What are the noise interference of switching power supply?
Aug 21, 2018| There are many sources of noise interference in switching power supplies, and the interference paths are various. The sources of noise interference can be summarized into the following three types:
1. Interference caused by the reverse recovery time of the diode.
2. Harmonic interference generated when the switch tube is working
When the power switch tube is turned on, a large pulse current flows, and during the off period, the current caused by the leakage inductance of the high-frequency transformer winding is abrupt, and spike interference is also generated.
3. Interference generated by the AC input circuit
Switching power supply input rectifiers also cause high frequency attenuation oscillations during reverse recovery. Generally, a large filter capacitor is connected behind the rectifier circuit. Therefore, the conduction angle of the rectifier tube is small, which causes a large charging current, which causes the AC current on the AC input side to be distorted, which affects the power quality of the power grid. In addition, the equivalent series inductance of the filter capacitor also has a large impact on the interference.