旋转变压器输出信号自动标定

Automatic calibration of output signals from resolvers

旋转变压器输出以角位置正余弦为包络的调幅信号,一般通过检波与解调获取角位置及角速度信息.检波后信号往往存在直流偏置、幅值不等和相位偏移,对其进行标定是实现高精度解调的前提.针对检波后信号的标定问题,提出了一种离线自动标定方法.设计状态观测器,对检波后两路信号的幅值及直流偏置进行估计;构造二元二次目标函数,利用梯度估计法,获取相位偏移.理论分析表明,与仅采用梯度估计法相比,此方法避免了目标函数多解问题.实验结果表明,此方法参数选择容易,具有较高的精度,是完全可行的.

The outputs of resolvers are amplitude modulated signals, one with the sine and the other with the cosine of angular position. In order to obtain the rotor angular position and velocity information, detection and demodulation are required. However, detection results often contain dc offsets, amplitude deviation and non-orthogonal phase shift. To enhance demodulation accuracy, a calibration procedure is necessary before de- modulation. An offline automatic calibration method was introduced to meet this need. A state observer was in- troduced to estimate the amplitude and de offsets of the detected signals. To estimate the phase shift, a two variable quadratic goal function was constructed, which can be resolved by gradient estimator. Compared with the method that using only gradient estimator, the multiple-roots problem was resolved. The validity of the cal- ibration method was proved by experiments. The proposed method doesn＇t need complicated parameter selec- tion, and converges to single root with high accuracy.