Dielectric characteristics of electric vehicle traction motor winding insulation under thermal ageing

The electric motor is the heart of the electric vehicle. It is crucial that any occurring faults are detected promptly so that a catastrophic failure is avoided. At the same time, deep knowledge of the degradation mechanisms is required to allow maximum performance at minimum cost. This paper focuses on this balance. Statistical results from measurements of unaged and accelerated aged winding insulation samples provide information about the degradation processes, enabling steps toward a reliable prognosis model of the motor's remaining life

Comparative measurements of the energy consumption of 51 electric, hybrid and internal combustion engine vehicles

Accepted versio

Computational fluid dynamics modelling of an entire synchronous generator for improved thermal management

This study is the first in a series dedicated to investigating the airflow and thermal management of electrical machines. Owing to the temperature dependent resistive losses in the machine's windings, any improvement in cooling provides a direct reduction in losses and an increase in efficiency. This study focuses on the airflow which is intrinsically linked to the thermal behaviour of the machine as well as the windage power consumed to drive the air through the machine. A full computational fluid dynamics (CFD) model has been used to analyse the airflow around all major components of the machine. Results have been experimentally validated and investigated. At synchronous speed the experimentally tested mass flow rate and windage torque were under predicted by 4% and 7%, respectively, by the CFD. A break-down of torque by component shows that the fan consumes approximately 87% of the windage torque

Diving into the vertical dimension of elasmobranch movement ecology

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements

China's exceptionalism and the challenges of delivering difference in Africa

This article explores the notion of 'China's exceptionalism' in Africa, a prominent feature in Beijing's current continental and bilateral engagement. 'China's exceptionalism' is understood as a normative modality of engagement that seeks to structure relations such that, though they may remain asymmetrical in economic content they are nonetheless characterised as equal in terms of recognition of economic gains and political standing (mutual respect and political equality). This article considers the burden that the central Chinese government has assumed through its self-construction and mobilisation of a position of exceptionalism and, concurrently, the imperatives that flow from such rhetorical claims of distinctiveness in terms of demonstrating and delivering difference as a means to sustain the unity and coherence of these rhetorical commitments

Discretisation-free battery fast-charging optimisation using the measure-moment approach

The development of safe and reliable battery fast-charging protocols is one of the key technologies needed to reduce our over-reliance on fossil fuel energy storage. Existing charging algorithms are typically generated by discretising a lumped parameter battery model in time and then solving a constrained numerical optimisation problem. One of the main limitations with this approach is that its performance is reliant upon the granularity of the time discretisation; too coarse a discretisation gives an inaccurate solution where the constraints may be violated between time steps; too fine a discretisation gives a rapid growth in computational complexity. To overcome this trade-off, a discretisation-free approach to solving the optimisation problem is proposed. By exploiting recent developments in the field of measure-moment theory, the method is able to generate discontinuous charging profiles from numerical solutions of a convex optimisation problem, which intrinsically satisfy the physical conservation laws of the model. Numerical examples highlight the potential of the approach for efficiently generating fast-charging protocols

Techno-economic and behavioural analysis of battery electric, hydrogen fuel cell and hybrid vehicles in a future sustainable road transport system in the UK

This paper conducts a techno-economic study on hydrogen Fuel Cell Electric Vehicles (FCV), Battery Electric Vehicles (BEV) and hydrogen Fuel Cell plug-in Hybrid Electric Vehicles (FCHEV) in the UK using cost predictions for 2030. The study includes an analysis of data on distance currently travelled by private car users daily in the UK. Results show that there may be diminishing economic returns for Plug-in Hybrid Electric Vehicles (PHEV) with battery sizes above 20 kWh, and the optimum size for a PHEV battery is between 5 and 15 kWh. Differences in behaviour as a function of vehicle size are demonstrated, which decreases the percentage of miles that can be economically driven using electricity for a larger vehicle. Decreasing carbon dioxide emissions from electricity generation by 80% favours larger optimum battery sizes as long as carbon is priced, and will reduce emissions considerably. However, the model does not take into account reductions in carbon dioxide emissions from hydrogen generation, assuming hydrogen will still be produced from steam reforming methane in 2030.Fuel cell vehicle Electric vehicle Hybrid vehicle