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针对变极距电容位移传感器提出了一种双频激励方法。同时采用低频、高频正弦电压源激励平板发射电极,通过电容耦合效应将极距变化转换为双频调幅信号,并通过高阻抗缓冲、带通滤波、精密整流电路获得双路位移调制电压信号。采用数字信号处理器(DSP)同步采集双路位移调制电压信号以及参考位移信号,对高、低频激励方式下的位移检测分辨率、纹波、动态响应速度等性能进行了对比分析。实验结果表明:双频激励时,通道间耦合作用较小,低频激励方式在位移分辨率、测量范围、线性度、抗干扰等指标上显著优于高频激励;高频激励在动态响应速度上具有明显优势。
A dual frequency excitation method is proposed for variable capacitance capacitance displacement sensor. At the same time, the low-frequency and high-frequency sinusoidal voltage source is used to excite the plate emitter electrode, and the polar variation is converted to dual-frequency amplitude modulation signal through the capacitive coupling effect. The dual-path modulated voltage signal is obtained through high impedance buffering, bandpass filtering and precision rectification circuit. The performance of displacement detection resolution, ripple and dynamic response speed under high and low frequency excitation modes were compared by using digital signal processor (DSP) to synchronously acquire dual displacement modulation voltage signals and reference displacement signals. The experimental results show that the coupling effect between channels is small when dual-frequency excitation is applied, and the low-frequency excitation method is significantly superior to the high-frequency excitation in displacement resolution, measurement range, linearity and anti-jamming; Has obvious advantages.