A Novel Inductor Loss Calculation Method on Power Converters Based on Dynamic Minor Loop

Abstract

Keywords: dynamic minor loop, iron loss, loss map, and PWM inverter In order to increase both the conversion efficiency and the power density of the power converters, a study on the loss reduction method on the magnetic component is one of the most important issue among the power electronics authorities. Traditionally, reduction methods of the magnetizing loss on the transformers and the ac motors have been studied. However, not so many reports regarding the inductor iron loss on the ac/dc filter inductor under the use of the high-frequency PWM switching condition have been reported. Difference of the iron loss between the transformers and the inductors depends deeply on both the amplitude and the waveform of the magnetizing current flowing thorough them. Especially on the inductors, the low-frequency current depends on the output current, and the high-frequency ripple current depends on the modulation condition of the converters. This means that the magnetic operating point and the shape of dynamic minor loop are changed according to the instantaneous amplitude of the low-frequency current. Also, the sum of the loss caused by dynamic minor loop usually dominate the iron loss of the inductor. Hence the loss calculation on the inductors are usually complicated compared to that on the transformers. Fig. 1 shows the proposed measuring system for the iron loss. This measuring system enables to measure the accurate iron loss. Also, this paper proposes a novel loss-map of the magnetic materials as shown in Fig. 2. By using this loss map, we can calculate the iron loss on the inductors in many kinds of converters by taking the magnetizing conditions of the inductors into account. In the case when we calculate the iron loss on the inductor on DC-DC converter, it is Fig. 1. Mesuring system enough to multiply the data on the loss map the switching frequency and the volume of the core. Futhermore, we propose a novel iron loss calculation method of the ac filter inductor on the PWM inverter by using the loss map. It is verified that the calculated results of the iron loss of the AC filter inductor on the PWM inverter coincide well the those on the experimental set up. It is concluded that the proposed loss map and the iron loss calculation method is useful for designing the optimal inductor used on the switching converters. Kenichiro Ishii * * MemberThis paper proposes a novel iron loss calculation method based on the loss-map of the magnetic materials. The distinctive feature of this method is that the iron loss on the inductors in many kinds of converters can easily be calculated even if the magnetizing conditions of the inductors are different. In this paper, the dynamic minor loop characteristics of the magnetic core on the condition of the switching converter are defined. Then, the dynamic measuring method of the dynamic minor loop by using the chopper circuit is presented. Next, some typical loss characteristics derived from the dynamic minor loop measurement is discussed. Also, a novel loss calculation method of the ...

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