Inductor design for common-mode and differential mode inductors

Power Electronics device often generates magnificent noise, which includes differential-mode (DM) and common-mode (CM) noise. An electromagnetic interference (EMI) filter is often required to meet the electromagnetic compatibility standards. Generally speaking, EMI filter contains two parts: a DM filter and a CM filter [1]. The common-mode inductor (or choke) is part of the CM filter; while the differential-mode inductor (or choke) is part of the DM filter. The research topic proposes winding structures which can be used to improve EMI performance. Chapter 2 states the toroid inductor design considerations and the design flow chart which is also shown in this section. Chapter 3 focuses on winding structures of CM and DM inductors. The theory of the induced voltage cancellation is introduced in this portion. The distribution of magnetic flux is demonstrated as well. Chapter 4 shows the simulated via ANSYS Maxwell. This chapter helps validate the previous design theory. Chapter 5 provides a series of measurement results. They are CM and DM impedance measurement, near field coupling induced voltage measurement, and near magnetic field measurement. Conclusion explains the advantage of the proposed technique.