Investigation of electromagnetic field coupling from DC-DC buck converters to automobile AM/FM antennas

DC-DC buck converters are widely used in modern automotive applications due to their high power efficiency. However, they are also a major cause of electromagnetic emissions due to the nature of the fast switching voltages and currents. In modern automobiles there are as many as 24 antennas [2015], and the number will continue to increase in coming years. The close proximity of electronic modules and antennas create a complex electromagnetic environment. Hence computational electromagnetic field simulation tools are required to predict the EM interactions early in the product development phase. This paper examines the electromagnetic interaction of 500 kHz buck converter with AM band antenna by measurement and simulation. Vehicle level interference in the AM band resulting from the buck converter is measured and analyzed. A mitigation technique achieving more than 27 dB of EMI noise suppression is suggested and numerically examined.