血泵大间隙磁力传动系统磁力矩相位角及电磁体温升研究

【作者】 祝忠彦；

【导师】 谭建平；

【作者基本信息】 中南大学 ， 机械电子工程， 2011， 硕士

【摘要】 将大间隙磁力传动系统用于可植入式微型永磁轴流式血泵的驱动,能有效解决血泵传统驱动方式存在的磨损、导线穿体感染及人体排异性等难以克服的工程和医学上的问题。然而,系统主从磁极间隙的增大将使其驱动力矩迅速减小,而采用等磁力矩相位角进行磁极切换并不能保证系统各磁极状态驱动力矩得到充分利用；系统驱动电磁体在其工作过程中不可避免要产生温升,温升过高既不能使人体适应,又会影响系统的长时间运行。必须为系统找到进行磁极切换的最佳磁力矩相位角和保证电磁体温升在允许的范围内,因此,本文对系统的磁力矩相位角及电磁体温升进行了研究：设计单磁极切换和双磁极切换两种产生驱动磁场的磁极切换方案,通过比较系统的耦合机理、驱动力矩、能量传递效率及电磁体损耗情况,选择采用双磁极切换方式来产生系统所需驱动磁场。利用ANSYS软件对系统驱动力矩进行仿真,通过分析永磁转子所受磁力矩与电磁体四种磁极状态下系统磁力矩相位角之间的关系,提出了系统磁极切换最佳相位角的概念及其求解方法；通过研究不同磁极位置对系统磁极切换最佳相位角的影响规律,得到了最佳相位角的近似计算公式。基于对电磁体传热机制的分析及电磁体各组成材料热性能参数的计算,利用ANSYS软件对电磁体温升进行了数值计算,揭示了电磁体工作时温度过高的问题,并从减少电磁体损耗、改善导热条件及散热条件三个方面提出了保证电磁体最高温度不超过50℃的理论措施。研究结果表明：研究所得系统磁极切换最佳相位角可使电磁体具有最大驱动力矩；通过减少电磁体损耗和改善电磁体散热条件能够有效降低电磁体温升,当电磁体单个线圈通电电流小于0.56A、空气流速大于3.5m/s及空气温度小于10℃时,可以保证电磁体最高温度不超过50℃。研究结论对提高系统驱动力矩、降低电磁体温升、完善血泵大间隙磁力驱动系统的设计方法、保证系统长时间可靠运行等具有重要的理论指导意义。更多还原

【Abstract】 Taking the large gap magnetic driving system as the way of energy supply for permanent magnet axial flow blood pump can conquer engineering and medical problems such as wear and infection and rejection brought by traditional driven approach effectively. However, the driving torque will decrease rapidly with the gap between poles increasing and can’t be utilized fully with equal phase angle, the temperature rise will be very high with magnetic working and the human body may not adapt and the reliability of the system may be affected. So phase angle of magnetic torque of the system must be controlled reasonably and temperature rise must be ensured to be lower than the permission.Two switching modes of poles for generating driving magnetic field were presented, single pole and double pole switching. The coupling mechanism and driving torque and the energy transfer efficiency and loss of the electromagnets of the system were compared. Choose double pole switching mode as the generating method at last. The driving torque of the system was simulated based on ANSYS software. The concept and solution of the best phase angle for magnetic field was presented through analyzing the relationship between the driving torque and phase angle for four pole-states of the electromagnets. The approximate formula for the best phase angle was drawn through analyzing the influence of the position of magnetic poles on the best phase angle of the system. The temperature rise was calculated using ANSYS software based on the analysis of heat exchange mechanism and determining thermal properties. It shows that the maximum temperature of the electromagnets is very high and measures to reduce temperature rise were studied through reducing loss and improving thermal conductivity and cooling conditions.The results show that the obtained best phase angles can get the largest driving torque, temperature rise of electromagnets can be reduced by minimizing loss and improving cooling conditions, When the electric current of a single coil is less than 0.56A, the air velocity is more than 3.5 m/s and the air temperature is less than 10℃, the maximum temperature of the electromagnets will be less than 50℃. The study conclusions have important theoretical significance for improving driving torque of the system and reducing temperature rise of electromagnets and improving large gap magnetic driving system of blood pump to ensure reliability of the system.更多还原