one of them is shown to have lower values (e.g. R=0.8, L=0.1m) than this in the MCSDK Profiler, on a IHM16M1 driver board. (the profiling completed, but I assume the determined values are to be regarded as unreliable?)

Can someone point me to descriptions of what type of gear & procedures are needed to profile a motor with lower values than these, to get the parameters to work with MCSDK?

Associate II

not very accurate, i tested out my motor with profiler with 0.66ohm and 0.25mh, i measure with 1.55ohm and 0.33mh between 2 motor wire and divide by 2 as it is 2 coils = 0.775ohm and 0.165mh

I'm not an expert, but a general LCR meter would be much better than this profiler, measure resistance with 4 wire clip

Senior II

The datasheet has the Rs, Ls values, but not Bemf constant & some others.
Would it likely improve anything if I modified the JSON for the motor by inputting the datasheet values for those - or maybe not, as they are then inconsistent with the other measured values?

While I get the motor to run from an MCSDK6.2 generated project when I add MC_StartMotor1(); to the main() myself (wheras the user button doesn't work)
But after ~ 20 minutes, the motor stops, for no apparent reason. This is repeatable.
Is this expected in MCSDK-generated example projects, is there some sort of counter or overflow somewhere?

Associate II

I have the same issue with a set of motors with Inductance < 1mH. 
Profiler unable to spin the motors. 
Not sure what you did to run your motor on the regular code. I will try and report if it will work.

By now, is a bad start for the ST dev kits and all small motors that I was planning to run with ST solutions.


I just would like to share with you that even if the profiler firmware is not able to profile your motor, it does not mean that you will not be able to control it with the MCSDK.

The MC Workbench has a dedicated configuration panel to allow you to fill your motor parameters manually. Those parameters can be retrieved manually as explained here: How To manually configure the motor parameters - stm32mcu

Last point, be sure that your power board is well dimensioned regards to your motor. Indeed, if the rated current of your power board is 10 times the one of your motor, the accuracy of the current measurement will not be good enough to allow a smooth control.