功率变换器磁元件磁芯损耗关键技术研究

Magnetic components are very critical for power converters in efficiency, power density and reliability. Current core loss test technologies have inherently great unavoidable errors for low loss magnetic cores under high frequency excitation with high impedance angle. Current core loss models are only applied in simple modeling under simple sinusoidal and square wave excitations. The accurate loss model under complex excitation waveforms operated in power converters is lack. These seriously limit the further developments in researches, analysis, designs and applications of the magnetic components. The new test method of core losses will be studied with the new point of view in this project, which can completely overcome the inherent errors of current methods in principle while keeping the advantages of simplicity and convenience in use with electrical mode and be also suitable for the complex waveform excitations in power converters; By the deep analysis of the errors and with the optimization, elimination and compensation processes, the much more accuracy improvement than that with traditional method will be achieved to meet the requirement of academic researches and practical applications; Combining with core loss mechanics analysis, dedicated core loss experiments and data intelligent process, the core loss basic features under complex waveform excitations will be studied to reveal the inherit impact factors on the core losses and the factors can be tested externally in electrical mode, so that to build the high accurate core loss general model for arbitrary complex waveform excitations. The studies and achievment of this project will promote the progresses of designs and applications of magnetic components in power converters.

磁性元件对功率变换器的效率、功率密度和可靠性具有重要影响。现有磁芯损耗测量技术对高阻抗角的高频低损耗磁芯存在难以避免的很大固有误差，现有简单损耗模型也仅适用于简单正弦和方波励磁波形，缺乏对功率变换器应用下复杂励磁波形的精确损耗模型，严重制约磁性元件的研究、分析、设计、应用及其深入发展。本项目将从新角度研究磁芯损耗测量新方法，从原理上完全克服现有方法固有误差，同时保持电气测量法简捷实用的优点，并能测量复杂励磁波形下的损耗；通过对新方法的误差分析，采取优化、消除以及补偿等综合措施，使得测量精度明显优于现有方法，满足研究分析和实际应用要求；结合磁芯损耗机理分析、损耗实验设计以及数据智能分析，研究磁芯在复杂任意励磁波形下的损耗特征，揭示对磁芯损耗有本质作用的具有外部电气可测性的各个影响因素，建立适用于任意复杂励磁波形下的磁芯损耗通用高精度模型。研究成果将促进功率变换器磁元件设计与应用水平提高。

随着开关功率变换器高频化和高功率密度的发展，磁性元件成为功率变换器进一步发展的瓶颈，其中磁芯损耗的测量和建模成为关键技术难题，也是磁性元件深入研究和优化应用的基础。. 项目首先深入分析并揭示了高频磁芯损耗传统交流功率测量方法误差大一致性差的根本原因；提出了新测量方法—直流功率测量法，基本思想是通过一个DC/AC逆变装置将直流逆变为交流作为被测磁元件励磁源，而由直流侧输入功率获得被测磁元件损耗，从而克服了交流功率测量方法误差大的根本问题；进一步建立了逆变装置本身的多参数损耗精确模型，提出采用定标的方法有效扣除逆变装置的杂散损耗；设计研制了DSP控制的磁元件损耗测量的完整系统；为了获得准确的磁元件损耗，提出了比对量热计新方法，并建立了测试装置系统；通过与量热计法的对比，验证了提出的直流功率测量方法的有效性，进一步提出功率差值测量新方法以及施加高、低频复合励磁波形的新方案，可以测量有气隙磁元件的损耗；同时还提出了扣除被测磁元件绕组损耗从而获得磁芯损耗的有效新方法。验证表明，研发的测量装置在被测磁元件阻抗角89度下误差能控制在5%以内。以上各项成果解决了高频磁芯损耗，尤其是高、低频复合励磁下测量磁芯损耗的难题，测试方法和装置有望成为国际和国内标准。. 项目在损耗测量研究和成果的基础上，通过大量的各种工况励磁下的测试，分析了包括磁密大小、频率、各种不同占空比PWM波形、直流偏磁以及高低频复合励磁等实际工况下各个因素对磁芯损耗的综合影响，结合磁芯损耗机理研究和分析，提出了新的磁芯损耗计算模型，可以计算磁芯在功率变换器各种复杂励磁工况下的磁芯损耗，与损耗测量结果较好吻合，为磁性元件损耗分析和优化设计提供了理论模型，有助于功率变换器产品效率和功率密度的提高。.成果包括撰写论文7篇，申请发明专利4项，直接培养博士生2名，硕士生4名，促进了磁性元件损耗测量方法的国际国内标准制定，得到国内外知名企业的重视和技术开发应用。