The Most Complete Summary of EMC Knowledge for Switching Power Supplies
The Importance of MC
As early as the early 1980s, the infant mortality rate in the obstetric ward area of a hospital in New Jersey, United States was quite high. At night, the warning light on the baby monitor always goes out for no reason. The nurses were very angry about this, so they turned off the monitors and walked back and forth one by one.
After a preliminary investigation, the professor found out the truth of this matter. It turned out that the transmitter of a nearby television station had obtained permission from the United States Communications Commission to increase its output power significantly after about midnight, but it must be restored to its original level before 6 a.m. or other designated time. The connecting cable between the nurse station and each baby's monitor resonates at these interference frequencies, causing the induced voltage to turn off the monitor warning light. Before the hospital discovered this problem, almost six children had already died.
Another example is a customer complaint that when a switching power supply was turned on in the computer room, the company's 100M speed local area network experienced a speed drop and stopped, while the 10M speed network was not affected. Turn off the power and the network will return to normal.
After experiments, it was found that the high-frequency interference signal of the switching power supply was coupled to the network line, causing the network to malfunction.
The History of EMC's Development: EMC was actually born with the rapid development of the modern electronic industry. By the end of the last century, with the rapid increase in electronic and electrical equipment. EMC has expanded to numerous fields, and it is no exaggeration to say that wherever there are electronic products, there are EMC issues. The requirements of Western countries are becoming increasingly stringent, and EMC has become one of the trade barriers for electronic products from developing countries to enter the Western market.
For enterprises, different EMC design concepts can lead to different costs and time waste.
EMC's Content
Basic concepts:
★ Electrical Compatibility
★ Electrical Interference
★ ElectromagneticSusceptibility
★ Electrostatic Discharges
★ RSRadiated Susceptibility
★ Electronic fast transients
★ SURGE
★ CSConducted Susceptibility
★ EMC=EMI+EMS
★ EMI=Conduction (Harmonic)+Radiation
