Electromagnetic Compatibility (EMC) Test Technology for Switching Power Supplies
Divide the equipment into two groups: one group refers to all industrial, scientific, and medical equipment that specifically generates or uses conduction coupled radio frequency energy to perform its own functional needs; The other group of equipment refers to all industrial, scientific, and medical equipment that specifically generates or uses electromagnetic radiation energy to meet functional needs such as material processing and electrical spark corrosion. From the above definition, switch mode power supplies belong to the group of devices.
In addition, GB4824-1996 divides equipment into two categories, A and B, based on the different power supply networks used by the equipment. Class A equipment refers to all industrial, scientific, and medical devices that are not for household use and are not directly connected to the residential low-voltage power grid; B-class equipment refers to industrial, scientific, and medical devices that are installed in household facilities and directly connected to residential low-voltage power grids. From the above classification, switch mode power supplies may be classified into these two categories of devices.
EMC design and EMC testing complement each other. The quality of EMC design should be measured through EMC testing. Only by predicting and evaluating the compatibility of EMC throughout the entire process of product EMC design and development can possible electromagnetic interference (EMI) be detected early and necessary suppression and protection measures be taken to ensure the electromagnetic compatibility of the system. Otherwise, if incompatible issues are discovered after the product is finalized or the system is built, it will require significant human and material resources to modify the design or adopt remedial measures.
EMC testing includes testing methods, measuring instruments, and testing sites. The testing method is based on various standards, the measuring instruments are based on the frequency domain, and the testing site is a prerequisite for conducting EMC testing and an important factor in measuring the level of EMC work. The EMC testing is greatly affected by the site, especially the strict requirements for electromagnetic radiation emission, radiation reception, and radiation sensitivity testing on the site. At present, commonly used experimental sites both domestically and internationally include open fields, semi anechoic chambers, shielded chambers, and transverse electromagnetic wave chambers.
This article will discuss the measurement instruments, equipment, testing sites, testing methods, and prospects of electromagnetic compatibility testing related to switch mode power supplies in China.
