What do you know about impedance analyzers and their parameters?
Ultrasonic element analyzer PV520A series is jointly developed by the Department of Automation of Tsinghua University and the Institute of Acoustics, Chinese Academy of Sciences, used for the comprehensive detection of piezoelectric ultrasonic devices and equipment. PV520A is a new generation of portable touch screen analyzer developed on the basis of PV70A.
The system can work in any voltage of AC220V-250V, power is 30W, the instrument comes with a special power supply, power supply socket is in the back of the instrument (the 5-core aviation plug). We could see many parameters in the touch screen of the impedance analyser, so what do you really know about them?
Resonance frequency Fs: the resonance frequency of series branch in equivalent circuit of piezoelectric transducer, under this frequency, the impedance of the piezoelectric transducer is minimal. Refer to the frequency value at “Fs” in the below graph.
Maximum conductance Gmax: the real part of the admittance of the resonant piezoelectric transducer, that is, the real admittance part at "Fs".
Half-power point F1 & F2: per the admittance circle graph, the real part is the frequency at Gmax/2, there are two frequency like this: F1 & F2, F1
Anti-resonance frequency Fp: the resonance frequency of parallel branch of piezoelectric transducer, under this frequency, the impedance of the piezoelectric transducer is maximum. Refer to frequency value at “Fp” in the above graph.
Free capacitance CT: the capacitance value of the piezoelectric device at 1kHz, this value is consistent with the value measured by the digital bridge.
Dynamic resistance R1: the resistance of the serial branch of piezoelectric transducer, R1=1/Gmax, Gmax is the maximum admittance.
Dynamic inductance L1:the inductance of the serial branch of a piezoelectric transducer, the formula: L1=R1/ 2π (F2-F1), R1 is dynamic resistance, F1 and F2 are the half-power points.
Static capacitance C0:C0=CT-C1, CT is free capacitance, C1 is dynamic capacitance. (Note: Static capacitance can also be calculated from the offset distance between the center of the admittance circle and the conductivity axis (G-axis), however, in real practice, the formula: C0=CT-C1 is often used. So, we use this formula here for the calculation of static capacitance.)
Planar electromechanical coupling coefficient Kp: this parameter is only used in piezoelectric ceramics; it reflects the parameters of the electromechanical coupling effect when the thin round plate is polarized and electrically excited along its thickness direction and doing the radial stretching vibration. The formula could be chosen in the software.
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