Study On Loss Measurement And Thermal Aging Device Of High Frequency Power Iron Powder Core

Magnetic components are the key devices to power electronic converters. Withthe development of power electronic converter towards high efficiency, high powerdensity and high reliability, the importance of magnetic components and its design isincreasingly obvious. Iron powder core, as a kind of metal powder core, because ofits lowest cost, has been widely used. However, thermal aging of iron powder core isa serious problem, which brings great difficulties in proper design and applications.Thermal aging problems make the core loss increase after the inductors with ironpowder cores run for a long period of time, resulting in much higher temperature riseand may lead to inductor failure and even cause safety accidents. In order to makethe use of iron power core with its cost-effective advantage and also to ensure thehigh reliability design, it is necessary to research the characteristic of thermal agingin iron powder core.First, this paper analyzed the mechanism and influencing factors of thermalaging in iron powder core. Then the poor accuracy problems of the existing methodsof core loss measurement were analyzed, especially when the impedance angle ofthe core characteristics closes to90°. To solve this problem, this paper proposed anew method, called as “indirect method” to measure core loss. And the automaticcore loss test kit and thermal aging test equipment were designed. The testequipment contains a PFC module, a DC/DC module with variable output voltageadjustment, a DC/AC inductor core excitation source and a micro-chip dataacquisition module for electrical and temperature data process. The test equipmentshows full functions, strong applicability and can automatically record and store thedata of core aging process. Finally, the prototype was built.