Line filter – The last barrier in the switch mode power supply

1-phase mains filter design

How can the power grid be protected from unwanted interference caused by a connected device? This application note describes the steps required to create a suitably dimensioned mains filter.

To avoid unwanted interference in the power grid, a mains filter is often required to suppress interference signals generated by a connected load. This application note explains the steps required to design a suitably dimensioned mains filter.

Simulations and measurements are used to compare discrete versions of a single- and two-stage mains filter. In addition, the different core materials of current-compensated chokes and their properties are explained.

Contents:

• Common mode, differential mode and LISN (Line Impedance Stabilization Network)
• Calculation of a one- and two-stage line filter
• Circuit simulation and realization
• Comparative measurements in the EMC chamber
• Calculations of varistor, leakage current and discharge resistance
• Mains filter layout and component selection
• Core materials for current-compensated chokes

Download: ANP015