Evaluating Piezoelectric Materials and Vibration Modes for Power Conversion

Piezoelectric components offer several potential advantages to power conversion including high power density and efficiency capabilities compared to magnetics at small scales. Converter architectures have been developed for efficient utilization of piezoelectrics, but without fundamental criteria for designing the piezoelectric components themselves. In this article, we derive figures of merit for the achievable efficiencies and power handling densities of piezoelectric materials and vibration modes based on realistic utilization in a power converter. These figures of merit are likewise accompanied by geometry conditions that serve as guidelines for high-efficiency high-power-density piezoelectric resonator design. We demonstrate use of these metrics to evaluate commercially available PZT and lithium niobate materials across seven vibration modes, and we validate the figures of merit and geometry conditions with numerical solutions of converter operation and experimental results. The proposed figures of merit are concluded to be highly representative metrics for the capabilities of piezoelectrics in power conversion, and these capabilities are shown to have favorable scaling properties for converter miniaturization.