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allObjects, I am using a sense resistor and a bidirectional current sense amplifier (Linear LT1999-10) that level shifts the current sense signal to 2.5V above ground and adds a gain of 10. if the voltage drop across the sense resistor is +100mV the output signal is 2.5V-1V=1.5V, if the voltage drop is -100mV (reverse current) the output signal is 2.5V+1V=3.5V, and I can either measure two signals: the 2.5V reference and the output signal from the current sensor and make a calculation. or I can add an inverting amplifier using an opamp, and add an offset to the noninverting input, and set the gain to make the output of the opamp swing from 0V (-100mV) to 3.3V (+100mV across sense resistor) so I can get a measurement signal that can be presented to a single ADC input. to get good accuracy one needs to do a calibration for offset and gain, and I use to take a series of readings, store them in an array and sort the array, then throw away the ten highest and the ten lowest readings, and average the remaining readings. kind of a median filter. the advantage is that the worst errors that are due to the high noise levels in a switching power converter are ignored, so the readings are fairly accurate and steady.
this gives enough accuracy for what I am doing (demonstrating how the power stage works and how it can be used in different configurations). the maximum input and output voltage level is 80V and I deal with current levels of up to 20A.
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tage
Do you have a) galvanic separation between the the measuring unit (looking at the drops at the shunts) and the control unit? - or b) do you just measure the voltages at both ends of the shunts and make the calculation? - or C) you may have a totally different way to get to the values.