EMI Noise Suppression PCB Diagnosis And Radiation

With the development of high speed print circuit board and power electronics technology, the radiated electromagnetic interference (EMI) noise generated by electronic device may influenced other devices seriously. Nowadays, the standard EM environment measurement as anechoic chamber can obtain the radiated EMI noise. On the one hand, the standard EM environment is complicated and can’t identify the radiated EMI mechanism. On the other hand, civilian industrial devices can’t afford the standard EM environment due to economical and technical conditions. Therefore,"low-end device, high-end technology" has been presented in EMC field.In view of the above problems, in this paper we studides on radiation EMI noise diagnosis and suppression methods of PCB, including three parts as following:(1) Fast reconstruction method for radiated targets was presented by using non-standard EM environment measurement based on current-driven common mode radiation model. According to PCB circuit and EM field analysis and CM impedance were modified. Furthermore, the full-wave model of common mode (CM) current was proposed in the radiation cable.(2) Radiated EMI mechanism description methods and suppression methods for radiated targets were put forward by employed the non-standard EM environment. Including:the CM radiation model, differential mode (DM) radiation model, the crosstalk radiation noise model, the cables radiation noise model and the impedance mismatch radiated noise model.(3) Radiated EMI noises generated by power system protection devices, RFID based system, electronic scale and electronic visual aids were analyzed by utilizing the suggest method. Meanwhile, the radiated EMI noise filters were designed in the paper.The theory and experiment results show that the radiated EMI characteristic and mechanism can be obtained efficiently by employed the suggest method. By using radiated EMI filter, radiated EMI noise can be reduced obviously and pass GB9254.