The Study Of Power Core Loss Model In Switching Converter

Higher frequency and smaller size become the new requirement for switching converter.Improve the frequency of switching converter is an effective means to reduce its volume, but it will brings many problems such as thermal dissipation. As the essential part of switching converter,magnetic component and its loss cannot be ignored. It is necessary for us to establish a core loss model with clear physical meaning in practical engineering, which can estimate and calculate power core loss trend under different excitation, and it will play an important role in improving performance and efficiency of switching converter. The paper mainly discuss the core loss,including following aspects:Firstly, the paper introduces characteristics of core loss, and then analyses the physical mechanism of eddy current loss, hysteresis loss and residual core loss. In fact, switching converter works under non-sinusoidal waveform. Taking core loss under sinusoidal excitation provided by manufacturer as the entry point. Based on core loss under sinusoidal excitation, we establish the core loss separated model to get hysteresis core loss Ph(sin) and eddy current core loss Pe(sin). Then propose an approximate method to exclude the effect of resistivity and bring area coefficient kAe to estimate core loss of core in different cross area. The experimental data validates the proposed method availability.Secondly, according to the practical working condition of magnetic component and different topology structures of switching converter, we generalize three typical waveforms including square waveform, rectangular waveform and square waveform with dead time. Then establish core loss model under these waveforms based on the mathematical relationship between non-sinusoidal waveforms and sinusoidal waveform.Accurate measurement for core loss is the basis of core loss research. Lastly, compare several common measurement methods of core loss and establish a measurement platform to simulate the actual working condition of magnetic component in switching converter. At the same time, look for a fast and convenient method to generate excitation waveforms. The liner compensation method is used to reduce the impact of power amplifier’s resistance. Mainly taking toroidal ferrite of TN32/19/13(3F3)and TX40/24/16(3C90) from Ferrcube company as example, compare with the predicted and the measured under rectangular waveform. The prediction results are in accordance with experimentally observed under rectangular excitation.