提高压电换能器导纳圆测量精度的方法研究

Improvement on Measurement Accuracy of Piezoelectric Transducer Admittance Circle

不同压电换能器的动态电阻、电容、电感和静态电阻、电容的值不同,这些参数均可从其对应的导纳圆中得到。分析了导纳圆测量中的两个重要影响因素:A/D转换器的量化误差、测量电阻。为提高导纳圆的测量精度,量化误差不变时不同的压电换能器需选择不同的测量电阻以保证所测量的两路正弦信号有适当的幅值比和相位差。测量电阻的值为压电换能器动态电阻值的0.15～3.5倍时,导纳圆半径的相对误差小于0.5%,测量电阻为动态电阻的0.7倍时导纳圆的相对误差最小。

Different piezoelectric transducers have different dynamic resistance,capacitance,inductance and static resistance,capacitance.These parameters can be obtained from the corresponding admittance circle.Two factors of quantizing error of A/D converter and measurement resistance in the admittance circle measurement have been analyzed in this paper.In order to improve measurement accuracy of admittance circle,different piezoelectric transducers need to choose different measurement resistances to ensure that two sinusoidal signals have right amplitude ratio and phase difference when the quantizing error is a constant.When the measurement resistance is in the value between 0.15 to 3.5 times of piezoelectric transducer dynamic resistance,the relative error of the admittance circle radius is less than 0.5%.When the measurement resistance is 0.7 times of the dynamic resistance,the admittance circle has the minimum relative error.