2019-07-13, 04:14 PM
Hi Skeyedoc,
TMHO. You should connect a 1k resistor from the IBT2 IS to ground that should give a 8.5 ratio from current to Vis (BTS7960 datasheet). So with a current of 15 Amps there should be 1,764 volt (15/8,5) on that resistor (with a max of 7 volt in current limit mode but standard that should be with 43 Amps/8,5=5.05 Volt). Off course you want the Arduino to measure and give the right current. Just for an example According to ohm's law a shunt of 0.05Ohm (one of the options with the Arduino/Pypilot) should give a voltage of 0.75 volt at 15 Amps (that is also what the code in motor.ino measures (low current 20 Amps Max) (1024/1,1(refvolt)=931 x 0,75V = 698,2 x 275 /128 =1500) therefore you could (and should because of the possible 7 volt) use a voltage divider of 100Kohm and 74Kohm that will result in a voltage of 1,764V/174KOhm X 74Kohm=0,7502 volt. So Your measured current should be reasonably right. I hope this will put you in the right direction and off course I can’t give any guaranties as most off the time I have no idea what I’m thinking or doing.
Greetings Rob
TMHO. You should connect a 1k resistor from the IBT2 IS to ground that should give a 8.5 ratio from current to Vis (BTS7960 datasheet). So with a current of 15 Amps there should be 1,764 volt (15/8,5) on that resistor (with a max of 7 volt in current limit mode but standard that should be with 43 Amps/8,5=5.05 Volt). Off course you want the Arduino to measure and give the right current. Just for an example According to ohm's law a shunt of 0.05Ohm (one of the options with the Arduino/Pypilot) should give a voltage of 0.75 volt at 15 Amps (that is also what the code in motor.ino measures (low current 20 Amps Max) (1024/1,1(refvolt)=931 x 0,75V = 698,2 x 275 /128 =1500) therefore you could (and should because of the possible 7 volt) use a voltage divider of 100Kohm and 74Kohm that will result in a voltage of 1,764V/174KOhm X 74Kohm=0,7502 volt. So Your measured current should be reasonably right. I hope this will put you in the right direction and off course I can’t give any guaranties as most off the time I have no idea what I’m thinking or doing.
Greetings Rob