Prediction of Common Mode Far-Field Radiation for a Low-Side Buck Converter With Cables via Feko Electromagnetic Simulation

The electromagnetic radiation emitted from the power converter is readily capable of inducing failure of the electromagnetic compatibility (EMC) certification. The development of an accurate and reliable radiation model as well as a prediction method could be effectively beneficial in resolving these challenges. This paper examines the equivalent driving sources and the electromagnetic prediction of the common mode (CM) radiation of a low-side Buck converter with cables. Based on crucial concept of CM voltage mutation, two distinct types of CM driving sources in such a Buck converter are examined: the same-direction sources and the opposite-direction sources. The radiation transfer functions for various types of driving sources are then obtained using three-dimensional (3D) modeling with an electromagnetic simulation tool, and then the far-field CM radiation is methodically evaluated via the superposition principle. Finally, a 30 MHz low-side Buck prototype with shielded cables is appropriately fabricated and tested, two suppression schemes are methodically suggested and verified, and the influence of the cable and printed circuit board size on the transfer functions are discussed in simulation. The proposed electromagnetic radiation mechanism, prediction method, and suppression schemes are anticipated to be of excellent significance in the analysis and optimization design of CM radiation in DC/DC converters.