大功率多相高速永磁电机损耗抑制方法与热管理技术研究

In high power applications, by adopting the direct-drive high speed motor, instead of the low speed motor driven with transmission system such as the gearbox, the system efficiency can be improved significantly, which shows huge energy saving potential. Based on the existing research foundation and aiming at the relatively huge losses and small heat dissipation area of the high-power multi-phase high-speed permanent magnet motor (HSPMMs), this project focuses on the investigations into loss reduction approaches and thermal management technologies of HSPMMs. Considering specific constraints such as large current flow, high operating and switching frequencies, the following subjects are explored: stator and rotor mechanical structures, winding arrangement, heat dissipation equipment, control system topology, as well as the inherent associations between certain parameters and loss and thermal phenomena. Efficiency and reliability of the drive system is achieved via the integrated design model analysis..Firstly, machine magnetic field, flow field and temperature field are developed by various methods including the Finite Element Analysis (FEA), Finite Volume Element Analysis, combined with the Lumped Parameter Network method, in an effort to reveal the impact of key parameters on system performances and to generalize the multi-field coupling computation algorithms of HSPMMs. In addition, design theory and optimal control strategy of HSPMMs equipped with output filter are studied in order to reduce the voltage and current harmonic contents and suppress the voltage change rate and common mode voltage. It is expected that the critical basic theories, technologies and analysis approaches relating to loss suppression and thermal management of multiphase HSPMMs will be grasped comprehensively throughout the research work, laying a solid theoretical and practical foundation for the growing popularization of high-power HSPMMs.

大功率场合下如能将低速电机经齿轮箱传动改为直驱式高速电机，可大幅提高系统效率，工业领域中节能潜力巨大。项目基于已有基础，针对大功率多相高速永磁电机损耗绝对值大，散热面积相对小，重点研究损耗抑制方法和热管理技术。在大电流、高工作频率、高开关频率等特定约束条件下，探寻定转子结构、绕组形式、散热结构、控制系统拓扑和参数与损耗、散热等的内在关联机制，通过集成设计模型研究，实现电机系统高效、可靠运行；采用有限元、有限体积元及集总参数网络计算方法分析电机磁场、流场与温度场，揭示关键参数对性能的影响规律，凝炼高速电机多场耦合分析方法；研究带输出滤波器的高速永磁电机控制系统相关的分析设计理论和最优控制策略，降低电压电流谐波含量和抑制电压变化率与共模电压。通过研究工作，全面掌握多相高速永磁电机损耗抑制与热管理的关键基础理论、技术和方法，为大功率高速永磁电机的推广使用打下坚实的理论与应用基础。

大功率高速永磁电机在透平机械、飞轮储能及分布发电等领域应用广泛。本课题针对该类电机频率高、损耗密度大、载波比低等特点，重点研究了损耗抑制方法、热管理技术及其控制策略。在电磁材料、运行频率、开关频率等约束条件下，本课题探索出了适合大功率高速永磁电机的拓扑结构、绕组形式、热管理系统及其控制策略，搭建了合理、高效的多场耦合仿真平台。以该平台为基础，本研究完成了3台不同功率、转速等级的高速永磁电机样机研制工作，相关成果已发表在国内外高水平期刊上并申请了相关专利，部分成果已经进行工业应用。. 具体而言，本课题研究了高频绕组特征及交流铜损耗分离和试验测量方法，设计了试验平台测定不同频率下交流损耗的量级，为大功率高速永磁电机绕组设计奠定了基础。在系统分析多种热管理系统机理的基础上，研究设计出适用于高频绕组高损耗密度下的近热源冷却系统，提出了相应的散热结构、仿真模型和试验测试方法，该散热结构下导体阈值电流密度可达20A/mm2，远高于传统的机壳冷却系统。高速电机转子部件温度敏感性高、损耗散失难度大，是制约性能提升的瓶颈。为此，研究分析了转子损耗的来源并进行了量化分离分析，首次提出利用高磁导率材料的屏蔽效应抑制转子涡流损耗的同时提高磁体利用率，通过理论分析、仿真计算和实验验证了所提方法的可靠性。针对高速大功率永磁电机高频、低载波比特性，对带LCL输出滤波器的控制策略进行了深入研究，首次提出了基于逆变器电压和电容电流反馈的动态解耦有源阻尼控制方法和基于小电流注入的电感辨识方法，实现全谐振范围内运行和对电感的高精度辨识，这部分内容现已成为领域内的研究热点。借助上述研究和实践，全面掌握了高速大功率永磁电机的设计理论、损耗抑制方法、热管理技术及最优控制策略。