How to rectify a failed conducted emission test of a PCS (Polymerization Processing System) for an energy storage system?

When the PCS conducted emission (CE) test fails, the following system steps can be followed for rectification:

1. Data Analysis: First, analyze the test spectrum to determine whether the out-of-range frequency is concentrated in the 150kHz-1MHz range (switching frequency and its harmonics) or the 1MHz-30MHz range (high-frequency ringing, etc.).

2. Mode Differentiation: By unplugging and plugging the LISN test leads or temporarily paralleling/removing the X capacitor and common-mode inductor, determine whether the out-of-range frequency band is dominated by common-mode noise or differential-mode noise.

3. Targeted Filter Enhancement: If the common-mode noise exceeds the limit, check and strengthen the common-mode inductor, for example: replace it with a higher impedance CM series inductor, or add a Y capacitor (pay attention to safety leakage current). If the differential-mode noise exceeds the limit, check and increase the size of the X capacitor, or add a differential-mode inductor.

4. Check Filter Grounding: Ensure that the grounding path of the filter, especially the Y capacitor, is extremely short and connected to a low-noise reference point.

5. Source Inspection: Check the switching waveform for severe ringing, optimize the drive, or add buffer absorption.

6. Layout check: Check whether the installation position of the input and output filters is close to the port and whether the wiring in front of and behind them is isolated.