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导语：旋转变压器，英文名resolver，安装于电机转子轴上，是电动汽车动力总成的"双眼"，动力系统怎么运行?运行的好不好?全凭这个不足巴掌大的小玩意儿。下面这段视频为我们介绍了旋变的工作原理，附带手打中英字幕，请鉴赏，手打不易，如果觉得不错，末尾点个"在看"支持下...
视频解析
How resolver work?
旋变是如何工作的？
The resolver consists of a stationary part called stator and a revolving part called rotor, which is attached to the motor shaft.
旋转变压器由两部分组成：固定部件-定子和旋转部件-转子，转子安装在电机轴上。
The primary winding of the stator is connected to a high-frequency sine signal, and this sine signal is transmitted to the rotor winding, because the stator primary winding and the rotor winding are acting together, like a transformer. Furthermore, we can name the rotor winding also as reference winding.
定子绕组作为变压器原边，接受励磁电压，转子绕组作为变压器副边，通过电磁耦合获得感应电压。高频正弦信号传输于定子初级绕组，随后 这 个正弦信号传输又作用到转子绕组上，定转子绕组像变压器一样共同作用。因此，我们也可以将转子绕组也称为参考绕组。
The relative magnitudes of the sine and cosine voltage are measured to determine the angle of the rotor relative to the stator.
通过测量正弦和余弦电压的相对大小，以确定转子相对于定子的角度。
To get the output signal, we have two secondary stator windings, that’s so called sine and cosine wingdings, which were displace angularly to each other by 90°.
为了获得输出信号，我们有两个次级定子绕组，即正弦和余弦绕组，它们彼此成角度地错开90°。
So, let's mount this resolver to the motor shaft and apply a high-frequency sine signal to the stator primary winding.
因此，让我们将此旋转变压器安装到电动机轴上，并向定子初级绕组施加一个高频正弦信号。
The pulsating alternating magnetic field of the rotor winding now induces an alternating voltage in the measuring windings sine and cosine. Their amplitudes, however, depend on the angular position of the rotor. If the rotor winding and the measuring winding are parallel to one another, the magnetic rotor field completely passes through the measuring coil, therefore they induced voltage is maximum and at 0° shaft angle, the cosine also has its maximum.
现在，转子绕组的脉动交变磁场在所测量绕组中产生正弦和余弦的交变波动。但是，它们的振幅取决于转子的角位置。如果转子绕组和测量绕组彼此平行，则转子磁场可以完全穿过测量线圈，此时，它们的感应电压最大。此外，在0°时，余弦也具有最大值。
If the rotor winding and measuring winding are at the right angle to each other, no voltage is induced. Let's turn the motor shaft 90°, and we can prove for these statements.
如果转子绕组和测量绕组彼此成直角，则不会感应到电压。让我们将电机轴旋转90°，我们可以证明这些说法。
Resolver signals at high speed
高速下的旋变信号
So, let's change the time base to our scope and watch them measuring signals. What you see now is that you get modulated sine and cosine measuring signal which you are also called envelope curve. It's now up to the resolver digital converter RDC to evaluate current rotor position and the rotation speed from the signal curves.
现在，让我们将时间基准设定到实际需求范围，并观察它们的测量信号。您现在看到的是得到调制的正弦和余弦测量信号，也可称为包络曲线。然后，由旋转变压器数字转换器R/D来根据信号曲线评估当前转子位置和转速。
Why use a resolver?
为什么要用旋变?
Well, unlike encoders, resolvers have no electronic components and therefore robust against soiling, vibrations and work safely even within a wide temperature range. This makes them highly reliable and environmentally resistant.
与编码器不同，由于没有旋变无电子元件，因此即使在较宽的温度范围内也能抵抗污染、振动等影响，安全地进行工作。这使它们具有高度的可靠性和环境适应性。
总结
结构上，可以把旋变理解成一种测量角度的小型交流电动机，用来测量旋转物体的转轴角位移和角速度，由定子和转子组成。
原理上，与普通变压器类似，区别在于普通变压器原边、副边绕组是相对固定，即输出/输入为常数，而旋变输出/输入随转子角位移相对位置的改变而改变，输出绕组的电压幅值与转子转角成正弦、余弦函数关系。其中，定子绕组作为变压器原边，接受励磁电压，转子绕组作为变压器副边，通过电磁耦合获得感应电压
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