Energy conversion models and characteristics under various inner connections of a novel packaged piezoelectric transducer for pavements

Abstract

The piezoelectric effect in piezoelectric transducers converts the mechanical energy into electrical energy to supply power to road facilities. The piezoelectric transducer designed in the 3–3 piezoelectric mode has been widely studied due to the consideration of power generation performance and load-bearing requirements. However, the conservative design of some external packages and the lack of theory in the internal connection design are two deficiencies of existing research on 3–3 piezoelectric mode transducers. Given the shortcoming of packages cannot make full use of the compressive properties of piezoelectric ceramics which weakens the energy conversion ability of the piezoelectric transducers, a novel piezoelectric transducer with full-pressure packaging was designed. For the lack of theoretical and systematic research on the spatial arrangement and electrical connection of piezoelectric materials inside piezoelectric transducers, from a theoretical point of view, the energy conversion models of piezoelectric transducers in four connection modes: stacked series, stacked parallel, array series, and array parallel were derived. Subsequently, through model verification tests, the influence of the four connection modes on the energy conversion characteristics of the piezoelectric transducer was systematically studied. Finally, the effect of connection mode on energy conversion was explained in a unified manner. Five methods of promoting the energy conversion of piezoelectric transducers were proposed. The study indicated that the connection mode affected the energy conversion of the piezoelectric transducer. Specifically, the maximum energy conversion potential of the piezoelectric transducer is only affected by the spatial arrangement. The electrical connection method determines the matching resistance, which can facilitate the piezoelectric transducer to exert the maximum energy conversion potential. In the stacked type, the peak energy conversion monotonously increases with the number of stacked layers, whereas the array type exhibits the opposite trend. Regardless of the spatial arrangement of the piezoelectric materials, when piezoelectric ceramics are connected in series, the optimal value of resistance increases with the number of piezoelectric ceramics, and the opposite is true when the connection is made in parallel. The normalization analysis pointed out that the connection mode affects the energy conversion of the piezoelectric transducer can be summarized as the volume index of the piezoelectric ceramic group affects its energy conversion. A larger ratio of height to diameter of the piezoelectric ceramic group can improve the energy conversion of the transducer. This article provides ideas for the packaging design of piezoelectric transducers and a theoretical reference for the design of internal piezoelectric ceramic connection methods.