Shrinking magnetic components to increase power converter density faces an up-hill battle against the physics of inductors at small volumes and high frequencies. As a solution, storing energy in mechanical vibrations via the piezoelectric effect enables power converter topologies devoid of magnetic components. Due to their intrinsic material properties, piezoelectric devices used for power conversion can be efficient and power-dense. Or can they? Previous analyses of piezoelectric materials for power conversion and modelling of piezoelectric-based power converters rely on small-signal measurements, and prototype converters have shown efficiency diverging from the small-signal model at high power. Moreover, the theorized material limits of piezoelectrics have little experimental backing. This paper presents an apparatus for testing the non-linearities and material limits of piezoelectric materials at high power, measures the large-signal performance of two common materials for piezoelectric power conversion, PZT and lithium niobate (LN), and gives an improved model to account for device non-linearities.
