Simulation and control of thickness-mode piezoelectric transducers
A new general three-port systems model of the thickness-mode piezoelectric transducer is proposed. This model is considered to have several substantial advantages over existing modelling techniques. In particular, it may be readily used to explain the underlying physical operation of ultrasonic transducers. The model has been developed in such a manner that the effects of arbitrary electrical load and source elements and mechanical matching layers may be incorporated. The use of z-transforms in the calculation of the transducer transient response has been investigated. This has resulted in a fast, efficient and accurate method for calculating the transducer response to arbitrary transient excitation. In the course of this work, the model has been verified extensively by computer simulation and experimental measurement. Excellent agreement was obtained between the theoretical and practical results for a comprehensive range of electrical and mechanical configurations. Techniques for controlling piezoelectric transmitters electrically have been investigated. This involves the generation of a precisely defined force transient, by exciting the transducer system with a calculated voltage. These methods were verified by simulation and experiment, and it is concluded that they offer a significant improvement over existing transducer control strategies. Finally, it is considered that the techniques and models proposed have made a significant contribution to the investigation of thickness-mode piezoelectric devices.