Evaluating Piezoelectric Materials for Power Conversion

Piezoelectric energy storage has several potential advantages for use in power conversion; it offers very high power density and efficiency capabilities, especially compared to magnetics at small scales. Converter architectures have been developed for efficient utilization of piezoelectrics, but without fundamental criteria for selecting the piezoelectric devices themselves. In this paper, we derive figures of merit for piezoelectric materials in power electronics based on achievable efficiency and power density, assuming realistic converter operation. We then apply these metrics to evaluate 51 commercially-available PZT piezoelectric materials and identify promising candidates. These figures of merit and their associated geometry conditions serve as guidelines for high-efficiency, high-power density piezoelectric resonator design, which we demonstrate and validate in LTSpice. With both mechanical efficiency and physical limits constrained, it is shown that piezoelectrics demonstrate favorable scaling properties for miniaturized power conversion.