Linear variable differential transformer
Rotary variable differential transformer
主要参考：
[1] 李稷. RVDT传感器仿真电路的设计与研究[J/OL]. 民用飞机设计与研究, 2011(2): 56-59. DOI:10.19416/j.cnki.1674-9804.2011.02.015.
RVDT
A rotary variable differential transformer (RVDT) is a type of electrical transformer used for measuring angular displacement. The transformer has a rotor which can be turned by an external force. The transformer acts as an electromechanical transducer that outputs an alternating current (AC) voltage proportional to the angular displacement of its rotor shaft.
旋转可变差动变压器（RVDT）是一种用于测量角位移的电力变压器。变压器具有可通过外力转动的转子。变压器充当机电换能器，输出与其转子轴的角位移成比例的交流 (AC) 电压。
In operation, an alternating current (AC) voltage is applied to the transformer primary to energize the RVDT. When energized with a constant AC voltage, the transfer function (output voltage vs. shaft angular displacement) of any particular RVDT is linear (to within a specified tolerance) over a specified range of angular displacement.
在操作中，交流 (AC) 电压施加到变压器初级，为 RVDT 供电。当使用恒定交流电压通电时，任何特定 RVDT 的传递函数（输出电压与轴角位移）在指定的角位移范围内都是线性的（在指定的公差范围内）。
RVDTs employ contactless, electromagnetic coupling, which provides long life and reliable, repeatable position sensing with high resolution, even under extreme operating conditions. Most RVDTs consist of a wound, laminated stator and a salient two-pole rotor. The stator, containing four slots, contains both the primary winding and the two secondary windings, which may be connected together in some cases. RVDTs offer advantages such as sturdiness, relatively low cost, small size, and low sensitivity to temperature, primary voltage and frequency variations.
RVDT 采用非接触式电磁耦合，即使在极端工作条件下，也能提供长寿命和可靠、可重复的高分辨率位置传感。大多数 RVDT 由绕线叠片定子和凸极两极转子组成。包含四个槽的定子包含初级绕组和两个次级绕组，在某些情况下它们可以连接在一起。 RVDT 具有坚固、成本相对较低、尺寸小以及对温度、初级电压和频率变化不敏感等优点。
通过对RVDT传感器工作原理的分析可见RVDT输出的两路差动电压信号为位移信号（\(X(t)=Asin\Omega t\)）和激励信号（\(i(t)=Isin\omega t\)）的乘积的函数，当铁芯偏离中心位置时，两路输出信号的增量相位相反，因此来用乘法的方法模拟传感器输出的两路信号，其中利用DA模拟传感器的位移信号：RVDT仿真电路的原理框图如图3 所示。
