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In today's society, with the development of science and technology, more and more digital and high-speed electronic devices are widely used in society various fields. While promoting social development, the electromagnetic interference generated by the application of electronic equipment has also brought electromagnetic pollution to the society. Electromagnetic pollution, water pollution, and air pollution are known as the three major sources of pollution in today's society. Due to the increasingly prominent problem of electromagnetic interference, the International Special Committee on Radio Interference (CISPR) issued CISPR-16, CISPR-15, and the European Committee for Standardization issued EN55015, EN55022 and other measures and standards, aiming at regulating electromagnetic interference at the point of electronic products Restrictions, thereby reducing social problems caused by electromagnetic interference.
EMI-9KB EMI conducted radiated interference test system
Electromagnetic interference (EMI) can be divided into There are two kinds of leakage interference and radiation interference. Leakage interference refers to the situation where a signal is coupled (interference) to another circuit network through a conductor medium in a circuit network; radiation interference refers to the signal source coupling (interference) signal to another circuit network or electronic equipment, and propagates through space . In high-speed PCB and system design, high-frequency signal lines, integrated circuit pins, and various connectors may have antenna characteristics, which emit electromagnetic waves that interfere with other systems or other subsystems in the system, affecting their normal operation. As we all know, the target of EMC testing is electronic devices, and lighting equipment, as an important component, naturally has corresponding restrictions. For example, the FCC certification of the United States, the CE certification of the European Union and other countries have put forward relevant testing items for LED lighting equipment. When it comes to electromagnetic interference, generally speaking, there are two sources of interference, one is leakage interference, which is mainly caused by the interference signals generated by electronic equipment interfering with each other through conductor media or public power lines. The detection frequency of leakage interference scanning for LED lamps starts from 0.15MHz and ends at 30MHz, and the detection frequency of leakage interference scanning for CE certification starts from 9KHz and ends at 30MHz. The other is radiation interference, which is mainly the interference signal generated by electronic equipment, which couples (interferences) the interference signal to another circuit network or electronic equipment through space. LED lights FCC certified radiationThe radiation interference scanning detection frequency starts from 30MHz and ends at 1GHz, and the radiation interference scanning detection frequency of CE certification starts from 30KHz to 300MHz.
In the lighting industry, there are two methods for EMI detection in the frequency band of 9KHz-30MHz, one is to use antenna and EMI receiver, according to CISPR15, EN55015 and GB17743 Standard; for low-frequency magnetic field equipment that may be generated by lighting equipment, according to CISPR16-1-4, three-coil antennas should be used to detect low-frequency magnetic field radiation interference. The detection mainly uses three-coil antennas and EMI receiversFor detection, it needs to be tested in a shielded room. Note: the three-coil antenna converts the low-frequency magnetic field components in the X, Y, and Z directions into RF signals, and transmits them to EMI receivers on three channels through a coaxial switch. The other is to use the LISN detection method, which needs to be detected by EMI receiver + artificial power network + LISN + detection software. It is to measure the interference generated by the power port of the lighting equipment under normal working conditions. For signal isolation, sampling, and impedance matching, it is provided to the EUT electrical channel, the EMI receiver measures the RF signal, and finally the EMI detection software performs analysis, processing, and judgment. This detection also needs to be carried out in a shielded room.
At the same time, the CDN method is also used for EMI detection in the 9KHz-300MHz band. Another method for detecting radiated electric field disturbances of lighting equipment is also provided in standards such as CISPR15, EN55015, and GB17743, that is, the CDN public mode terminal voltage method. The CDN method mainly includes EMI receiver, CDN, attenuation devices, etc., this test must be carried out in a shielded room. Due to the increasingly prominent problem of electromagnetic interference, the International Special Committee on Radio Interference (CISPR) issued CISPR-16 specifications for radio interference and disturbance-free measuring instruments, and for the lighting industry, CISPR proposed CISPR-15 electronic lighting and other related equipment radio The specifications of interference characteristics and measurement methods, and various countries have promulgated various EMI lighting testing specifications according to their own conditions, such as EN55015-2007 issued by the European Union, and GB17743-1999 issued by my country. For EU member states, the EN55015 standard (refer to CISPR-15) is applicable to traditional lighting equipment with a frequency exceeding 100Hz, such as incandescent lamps, fluorescent lamps, and self-rectifying energy-saving lamps. The frequency of such equipment usually does not exceed 30MHz, but for In the emerging LED lighting industry, the frequency generally exceeds 30MHz, and CE certification clearly proposes a scanning frequency range from 30MHz to 300MHz.
