EMI Filters

This chapter focuses on conducted EMI emissions which are generally defined as undesirable electromagnetic energy coupled out of an emitter or into a receptor via any of its respective connecting wires or cables. The objective of studying conducted EMI is to understand how the noise is generated and to find the solution to reduce its impact in order to meet the EMC requirement for the equipment or system. The chapter utilizes a DC‐fed motor drive example to illustrate the EMI noise measurement. The EMI filter design constraints include performance constraints related to performance specifications and physical constraints related to component physical capabilities. The chapter presents the models which are needed for the constraints as functions of design conditions and design variables. These models include: EMI noise with EMI filters; leakage current; loss model; and inductor and capacitor physical constraints models.