How to select the input EMI filter for an energy storage system PCS?

The selection of a PCS input EMI filter must be based on electrical specifications, noise spectrum, and safety requirements. First, determine the DC operating voltage and maximum continuous input current. Then, analyze the noise characteristics and determine the common-mode and differential-mode noise frequency bands and amplitudes to be suppressed through pre-testing or simulation. Selection steps:

1. Common-mode inductor: Select based on the current and required impedance frequency curves. For example, the CMZ series can be selected for high-power applications, and the CML series can be selected for compact designs. It is important to ensure that its saturation current is greater than the peak current.

2. X capacitor: Connected between the positive and negative DC buses to suppress differential-mode noise. The capacitance value is limited by the inrush current; a DC film capacitor must be selected.

3. Y capacitor: Connected between the bus and protective ground, providing a loop for common-mode noise. Its total capacitance value is strictly limited by safety leakage current; a safety-certified ceramic capacitor must be used.

Finally, it is necessary to verify whether the temperature rise of the filter under full load is acceptable.