Plug-in Hybrid Electric Vehicle Technology Research Articles

From NEDC to WLTP: Effect on the Energy Consumption, NEV Credits, and Subsidies Policies of PHEV in the Chinese Market

The switching from new European driving cycle (NEDC) to worldwide harmonized light vehicles test procedure (WLTP) will affect the energy consumption of plug-in hybrid electric vehicle (PHEV), and then affect the new energy vehicle (NEV) credit regulation and subsidy policy for PHEVs. This paper reveals the impact on energy consumption, NEV credit regulation, and subsidy policy for PHEV in the Chinese market of the switching from NEDC to WLTP based on qualitative analysis and quantitative calculation. The results show that the WLTP procedure is stricter than NEDC in the determination of road load, test mass, driving resistance forces, and tire selection. Firstly, the electricity consumption (EC) of PHEV in charge-depleting mode (CD) under the WLTP procedure is 26% higher than NEDC on average, which makes the all-electric range (AER) significantly lower under WLTP. The weight EC tested in the WLTP procedure is higher than NEDC. Secondly, the fuel consumption (FC) of PHEV in CD mode is related to the adjustment of the engine management system (EMS) and the size of battery energy under the WLTP procedure. For the FC in the charge-sustaining (CS) mode of PHEV under the WLTP procedure is 20% higher than NEDC on average. However, the weight fuel consumption of PHEVs under WLTP with a long AER may be lower than that of NEDC due to the characteristics of utility factor in the WLTP procedure. Thirdly, most PHEVs fail to meet the requirements of 50 km AER due to the switching of the test procedures. However, the Chinese government reduced the technical specification of PHEV’s AER under the WLTP procedure to 43 km to support the development of PHEV technology. It ensures that the switching of test procedures does not change the treatment that they could obtain, the NEV credits, and subsidy as a NEV in China. However, the increasing of the EC in CD mode and the FC in CS mode under the WLTP procedure makes the PHEV obtain lower credit and subsidy multiple compared with NEDC procedure.

CO <sub>2</sub> Well-to-Wheel Abatement with Plug-In Hybrid Electric Vehicles Running under Low Temperature Combustion Mode with Green Fuels

<div class="section abstract"><div class="htmlview paragraph">Plug-in Hybrid Electric Vehicles (PHEVs) can be considered as the most promising technology to achieve the European CO<sub>2</sub> targets together with a moderate infrastructure modification. However, the real benefits, in terms of CO<sub>2</sub> emissions, depend on a great extent on the energy source (fuel and electricity mix), user responsibility, and vehicle design. Moreover, the electrification of the powertrain does not reduce other emissions as NOx and particulate matter (mainly soot). In the last years, low temperature combustion (LTC) modes as the reactivity controlled compression ignition (RCCI) have shown to achieve ultra-low NOx and soot emissions simultaneously due to the use of two fuels with different reactivity together with high exhaust gas recirculation (EGR) rates. Therefore, the aim of this work is to assess, through numerical simulations fed with experimental results, the effects of different energy sources on the performance and emissions of a series RCCI PHEV. The dual-fuel engine was fueled with diesel as high reactivity fuel and bioethanol as low reactivity fuel. The powertrains are optimized to meet the European homologation legislation (WLTP) for PHEVs. The tailpipe emissions and fuel consumption of the series RCCI PHEV is analyzed and compared to the OEM no-hybrid passenger vehicle running under conventional diesel combustion and RCCI. A life-cycle analysis (LCA) is performed to evaluate the potential of the different energy sources to reduce the overall CO<sub>2</sub> emissions. Different electricity sources are investigated as well as different liquid fuels: e-diesel and bio-ethanol. The series RCCI PHEV technology achieved the tank-to-wheel 50 g/km CO<sub>2</sub> emissions target with medium battery size (13 kWh). In addition, thanks to the RCCI technology, the vehicle is able to meet the Euro 6 NOx and soot limits. The LCA shows that, depending on the fuel source, the total CO<sub>2</sub> reduction benefits variate. Also, the final use and the charging events of the series PHEV have a great impact in this sense.</div></div>

Comparative Analysis of Technical Route and Market Development for Light-Duty PHEV in China and the US

China and the US have become the world’s largest plug-in hybrid electric vehicle (PHEV) markets. Powertrain architecture is the framework of PHEV technology which represents its technical route. The research on the market development and technical route of Chinese and American PHEV is helpful to grasp the internal law of the global PHEV market and technology situation, and thus is significant to lay out a development strategy and technical route but has not been sufficiently studied. Therefore, an evaluation method of three dimensions combining market sales, powertrain architectures and performance indexes was proposed for comparative analysis, and PHEV mainstream architectures were put forward. Besides, qualitative evaluation levels from nine dimensions were built for architecture analysis, and fuel consumption to curb weight (FC2CW) as an indicator was introduced for economy evaluation. Some conclusions can be drawn: (a) The most mainstream architecture in sales volume is four-wheel drive (4WD) Bridge, and that in models’ amount is P2 in China, while those respectively are PS and P2 in the US. This reflects that a difference exists between the choice of the consumers and that of the automakers, and another difference also exists between the two countries. (b) With the phasing down of subsidies, the single-motor parallel architecture may become the first choice of China’s next technical route, while the 4WD Bridge will still be the main architecture for sports utility vehicles (SUVs) or sports car. (c) Among the models of the top five sales, the types and sales of SUVs in China are significantly more, however, the fuel economy rankings of theirs in the US are relatively better. (d) It is difficult to distinguish which architecture has the absolute best economy, but the fuel economy of the series type in the two markets is not very good.

Emissions reduction from passenger cars with RCCI plug-in hybrid electric vehicle technology

Hybrid Electric Vehicles (HEVs) can be considered as a potential technology to promote the change from conventional mobility to e-mobility. However, the real benefits in terms of CO2 emissions depend on a great extent on their mode of use, vehicle design and electricity source. On the other hand, in the last few years, advanced combustion modes as Reactivity Controlled Compression Ignition (RCCI) showed great advantages in terms of NOx and soot emissions reduction. This paper has the purpose of assessing, through numerical simulations fed with experimental results, the potential of different hybrid vehicles when used together with a low temperature combustion mode. In particular, the dual-fuel Mild (MHEV), Full (FHEV) and Plug-in (PHEV) hybrid electric vehicles are tested and compared to the original equipment manufacturer (OEM) and the conventional dual-fuel powertrain, both no-Hybrid vehicles. The powertrains are optimized to meet the current European homologation legislation Worldwide Harmonized Light Vehicle Test Procedure (WLTP). After that, a deep analysis is performed in terms of performance and emissions. Lastly, a life-cycle analysis (LCA) is performed to evaluate the real potential of the different technologies. The results show that the PHEV has the highest benefits in terms of fuel consumption and engine-out emissions. With this technology, it is possible to achieve the 50 g/km CO2 target for the PHEVs with a medium battery size (15 kWh), while NOx and soot levels are under the Euro 6 limits. In addition, the RCCI technology shows great benefits to achieve the Euro6 soot level for the other hybrid platforms. The LCA shows that the PHEVs can achieve 12% reduction of the total CO2 with respect to the FHEVs, and 30% with respect to the no-hybrid diesel platform.

USING NATIONAL SURVEY RESPONDENTS AS CONSUMERS IN AN AGENT-BASED MODEL OF PLUG-IN HYBRID VEHICLE ADOPTION

Plug-in hybrid electric vehicles (PHEVs) offer the potential to significantly reduce greenhouse gas emissions, if vehicle consumers are willing to adopt this new technology. Consequently, there is much interest in exploring PHEV market penetration models. In prior work, we developed an agent-based model (ABM) of potential PHEV consumer adoption that incorporated several spatial, social, and media influences to identify nonlinear interactions among potential leverage points that may impact PHEV market penetration. In developing that model, the need for additional data to properly inform both the decision-making rules and agent initialization became apparent. To address these issues, we recently conducted and analyzed an extensive consumer survey; in this paper, we modify the ABM to reflect the survey findings. A unique aspect is a one-to-one correspondence between agents in the model and survey respondents, and thus yielding distributions and cross correlations in agent attributes that accurately reflect the survey population. We also implement a used-PHEV market, and allow agents to purchase new or used compact PHEVs or vehicles of their current type. Based on our prior survey response analysis, our modified model includes a PHEV-technology threshold component, a multinomial logistic prediction of willingness to consider a compact PHEV based on dynamically changing attitudes, and agent-specific delay discounting functions that predict the amount agents are willing to pay up front for greater fuel savings. We thus independently account for agents’ discomfort with the new PHEV technology, their desire to drive a more environmentally friendly vehicle, and their willingness to pay a higher sticker price for a PHEV. Results of ten survey-based ABM scenarios are reported with implications for policy-makers and manufacturers. We believe close integration of the design of consumer surveys and the development of ABMs is a key step in developing useful decision-support models; this paper serves as an example of one way to achieve that.

Interpersonal Influence within Car Buyers' Social Networks: Applying Five Perspectives to Plug-in Hybrid Vehicle Drivers

Although interpersonal influence is thought to play in important role in proenvironmental consumption behavior, mechanisms of influence are not well understood. Through literature review, we identify five theoretical perspectives on interpersonal influence: contagion, conformity, dissemination, translation, and reflexivity. We apply these perspectives to car buyer perceptions of plug-in hybrid electric vehicles (PHEVs), a technology with attributes that can be perceived as functional, symbolic, private, and societal. The context is a PHEV demonstration project in which 275 interpersonal interactions were elicited from interviews with 40 individuals in 11 different social networks in northern California. Results demonstrate how perspectives shape research findings. Contagion, conformity, and dissemination provide useful concepts regarding perceptions of functional, symbolic and societal PHEV attributes, respectively. However, translation and reflexivity provide language and theoretical depth to describe observed perceptions and motives, while also addressing dynamics in these perceptions and in consumer values. Utilizing these differing perspectives facilitated observation that participants are more amenable to developing new, prosocietal interpretations of PHEVs if they: (i) easily form a basic functional understanding of PHEV technology, (ii) are in a transitional state in their lifestyle practices, and (iii) find supportive prosocietal values within their social network. Results demonstrate the importance of integrating complementary research perspectives to better understand consumer valuation of technologies with environmental benefits.

U.S. Department of Energy – Advanced Vehicle Testing Activity: Plug-in Hybrid Electric Vehicle Testing and Demonstration Activities

The U.S. Department of Energy’s Advanced Vehicle Testing Activity tests plug-in hybrid electric vehicles (PHEV) in closed track, dynamometer, and on-road testing environments. The purpose of this testing is to determine the potential of PHEV technology to reduce petroleum consumption. It also allows documentation of PHEV driving and charging profiles and electric charging infrastructure requirements. As of March 2009, the Advanced Vehicle Testing Activity has initiated testing on 12 PHEV models from aftermarket conversion companies and original equipment manufacturers. In addition to performing controlled dynamometer and on-road testing, AVTA has collected in-use data from 155 PHEVs operating in 23 U.S. states and Canadian provinces. This fleet has demonstrated an average increase in cumulative fuel economy of 22 to 55% when in charge depleting mode, as compared to charge sustaining mode. Charge depleting range has varied from 32 to 64 miles, depending on the vehicle and battery pack. In ideal conditions, some vehicles have achieved monthly fuel economy results of 80 to 120 miles per gallon through frequent charging and less aggressive driving styles.

Cost-Benefit Analysis of Plug-In Hybrid Electric Vehicle Technology

Plug-in hybrid electric vehicles (PHEVs) have emerged as a promising technology that uses electricity to displace petroleum consumption in the vehicle fleet. This paper presents a comparison of the costs (vehicle purchase costs and energy costs) and benefits (reduced petroleum consumption) of PHEVs relative to hybrid electric and conventional vehicles. A detailed simulation model is used to predict petroleum reductions and costs of PHEV designs compared to a baseline midsize sedan. The analysis finds that petroleum reductions exceeding 45% per vehicle can be achieved by PHEVs equipped with 20 mi (32 km) or more of energy storage. However, the long-term incremental costs of these vehicles are projected to exceed US$8,000. A simple economic analysis is used to show that high petroleum prices and low battery costs are needed to make a compelling business case for PHEVs in the absence of other incentives. However, the large petroleum reduction potential of PHEVs provides strong justification for governmental support to accelerate the deployment of PHEV technology.