Analysis and reduction of the near magnetic field radiation from magnetic inductors

The near magnetic field radiations from power electronics systems are very important as they generate EMI and degrade EMI filter's performance. This paper discussed the near magnetic field radiation behavior of magnetic components including differential mode (DM) and common mode (CM) inductors. The sources and the main radiation mechanism are identified for different inductor structures with either CM or DM excitations. A novel CM inductor structure is proposed to greatly reduce near magnetic field radiation due to DM currents and increase its high frequency CM performance. It also greatly increases its DM inductance which is good to attenuate DM noise. 3D Finite Element Analysis (FEA) models were developed for inductors. Both simulations and experiments were conducted to validate the analysis and the developed theory and technique.