Study On The Conducted EMI Character Of DC Power Supply Carrying A Chopper With Variable Load

EMC (electromagnetic compatibility) of DC (Direct Current) power supply, especially the DC power supply in naval ships, plays a crucial indicative role in military. The DC power supply in the naval ship, often articulates power electronic converters and some DC loads, and requires all power electronic converters which result in some EMI(electromagnetic interference )to DC power electronics good performance, which can be guaranteed throughout the DC power supply system with good electromagnetic compatibility , thus in a favorable position in the military equipment. Therefore, very strict requirement is requested for the EMC of DC power supply. And on the basis of the requirement, the study on the EMI character of DC power supply carrying a chopper with variable load, is of important theoretical and practical value.Some research, with regard to the DC power supply system carrying a chopper with variable load, is completed in this paper as following: (1) EMI frequency domain equivalent model of this system is founded. Frequency domain analysis method is applied to analyze and calculate the interference source, and found the interference routine model. Then LISN(line impedance stabilize network) common interference circuit wave is simulated by Matlab7.0. Compared with the experiment's measure results, it is proved that the proposed model is feasible and correct. (2) On the basis of this EMI model, some experiments and analysis are carried out ,for practical application, as to the common EMI character of DC power supply resulting from a chopper with variable load during 0~150kHZ, 150k~1MHZ,and 1MHZ~30MHZ frequency ranges. Some conclusions, combined with experiments waveform and frequency domain system known models, are drawn that the common conducted interference current, resulting from the chopper in DC power supply, will reduce with the increase of the resistance or inductance load.Some theoretical analysis and experiments as to the common conducted EMI character, resulting from the chopper in DC power supply, are done, and it will provide some references about studying on DC power supply system's conducted interference.