In this study, the power density of a two-stage, i.e., LCLCL, electromagnetic interference (EMI) filter for a 10 kW three-phase, T-type three-level, boost-type PWM rectifier system is optimized concerning construction volume. It is found that reasonable boundary conditions limit or define most component values and only few degrees of freedom are remaining. In this context, the ratio of the first filter stage's common to differential mode inductance, k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> = L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cm,1</sub> /L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dm,1</sub> , is identified to particularly affect the total filter volume. For given switching frequency and DC-link voltage of f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> = 48 kHz and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> = 700 V, a flat minimum of the overall filter volume results for 10 <; k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> <; 40. The boxed volume of the filter realized for k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> = 18 is 763 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (46.6 in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ), which corresponds to a filter power density of 13.1 kW / dm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (215 W / in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ). Measurements of conducted EMI confirm that the rectifier system complies with the considered limits of conducted EMI (CISPR 11, class A).