Determination of the layout influence on the effectiveness of a three-phase common mode filter by using equivalent circuits and PSpice

Conducted and radiated disturbances of motor driver associations are due to differential and common mode currents. Common mode filters are usually used to evacuate common mode currents from the static converter to the earth. In consequence, such structures play a main role in disturbance reduction and are widely used in industry. However, stray elements of components and layout can reduce the filtering effectiveness. A modeling method taking into account all stray elements of industrial multilayer structures is presented. A three-phase common mode filter is modeled and optimized. This filter is implemented in a four layers industrial motor driver. The common mode inductance is modeled using complex inductive equivalent model. The layout impedance is computed using PEEC method. The electric computing is achieved using Spice.