【作者】 潘东华；

【导师】 王铁成； 李立毅；

【作者基本信息】 哈尔滨工业大学 ， 电机与电器， 2013， 博士

【摘要】 无铁心直流直线电机（Coreless Direct Current Linear Motor，CLDCLM）也称为音圈电机，具有结构简单、近零推力波动、高动态响应及高可靠性等优点，与压电陶瓷、超磁致伸缩等短行程、高精度的执行器相比，具有非接触传动和长行程的特点，广泛应用在超精密定位伺服系统中。超精密定位伺服系统对执行器的要求主要包括：高推力密度、近零散热（电机与外界几乎无热交换）、高动态响应及严格外形、质量约束等。这无疑对无铁心直流直线电机提出了更为苛刻的设计要求，本文针对以上需求开展电机拓扑结构、电磁和温度特性参数解析表达式及多物理场多目标优化设计方法等问题的研究。首先，针对推力密度高、推力波动低的需求提出了一种Halbach阵列、串并联磁路结合的次级结构，具有超薄冷却结构的无铁心初级结构的直流直线电机。Halbach阵列及串、并联磁路结构有效地减小了电机轭板厚度，提高了直流直线电机的推力密度；采用增添冷却结构的方式可提高无铁心电机绕组电流，进一步提高电机推力密度，并且可有效抑制电机温升，从而实现电机与外界环境无热交换。基于无铁心直流直线电机电磁边界简单的特点，采用镜像法与等效磁荷法结合的方式建立起无铁心直流直线电机的气隙磁场的三维数学模型。在磁场模型中，通过等效磁路法搭建起电机导磁材料的饱和系数模型，有效地提高了该类电机磁场模型的精度，为电机精确推力计算奠定理论基础。通过有限元仿真软件证明了该模型具有更为广泛的尺寸通用性，并且该模型与有限元三维场计算相比大幅度地削减了计算时间，为无铁心直流直线电机甚至无铁心电机的全局性优化提供了充分的理论依据。在此基础上，推导出电机推力密度、推力波动、电机常数等重要性能指标的关系式以及电阻、电感的解析表达式。在精确的气隙磁场数学模型基础上，分析了绕组端部对无铁心直流直线电机出力的影响机理，推导出绕组直边、端部产生推力在X、Y和Z方向分量的解析表达式，并通过分析给出了非驱动方向寄生力的抑制方法。首次提出了推力系数刚度这一概念描述推力系数随电机初级、次级相对位置变化时的衰减规律，从而作为评价该类电机性能优劣的标准。首次提出了反接串联感应电动势方法从根源上抑制冷却结构的电涡流阻尼力，得到了一种新型抑制电涡流阻尼力的超薄型冷却结构，并推导了阻尼系数的数学模型。通过实验证明了上述模型的准确性。打破了视电机为同一刚体的模型束缚，揭示了无铁心直流直线电机机械结构振荡引发的推力波动的产生机理，并建立电机初级的多刚体多自由度动力学模型。在以上电机推力及扰动力的分析及数学模型指导下，建立了高精度的无铁心直流直线电机动力学模型，为其控制系统的前馈补偿模型奠定了理论基础，通过系统仿真证明了前馈补偿方法的可行性。搭建无铁心直流直线电机热网络法数学模型，并成功预测了电机初级侧表面的高温区，提出了增加导热支路方法降低无铁心直流直线电机初级的侧表面温度，通过温度场仿真及冷却实验验证了该方法的可行性。冷却结构不仅提高了绕组持续电流的密度，满足电机高推力密度的需求，同时突破了超精定位系统中电机近零散热的技术瓶颈。通过热网络模型及有限元模型得到了冷却板的热特性规律，为后续电机多物理场综合优化奠定了理论基础。最后，定义七个尺寸比例系数，结合无铁心直流直线电机设计尺寸输入条件对其电磁结构、冷却结构尺寸进行了完整的参数化建模。以无铁心直流直线电机的电磁模型、散热功率模型及尺寸参数化模型为基础，采用遗传算法构建该电机多目标优化函数，以电机行程、表面温升和外形尺寸等为约束条件，对无铁心直流直线电机进行多物理场综合设计、优化研究。该方法实现了电磁性能、冷却性能及外形尺寸的兼顾设计，解决了无铁心直流直线电机的多物理场耦合、多目标优化的复杂性设计，实现了无铁心直流直线电机高推力密度、低推力波动及近零散热等电机性能的共存。更多还原

【Abstract】 Coreless Direct Current Linear Motor (CLDCLM) has some advantages such as a simple structure, less thrust fluctuation, high dynamic response and high reliability. The CLDCLM has larger stroke than traditional ultra-precision actuators (such as piezoelectric and giant magnetostrictive actuators), and do not use contact transmission principle for having higher positioning accuracy to be adopted in nanopositioning system. In nanopositioning system, the requirements of actuator are very strict, including high thrust density, no heat exchange, high dynamic response and strict shape constraints. In this thesis, the topology of CLDCLM is proposed; and the electromagnetic and temperature fields of CLDCLM are analyzed; and the electromagnetic and thermal analytical models are established; and the method of multi-object optimization is researched.Firstly, the topology of CLDCLM is proposed, which adopts Halbach array and series-parallel combination magnetic circuit, and has thin cooling structure. Halbach array and series-parallel combination magnetic circuit can reduce the height of yokes for improving the thrust density; cooling structure suppresses the temperature rise of CLDCLM for keeping no heat exchange, and improves the thrust density which is lower due to having air-core structure.Based on the simple boundary of CLDCLM, the electromagnetic model is established by the image method and surface magnetic charge model. And then the saturation coefficient is added in the analytical model to describe the nonlinear magnetic circuit by equivalent electromagnetic circuit approach. This electromagnetic model of CLDCLM is proved by finite element method (Comsol software), so this model has the versatility to lay the theory basis of the CLDCLM optimization design. Then, the analytical expressions of thrust density, thrust fluctuation and motor constant are obtained. And the method of CLDCLM’s resistance and inductance are proposed.Based on the electromagnetic model of CLDCLM, the part of CLDCLM thrust is researched, which is produced by winding end. The parasitic force of CLDCLM is non-driving direction force, and is produced by straight and end of windings. The suppression method of the parasitic force is obtained by the analysis. The relationship of thrust and position is like stiffness, which is a concept in mechanics, so the relationship is defined ‘thrust stiffness’ firstly. The thrust stiffness can describes the variation of the thrust with the position to be as the evaluation standard of motor performance. Then, a new method is introduced to suppress eddy current by offsetting back EMF in cooling plates. Based on the electromagnetic theory, the analytical model of new cooling plate is established. The Structural deformation and vibration would bring thrust fluctuation, and the model of this thrust fluctuation could be is discribed by multi-rigid-body and multi-degree-of-freedom model of CLDCLM primacy. By using above models, the accuracy of CLDCLM dynamic model is improved. The work lays theoretical foundation for feedforward control system of CLDCLM.The thermal model of CLDCLM is established by thermal network method, and then the high temperature region of CLDCLM primary side surface is predicted by this thermal model. Cooling structure not only improves the winding continuous current density to realize higher thrust density for meeting the needs of the ultra-precision positioning system, but also breaks technology bottleneck of the ultra-precision positioning system which is no heat exchange between motor and environment. The thermal conductivity branch is added to suppress the surface temperature of CLDCLM, which is proved by the FEM and testing. Some important parameters is calculated by FEM to lay the theory basis of the CLDCLM optimization design.Finally, the whole parameterized model of CLDCLM is established by seven dimension ratio parameters which are defined in this thesis. Based on the above electromagnetic and thermal models, the analysis and optimization of CLDCLM is researched by Genetic algorithm (GA) when stroke, surface temperature and sharp of CLDCLM are constrains. The electromagnetic performance, cooling capability and sharp of CLDCLM are designed at the same time, so the optimization of CLDCLM based on Multi-physical Fields is achieved. Finally, the CLDCLM, which is designed by this design method, has high thrust density, little thrust fluctuation and no heat exchange for meeting the needs of the ultra-precision positioning system.更多还原