A Study on Calculation and Mitigation of Minor Hysteresis Loss of Magnetic Materials on Inductors, and High-Efficiency Utility Interactive Inverters utilizing Low Loss Inductors

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In this research, minor-hysteresis-loss on the inductor magnetic core which is caused by the high-frequency switching action of the PWM inverters has been studied and also a novel loss calculation method is invented. Also, effective design method in which accurate loss estimation taking in to account is proposed by utilizing the novel calculation method Major achievements on this research are as follows,1) Development of Precise Measuring Method of Minor-Hysteresis Loss on the Inductor Core :On the design process of power converters, accurate loss prediction and calculation are one of the most important issues. The loss calculation method on the power semiconductors has been studied and many useful methods have already been proposed. On the centrally, precise and effective loss calculations of the inductors used on the dc chopper circuit and ac inverter circuit did not have been studied well. The main reason for that is difficulty of grasping the nonlinear phenomenon of the magnetic ma … More terials on the inductor. This study focused on the accurate measurement of magnetic hysteresis loss on the magnetic materials which dynamically changes according to the operation condition on the power converters. The researchers have been studied the measuring method of dynamic minor-hysteresis loop on the chopper inductor. And, accurate measuring method based on the B-H analyzer is successfully developed. Based on the measured results, a novel loss expression method, which we call it "Loss map", is also proposed which enables to calculate the inductor core loss at arbitrary condition of the chopper circuit is invented. This result confirms the experimental results very well.2) Development of Iron Loss calculation of ac Filter Inductor on the PWM Inverter.Iron loss of ac filter inductor of which operates in the PWM inverter circuit is developed. The dynamic hysteresis locus of the ac filter inductor on the PWM inverter has different characteristics compared to that on the dc chopper circuit. The most crucial feature of the locus on the B-H plane is that the locus caused by the modulation signal does not form a closed shape, and hence it is difficult to calculate the iron loss in each switching period. In this study, the researchers have developed a quasi closed loop concept which enables to predict the iron loss on each switching periods. By using this method, researchers have showed that the difference of loss distribution of the iron loss is completely different depending upon the PWM modulation method. This result clearly confirms why the loss on the inductor is different depending on the modulation methods. Less