How can interference coupling be avoided in the EPS sampling loop?

The voltage and current sampling circuit of an EPS is highly susceptible to noise coupling interference from power switches, affecting control accuracy and protection reliability. Measures to avoid coupling include:

1. Physical isolation: Placing the sampling circuit (sensor, operational amplifier) on the PCB in a "clean area" away from power devices and traces, separated by a grounding isolation strip.

2. Shielding and grounding: For sensitive sampling traces, use ground lines or guard traces to surround and shield them on both sides and below.

3. Filtering design: Before the sampling signal enters the ADC or operational amplifier, set up a low-pass filter network (RC filter) to filter out high-frequency noise. For differential sampling, a common-mode inductor can be used at the front end.

4. Using isolation devices: For high-side sampling or long-distance sampling, use isolated operational amplifiers or isolated ADCs to cut off conducted coupling paths.

5. Power supply decoupling: Provide an extremely clean power supply to the sampling chip and operational amplifier, using low-noise LDOs and placing decoupling capacitors nearby.