DESC0023822

Statement of the problem – The proposed Advanced Multiport Solar Converter (AMSC) project directly addresses the problem the Department of Energy (DOE) presents in its Topic C56-15(a) – to incorporate wide-bandgap-based devices into a power conversion topology “designed to integrate and optimize distributed energy resources – in particular solar generation – with energy storage capabilities and infrastructure for electric vehicle charging.” As stated in the topic description, such advances have the potential to “accelerate decarbonization of the electricity and transportation systems.” How this problem is being addressed – Our approach to addressing this problem is to develop an advanced power converter with a topology uniquely suited to take advantage of the benefits offered by gallium nitride (GaN) high electron mobility transistors (HEMTs), using a Modular Multiport Converter (MMC) design that enables a broad range of power conversion applications. Our proposed research will include evaluation of multiport converter designs that can reduce the number of converter devices required to integrate multiple distributed energy resources (DERs), focusing on use of GaN devices to improve efficiency and reduce converter size. Our focus is on GaN HEMTs because they offer high electron mobility and critical electric field strength, which can reduce thermal losses and enable use of smaller heat sinks, transistor structures, and filter components. The MMC design approach will help overcome any limitations on the voltage capacity of GaN devices, potentially making our GaNbased converter competitive with silicon carbide-based converters, even for higher voltage applications. What will be done in Phase I – RockeTruck and Sandia National Laboratories will collaborate to evaluate four main converter design features: use of GaN semiconductors, the MMC architecture, multiport design, and utilization of a triple active bridge (TAB) topology to facilitate this approach. After completing a top-level study to confirm the feasibility of this overall approach, we will perform modeling and design analysis to define converter components in more detail and to develop alternative layouts. Trade studies will be performed in five key areas: Switching Devices, Filter Capacitors and Magnetic Components, Thermal Management, Electrical and Electronic Controls, and Structural & Mechanical Integration. Once the optimal AMSC design is selected, RockeTruck's team will develop detailed plans for manufacturing and validation of a prototype AMSC during Phase II. Commercial Applications and Other Benefits – The planned AMSC advances will simplify converter manufacturing and enable converters to be cost-effectively manufactured domestically by reducing the size and complexity of heat sinks, inductors, and capacitors. This will in turn drive down the costs of Integrated Energy Systems that use the new converter technology, helping to stimulate greater adoption of solar photovoltaic (PV) power, battery energy storage, and electric vehicle (EV) charging. These outcomes will reduce greenhouse gas emissions, toxic pollutants, and dependence on fossil fuels, which in turn will help offset global warming and improve public health, while creating new economic opportunities for domestically-produced sustainable energy systems. Key Words – converter, solar inverter, DC-to-DC converter, gallium nitride, wide bandgap semiconductors, solar PV, energy storage, electric vehicle charging, microgrids. Summary for Members of Congress – Achievement of national sustainable energy goals and equitable energy outcomes will require technological advances to make deployment of solar PV and other DERs simpler and more affordable. The proposed AMSC project will help achieve this by driving down the cost of procuring and integrating the power conversion devices required to efficiently perform the power conversion required to integrate solar PV with battery storage, EV charging, and other DERs. This will reduce America's reliance on fossil fuels and result in significant reductions in emissions of toxic substances and greenhouse gases.