The Research Of Electromagnetic Interference(EMI) Site Test Technology Of The Complex Electromechanical Equipment

With the electronic and electrical devices of the complex electromechanical equipment integrating into a much greater degree, the Electromagnetic Compatibility(EMC) issue has become increasingly prominent, and turned into a technical barrier to the export of large complex electromechanical equipment of China. To solve this problem, the research of EMC test has got more and more attention. EMI standard tests should be performed in a specified field. However, due to various reasons such as the difficulties to find the Open Area Test Site(OATS), the high cost and the limited size of the anechoic chamber etc., lots of complex electromechanical equipment cannot be tested in a standard field and only can be evaluated in the manufacturing and installation site. In this thesis, the research object is EMI site test of the complex electromechanical equipment, focusing on studying the scheme of EMI site test of the complex electromechanical equipment and the ambient noise culling algorithm. Test and verification has been carried out in industrial field.Firstly, this thesis has given a brief introduction to the classification and principles of the EMC test, summarized the current state of site test research, analyzed the characteristics and problems of site test of the complex electromechanical equipment, put forward the test scheme, and constructed the test system based on the requirements of site test to equipment.Secondly, it has analyzed the sources and characteristics of the ambient noise in site test, found out the shortcomings of traditional difference method, processed the environmental noise signal by using the amplitude and frequency offsets processing technology, designed the whole algorithm through difference calculation and difference compensation, and compared the results with the standard darkroom test results and the results from the existing difference method. The research results have shown that the present research algorithm can eliminate environmental permanent narrowband signal effectively, and the calculation result is closer to the actual numerical value than the existing difference method.Thirdly, based on the standard specification and the characteristics of site test of the complex electromechanical equipment, the reasonable test parameter has been confirmed by careful calculations to each parameter of radiated disturbance and conducted disturbance in site test.Finally, under the industrial environment, by using the constructed test system, EMI tests have been conducted to two kinds of representative complex electromechanical equipment. We have obtained the relevant test results, analyzed the existing problems, found out the causes of interference by employing the equipment of seeking interference sources, proposed corresponding corrective measures and reached the anticipative goals. This research has offered a useful reference for the EMC design of complex electromechanical products.