i am running a bldc motor Infineon TLE9879 chip. Now i want to measure the current flowing through the motor. so i use the current sense amplifier where the motor current is converted to a voltage by means of a shunt resistor RSH(0.005 ohm).
I want to measure current from 0.1amp to 3Amps which gives the voltage drop at RSH (0.1*0.005=0.0005volts to 3*0.005=0.015volts). Considering 5V reference voltage of ADC I will not be able to get a good number for the above voltage drop. Also with the maximum gain of CSA the output is still negligible. The data sheet says you need to do linear calibration but how to do it for the entire current range? If anyone has experience with CSA please share how to do it? Attachment CSAdatasheet
I am adding some new information here. Actually, when I checked the current in one of the phases of the bldc motor it appears like the following Its amplitude increases as the load on the motor increases.
I was doing a mistake of reading the ADC value in every 100ms without any synchronisation with the actual current waveform. That's why the ADC value always shows the offset value of the opamp. I think I need to measure the RMS value of the voltage developed at the shunt. Please let me know if I am correct!!!