Abstract:

The existing measurement methods of equivalent circuit parameters of piezoelectric transducers are complex and easy to affect the normal operation of transducers， so it is difficult to measure the equivalent circuit parameters of transducers in real time. In order to solve this problem， based on the analysis of the phase-frequency characteristics of the transducer， a real-time measurement method of the equivalent circuit parameters of the piezoelectric transducer was proposed based on the least square fitting， and the corresponding measurement system was designed. The series resonant frequency of the transducer was locked by frequency sweep and peak current detection， and the driving frequency was fine-tuned several times near it to obtain the impedance angles at both ends of the transducer at the corresponding frequency. Based on the minimum residual sum of squares， a set of model parameters with the highest degree of fitting was obtained， and the equivalent circuit parameters of the piezoelectric transducer were solved by combining the deduced calculation formula. Using simulation and experiments to test the measurement method. The simulation results show that the relative error of the measurement results relative to the impedance analyzer is within ±1%. The experimental results further validate the effectiveness of the measurement method. The measurement results have a relative error of within ±4% compared to the impedance analyzer， and are applicable in cases of load variation. The program running time is 185\mathrm{\mu }\mathrm{s}. This method has high measurement accuracy and fast operation speed， enabling real-time measurement of the equivalent circuit parameters of piezoelectric transducers.

Key words: piezoelectric transducer, equivalent circuit parameter, real time measurement, data fitting, least squares method

摘要：

现有压电换能器等效电路参数测量方法较复杂且容易影响换能器的正常工作，难以做到对换能器等效电路参数的实时测量。在分析换能器相频特性的基础上提出了一种基于最小二乘法拟合的压电换能器等效电路参数实时测量方法，并设计了相应的测量系统。该方法通过频率扫描与峰值电流检测锁定换能器的串联谐振频率，在其附近数次微调驱动频率，获取对应频率下的换能器两端阻抗角，以最小残差平方和作为判断依据，得到一组拟合程度最高的模型参数，并结合所推导的计算公式求解出压电换能器等效电路参数值。使用仿真和实验对测量方法进行了检验，仿真结果表明，测量结果相对于阻抗分析仪的相对误差在±1%以内；实验结果进一步验证了该测量方法的效果，测量结果与阻抗分析仪相比其相对误差在±4%以内，且适用于负载变化的情况，程序运行时间为185 \mathrm{\mu }\mathrm{s}。所提方法测量精度较高，运算速度快，能够实现压电换能器等效电路参数的实时测量。

关键词: 压电换能器, 等效电路参数, 实时测量, 数据拟合, 最小二乘法