Essay代写：Electromagnetic compatibility－r51due

下面为大家整理一篇优秀的essay代写范文- Electromagnetic compatibility，供大家参考学习，这篇论文讨论了电磁兼容的问题。电磁兼容，指的是不同设备发射的电磁波可以相互兼容，互不影响。电磁兼容按照电磁波传输方式的不同也可以分为传导和辐射。传导是指在电磁波以有线的方式在线缆中传输，辐射则是至电磁波在空间以无线的方式进行传输。

As the name implies, electromagnetic compatibility means that the electromagnetic waves emitted by different devices can be mutually compatible and mutually exclusive. Today's society with mobile phones, wireless routers, a wide range of applications, a variety of wireless communication technology into people's daily life, such as GSM, CDMA, WCDMA, LTE, WiFi, Bluetooth, GPS navigation and so on, as well as the upcoming 5G era, you can imagine, People's lives will increasingly be connected with wireless communication technology. But do you know that all wireless communication is not inseparable from the same thing, that is, electromagnetic waves.

In the 1888, the German physicist Hertz used experiments to prove the existence of electromagnetic waves. In memory of him, Hertz was used as a unit of fluctuation frequencies. The discovery of electromagnetic waves has brought many conveniences including wireless communication, such as infrared detection, microwave heating, ultraviolet sterilization, X-ray perspective and so on. But electromagnetic waves can also bring harm. For example, the weather dry people near or contact the electrical appliances, can produce discharge phenomenon, instantaneous voltage of up to thousands of or even tens of thousands of volts, may cause electrical failure; when charging, the voltage fluctuation of the power supply network, the short-time pressure drop, will produce the low-frequency conduction interference, also may damage the equipment. In addition, during the war, electromagnetic weapons generated high-power interference but the other side of the electronic and communication equipment can not work. Therefore, the concept of electromagnetic compatibility with the discovery of electromagnetic wave has gradually developed and is valued.

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To be exact, electromagnetic compatibility has two meanings. On the one hand, when a device is working properly, it produces electromagnetic fields must be lower than a certain limit, will not interfere with the normal work of other equipment, this concept is called EMI; on the other hand, a device must have a certain anti-interference capability to ensure that the electromagnetic field produced by other equipment is not disturbed, This concept is called electromagnetic immunity.

Electromagnetic compatibility According to the different modes of electromagnetic transmission can also be divided into conduction and radiation. Conduction refers to the transmission of electromagnetic waves in a wired way, in which the radiation is transmitted wirelessly in space.

According to the above classification method, the electromagnetic compatibility problem can be divided into conduction harassment, radiation disturbance, conduction immunity, radiation immunity, and other electromagnetic compatibility includes electrostatic discharge, voltage fluctuation, harmonic flicker, electric fast pulse group, surge, voltage sag and magnetic field interference research.

In order to verify that the equipment has qualified electromagnetic compatibility, and can be duplicated, comparable, all major countries or regions have set up specialized agencies, the development of electromagnetic compatibility standards, standardized testing methods, test environment and testing equipment. At present, the world's most widely accepted is the International Electrotechnical Commission IEC developed CISPR series standards. Here's a look at some of the most common EMC test cases specified in the standard.

Conduction disturbance refers to the interference of the surrounding environment by the cable, the power port and the control port when the current or data is transmitted in the online cable. Its testing principle is relatively simple, take the power port as an example. In order to measure the disturbance caused by the device in the power port, the artificial power supply network must be connected to the power supply, which can filter out the clutter of the power supply and provide the eut with a stable matching impedance. The eut is then connected to the power supply and the receiver is also connected to the AMN. In order to avoid the eut during the power generation of a large-scale transient signal, resulting in damage to the receiver, but also need to AMN and receiver between the limiter. For non-landing devices, such as mobile phones, televisions and other eut, the test needs to be placed at 80cm high, at least 1mx1.5m of the non-conductive table; for landing equipment, it needs to be placed on the ground for testing, but between the ground and eut the highest 15cm insulating layer is required. The specific configuration is shown in Figure 1.

The electromagnetic field generated by the RF transmitter can be interfered by coupling it to the inside of the device by eut some or some of the cables, such as power cords, signal lines, control lines, etc. Conduction immunity is the ability to test the eut against this interference. The test principle is shown in Figure 2:

First, the signal generator generates 1KHZ, 80%am modulated sine wave interference signal, amplified, matched, filtered, to meet the standard of the level of harassment voltage, through the injection equipment added to the eut. Injection equipment preferred coupling/decoupling network, generally done in a box called a CDN. The reason is that the CDN can provide the best test repeatability and protect the assistive devices. At present, there are various types of CDN can be applied to power lines, signal lines and so on. But there are still cases where the CDN is not available and must be injected in other ways, such as a current clamp. The test is performed in a 150k~80mhz frequency range of 1%, and the eut function is monitored at each frequency point.

The measurement of radiation disturbance is much more complicated than conduction disturbance. The first is the site requirements. Radiation disturbances usually need to be tested in open fields. The ideal open field is a site without any electromagnetic interference. such as, no buildings, cables, trees, etc., underground also can not have pipes, cables and other things.

Such venues are clearly not easy to find, especially in economically developed areas. Therefore, other alternative venues are set out in the standard: semi-anechoic chamber and anechoic chamber. The half anechoic chamber means that the absorbing material is installed in the periphery and the top of the ground, so there is little reflection of the electromagnetic wave except the ground. The whole anechoic chamber is on the basis of the half wave, and the absorbing material is added to the ground, which is actually simulating the free space of direct wave. Usually, the radiation disturbance test under 1G is carried out in a half anechoic chamber, and more than 1G uses a full anechoic chamber.

Before the test, Eut and its accessories were placed on a 80cm high table at the normal working state, at least 1mx1.5m, and the material is non conductive. The reference points of the eut and its attachments are 10m and 3m. At the time of the test, the table is rotated 360 degrees with the placed Eut and its accessories, and the antenna is moved within the 1~4m range to find the maximum value.

Radiation immunity refers to the interference signal through the antenna radiation out, in the eut space around the formation of a certain level of field strength, such as 3v/m, and then verify that eut will be disturbed. The principle and conduction immunity is similar, interference source signal is also 1KHz, 80%am modulated sine wave, different is needed in the whole anechoic chamber, verify the frequency 80mhz~6ghz, step into 1%. Field-level verification is required before the first radiation immunity test is performed. UFA is a hypothetical 1.5mx1 5m plane that divides 16 points evenly on this plane. As shown in Figure 3. At each point, use the same frequency range and step as the test, and constantly adjust the power, so that the level of field strength remains unchanged. After completion, 16 power values are obtained at each frequency point. These 16 values are sorted by high-low, at least 12 of the top and bottom of the lowest difference within 6dB, and record the maximum value of the power is PC. If this condition is met, it is indicated that eut can be placed in the UFA for immunity test.

To control the input of the signal generator and the power amplifier, the PC value recorded at each frequency point is used for UFA verification. Ensure that the eut is exposed to the required field strength. Then observe whether the eut is working properly.

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