| With the development of the Times,switching power supply has a wide range of applications and great development potential.Rectifying circuit of switching power supply because of its circuit,high frequency transformer and rectifier diode and other components in the process of work there will be a transient high voltage,high current,it is because the voltage and current in change among these components,let the switch power supply has become a high-frequency interference sources,has produced many electromagnetic compatibility problem in the system.Because of the importance and particularity of switching power supply,it has been listed as one of the first batch of six products tha tcarry out the compulsory supervision and management of electromagnetic compatibility.Therefore,solving the electromagnetic compatibility problem of switching power supply is an important measure to promote the application and development of switching power supply.Based on this situation,this paper analyzes the electromagnetic interference of switching power supply.To understand the electromagnetic interference of switching power supply,it is necessary to carry out analysis and research from the aspects of the working principle of switching power supply,the generation of the interference source,the propagation way of the interference,the disturbed equipment and the prediction and simulation method of the interference.At present,the development of electromagnetic compatibility technology in China has been improving day by day.Referring to the EMC standards of CISPR,China has issued and implemented the EMC standards.Therefore,it is particularly important to be familiar with the EMC standards of switching power supply and the analysis and design methods of EMC system.Only products conforming to the standard requirements can enter the market and standardize the market production.In the design of switching power supply,electromagnetic compatibility should be designed throughout the whole design cycle of switching power supply in order to design the best functional products with the best efficiency ratio.Most of the switching power supply design adopted AC/DC,DC/DC cascade form,for the typical switch power supply circuit,analysis the mechanism of switch power supply emi,according to the working principle of the circuit of the use of various components and specific characteristics to analyze electromagnetic interference source of switch power supply,make clear the switch power supply emicoupling paths is important for the analysis of switching power supply the electromagnetic compatibility.According to the coupling path of EMI,it can be divided into conduction and radiation.In this paper,the conducting interference of switching power supply is analyzed,the path model of differential mode and common mode noise is analyzed,the circuit model of conducting interference is established,and the testing method of conducting interference is given.At present,the simulation of switching power supply is mainly in time domain and frequency domain.However,because the power field effect tube is the core interference source in the time domain analysis,the simulation of it usually takes too long or does not converge,and the topology structure of the circuit will change due to the conduction and off of the switching device,which brings difficulties to the time domain analysis.Through frequency domain analysis of noise and interference propagation path model is set up,offer different spectrum analysis of the interference filter case,get such a conclusion,the key measures for suppression of the noise transmission is to provide a flow of low impedance noise source channels,make noise in the channels of transmission and radiation is weakened and the influence. |
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