Yinghua Dong

Conductive EMI noise analysis for large power switched reluctance machine

Conductive EMI noise analysis for switched reluctance machine (SRM), including noise diagnosing by the separator and noise suppression, are presented in this paper. Firstly, the CM and DM noise current loops in SRMs power converter are discussed, and the noise separator based on 0°/180° splitter is employed for noise diagnosis. Then, the EMI filer design and the radiator-ungrounded method are proposed for SRM noise suppression. Experimental results show that the noise diagnose method is valid and reliable for EMI filter design, and the AC input of SRM influence the total noise greatly. Moreover, the proposed EMI filter technique is verified to satisfy EMC standards, and its noise decline rate reaches to 30%. The radiator-ungrounded method is testified to be effective against CM noise.

Study on impedance extraction methods applied in conductive EMI source modeling

Two-current probes method and S-parameter method are studied comparatively for conductive EMI noise source modelling in this paper. Firstly, the basic theory of the two-current probes method and S-parameter method are introduced for noise source impedance extraction. Secondly, ZX and Zsetup are important intermediate results in the two methods, therefore their extractions are analyzed respectively. Moreover, the single probe method is proposed to obtain better accuracy, stability and low-cost. The experimental results show that due to the parasitic effect, the lengths of short wire in two-current probes method have negative effects on Zsetup extraction. And the direct measurement method in S-parameter method is superior in Zsetup extraction. The inaccuracies of the two-current probes method and S-parameter method for ZX amplitude extraction reach to 4% and 1.5%, and S-parameter method has a comparatively better performance on both ZX amplitude and phase extraction.

Radiated EMI estimation for power line communication based on conducted noise separation network

A new method is proposed to estimate power line communication radiated EMI noise. By using the noise separation to extract common mode (CM) noise current, the radiated EMI noise can be estimated according to the relationship between the radiated EM field and the CM noise current. The experiment results show that the radiated EMI noise is decreased obviously, while the CM current is suppressed by using ferrite core.

Investigation on electromagnetic interference in new energy inverter system

In this paper, a new method is proposed to test the conducted electromagnetic interference (EMI) noise of new energy based on analysis the internal structure and measuring principle of line impedance stabilization network. A more accurate measurement of conducted EMI noise in new energy system can be provided by this method in order to design the appropriate filter for conducted EMI noise suppression. In addition, by adding capacitor and inductance in DC side can reduce the EMI noise as well. The result of experimental shows the method is effective.