Low-cost battery impedance monitoring for more efficient and reliable electric vehicles

The urgent global demand for clean and sustainable energy generation and for a dramatic decrease in polluting emissions from vehicles has recently boosted the development of battery and fuel cell technology for electric and hybrid vehicles.

The development of battery technology has now become a priority for the UK Government, as confirmed by the investment of £246 million in 4 years for the ‘Faraday Challenge’, part of the Industrial Strategy Challenge Fund launched a few months ago. The rationale for this funding is that battery technology is not ready yet for a massive penetration of electric vehicles into the market, as cost, efficiency, energy density and reliability need to be significantly improved.

Accurate but low-cost measurement techniques for in-situ battery condition monitoring represent a fundamental contribution towards the achievement of such important goals. Indeed, while accurate and sophisticated measurements are typically carried out in laboratory tests, the monitoring systems installed in commercial products (including electric vehicles) are much simpler and significantly less accurate and reliable.

Recent research carried out by Dr Ferrero and his team has proposed an innovative and promising solution, based on the use of smart power converters, to achieve low-cost but accurate battery monitoring in electric vehicles (and other applications as well), since power converters are already available in almost all commercial products. The monitoring capability would then be embedded in the power converter, which would perform impedance measurements on the battery while converting the generated power, allowing a reliable estimation of the battery state of charge (SOC) and state of health (SOH) at almost zero additional cost.

Although preliminary feasibility studies have been already successfully concluded on small-scale batteries and fuel cells, the development of a full proof-of-concept prototype requires a dedicated research project to address the measurement challenges that arise from the need to continuously monitor a large number of cells in the battery packs, and to carry out impedance measurements in a wide frequency range, from millihertz to kilohertz, which require advanced signal processing techniques to deal with the non-steady-state operating conditions of the battery, subject to a continuously changing load in electric vehicles.

The project has a strong multi-disciplinary nature, as it involves modelling of electrochemical processes, design of power converters and development of hardware and software for signal acquisition and processing. Students with backgrounds in electrical engineering, electronics, chemical engineering or related disciplines are all welcome to apply.

Because of its multi-disciplinary nature, the student will be supervised by an inter-disciplinary team of academics within the University of Liverpool, namely Dr Roberto Ferrero (primary supervisor) from the Department of Electrical Engineering & Electronics, Prof Laurence Hardwick from the Stephenson Institute for Renewable Energy, and Dr Edoardo Patelli from the Institute for Risk and Uncertainty. They will provide all the necessary theoretical and practical support, and will allow the student to benefit from engaging with inter-disciplinary research communities, including a Centre for Doctoral Training in Risk and Uncertainty.