firmware settings questions:

Question

Posted on March 22, 2015 at 16:32Hi!I have 2 little problem:1:My Shunt value is  0.0005 ohm. Can i set it somehow in the motor firmware.The original lowest possible value is 0.001 ohm.2:I use 1 shunt settings, and STM32F303VC controller ic. This IC has internal OAMP and comparator.I want to use the embedded HW OCP protection, but i got warning: A1/A3/A7 used in phase current feedback. It is correct because it must be shared pin between oamp and comparator. Why i got error message? Do i miss something?When i choose the 3 shunt setings, and all othtr settings are same the (A1/A3/A7 one of them)  pin is sahere but no error message.''SDK40x-STM32303C-EVAL-IHM045V1-Shinano-SINGLE-DRIVE.stmc''I modified this example from 3 shunt to 1 shunt, and got error mesage.If i use external OC protection this settings are works fine.Thank,Gabor

Gigi · Answer

Posted on March 23, 2015 at 09:05Ciao Regarding point 2, it is a known problem of workbench that consider a pin conflict the sharing of this pins. We are working to resolve it for the next version. For point 1 there is no much thing to do. You can adjust the parameter in the FW by hands but the problem is that some other parameters like for instance the current PI controller tuning is done considering the value present in the WB. My question is why you need such low value of shunt resistor? Considering the usual maximum drop of 0.5 volt on it, this means 1000Amps! Otherwise if you are working with less current, it means that you have a drop on Rshunt that is very small and this can create some problem in the signal over noise ratio. For that reason we limit the shunt resistor in such way. Moreover if you need to work with more that 30A of current the proposal is to use an insulated current sensor based on Hall effect. Ciao Gigi

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