Development of impedance measurement system of piezoelectric devices

Based on the equivalent circuit model of piezoelectric devices, using the theory of admittance circle diagram to measure the transducer impedance parameter and the theory of zero-cross detection to measure the phase difference, an impedance measuring system of piezoelectric devices performance parameters is developed. In the developed system, a sine wave with fixed amplitude and variable frequency is generated by a microcontroller. After being amplified by power amplifier, the piezoelectric device is driven to vibrate by the generated sine wave at high frequency. Then, the microcontroller collects the voltage, current and phase difference during the working process of piezoelectric devices. The collected signals are transmitted to PC by the serial port. Based on the man-machine interactive interface of Labview, the impedance characteristic parameters and graphics of piezoelectric devices can be displayed. The experimental results show that the developed system is capable of measuring the main parameters of piezoelectric devices and of displaying the dynamic characteristic impedance curves. The developed impedance measurement system can also be used for the parameters testing and performance evaluation of piezoelectric devices.