Evaluation of the iron loss of an inductor based on dynamic minor characteristics

This paper discusses the iron loss characteristics of magnetic materials used in the chopper circuits of pulse width modulation (PWM) inverter circuits. A distinctive feature of this method, previously reported by the authors, is that the iron loss map is created by measuring the dynamic minor loop traced on the B-H plane, and it can be a useful method for calculation of the inductor iron loss in a dc chopper circuit as well as a PWM inverter circuit. In order to encourage the wide use of this method in the design of the power converters, this paper provides the characterization of loss map data in several magnetic materials, such as an iron-powder core, an amorphous core and a silicon-steel core. In addition to the loss caused by the hysteresis phenomenon, the loss caused by eddy current phenomena is discussed. Influenced by the eddy current loss, the shape of the dynamic minor loop tends to be rhombic when the inductors are magnetized using a pulse voltage, whereas the shape is oval when they are magnetized using a sinusoidal voltage. The increase in the amount of loss caused by the eddy current in each of these magnetic materials is also discussed.