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Summary of EMI interference source of LED switching power supply

Writer:www.turnmax-tech.comSource:www.turnmax-tech.com Date:2016-04-22
ED switching power supply is widely used in the field of lighting, industry and communication, however, in the process of application and debugging, EMI interference is still one of the more common problems. So, this allows engineers to feel the source of the disturbance is also a source of interference in it?
 
LED switching power supply in recent years as a more popular switching power supply, in the debugging process, once the EMI interference, the interference problem mainly consists of two parts, internal and external. Internal interference is embodied in the power switch tube, rectifier diode, high frequency transformer and other components, the external environment of the main interference from the jitter, lightning, external radiation, etc.. Then we come to the analysis of one by one.
 
First of all, the power switching tube caused by the EMI interference problem. Due to in the operation of the LED power supply, power switch tube in the on-off rapid cycling state transitions, di / dt and DV / dt are in a dramatic transformation. Therefore, power switch tube is coupled with the electric field of the main interference source, is coupled to the magnetic field of the main interference source.
 
And the high frequency transformer can also produce large EMI interference problem. Under the premise of opening of switching power supply, high-frequency transformer of EMI source concentration is reflected in the leakage inductance corresponding to the di / DT Fast loop transformation, so high-frequency transformer and power switching tubes and magnetic coupling of the important interference source.
 
Rectifier diode is also interference (EMI) part of the problem of internally generated, under normal opened, the diode rectifier of the EMI source concentrated reflected in the reverse recovery characteristics, the reverse recovery current intermittent point will produce high DV / dt in the lead inductance inductance and stray inductance, resulting in strong electromagnetic interference. In addition, the PCB is also switching power internal cause of EMI, accurate to say, PCB is the source of interference in a coupled channel, merits of PCB will be directly corresponds to the quality of the source of EMI suppression.

TypeInfo: Corporate News

Keywords for the information:Power Supply