Research On Improving EMC Of The Power Supply

With the development of modern electronic technology and power devices,the switching power supply are widely used in various fields of communication,automatic contol and household appliances,because of small size,light weight,high performance and so on. But, the operating state of switching power supply is the high freguency switch, there will produce very high current change rate and the voltage change rate in the internal, it will lead to the power supply to generate a strong electromagnetic interference. The singal of electromagnetic interference not only of grid damage caused by pollution,but also directly affect the other electrical equipment and the working of itself, and also caused by electromagnetic pollution at the same time, it will restrict our production and life.Therefore how to solve the problem of electromagnetic interference to become the modern switching power supply design problems to be solved.In the early sixty century, as a discipline the electromagnetic compatibility (EMC) began to have more comprehensive development. At present, a set of complere EMC system has already formed in some developed countries such as the USA and the European Union. This system includes the authoritative standard; the professional committee to specifiesing the standard, such as VDE; the effective management mechanism; high precision automatic test system; and they had developed a lot program about EMC prediction、analysis and design, and developed a number of improvements to the EMC of new materials、new technology、new product. It can make sure of that products have the overall gain control from designing, manufacture, market access and using. In our country, because of the ecomomy in the past is relatively weak, the electronics industry is relatively backward, the contradition of the EMC is not very prominent, so the research on the EMC started very late, with China’s accession to the WTO, the companies in our country pay more and more attention to the EMC, it makes that the development speed of EMC in China is very quickly. However, because there is a certain gap in the technology between the domestic and foreign,the new materials, technology and product to improving domestic EMC is very little, and we have not the program of prediction, analysis and design product,these are why the designer still needs to improving in practice,with the requirements of the cost control in our companies.This article mainly through the design of a60W (output DC12V5A) power supply for electronic refrigerator product.In the article we draw lessons from the mechanism of the switching power supply electromagnetic disturbance and the rectification method of the EMC, and make the EMC performance of the machine to meet the certification requirements. In order to carry out studying on some design problems about the EMC of the switching power supply.