How to choose between EPS π-type and L-type filters?

The choice between π-type and L-type filters in EPS (Electric Power Filter) is based on source impedance, load impedance, and filtering requirements. L-type filters (inductor-capacitor) have a simple structure, provide first-order attenuation, and are suitable for applications with low source and load impedances and less stringent requirements, but they are more sensitive to changes in source and load impedance. π-type filters (capacitor-inductor-capacitor) have capacitors at both ends, suitable for high source impedance and low load impedance, providing higher differential-mode insertion loss and better high-frequency attenuation. They are a common structure for input port filtering, but may generate higher inrush current. The key to the choice lies in analyzing the noise source impedance and load impedance: selecting a topology that allows for a larger impedance mismatch across the filter to achieve the optimal actual insertion loss. For EPS input filtering, the π-type structure is more common; while for interstage filtering between two filters, L-type or π-type filters may be selected based on the impedances of the preceding and following stages.