Impact of interleaving on EMI noise reduction of paralleled three phase voltage source converters

This paper presents a systematic design method to select the interleaving angle to reduce the EMI noise in a paralleled three-phase voltage-source converters motor drive system. The EMI noise analysis equivalent circuits for a motor drive system are given and double Fourier integral analysis is used to analyze the impact of interleaving on EMI noise sources. With the consideration of noise propagation path impedance, the design method of interleaving angle selection is analyzed in detail. When system switching frequency and system load and source impedance are determined, the optimal interleaving angle can be calculated based on the system impedance resonant frequency and system switching frequency. Verifications are carried out through both the simulation of a 100kW motor drive system and the experiment on a scale-downed 2kW system. The results show that by using calculated optimal interleaving angle based on the method proposed in this paper, the EMI noise can be reduced by 10∼12dB in the impedance resonant frequency range which can reduce the EMI filter size significantly.