Transportation accounts for 27% of our nation's total energy consumption, 71% of our petroleum consumption, and 34% of our total greenhouse gas (GHG) emissions, based on EIA data. Increased adoption of electric vehicles (EVs) will reduce our transportation-related energy consumption, carbon emissions, and our dependence on foreign oil. EVs achieve these benefits by operating on electrical energy stored from our nation’s increasingly low-carbon electric grid. However, the batteries which store the energy are costly, heavy, and take hours to fully charge, thus limiting the adoption of EVs. A wireless charging infrastructure that is powerful, highly efficient, and easy to use affords tremendous potential for increased adoption of EVs.
Project Innovation + Advantages:
The University of Colorado, Boulder (CU-Boulder) proposes to develop a capacitive wireless power transfer (WPT) architecture to dynamically charge EVs. Dynamic charging poses serious technical challenges. Transmitters must be connected to the plates in the road while rectifiers and battery charging is integrated with the plates in the vehicle. While energy transfer through the air is efficient, the large distance between the embedded vehicle plates and the road results in a weaker pairing between the two. To effectively transfer kilowatts of power without exceeding safe voltages, the operating frequency of the resonant inverters has to be very high. Today’s WPT systems operate with resonant magnetic fields focused with hefty ferrite cores and losses in these ferrites limit the frequency at which these systems can operate to less than 150 kHz. This project focuses on capacitive WPT with potentially higher efficiency than resonant inductive power transfer, while reducing size and cost. The team will develop a novel MHz frequency capacitive WPT system that safely operates within the industrial, scientific, and medical (ISM) radio spectrum. The team's WPT technology aims to improve EVs by reducing the need for expensive and bulky on-board batteries, enable unlimited driving range, and accelerate electric vehicle penetration. The project aims to design a 1-kW 12-cm air gap capacitive WPT, which targets >90% efficiency and 50 kW/m2 power transfer density, a power density improvement of 2 over current methods.