Optimized Resonators for Piezoelectric Power Conversion

• Published in: IEEE open journal of power electronics Vol. 2; pp. 212 - 224
• Main Authors: Braun, Weston D., Stolt, Eric A., Gu, Lei, Jeronimo Segovia-Fernandez, Jeronimo, Chakraborty, Sombuddha, Lu, Ruochen, Rivas-Davila, Juan M.
• Format: Journal Article
• Language: English
• Published: IEEE 2021
• Subjects: Capacitance; DC-DC power converters; Inductors; Integrated circuit modeling; piezoelectric devices; Resonators; RLC circuits; Switches
• ISSN: 2644-1314; 2644-1314
• DOI: 10.1109/OJPEL.2021.3067020

The performance of inductors at high frequencies and small sizes is one of the largest limiting factors in the continued miniaturization of dc-dc converters. Piezoelectric resonators can have a very high quality factor and provide an inductive impedance between their series and parallel resonant frequencies, making them a promising technology for further miniaturizing dc-dc converters. In this paper we analyze the impact of resonator parameters on the performance of the piezoelectric resonator based dc-dc converter, derive the optimal load impedance and efficiency limits, and analyze the impacts of varying conversion ratio and load impedance. This work is accompanied by a prototype dc-dc converter using a piezoelectric resonator fabricated from lithium niobate. The piezoelectric resonator has a quality factor of 4178 and a coupling coefficient, <inline-formula><tex-math notation="LaTeX">k_t^2</tex-math></inline-formula>, of 29%. The converter is able to achieve high efficiency zero voltage switching and a continuously variable conversion ratio without the use of any discrete inductors. It achieves a maximum power output of 30.9 W at an efficiency of 95.2% with a power density of 6.76 <inline-formula><tex-math notation="LaTeX">\frac{\text {W}}{\text {cm}^3}</tex-math></inline-formula>.