Solution to the emc problem of communication stabilized power supply
Communication switching power supply is widely used in program-controlled exchange, optical data transmission, wireless base station, cable TV system and ip network because of its advantages of small size, light weight, high efficiency, reliable operation, and remote monitoring. The power core of the work.
With the development of information technology, information technology equipment is spread all over the country, from developed central cities to remote mountainous areas, providing great convenience for communication and information transmission between people. Due to the differences between urban and rural areas, the power supply network of communication equipment has both a stable power grid power supply mode and an independent small hydropower power supply mode. In the power supply mode of small hydropower stations, due to changes in water volume, large changes in user power consumption, and unstable operation of power generation equipment, severe grid waveform distortion and large voltage fluctuations are caused. A severe test is formed with a switching power supply.
Railway communication and electric power communication are developing and expanding. Because the electric locomotive passes by, a strong induced voltage is generated, which causes a large fluctuation in the ground voltage, which causes a large fluctuation in the grid voltage. The strong electric field is easy to cause the instantaneous instability of the switching power supply equipment. Although the grid voltage is stable, the communication switching power supply operating near the high-voltage grid is easily affected by the interference of strong electromagnetic fields caused by grid load changes.
Communication switching power supplies used in base stations are more vulnerable to lightning attacks because they are mostly installed on taller buildings or mountain tops.
Therefore, the communication switching power supply must have strong anti-electromagnetic interference ability, especially the ability to adapt to lightning strikes, surges, and grid voltage fluctuations, and it must also have sufficient anti-interference ability for electrostatic interference, electric fields, magnetic fields, and electromagnetic waves. Ensure the normal operation of itself and the stability of power supply to communication equipment.
On the other hand, because the power switch tube, rectifier or freewheeling diode and main power transformer inside the communication switching power supply work under high voltage, high current and high frequency switching mode, the voltage and current waveforms are mostly square waves. In the square wave switching process of high voltage and high current, serious harmonic voltage and current will be generated. On the one hand, these harmonic voltages and currents are transmitted through the power input line or the output line of the switching power supply, causing interference to other equipment and the power grid that are powered on the same grid as the communication power supply, and at the same time affecting equipment powered by the communication power supply, such as program-controlled switching equipment. , wireless base stations, optical transmission equipment, and cable TV equipment, etc., which cause interference to the equipment, making the equipment unable to work normally; performance degradation. Part of the electromagnetic field radiates to the surrounding space through the gap of the switching power supply casing, and propagates through the space together with the radiated electromagnetic field generated by the power line and the DC output line, causing damage to other high-frequency equipment and equipment sensitive to electromagnetic fields. Interference, causing other equipment to work abnormally.
