Development of a levitated motor for liquid hydrogen car pumps

将自传感技术应用于主动磁轴承（AMBs）是非常有前景的。我们小组一直在研究在液氮中工作的主动磁轴承。当普通的AMBs在液氮中使用时，它们不能很好地工作。液氮温度过低，导致amb的位移传感器无法工作。为了使用在液氮中工作的位移传感器，必须购买特别开发的非常昂贵的传感器。我们已经为在液氮温度下使用的AMBs开发了一种位移传感器。在这项研究中，位移传感器不仅在液氮中进行了评估，而且在空气中进行了评估。本文还讨论了自传感AMBs的动力学特性。自感测AMBs由一个转子（轴）、一对带有四个电磁铁的AMBs和一个驱动电机组成。转子由一对用于AMBs的铁部件组成，直径24毫米，长160毫米，重0.37公斤。驱动电机为永磁式电机，由一个永磁转子、四个驱动电磁铁和检测旋转角度的霍尔传感器组成。马达转动时没有任何机械触点。自感传感器的工作原理是基于差动变压器。AMB有上下四个线圈的电磁铁。上电磁铁的两个初级线圈由PWM放大器励磁。感应电压被引入两个次级线圈，用于感应位移。结果表明，在液氮温度下，输出电压与转子垂直位移在-0.3 ~ 0.3 mm范围内呈线性关系。研究了AMBs的脉冲响应。因此，在脉冲响应中观察到阻尼的自由振动曲线。振动曲线似乎呈指数递减。从这些结果来看，自传感AMBs对于抑制转子振动是有用的-即使在低温环境中也是如此。少

Applying self-sensing technique to active magnetic bearings (AMBs) is very promising. Our group has been studying active magnetic bearings working in liquid nitrogen. When normal AMBs are used in liquid nitrogen, they do not work well. The displacement sensors for the AMBs do not work due to the low temperature of liquid nitrogen. In order to use displacement sensors working in liquid nitrogen, very expensive sensors which are especially developed would have to be bought. We have developed a displacement sensor for the AMBs used at the temperature of liquid nitrogen. In this study, the displacement sensors are evaluated not only in liquid nitrogen, but also in air. Dynamics of the self-sensing AMBs are also discussed.The self-sensing AMBs consist of a rotor (shaft), a pair of AMBs with four electromagnets, and a driving motor. The rotor consisted of a pair of iron parts for the AMBs, and measures 24 mm in diameter, 160 mm long and 0.37 kg in weight. The driving motor was a PM-type moto … More r which consisted of a rotor with permanent magnet (PM), Four electromagnets for driving, and Hall sensors for detecting the rotation angle. The motor spun without any mechanical contacts.The principle of the self-sensing sensors is based on a differential transformer. The AMB has upper and lower electromagnets with four coils. Two primary coils of the upper electromagnet are excited by the PWM amplifiers. The induced voltage is led to the two secondary coils for sensing displacements. From the results, the relationship between output voltage and vertical rotor displacement at liquid nitrogen temperature is linear in the displacement range from -0.3 to 0.3 mm.The dynamics of the self-sensing AMBs were studied. Impulse responses for the AMBs were investigated. As a result, damped free-vibration curves are observed in impulse responses. The vibration curves seem to decrease exponentially. From these results, the self-sensing AMBs are useful for suppressing the rotor vibrations - even in the low temperature environment. Less