Study of conducted EMI reduction for three-phase Vienna-type rectifier

The problem of electromagnetic interference (EMI) plays an important role in the design of power electronic converters, especially for airplane electrical systems. This paper explores techniques to reduce EMI noise in three-phase Vienna-type rectifiers. The design approach is using a high-density EMI filter to satisfy the EMI standard. In particular, the cause of high noise at high frequencies is studied in experiments, and the coupling effect of the final stage capacitor and inductors is investigated. The use of random PWM for EMI noise reduction is also presented. The performance of random PWM in a Vienna-type rectifier is verified by theoretical analysis and experimental results. The approaches discussed in this paper significantly reduce the EMI noise in the Vienna-type rectifier, and therefore the filter size can also be reduced.