声波测井压电换能器多频点阻抗匹配技术研究

Research on broadband impedance matching technique of acoustic logging piezoelectric transducer

针对声波测井压电换能器的多频点阻抗匹配技术展开研究,首先采用多模态等效电路精确描述了换能器的导纳特性;然后通过分析多模态阻抗匹配理论,设计电感-电容复合阻抗匹配网络,并结合换能器等效电路进行参数优化和电路仿真。实验表明,相比于换能器没有阻抗匹配的测试结果,该阻抗匹配技术可大幅提高换能器在谐振频率附近多个频率处的有功功率,频带内的有功功率平均提高了30倍,从而改善换能器的激励带宽和激励效率,提高测井仪器的适应性、探测深度和分辨率。

In this paper,the multi-frequency points impedance matching technique of the acoustic logging piezoelectric transducer is studied.First,the multi-frequency points admittance characteristics of the transducer are accurately described by using the multimode equivalent circuit.Then,the theory of multi-frequency points impedance matching is analyzed,and the inductance-capacitance composite impedance matching network is designed.On this basis,by combined with the equivalent circuit of transducer the parameter optimization and the circuit simulation are carried out.Experiments show that compared with the test results of the transducer without impedance matching,the proposed impedance matching technique can greatly improve the active power of the transducer at several frequencies near the resonant frequency and increases the active power in the frequency band averagely by 30 times.In this way,the excitation bandwidth and efficiency of the transmitting transducer are greatly improved,and the adaptability,detection depth and resolution of the logging instrument are improved.