Switching Power Adapters

Switching power adapters or electronic devices have EMC requirements and corresponding test methods. When designing a switching power adapter or electronic equipment, it is necessary to make its electromagnetic compatibility index meet the requirements. However, the means and methods of electromagnetic compatibility design and indicator requirements do not have a clear numerical relationship, that is, electromagnetic compatibility design has a certain degree of ambiguity, after a long period of exploration and practice, has formed a number of specifications to improve the electromagnetic compatibility indicators of great benefit. In the electromagnetic compatibility design of switching power adapter, grounding technology, lightning protection and anti-static technology play a big role in ensuring the reliability of electronic equipment. Here we first understand the role of grounding of switching power adapter:
Grounding is an important part of the switching power adapter or other electronic equipment, not only directly affects the quality and normal operation of the switching power adapter, but also plays a role in protecting equipment and personal safety. Grounding is the most important design content of electromagnetic compatibility, for the suppression of conducted interference has obvious effect, and has the advantage of good economy.
The protective grounding of switching power supply is usually based on the earth's potential as a reference, with the earth as the zero potential. Circuit grounding is a potential reference point in the circuit system, you can set the point potential as a relative zero potential, it is generally not the earth zero potential. For example, electronic circuits are often equipment, metal base, racks, chassis, etc. as the zero potential or "ground" potential, they are sometimes not necessarily connected to the earth, the equipment at this time, the internal "ground" potential is not necessarily the same as the earth's potential, there is a difference in potential (called the suspension voltage), the potential of the ground is not necessarily the same as the earth. Potential difference between them (called suspended voltage or coupling voltage). However, in order to prevent lightning strikes and potential difference between the equipment and the operator caused by the danger, usually should be the equipment frame, chassis and other metal structures connected to earth.
For two-phase (zero and fire) input charger or power adapter, the input is not connected to the earth line, and the shell is a plastic part, can not be connected to the earth through the wire, at this time the output to the earth coupling voltage (also known as the suspended voltage) with the power adapter insulation resistance, distribution capacitance, leakage resistance to the ground and so on, relying on the double insulation or strengthen the insulation for the protection against electric shock, Y capacitance, photocouplers and high-frequency transformer insulation materials. Y capacitors, opto-couplers and high-frequency transformer insulation materials and structure, insulation resistance, resistance to electricity, leakage current should be strict requirements.
Switching power supply circuit grounding is in order to discharge the charge or establish the circuit reference level and set the wire connection. In switching power supply, grounding is an important method of suppressing electromagnetic noise and preventing interference, the grounding of the metal structure body is also the shielding and safety design content, these all play an important role in the electromagnetic compatibility of electronic equipment.
The role of switching power adapter grounding mainly includes the following aspects:
1. Improve the stability of the switching power supply circuit system work, which is conducive to suppressing interference.
The ground of the switching power supply is connected to the earth, which can improve the stability of electronic equipment and circuit system work. Electronic equipment, if not connected to the earth, it will present a certain potential relative to the earth, the potential will change under the action of the external interference field, thus leading to circuit system instability, if the electronic equipment "ground" connected to the earth, so that it is in the real zero potential, can effectively suppress interference. 2.
2. switching power supply grounding can discharge due to electrostatic induction in the chassis on the accumulation of charge, to avoid interference caused by the accumulation of charge. Grounding can discharge the charge accumulated on the chassis and lines due to electrostatic induction, avoiding the interference and damage caused by the high voltage formed by the accumulation of charge, which leads to the internal discharge of the equipment. Switching power supply chassis grounding can realize the purpose of electrostatic shielding and electromagnetic shielding.
3. Switching power supply grounding can provide safety for electronic equipment and operators. The output of the switching power supply adapter or the chassis of the electronic equipment has zero potential to the earth, and there is no suspended voltage, which will not produce electrostatic electricity and electric shock feeling.

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

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