Kohei Masuda

Modeling EMI Due to Display Signals in a TV

Modeling the electromagnetic emissions from a complex product such as a TV presents many challenges due to the complexity of electromagnetic interaction between multiple noise sources and interconnected resonant structures. A set of advanced methods such as the design and use of substitution boards for electromagnetic interference analysis, a practical simulation model for verifying the accuracy of the passive structures of the TV, an empirical scaling factor for incorporating the main processing board using the Huygens Equivalence theorem and modeling the radiation due to the flex cable based on active probe measurements is presented. The combined model comprised of the relevant noise sources and structures allowed the prediction of the most critical radiated emissions and the total radiated power caused due to the display signals.

Radiated EMI Estimation From DC–DC Converters With Attached Cables Based on Terminal Equivalent Circuit Modeling

An equivalent two terminal model based on the Thevenin equivalents describes the common mode (CM) currents on the input and output side of two widely used types of dc-to-dc power converters—buck and boost. Thus, it describes a nonlinear circuit by a linear equivalent circuit. The maximized spectrum of the CM currents is extracted for converters with stochastic signals using a novel characterization procedure. The extracted Thevenin model is used in co-simulation combined with a full-wave electromagnetic solver to predict the radiated emissions from the system consisting of the shielded dc–dc converters with attached cables and a DC brushless motor as load. The results using the terminal model agree well with the measurements providing that the actual CM loads are within the range of CM loads used while obtaining the Thevenin equivalent circuit.

Common mode current prediction from a power converter with attached cables based on a terminal equivalent circuit model

An equivalent two terminal model based on Thevenin equivalents describes the common mode currents on the input and output side of a buck converter. A linear equivalent terminal model of the buck converter is created based on measured common mode currents for various common mode loads up to 300 MHz. The results using the terminal model agree well with the measurements for common mode load values that are within the range used for creating the terminal model, however, for loads far away from the characterization load range larger differences occur, as the power converter is a non linear circuit which is modelled by a linear equivalent circuit.