How can EPS multi-stage filtering avoid resonance?

Multi-stage filtering (e.g., LC-LC) in EPS can improve high-frequency attenuation, but improper impedance matching between stages can cause resonance at specific frequencies, amplifying noise. The core strategies to avoid resonance are impedance mismatch and the introduction of damping. Specific methods include:

1. Parameter mismatch design: Creating a gap between the cutoff frequencies of the two filter stages, with one stage primarily handling low to mid-frequency frequencies and the other targeting high frequencies, preventing both stages from having simultaneously low impedances.

2. Adding damping resistors: Connecting a resistor in parallel with the filter inductor or a small resistor in series with the filter capacitor branch to form an RC damping network, consuming resonance energy and flattening the filter's impedance-frequency curve.

3. Optimizing interconnection layout: Shortening the connection lines between two filter stages to reduce distributed inductance.

4. Simulation-assisted verification: Performing frequency domain impedance scanning or AC simulation during the design phase to pre-identify and adjust parameter combinations that may cause resonance, ensuring stable attenuation across the entire frequency band.