Introduction to electromagnetic interference suppression methods for switching power supplies
Suppress various electromagnetic interference sources in switch mode power supplies
In order to solve the distortion of input current waveform and reduce the harmonic content of current, switching power supplies need to adopt power factor correction (PFC) technology. PFC technology makes the current waveform follow the voltage waveform and corrects the current waveform to approach a sine wave. Thus, the current harmonic content is reduced, the input characteristics of the bridge rectifier capacitor filter circuit are improved, and the power factor of the switching power supply is increased. Different methods can suppress electromagnetic interference from different perspectives, and Minrong Electric has made a lot of technical investment and put in a lot of effort for this. Minrong Switching Power Supply has achieved significant results in electromagnetic interference suppression, and Minrong Electric's efforts have cast Minrong Switching Power Supply as an increasingly dominant player in the industry.
Soft switching technology is an important means to reduce losses in switching devices and improve their electromagnetic compatibility. Switching devices generate surge currents and peak voltages during the switching process, which are the main causes of electromagnetic interference and switching losses. The use of soft switching technology can effectively suppress electromagnetic interference when switching transistors at zero voltage and zero current. The use of buffer circuits to absorb peak voltages at both ends of switch tubes or primary coils of high-frequency transformers can also effectively improve electromagnetic compatibility characteristics.
The reverse recovery problem of the output rectifier diode can be suppressed by connecting a series saturation inductor. The iron core of a saturated inductor is made of magnetic material with a rectangular BH curve. Like the materials used for magnetic amplifiers, this type of inductance made from magnetic cores has high magnetic permeability. The magnetic core has a nearly vertical linear region on the BH curve, which is easily saturated. In practical applications, when the output rectifier diode is conducting, the saturated inductor operates in an inductive characteristic state, equivalent to a section of wire; When the diode is turned off and restored in reverse, the saturated inductance is in an inductive characteristic state, which suppresses the significant changes in reverse restoration current and suppresses its external interference.
