EMC (electromagnetic compatibility) is a characteristic of a product, translated as electromagnetic compatibility, which includes two aspects: EMI (electromagnetic interference) and EMS (electromagnetic susceptibility).

EMI(Electromagnetic interference) refers to the amount of electromagnetic interference that interferes with other electrical products. EMS (electromagnetic susceptibility) electromagnetic susceptibility, also known as electromagnetic immunity, refers to the degree of resistance to electromagnetic interference caused by other electrical products.

Therefore, to solve the electromagnetic compatibility EMC, on the one hand, we must filter out the external electromagnetic interference (radiation + conduction) introduced from the power line, on the other hand, we must also reduce the noise interference emitted by the own equipment to the outside, so as not to affect the performance of other electronic equipment in the same electromagnetic environment. normal work.

In switching power supplies, the rapid changes in current and voltage caused by the high-frequency turning on and off operations of power devices are the main causes of EMI. EMC filters are mainly used to filter out conducted interference, suppress and attenuate the interference and influence of noise signals generated by the outside world, and at the same time suppress and attenuate interference caused by equipment to the outside world. Radiation interference is mainly filtered through shielding.

Judging from the function of the filter, its function is to allow signals of a certain frequency to pass through, while signals of other useless frequencies are greatly suppressed. It is essentially a frequency selection circuit. For example, our common low-pass filter function is to allow the low-frequency or DC components in the signal to pass and suppress the high-frequency components or interference noise. Some electromagnetic interference has strong hidden

Concealment, but at the same time, it may cause us great losses and even endanger life safety. For example, it may cause automated equipment to malfunction, cause medical equipment to lose control, etc.

Noise can be divided into conductive noise interference and spatial noise interference according to the propagation path. Conducted interference mainly propagates through conductors, coupling (interfering) signals on one electrical network to another electrical network through conductive media, and its spectrum is mainly below 30MHz. The spatial noise interference source couples (interferes) its signal to another electrical network through space, and the frequency range is higher than the frequency range of the conducted noise.

The rate is much wider, 30Hz-30GHz. Conducted noise interference can be suppressed and attenuated by designing filter circuits or adding filters. Space radiation interference is mainly achieved by applying sealing and shielding technology to implement electromagnetic sealing on the structure.

Conducted noise interference is divided into two types: differential mode interference and common mode interference. Differential mode interference is the noise between two power lines (referred to as line-to-line). It is mainly suppressed and attenuated by selecting appropriate capacitors (X capacitors) and differential mode coils. Common mode interference is the noise from two power lines to the ground (referred to as line-to-ground). It is mainly determined by selecting the appropriate capacitor (Y capacitor) and the common mode line.

circles for suppression and attenuation. Our common low-pass filters generally have the function of suppressing both common-mode and differential-mode interference.

Space noise interference is divided into induction interference and radiation interference.

The main solutions to power supply EMC are electromagnetic interference suppression, electromagnetic radiation control and improvement of anti-interference capabilities.

1. Electromagnetic interference suppression:

(1) Filtering: By using filters, electromagnetic interference generated by electronic equipment can be reduced. Filters can be installed on power and signal lines to reduce conducted interference. For high-frequency electromagnetic interference, corresponding filters can be used.

(2) Shielding: Shielding is an effective method to reduce electromagnetic radiation. By using a shell or shield made of conductive materials, electromagnetic radiation can be reflected or absorbed to reduce its impact on the outside world.

(3) Grounding: Grounding is to connect electronic equipment to the earth to reduce the conduction of electromagnetic interference. By connecting the device to a low-impedance ground wire, the interference current can be directed into the earth, preventing it from interfering with other devices.

2. Electromagnetic radiation control:

(1) Optimized design: By optimizing circuit design and layout, the electromagnetic radiation generated by electronic equipment can be reduced. For example, rationally arrange components and signal lines on the circuit board to reduce mutual interference between them.

(2) High-frequency modulation: High-frequency modulation is a method of reducing electromagnetic radiation by converting signals into a high-frequency range. Because high-frequency electromagnetic waves have shorter wavelengths, they are more difficult to penetrate objects and affect the outside world.

3. Improved anti-interference ability:

(1) Redundant design: By adding redundant components or backup systems, the anti-interference ability of the equipment can be improved. For example, use multiple power modules or backup processors to ensure that the device can still operate normally when it is subject to electromagnetic interference.

(2) Fault detection and recovery: By implementing a fault detection and recovery mechanism, errors can be automatically detected and repaired after the device is subject to electromagnetic interference. This can include detecting circuit failures, reconfiguring the system, restarting equipment, etc.

Henryuan's chargers and switching power supplies have improved EMC margin through advanced interference weakening design and have good EMC performance. They have helped many customers in the design of the whole machine and thus obtained the whole machine certifications. To choose chargers and switching power supplies with good EMC performance and high-quality chargers and switching power supplies, please choose Henryuan.

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