How can filtering in the PCS sampling loop of an energy storage system not reduce accuracy?

When adding a filter network to the voltage and current sampling loop of a PCS, a balance must be struck between noise suppression and accuracy maintenance. For low-frequency or DC sampling, an RC low-pass filter is typically used, but its resistance introduces errors and temperature drift. Optimization methods include:

1. Selecting high-precision, low-temperature-drift thin-film resistors.

2. Placing the filter resistor after the op-amp buffer, avoiding direct series connection in the sensor signal path.

3. For high-frequency noise, common-mode filtering can be used before the sampling signal enters the ADC, for example, using small CML or CMC series common-mode inductors on the differential sampling lines to suppress common-mode interference without affecting the differential signal.

4. Optimizing PCB layout: keeping sampling traces away from power sections and using shielding or grounding protection; placing filter capacitors as close as possible to the ADC pins and ensuring that their dielectric absorption effect does not affect DC accuracy.