Design and Implementation of an Ultrasonic Transducer Driving Circuit with Frequency Calibration Using Current Integrating Method
Date Issued
2014
Date
2014
Author(s)
Kang, Yi-Chen
Abstract
In this thesis, a calibration method which traces the proper operating frequency of an ultrasonic transducer is proposed. The ultrasonic transducer converts electrical energy into acoustical energy and vice versa. However, the characteristics of piezoelectric materials will change with the environment, the process deviation, the damage of the material and so on. Thus, the proper operating frequency of the ultrasonic transducer will not be the same in different circumstances. The drift of the proper operating frequency may decrease the strength of the ultrasonic wave. In this thesis, a driving circuit for the ultrasonic transducer with automatic frequency calibration has been designed. A control circuit detects the phase difference between the driving voltage and the input current to obtain the proper operating frequency. The transducer is driven by square wave in order to reduce the effect of the parallel capacitance, which gives the input current an unwanted phase shift. An integrator collects the information from the phase difference and the input current amplitude to extend the frequency tracing range. Finally, we conducted experiments with three ultrasonic transducers which have different characteristics. The experimental results show that the operating frequencies are calibrated with errors less than 0.86 %.
Subjects
壓電效應
超音波換能器
頻率校正
驅動電路
電流積分方法
Type
thesis
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