【作者】 吴健；

【导师】 陈安斌；

【作者基本信息】 哈尔滨工业大学 ， 制冷与低温工程， 2008， 硕士

【摘要】 超导电机是利用超导技术及超导材料研制的一种高性能电机。由于用超导线圈代替了常规铜绕组,提高了绕组的载流能力,可以产生很大的磁场而又几乎无焦耳热损耗,因而具有一系列的先进的技术和经济特性。随着高温超导材料技术的发展,材料的临界温度、电性能和机械性能都得到极大提升,使采用高温超导材料的电机要考虑的制冷功率比低温材料低的多。因此,高温超导电机已经成为电机研究的一个重要方向。对于传统结构的高温超导电机,尽管采用超导材料对电机性能上有很大提升,但是也带来一系列问题:超导绕组的绕制受限于超导材料的机械性能、超导绕组的低温冷却、旋转密封、复合力矩管等等。这些问题成为高温超导电机发展的重要限制。考虑到低速、大转矩电机在船舶推进和风力发电方面的应用,同时考虑传统电机结构产生的技术难点,基于先进高温超导材料的性能特性提出了一种新型高温超导电机的设计方案——轴向感应子式高温超导电机。该类电机在结构上有一些典型特点,如全超导结构、轴向气隙、超导绕组静止、液氮冷却等等。与高温超导电机发展对应的是低温系统的发展。相对简单、费用较低、更高效率、稳定性高的低温系统的研制是高温超导电机进一步商业化的基础。轴向感应子式高温超导电机由于感应子的结构特点,可以采用过冷氮冷却。本文将归纳分析各种过冷氮低温系统的结构流程、工作原理和初步设计,提出了一种新型过冷氮低温冷却系统。新型低温系统采用热虹吸子系统联接了正常工作模式和备份运行模式,避免了开式系统的运行成本高和闭式系统稳定性低的缺点。高温超导电机的设计都是基于超导材料的性能和由材料组成的绕组的性能来进行的。对于低温系统研究,更为关注的是超导绕组在给定的冷却方式和磁体所处磁场环境等条件下的热稳定性,即给定的冷却方式能否满足磁体温度裕度的要求。以磁体精确模型为分析对象,把磁滞损耗作为内热源加载,边界上采用温度稳定边界条件,进行HTS磁体稳态运行时热稳定型分析,得到稳态时磁体温度分布。最大温度点温度为66.13K,位置为靠近端部,磁体温度稳定性良好。另一方面,从低温系统功耗的角度,对高温超导磁体运行温度进行优化。从分析中得,当交流磁体和直流磁体工作温度在60～70K之间时,对应的低温系统具有较低的功耗。直流磁体工作温度的最优值为65K,此时系统功耗低至85W。交流磁体最优工作温度为70K,此时功耗值为245W,高达直流磁体最优功耗的两倍多。即过冷氮低温系统用于冷却HTS磁体系统功耗较小。最后根据12.5kW轴向感应子式样高温超导电机热负荷要求,给出了300W/66K开式过冷氮低温系统的初步设计。更多还原

【Abstract】 Superconducting motor is a new kind high performance motor which utilizes superconducting technology and material. As using superconducting coils instead of routine copper windings, the current carrying capacity of motor windings is improved greatly. Higher magnetic field and almost no AC loss make the superconducting motor have series of advanced technology and economy characteristics. With the development of high temperature superconducting (HTS) material, critical temperature, electrical properties and mechanical properties are promoted greatly. The cooling power of superconducting motor using HTS material is much less than using LTS material. Therefore, HTS motor becomes an important research direction of motor research.As to conventional HTS motor, though there is great improvement of motor performance, it also bring up some problems, such as superconducting winding making method, cryogenic cooling of superconducting windings, rotary sealing, and composite torque tube etc. These problems have become key restrictions of HTS motor’s development.Considering the application in the field of ship propulsion and wind power generation of the low speed, large torque motor and simultaneously considering technical difficulties brought by conventional HTS motor structure, we proposed a new design scheme, axial flux and inductor type flux control high temperature superconducting motor. This kind motor has some typical structure characteristics, such as fully superconducting, axial direction air gap, static superconducting winding and liquid nitrogen cooling etc.Corresponding with HTS motor development, cryogenic system gained rapid development. Simple, low cost, higher efficiency and stability cooling system is the base of commercialization of HTS motor. As axial flux and inductor type flux control high temperature superconducting motor can be cooled by sub-cooled liquid nitrogen, sub-cooled liquid nitrogen cryogenic system becomes a hot research point. This paper will conclude and analyze different kinds of sub-cooled liquid nitrogen cryogenic system, including structure process, working principle and preliminary design. At last, a new structure for sub-cooled liquid nitrogen cryogenic system is proposed. The new system uses thermosyphon subsystem to connect the normal operation and back-up operation that avoid the high cost of open-cycle system and low stability of closed-cycle system.HTS motor is designed basing on properties of superconducting material and windings. As to cryogenic system, there is a growing concern about the thermal stability under given cooling method and magnet surrounding environment condition. That is the given cooling method can satisfy the temperature margin demand. Considering the accurate magnet model as analysis object, the thermal stability of HTS magnet was analysed to get the temperature distribution. The highest point of temperature is 66.13K and the positon is near the end region of the magnet. This means the thermal stability of HTS is high.On the other hand, this paper did the optimum design of HTS magnet’s operating temperature at the angle of system power dissipation. From analysis result, the cooling system has low power dissipation when the operating temperature between 60~70K. The optimal temperature for dc magnet is 65K while the power dissipation is as low as 65W. The optimal temperature for ac magnet is 70K while the power dissipation is as low as 245W. That is to say it is good to use sub-cooled nitrogen to cool the HTS magnet from power dissipation point.Lastly, the paper did the preliminary design of a 300W/66K sub-cooled nitrogen crygogenic system for the thermal load requirement of 12.5 kW inductor type flux control high temperature superconducting motor.更多还原