FPeT: Framework for designing piezoelectric transformer power supplies

Most electrical equipment requires a power supply which usually incorporates a magnetic transformer to provide safety isolation and to step up or step down the input voltage. Piezoelectric transformers (PTs) offer an exciting alternative to conventional transformers particularly in applications requiring high power density, low electromagnetic interference and high temperature operation. Their widespread adoption is hindered, however, by the need for power supply designers to possess knowledge and training in both materials science and power electronics, combined expertise that is rarely found in industry or even academia. This lacking knowledge base represents a real impediment for power supply manufacturers who may wish to adopt PT technology and consequently PTs have only seen marginal market penetration.

The project addresses these issues by producing a multi-physics design framework which provides abstraction from the fundamental science and therefore allows the design engineer to focus on the overall system design. The framework converts a high-level power supply specification into a PT power supply solution through a series of circuit and materials based transformations. An optimisation process (using evolutionary computing and finite element analysis) produces a fully characterised final design. The output of this process includes a circuit design and a "recipe" for the piezoelectric transformer, including materials and construction details presented in a format suitable for manufacture. The framework will be encapsulated in a user-friendly software design tool and validated against real-world power supply applications suggested by the project's industrial partners thereby ensuring the relevance of the research.

The research, which will transcend the traditional barriers between electrical engineering and materials science, has an investigatory team with expertise in both areas. As well as developing a framework, the research will develop novel piezoelectric materials particularly suited to high temperature operation, finding promise in a number of application areas including aerospace, oil/gas exploration, electric vehicles and for remote monitoring in harsh environments. Additionally, the need for environmentally damaging lead-based PTs will be diminished through the development of new materials which comply with Restriction on Hazardous Substances 2016.

The research programme will culminate in an open workshop where industry and academic researchers can learn about PT power supplies and evaluate the design tool for themselves. To ensure that the research remains industrially relevant we have partnered with several leading companies who will provide expertise and commercial drive and in return they will receive proof-of-concept power supplies ready for commercialisation.

This project's impact will be felt across several domains. Foremost, the development of the framework and its embodiment within a software design tool lowers the barriers to market entry for UK PLC. The UK is already a world leader in many innovative technologies sectors (including instrumentation, aerospace, medical). Piezoelectric transformer (PT)-based power supplies units (PSUs) will facilitate a step change in performance in a number of these areas owing to their reduced size, ability to operate in high temperature environments and lack of magnetic sensitivity. For the project partners specifically, this proposal will provide a low risk platform through which they can evaluate piezo technologies for their applications, thereby propelling their improved, PT-augmented technologies up the TRL ladder. To assist this impact, their membership of a steering group will guide the project towards real-world high-impact demonstrators.

The project treats the PT PSU design holistically, requiring expertise in PSU design and in electroceramic manufacturing. For academics worldwide, this valuable approach develops a new perspective accounting for what is simultaneously achievable in both the materials and electrical domains. This novel design approach may be replicated by other researchers, providing a lower entry point to PT power supplies and providing a benchmark to measure progress against. The novel materials, analytical models and optimisation procedures developed during this work will be transferable to researchers in a wide range of disciplines.

Through this project, the University of Sheffield will cement its position as a national leader in power electronics and electroceramics, will be propelled to the forefront of PT research worldwide and will strengthen its interdepartmental research links. The research staff involved (PDRAs, investigators, technical staff) will have unique interdisciplinary skills which will benefit future research at Sheffield and inform their teaching.

The mutual secondments between Sheffield and Prof Andersen's leading team at DTU, Copenhagen will facilitate expert knowledge exchange and build a strong relationship between two institutions. DTU has unique relationships with a number of local industries, keen to adopt PT technologies. Sheffield's secondment will allow its researchers to interact directly with these industries, while learning from DTU's own expertise. DTU will receive first-hand experience and expertise in the novel framework and contribute to the design tools and demonstrators. Meanwhile, a visiting researcher from Denmark will be invited to the UK to provide a new perspective on our research. Both visitors will therefore have a broadened knowledge base which will improve their employability and provide benefit to their respective institutions.

The tutorial workshop held towards the end of the project will provide a showcase for the framework and offer hands-on experience in PT design to industrialists and academics. The aim of this tutorial is to break down the barriers to PT adoption thereby encouraging industrial proof-of-concept research which draws on the outcomes of this project, accelerating progression through the technology readiness levels and pushing the market forwards.

Several leading companies have already pledged their support to this exciting project and together they have committed over £95k to support the production and evaluation of industrially relevant demonstrators for their cutting edge applications. The collaboration between Ionix and Converter Technology facilitated by the project will create additional synergies, for example, the opportunity for Ionix's expertise in high temperature materials to be matched to Converter Technology's high temperature power supplies for harsh environments. Meanwhile the involvement of HMGCC demonstrates the significant positive impact this work will have in national security.