Loss evaluation of AC filter inductor core on a PWM converter

Abstract

This paper presents a core loss evaluation of AC filter inductor used on PWM converters. In order to increase the power density of the converters, high-frequency switching techniques have been applied. However, because of the limitation of cooling capability, reduction of volume of the passive components, especially the magnetic components, are limited. In order to overcome the problems, it is necessary to evaluate the loss of the magnetic components. However, conventional iron loss evaluation method, such as Steinmetz equation, cannot possible to evaluate the core loss, because those cannot take the dc-bias magnetizing condition into account. The authors have been proposed two kinds of iron loss evaluation method, the one is “a loss-map method” and the other is “an inductor loss analyzer (ILA)”. A distinctive feature of those methods is that one can know the iron loss during each switching period on the PWM inverters. Also, former one is suitable for accurate calculation of the core loss in designing process, and the later one is suitable for measuring the core loss on the practical system. By using those methods accurate design and evaluation of the iron loss can be made, and hence high power density design of the converters is realized. In this paper, firstly, a loss-map method which enables to calculate the iron loss of the ac/dc inductor in each switching period of the PWM inverter is briefly described. In the next section, an accurate measuring method of the iron loss of the ac filter inductor operating in a real PWM inverter is described. And it is proved that calculated and measured results coincide well. In the final section, iron loss characteristics of the ac filter inductor with various operating conditions of PWM inverter are discussed.