The Pulse Group Suppression of Switching Power Supply
Switching power supply can be used as an electronic device alone, but more often, switching power supply is used as a component with each electronic device. Therefore, switching power supply has its particularity, and the electromagnetic compatibility of switching power supply is related to the normal use of every electronic device. Because of this, the EMC performance of an electronic device depends on the EMC performance of the switching power supply first.
① Pulse group suppression of switching power supply.
As far as switching power supply is concerned, regardless of the input filter of switching power supply, the switch
The suppression effect of power supply circuit itself on burst interference is really very low. The main reason is that the essence of burst interference is high-frequency common-mode interference, and the filter capacitors in switching power supply circuit are all set to suppress low-frequency differential-mode interference. The electrolytic capacitors are not enough to suppress the ripple of switching power supply itself, let alone the pulse burst interference with harmonic components above 60MHz. Therefore, when observing the pulse burst waveforms at the input and output of switching power supply with oscilloscope, there is no obvious effect.
Considering that burst interference is common-mode interference.
As far as switching power supply is concerned, adopting input filter is the first important measure to suppress the pulse group interference suffered by switching power supply.
Secondly, the design of high-frequency transformer in switching power supply line, especially the adoption of shielding measures, has a certain inhibitory effect on pulse group interference.
Furthermore, the bridge capacitor between the primary circuit and the secondary circuit of the switching power supply can provide a path for the common-mode interference that enters the secondary circuit from the primary circuit to return to the primary circuit, which is right.
It also has a certain inhibitory effect on pulse group interference.
Finally, adding a common-mode filter circuit (common mode choke and common-mode capacitor) at the output of the switching power supply can also play a certain role in suppressing the burst interference.
