Predicting Core Loss Of Amorphous Nanocrystalline Materials Under Complex Excitation

Core loss is an important component that can not be neglected in power equipment such as motors and transformers.The loss of traditional silicon steel sheet increases sharply with the increase of frequency,while the ferrite magnetic material has a low saturation magnetic flux density.Therefore,the advantages of amorphous and nano-crystalline magnetic materials are gradually emerging due to their excellent magnetic properties,such as high permeability,high initial permeability and low high-frequency loss.What’s more,with the development of power electronic devices goes to power maximization,volume miniaturization and frequency broadening,it’s a trend that amorphous and nano-crystalline materials replace traditional silicon steel sheet and ferrite magnetic material as power electronic device core.The absence of magnetic properties data of amorphous and nano-crystalline materials is an important factor restricting the development of power electronic device cores.Due to the complex working conditions of power electronic devices,accurate measurement and modeling of core losses in amorphous and nano-crystalline magnetic materials under complex excitation are necessary.In this paper,the structure of iron core loss is analyzed firstly,and the mechanism of hysteresis loss,eddy current loss and residual loss are expounded.Then,a typical model for calculating core loss under sinusoidal excitation is introduced,such as Steinmetz empirical formula and iron loss separation model.The two models are simple and easy to use and have high accuracy,so they are the most commonly used methods to calculate the core loss under sinusoidal excitation.Aiming at the non-sinusoidal excitation frequently occurring in actual working conditions,the existing calculation methods of iron core losses based on the original Steinmetz empirical formula(OSE)and the modified iron loss separation calculation model are summarized.The above correction methods are compared and analyzed,and the formula for calculating the iron loss under the excitation of square wave,rectangular wave and triangular wave is derived.Accuracy and applicability of the above formulas are analyzed and compared in detail.In this paper,an oscilloscope measuring method is used to build a measuring platform which can simulate the actual working conditions of iron core,and the magnetic properties of ring shaped amorphous and nano-crystalline cores are tested.Core loss values of the two cores under different frequency and different magnetic density are measured.At the same time,the original Steinmetz equation parameters and iron loss separation model were used to fit the data,and two kinds of materials in square wave,rectangular wave and triangular wave excited by the correction method of analytical solution.Core loss model under various excitation were calculated and the measured values of density and loss of contrast,precision and application for these types of models are verified.