Electromagnetic Compatibility Experimental Research For AC-DC Power Adapter

AC-DC switching power supply is a very suitable product for high-power supply.In order to get a stable DC current output,one must limit the input current at 50~60Hz AC frequency,and perform the rectification and filtering processing.This leads to not only a relatively large storage capacity,but also serious electromagnetic compatibility problems.In this paper,the electromagnetic compatibility measurement experiments of AC-DC power adapter were studied.Generally speaking,when the switching power supply is working,components will interfere with each other due to the high frequency signals.They could be out of conduction through the power line in a common mode or a differential mode,meanwhile,the electromagnetic energy radiated from the surrounding space is formed.Such electromagnetic interferences can be suppressed through filtering,shielding and grounding technologies.In this work,the electromagnetic compatibility of AC-DC power adapter was measured at darkroom within temperature 22-25 ℃,relative humidity 40-54%,pressure950-1050 mbar environment.Based on the measurement standards of EN55022,55024,61000-3-2 and 61000-3-3,the radiation interference,conducted interference,harmonic current and voltage fluctuations were measured,and the uncertainties were also calculated.As a result,most radiation emission detections of electromagnetic compatibility of the AC-DC power adapter are in line with the measurement standards,although the harmonic current did not follow the measurement standard of EN 61000-3-2: 2014.According to the CISPR 16-4 "radio disturbance and immunity measuring apparatus and methods-Part fourth:EMC measurement uncertainty ",all the measured values listed in the test report were found to be within confidence intervals of approximately 95%,the measurement uncertainties within± 4.5dB at different frequencies.