Hi,
I'm using TMDSHVMTRPFCKIT with Sensorless BLDC Motor project, my project involves measuring the current of the u, v, w phase, as shown in the attached figure. I understand how the shunt resistors are used and why the offset value is set to 1.65V, like the link below.
http://e2e.ti.com/support/applications/motor_drivers/f/38/t/299020.aspx
My problem is how can I get the current value, I tried the code
u_phase_current = _IQ12toIQ(AdcResult.ADCRESULT5)-_IQ(0.500).
Assuming that the offset value _IQ(0.500) is already calibrated, what does the 0.5 mean? Does that mean the range of the measured current is scale into 0 ~ 1 ? For example, the current I measure is the maximum peak current 10 Amp, so ,from the watch window, I should get the value of 1 without offset or 0.5 with offset, right?
To sum up, I need to read the exact value of the current, i.e. when the current of u phase is 0.2 Amp, I can read the value 0.2 under IQ math.
Any help would be greatly appreciated.
Best regards, Samuel