The EMC Predicting Research Of The Computer Switching Mode Power Supply

With the development of the science and the technology, more and more electronic equipments lie in the same close quarters. In these equipments, different circuits need be placed very close. It will result in interfering with each other. And more, with the development of integrate circuit and super large-scale integration; more circuits must be placed in the smaller place. Therefore the probability of being interfered would be increased. Now, modern electronic engineers must take into account the EMC (electromagnetic compatibility) of the electronic equipments, when they design a product. The predicting of EMC may solve the EMC problem before the products being made; it may save a mass of time and money. The main algorithm of the predicting of EMC includes field method, circuit method and field and circuit uniting method. It is one of the main and most serious jam caused by the switching mode power supply in the computer .In this article, we discuss the EMC predict of the computer mode switching power supply by using the field analyzing method. It is realized by using more commercial software being united. We emphasize the radiation disturbing simulation of the switching transformer and the printed circuit board (PCB) of the computer switching mode power supply. First of all, the EMC problem of the switching mode power supply is discussed theoretically. The interference reason caused by the switching mode power supply of computer is analyzed. The restraining measures also be discussed. The measures include reducing the interference energy of the interference source,destroying or weakening the path of interference noise spreading,shielding and reasonable placing and routing et. Secondly, the EMC predict of the switching transformer of the computer switching mode power supply is discussed. The software PEmag and Maxwell EM of Ansoft Co. uniting are adopted to analyze, and then get the relevant electromagnetic field plot. According to the plot, the conclusion that the EMC problem of the switching transformer is magnetic energy leaking mainly can be drawn. In order to increase the EMC of the switching transformer, the measures of the magnetic shielding or using high guiding magnetic material to reduce the leaking of the magnetic energy should be taken. Thirdly, the EMC predict of the PCB of the switching mode power supply is discussed. The software Cadence PSD14.2 and Ansoft Designer are adopted to execute the task, and the near field plot of the PCB can be get. According to the near field plot, the circuit design can be improved. Finally, the summary is made and main results are given.