Suppression of groups of pulses in switching power supplies
Switching mode power supply can be used individually as a piece of electronic equipment, but more often switching mode power supply is used as a component with each piece of electronic equipment. Therefore, switching power supply has its own special characteristics, switching power supply electromagnetic compatibility performance is related to the normal use of each piece of electronic equipment. Because of this, the electromagnetic compatibility of an electronic device is good or bad, the first thing to look at the switching power supply electromagnetic compatibility performance is good or bad.
① Pulse group suppression of switching power supply
In terms of switching power supply, leaving aside the input filter of switching power supply, the suppression effect of switching power supply line itself on the pulse group interference is really very low, the reason is mainly because the essence of the pulse group interference is a high-frequency common-mode interference, and the filter capacitance in the line of switching power supply is aimed at the suppression of low-frequency differential-mode interference and the setting of electrolytic capacitors for the ripple suppression of the switching power supply itself is not enough, not to mention the harmonic components. The electrolytic capacitors are not enough to suppress the ripple of the switching power supply itself, not to mention the suppression effect on the harmonic components of the pulse group interference of more than 60MHz. Therefore, when observing the pulse group waveforms of the input and output of the switching power supply with an oscilloscope, there is no obvious attenuation of the interference.
Considering that the pulse group interference is a common mode nature of the interference.
As far as the switching power supply is concerned, the use of input filters is an important measure for the switching power supply to suppress the pulse group interference.
Secondly, the design of the high-frequency transformer in the switching power supply line, especially the use of shielding measures, has a certain suppression effect on the pulse group interference.
Again, the switching power supply primary circuit and the secondary circuit between the cross-connect capacitance, can be from the primary circuit into the secondary circuit of the common mode interference return to the primary circuit to provide a path, on the
It also has a certain suppression effect on the pulse group interference.
Finally, adding a common mode filter circuit (common mode inductor and common mode capacitor) to the output of the switching power supply can also play a role in suppressing pulse group interference.
