Prediction of conducted emissions produced by a DC-DC-converter using component parasitics and partial inductances

In this contribution, a comprehensive approach to predicting conducted emissions produced by a switched-mode power converter is presented. The prediction is based on a SPICE model. As an example, a DC-DC-converter is analyzed. Both the semiconductors (MOSFET, diode etc.) and the passive discrete elements as inductors and capacitors are modeled by processing datasheet information, manufacturer-provided models and/or measurements. In order to include parasitic inductances of a converter´s printed circuit board in the model, the concept of partial inductances is applied. The parasitic inductance extraction is merely based on CAD/layout data of the PCB. Hence, an existing prototype of the switched-mode power converter´s printed circuit board is not required to perform the prediction. Thus, the prediction can be done early in the development process. To ensure comparability of prediction results and EMC regulation measurements, the measurement setup (line impedance stabilization network, load, interconnections, EMI test receiver signal processing) is modeled. The applicability of the proposed approach is validated by performing an emissions measurement and comparison of prediction and measurement. The approach is suitable to predict an upper emissions level boundary.