【作者】 李奕良；

【导师】 张小章；

【作者基本信息】 清华大学 ， 核科学与技术， 2008， 博士

【摘要】 储能飞轮的发展存在追求高储能密度和追求大输入输出功率两个方向,近来此二者有融合趋势形成同时具备两项优点的更先进储能飞轮。本人在前人工作基础上,在飞轮技术以上两个发展方向,具体到转子结构与支承关键技术,展开了深入的理论研究与试验工作。在复合材料环向缠绕高储能密度飞轮转子的强度研究工作中:(1)引入轮体固化降温工艺应力概念。通过理论计算和实例对比分析,得出此固化应力重要性仅次于离心载荷所致应力、对复合材料飞轮成功制造及最终储能指标有重大影响的结论。提出工艺改进措施,在理论上将现有转子结构储能密度提高37%。(2)提出加力缠绕配合在线固化的轮体制造新思路。发展完善了厚壁圆筒缠绕理论方法及计算手段。确立了精确抑制飞轮径向应力所需加力缠绕张力制度的定义及计算方法。设计出的预应力飞轮在现有材料及结构尺寸下,可以达到140Wh/kg的高储能密度指标。研究中提出一种计算方法解决复材缠绕飞轮体加工及使用过程中遇到的大多数力学问题。针对立式20kW/1kWh储能飞轮系统,研制出上端高效永磁轴承。轴承以轴向反向充磁的内外双钕铁硼永磁环为磁源,同时配以合金钢导磁铁轭及转环形成微漏磁磁路,实现工作间隙1mm时,承载力在kN量级。此新结构永磁轴承具有结构紧凑、可超高速旋转并不受转子温升影响的优良特性。为提高飞轮储能密度和实现飞轮系统较大功率充放电,开展了大量的工程实际试验研究工作。对复合材料环向缠绕的高储能密度飞轮转子进行强度试验,达到实验极限转速905r/s,轮缘线速度796m/s,储能密度48Wh/kg的国内优秀指标;深入分析初步得出试验转子失效机制。建立一套20kW/1kWh储能飞轮样机,有效的力学设计计算以及大量的系统运行试验初步掌握了此新结构样机的动力学特性,为进一步的结构参数调整打下良好基础。更多还原

【Abstract】 High energy density and high power density are two directions in flywheel energy storage systems (FESS) development. There is a trend of including these two advantages into better high-speed high-power flywheels. In-depth theoretical study and a great deal of experimental research on flywheel rotor and bearing technology has been done for improving the energy density and power rating of the tested FESS.Through strength analysis of composite flywheel rotors made by fiber winding: (1) The concept was introduced for thermal residual stress generated in normal curing and cooling phase of fiber winding process. Comparison of theoretical calculation with experiment result has shown that, this stress is an important factor that influences flywheel safety and performance. An improved fabrication process was proposed which could increase the rotor performance by 37%. (2) Tensioning winding with in-situ curing, which is a new rotor fabrication technology is also proposed to enhance rotor radial strength by producing radial prestress. The theory and calculation method of thick-wall cylinder winding is developed and completed. The dissertation also shows how to define and calculate a set of fiber tensioning force for certain radial prestress. With same material and structure size, the new prestressed flywheel can reach an energy density as high as 140Wh/kg. An effective calculation method that can solve most of the mechanics problems met during the manufacture and use of fiber-enforced flywheel is developed.An upper permanent magnetic bearing (PMB) was designed for high-power vertical energy storage flywheels. The bearing consists of a radial two PM-ring stator and an alloysteel magnetic-conducting rotor which allow it to work at super high speed and to avoid thermal impact from flywheel rotor. With minimized bearing size and magnetic leakage, the bearing has an axial unloading force of kNs at working gap of 1 mm.Intensive experiments have been done to improve the energy density and power rating of FESS. Spin tests of high speed flywheel rotors achieve ultimate speed 905r/s, circumferential speed 796m/s and energy density 48Wh/kg. Failure analysis was done to the rotor. A new 20kW FESS was set up. After effective finite element analysis simulation and plenty of spin tests, the rotor system behavior is fairly understood, which is helpful and necessary to improve the design.更多还原