How switching power loss is measured on digital oscilloscopes
According to GB4824-1996 standard classification of interference sources, the equipment is divided into two groups: a group of equipment is to play its own functional needs and contains specialised in the generation or use of conduction-coupled radio frequency energy of all industrial, scientific and medical equipment; the other group of equipment is to meet the functional needs of the material processing, spark corrosion and other functional needs and contains specialised in the generation or use of electromagnetic radiation energy All industrial, scientific and medical equipment. From the above definition, switching power supply when belonging to ** group equipment.
In addition, GB4824-1996 according to the equipment used by the power supply network, the equipment is divided into two categories A, B. Class A equipment is non-domestic, not directly connected to the residential low-voltage power grid of all the facilities of industrial, scientific and medical equipment; Class B equipment is in the domestic facilities and directly connected to the residential low-voltage power grid of the facilities of the industrial, scientific and medical equipment. From the above classification, switching power supply may belong to these two categories of equipment.
EMC design and EMC testing are complementary to each other, EMC design is good or bad through the EMC test to measure, only in the product's EMC design and development of the whole process of EMC compatibility prediction and assessment, in order to early detection of possible electromagnetic interference (EMI), and to take the necessary suppression and protection measures, so as to ensure that the system's electromagnetic compatibility. Otherwise, when the product is finalised or the system is built and then found to be incompatible with the problem, it is necessary to spend a lot of money on manpower and material resources to modify the design or the use of remedial measures.
EMC testing includes test methods, measuring instruments and test sites. Test methods based on various types of standards, measuring instruments based on the frequency domain, the test site is a prerequisite for EMC testing, but also an important factor in measuring the level of EMC work.EMC testing by the site has a great impact, especially with electromagnetic radiation emission, radiation reception and radiation sensitivity test on the site of the most stringent requirements. At present, domestic and foreign commonly used test sites are open field, semi-electromagnetic wave dark room, shielded room and transverse electromagnetic wave chamber.
In this paper, we will discuss the measurement instruments and equipment and test sites related to switching power supply EMC testing, test methods and outlook for China's EMC test technology and other issues.
