Modeling the impact of battery degradation within lifecycle cost based design optimization of heavy-duty hybrid electric vehicles

The optimal design of hybrid electric vehicle (HEV) powertrains from a systems perspective is critical to realize the maximum benefits for a given application. This is particularly true in the heavy-duty vehicle space where the major challenges are: (i) greater emphasis on economic viability, (ii) reluctance to take on risk associated with new technologies, and (iii) numerous diverse applications that preclude a one-size-fits-all approach to hybrid-electric powertrain design. Past studies on HEV powertrain design have either ignored battery degradation, or failed to holistically capture its impact from a lifecycle cost perspective. The focus of this effort is the development of a model-based framework that enables parametric optimization of the design and control of hybrid electric vehicles while accounting for the degradation of the lithium-ion battery and its impact on the total cost-of-ownership of the vehicle. Two different implementations of such a framework are described. The first implementation explores a very high-fidelity approach to enable engineering design optimization across a small parameter space. It captures the impact of battery degradation on fuel consumption and battery replacements over the vehicle life by incorporating a high-fidelity electrochemical battery model capable of predicting degradation, and degraded performance, into the powertrain simulation. An electric motor and battery size optimization problem is studied for a parallel HEV transit bus application. Results show that different optimal component sizes are obtained when different optimization objectives, such as net present value, payback period, internal rate of return, or simply the day 1 fuel consumption, are considered. Accounting for the battery degradation in the powertrain simulations shows fuel consumption increasing by up to 10% from day 1 to end-of-life of the battery. These results highlight the utility of the proposed implementation in enabling better design decisions as compared to methods that do not capture the evolution of vehicle performance and fuel consumption as the battery degrades. However, the high-fidelity electrochemical battery degradation model and the interval-by-interval simulation approach used in this implementation are computationally too expensive for a large-scale design study. In contrast, the second implementation uses a simpler empirical battery model to enable a large-scale study over a 10-parameter design space, over multiple architectures and vehicle applications. This implementation is designed to aid heavy-duty vehicle and powertrain component manufacturers in identifying market opportunities and planning future products. The design space explored in this work includes three powertrain component sizing parameters, four control strategy parameters and three vehicle uncertainty parameters. Multiple drive cycles were simulated across the Class 5-7 medium-duty truck and Class 7-8 transit bus applications for both parallel and series plug-in hybrid electric vehicle (PHEV) powertrain architectures with charge depleting and charge sustaining modes of operation. These simulation results were then evaluated for real-world economic viability under different economic assumptions corresponding to the 2015, 2020, 2025 and 2030 time frames. Sensitivity of the economic viability of solutions was also studied with respect to the vehicle uncertainty parameters, economic assumptions and vehicle utilization assumptions. (Abstract shortened by ProQuest.

Impact of propulsion system R and D on electric vehicle performance and cost

The efficiency, weight, and manufacturing cost of the propulsion subsystem (motor, motor controller, transmission, and differential, but excluding the battery) are major factors in the purchase price and cost of ownership of a traffic-compatible electric vehicle. The relative impact of each was studied, and the conclusions reached are that propulsion system technology advances can result in a major reduction of the sticker price of an electric vehicle and a smaller, but significant, reduction in overall cost of ownership

Comparison of energy consumption and costs of different HEVs and PHEVs in European and American context

This paper will analyse on the one hand the potential of Plug in Hybrid electric Vehicles to significantly reduce fuel consumption and displace it torward various primary energies thanks to the electricity sector. On the other hand the total cost of ownership of two different PHEV architectures will be compared to a conventional cehicle and a HEV without external charging

Using mobility information to perform a feasibility study and the evaluation of spatio-temporal energy demanded by an electric taxi fleet

Half of the global population already lives in urban areas, facing to the problem of air pollution mainly caused by the transportation system. The recently worsening of urban air quality has a direct impact on the human health. Replacing today’s internal combustion engine vehicles with electric ones in public fleets could provide a deep impact on the air quality in the cities. In this paper, real mobility information is used as decision support for the taxi fleet manager to promote the adoption of electric taxi cabs in the city of San Francisco, USA. Firstly, mobility characteristics and energy requirements of a single taxi are analyzed. Then, the results are generalized to all vehicles from the taxi fleet. An electrificability rate of the taxi fleet is generated, providing information about the number of current trips that could be performed by electric taxis without modifying the current driver mobility patterns. The analysis results reveal that 75.2% of the current taxis could be replaced by electric vehicles, considering a current standard battery capacity (24–30 kWh). This value can increase significantly (to 100%), taking into account the evolution of the price and capacity of the batteries installed in the last models of electric vehicles that are coming to the market. The economic analysis shows that the purchasing costs of an electric taxi are bigger than conventional one. However, fuel, maintenance and repair costs are much lower. Using the expected energy consumption information evaluated in this study, the total spatio-temporal demand of electric energy required to recharge the electric fleet is also calculated, allowing identifying optimal location of charging infrastructure based on realistic routing patterns. This information could also be used by the distribution system operator to identify possible reinforcement actions in the electric grid in order to promote introducing electric vehicles

Forecasting the state of health of electric vehicle batteries to evaluate the viability of car sharing practices

Car sharing practices are introducing electric vehicles into their fleet. However, literature suggests that at this point shared electric vehicle systems are failing to reach satisfactory commercial viability. Potential reason for this is the effect of higher vehicle usage which is characteristic for car sharing, and the implication on the battery state of health. In this paper, we forecast state of health for two identical electric vehicles shared by two different car sharing practices. For this purpose, we use real life transaction data from charging stations and different electric vehicles’ sensors. The results indicate that insight into users’ driving and charging behaviour can provide valuable point of reference for car sharing system designers. In particular, the forecasting results show that the moment when electric vehicle battery reaches its theoretical end of life can differ in as much as ¼ of time when vehicles are shared under different conditions

Plugging the gap – can planned infrastructure address resistance to adoption of electric vehicles?

Non peer reviewe

Comparative Analysis of European Examples of Freight Electric Vehicles Schemes—A Systematic Case Study Approach with Examples from Denmark, Germany, the Netherlands, Sweden and the UK.

E-Mobility is a hot topic, in the public policy area as well as in business and scientific communities. Literature on electric freight transport is still relatively scarce. Urban freight transport is considered as one of the most promising fields of application of vehicle electrification, and there are on-going demonstration projects. This paper will discuss case study examples of electric freight vehicle initiatives in Denmark, Germany, the Netherlands, Sweden and the UK and identify enablers and barriers for common trends