AC To DC Power Adapters

How to solve interference caused by power adapters

Power adapters are sometimes interfered by external factors during use, so how should we avoid such interference?

External interference to the power adapter, such as AC cable harmonic current, AC cable conduction interference, electromagnetic field radiation interference, etc., can only be solved by reducing the interference. On the one hand, we can strengthen the design of the input/output filter circuit, improve the performance of the active power factor compensation (APFC) circuit, reduce the rate of change of voltage and current of the switching tube and rectifier and the continuity diode, and use a variety of soft-switching circuit extensions. Composition structure and control methods; strengthen the role of shell shielding, improve the shell gap leakage, and do a good job of grounding.

External anti-interference capabilities, such as surge and lightning strikes, should be optimized for lightning protection of AC input and DC output ports. Lightning strikes can be solved by a combination of zinc oxide varistors and gas discharge tubes. For electrostatic discharges, use TVS tubes and corresponding grounding protection, increase the distance between signal circuits and the enclosure, or select equipment with anti-static interference.

Reduce the power adapter internal interference, should start from the following aspects: pay attention to the digital and analog circuits and single-point grounding, high-current circuits and small-current single-point grounding, especially current and voltage sampling circuits, to reduce the common resistance to interference, reduce the impact of ground loop; wiring should pay attention to the distance between the neighboring lines and the nature of the signal, to avoid interfering with each other; to reduce the impedance of the ground line; to reduce the high-voltage high-current lines, the Especially the primary side of the transformer and switching tubes, power supply filter capacitor circuits surrounded by the area; reduce the area surrounded by output rectifier circuits, renewal diode circuits and DC filter circuits; reduce the leakage inductance of the transformer and the distribution capacitance of the filter capacitance; and use the filter capacitor with high resonant frequency.

In terms of the propagation channel, appropriately add the TUS and high-frequency capacitors with high anti-interference capability, ferrite beads and other components to improve the anti-interference capability of the small-signal circuits; the small-signal circuits close to the shell should be added with appropriate insulation and voltage resistance treatment, etc.; the heat sinks of the power devices and the main transformer should be grounded correctly in the electromagnetic shielding layer; the grounding plate should be used for the shielding of a large area between the various control units; and in the rectifiers, electromagnetic coupling and machine ground arrangement, etc., to improve the stability of the internal work of the power adapter.

If you want to know more about switching power supply information, you can consult Xiamen Eahunt Electronics.

Whatsapp:+86 13860786068

Email: athene-cai@eahunt.com

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