Precise experimental determination of electrical equivalent circuit parameters for ultrasonic piezoelectric ceramic transducers from their measured characteristics

Abstract

The letter is devoted to a method for determining electric equivalent circuit parameters of piezoelectric ceramic transducers from their resonance characteristics. These parameters represent equivalents of mechanical damping, effective weight of the oscillating element, compliance of the mechanical element and static capacitance associated with the transducer material. This method is considered cost efficient, focuses on transducers commonly available on the market and is presented on a specific transducer – transmitter. The acquired parameters are important for performing subsequent simulations and defining their suitability for a particular application. However, these parameters are not included in the usual technical documentation of the commercially available piezoelectric ceramic transducers. The key part of this letter is an iterative process of finding the parameters. Before starting the iteration process, it is very important to set default values of these parameters. Then, a linearized system of equations, based on expressing a real part of the impedance, is used to determine these parameters. The advantage of this method is its simplicity to measure only the two above-mentioned characteristics, from which the required parameters can be then calculated. Thus, there is no need for expensive circuit analyzers, which are able to determine these parameters directly. Although the iterative process includes a large number of steps, and therefore can be relatively time consuming, it can be performed on a commercially available computer technology.