Collaborative Research: Integrated Piezoelectric Resonators: Changing the Paradigm of Power Conversion for Transportation

This NSF project aims to develop a new generation of integrated piezoelectric resonator-enabled power converters that reduce the size, weight, and energy loss of incumbent power electronics used in electrified transportation. The project will bring transformative change by replacing bulky magnetic inductors and transformers, often the heaviest and least scalable parts of today’s converters, with microfabricated piezoelectric resonators that store and transfer energy through controlled mechanical vibration, enabling higher switching frequencies and higher power density. This will be achieved by co-designing resonator devices, power-converter topologies, controls, and packaging so that the electrical and mechanical subsystems operate as a single integrated energy-conversion platform. The intellectual merit of the project includes establishing fundamental design rules and validated models that connect resonator material, geometry, and performance to converter efficiency, stability, and scalability at megahertz frequencies. The broader impacts of the project include advancing efficient, compact power conversion to accelerate clean electric vehicles and emerging electric aircraft, improving national energy efficiency, and providing openly accessible educational modules, hands-on research training, and public outreach activities. The proposed research addresses a core bottleneck in modern converters: magnetic components, such as inductors, dominate size/weight and incur losses that make it difficult to simultaneously increase power density, maintain high efficiency, and meet stringent size/weight limits. Piezoelectric acoustic resonators can offer much higher energy density, but they are not drop-in substitutes because their impedance is frequency-selective and can be affected by spurious modes, parasitics, temperature drift, and nonlinearity. The project integrates two coupled research thrusts. First, the team will design and demonstrate compact, high-coupling, low-loss acoustic resonators and piezoelectric transformers using lithium niobate and lithium tantalate, which our initial studies suggest can outperform other piezoelectric materials like conventional PZT, and multilayer piezoelectric stacks to increase power handling. Second, the team will develop resonator-compatible power conversion architectures and control/drive electronics using wide band gap semiconductor switches to operate efficiently at megahertz-class switching frequencies, scale power using multi-resonator approaches, and avoid regions impacted by spurious modes. To enable practical deployment, the work will establish wafer-level microfabrication and bonding processes, develop packaging that reduces parasitics and thermal resistance, and quantify reliability limits through safe-operating-area and failure-mode characterization over temperature and time. The expected outcomes are scalable design methodologies and prototype demonstrations that validate an integrated, manufacturable path to high-efficiency, high-power-density converters for transportation and other compact systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2530884 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Juan Rivas Davila | Institution: Stanford University, STANFORD, CA | Award Amount: $300,000 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2530884 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2530884.html