轨道交通直驱牵引用多气隙轴向磁通-磁场调制永磁电机系统的关键技术研究

As the key technology of the next generation for urban rail transit train, direct-driven traction system has the advantage of low noise, low power loss, high reliability and high transport capacity. However, the current direct-driven traction machine is still facing a few problems such as torque density and thermal load. Even though novel torque generating mechanism of the magnetic field modulation machine is capable of increasing torque density significantly and lower thermal load, issues in power factor and end winding length is still unsolved. Aiming at the application problems of magnetic field modulation mechanism in high-performance rail traction area, a novel permanent magnetic field modulation machine is proposed based on multi-air-gap axial flux topology. Focusing on permanent magnetic direct-drive machine, which is the core equipment of this traction system, in order to determine the machine design and control methodology of this novel machine, several studies have been carried out. A research on the magnetic optimization of axial flux topology and magnetic modulation mechanism is proposed to solve issues like power factor and torque density. Cross de-coupling method and frozen permeability finite-element-analysis is utilized to calculate motor parameter matrix , based on which a nonlinear decoupling mathematical model with variable parameters is established. In order to improve dynamic response capability during traction and braking. Finally, a set of analysis methodology and design criterion for multi-air-gap axial flux- magnetic field modulation machine is built to lay the theoretical and technical foundation of this novel machine’s commercial applications in rail transportation.

作为下一代城市轨道交通列车关键技术，直驱牵引系统具有低能耗、低噪音和高可靠性等优点，但是当前直驱牵引电机依然面临转矩密度和发热等问题。磁场调制电机具有转矩平滑、反电动势谐波少、理论转矩密度高的优点。本项目针对直驱牵引系统应用的迫切需求，提出并研究一种基于多气隙轴向磁通拓扑结构的磁场调制永磁电机，研究多气隙定、转子合理布局、磁钢优化设计和环形绕组理论，解决传统磁场调制电机的漏磁高、端部绕组长、功率因数低的问题；研究非正弦激励下的磁钢涡流和铁耗；计算提取电流激励下直-交轴磁链，研究电源限制条件的电机转矩-速度能力曲线，建立磁场调制电机牵引适应性设计理论；基于冻结磁导率的有限元方法，建立非线性变参数解耦数学模型，研究电流前馈式电压余量调节方法，提升牵引和制动过程的控制性能。拟建立一套适合多气隙轴向磁通-磁场调制电机系统的分析方法和设计准则，为该新型电机在轨道交通领域的商业应用奠定理论和技术基础。

磁场调制电机作为一种新型电机结构，因其转矩密度高、转矩输出平滑等特点受到越来越多的关注。本项目以轴向磁通磁场调制永磁电机作为研究对象，针对现有磁场调制永磁电机存在的低功率因数、长绕组端部、转矩密度无法实现进一步提升等短板，提出了一种新型的三转子双定子磁钢辐条阵列式轴向磁通游标永磁电机拓扑。相比传统轴向磁通分数槽集中绕组电机，本项目提出的新型轴向磁通游标永磁电机在功率因数上与其相当，转矩密度提升了近一倍。项目发表SCI论文16篇，获发明专利授权3项、受理5项。论文本项目的主要研究内容和成果如下：.（1）基于现有磁场调制电机的短板，提出了一种新型轴向磁通游标永磁电机拓扑。建立了转子辐条阵列式轴向磁通游标永磁电机的磁路模型，推导了电机解析公式。基于磁钢辐条阵列式转子磁势不连续的特点，作者选用递推的思路基于绕组理论建立并推导了电机的气隙磁密、反电势及转矩公式。.（2）探究了极比对三转子双定子磁钢辐条阵列式轴向磁通游标永磁电机拓扑的影响。从比较结果可以看出，在电机尺寸参数相同的条件下，极比越大，电机的转矩密度和转矩脉动越大，功率因数越小。因此，在选择电机极比时需根据用户需求进行合适的取舍。.（3）由于电机结构复杂，且需进行多目标优化，项目选用了NSGA-Ⅱ算法对三转子双定子磁钢辐条阵列式轴向磁通游标永磁电机拓扑进行尺寸优化。通过限定电机定子槽面积，以定子槽深、槽宽，内外转子磁钢厚度及极弧系数六个尺寸参数为主要优化变量，该电机的最优设计方案被提出，当铁芯外径220mm、电负荷A= 135 A/cm、电流密度J= 4.56 A/mm2时， 转矩密度高达32.9Nm/L。.（4）发明了一种适合于双定子轴向磁通电机结构的“分离式”双三相绕组结构，揭示了故障工况磁动势谐波对转子涡流损耗的影响机理，在容错控制工况下转子涡流损耗减少70%，从根本上解决了传统多相电机故障工况转子涡流损耗急剧增加、磁钢过热退磁的问题。