Abstarct: This thesis investigates the design and implementation of electromagnetic interference filter for a three-phase inverter aimed to reduce the conductive emission level. In this design, common and differential modes of conducted emissions are brought to standard levels. To design, the conducted emission level must be first measured, and due to correct measurement, the test setup must be provided. In the next step, after measuring the conducted emission and comparing it to the standard level, the minimum amount of attenuation required to pass the EMC standards is calculated, and with the required attenuation, the desired filter design can be done. By determining the minimum required attenuation, the corner frequency can be calculated for both common and differential modes. This frequency is calculated according to the filter structure, and then filter elements are determined. During the determination of the filter elements, the leakage current is also considered which is limited by standards. Leakage current is the criterion for determining the capacitor of the common mode. After determining the corner frequency and capacitor of the common mode, the required choke value is obtained in a common mode. The differential mode filter can be designed in the same way with this difference that in this case, the leakage current limitation is not meaningful, so there is more freedom to choose the inductor and capacitor. In order to check the function of the filter, it was made according to the design.The filter efficiency for providing the required attenuation and bringing the conducted emission level to below the defined standard level was evaluated. The results indicate a significant reduction in the conducted emission level in inverter. Further, the insertion loss of filtering has been improved using a nanocrystal core as well as a new winding method.