Electric vehicles’ energy consumption measurement and estimation

Use of electric vehicles (EVs) has been viewed by many as a way to significantly reduce oil dependence, operate vehicles more efficiently, and reduce carbon emissions. Due to the potential benefits of EVs, the federal and local governments have allocated considerable funding and taken a number of legislative and regulatory steps to promote EV deployment and adoption. With this momentum, it is not difficult to see that in the near future EVs could gain a significant market penetration, particularly in densely populated urban areas with systemic air quality problems. We will soon face one of the biggest challenges: how to improve efficiency for EV transportation system? This research takes the first step in tackling this challenge by addressing a fundamental issue, i.e. how to measure and estimate EVs’ energy consumption. In detail, this paper first presents a system which can collect in-use EV data and vehicle driving data. This system then has been installed in an EV conversion vehicle built in this research as a test vehicle. Approximately 5 months of EV data have been collected and these data have been used to analyze both EV performance and driver behaviors. The analysis shows that the EV is more efficient when driving on in-city routes than driving on freeway routes. Further investigation of this particular EV driver’s route choice behavior indicates that the EV user tries to balance the trade-off between travel time and energy consumption. Although more data are needed in order to generalize this finding, this observation could be important and might bring changes to the traffic assignment for future transportation system with a significant share of EVs. Additionally, this research analyzes the relationships among the EV’s power, the vehicle’s velocity, acceleration, and the roadway grade. Based on the analysis results, this paper further proposes an analytical EV power estimation model. The evaluation results using the test vehicle show that the proposed model can successfully estimate EV’s instantaneous power and trip energy consumption. Future research will focus on applying the proposed EV power estimation model to improve EVs’ energy efficiency.     

Environmental assessment of electrification of road transport in Norway: Scenarios and impacts

The study develops scenarios regarding the introduction of electric vehicles to the passenger vehicle fleet of Norway to reach the 2020 Norwegian greenhouse gas reduction target and a more extreme target to limit global temperature increase to two degrees. A process-based life cycle assessment approach is integrated with a temporally variable inventory model to evaluate the environmental impacts of these scenarios. We find that greenhouse gases in the reference scenario increase by 10% in 2020 in comparison to 2012; while for the more intensive improvements in conventional vehicles, this increase is reduced to 2%. For electric vehicles deployment scenarios, although the fleet share will reduce the tailpipe greenhouse gas emissions by 8–26%, with the upper end representing the two-degree reduction target, emissions reductions over the entire life cycle are only 3–15%. Electric vehicles also reduce emissions of NO_x, SO₂ and particulates reducing acidification, smog formation and particulate formation impacts, however, with addition of large numbers of electric vehicles significant trade-offs in toxicity impacts are found.     

船电产品设计与开发中的电磁兼容问题浅析

本文根据笔者在船舶电气电子产品设计与开发中碰到的电磁兼容问题，分析了其产生原因，介绍了解决电磁干扰问题的多种解决措施。     

Assessing the impact of long-term mobility choice motivation and short-term mobility means connotation on the use intention of electric cars in rural areas

In this study several hypotheses comprising a heuristic framework derived from rational-choice (RC) premises and regarding some potentially influencing variables on future use intention of different vehicle types are tested with a rural area sample. Especially the differentiation between long-term vs. short-term as well as functional/rational vs. extra-functional/emotional motivators is assessed. Results suggest a predominance of functional motivators and rational connotations over extra-functional/emotional ones. The models to check whether short-term or long-term effects dominate did not clearly confirm a predominance of long-term factors as hypothesized. In several regression models a moderating effect of rational short-term connotations on different long-term motivators was found, thus contributing notably to the prediction of future vehicle use-intention. The need for further research and theory-driven modeling is briefly discussed.     

Electric vehicles in multi-vehicle households

The suitability of an electric vehicle of a given range to serve in place of a given conventional vehicle is not limited by the daily travel over distances within that that range, but rather by the occasional inconvenience of finding alternative transport for longer trips. While the frequency of this inconvenience can be computed from usage data, the willingness of individual users to accept that replacement depends on details of available transportation alternatives and their willingness to use them. The latter can be difficult to assess. Fortunately, 65% of US households have access to the most convenient alternative possible: a second car. In this paper we describe an analysis of prospective EV acceptance and travel electrification in two-car households in the Puget Sound region. We find that EVs with 60 miles of useful range could be acceptable (i.e. incur inconvenience no more than three days each year) to nearly 90% of two-car households and electrify nearly 55% of travel in those households (32% of all travel). This compares to 120 miles range required to achieve the same fraction of electrified travel via one-for-one replacement of individual vehicles. Even though only one third of personal vehicles in the US may be replaced in this paradigm, the ‘EV as a second-car’ concept is attractive in that a significant fraction of travel can be electrified by vehicles with modest electric range and virtually no dependence on public charging infrastructure.     

Factors affecting electric vehicle sharing program participants’ attitudes about car ownership and program participation

There are growing concerns on traffic congestion, climate change and parking problems in major cities. Faced with these concerns, policy makers have sought sustainable transportation options including electric vehicle sharing programs (EVSPs). The city of Seoul with 10 million people also has recently launched an EVSP to provide citizens with an alternative travel mode. This study attempts to explore factors affecting the EVSP participants’ attitudes about car ownership and program participation. To do this, a web-based survey was conducted for the participants of the Seoul EVSP, asking their satisfaction levels for the components of the EVSP. Then, using 533 responses of 1772 EVSP members (a response rate of 30%), ordered probit models were developed for three types of attitudes: (1) willingness to dispose of a car, (2) willingness to purchase an EV and (3) willingness to continue participating in the EVSP. The estimated models suggested that participants’ social and economic perspectives were the most important factors affecting the participants’ attitudes. In addition, the attitudes varied depending on personal characteristics such as gender, age and income. Although this study was conducted in the early stage of an EVSP, its results are expected to provide insights into a better EVSP design.     

无刷直流推进电动机稳态性能的仿真

建立无刷直流推进电动机的稳态仿真数学模型,利用特征向量法以及对称性边界条件进行求解,得到定子三相电流的稳态解,并与动态仿真的结果进行对比,验证了该方法的正确性。     

查找电源混电故障的几种方法

在朔黄线开通过程中对几处电源混电故障的查找，没有机械地按照惯例采用断电源环线的方式进行，而是根据故障现象，采用了不同的方法进行故障处理，减少了故障处理时间及对运输的干扰。     

信号产品接线端子选型

论文对信号产品常用的两种典型接线端子特性进行了介绍,详细分析了选型方法,包括电气间隙、接线容量以及电流负荷能力。     

The lurch towards formalisation: Lessons from the implementation of BRT in Johannesburg,South Africa

The City of Johannesburg, South Africa, implemented the first phase of its Bus Rapid Transit (BRT) system named Rea Vaya between 2009 and 2011. The system design and organisational arrangements drew heavily on precedents from South America, especially insofar as BRT is used as an instrument for securing the transformation and formalisation of a fragmented and problematic informal public transport industry. Despite the inevitable transition problems, the formalisation scheme appears to be generally successful – an outcome that surprised many analysts as it follows a long history of mistrust, resistance, and unsuccessful interventions between government and the minibus taxi industry. The paper offers an analysis of the reasons for the successful transformation of participating taxi operators, by using a life-cycle analogy. We argue that the minibus-taxi industry in South Africa has reached a state of stasis and maturity, with limited opportunities for further growth in its present form. BRT, as it is implemented locally, offers opportunities for re-invention – for moving onto new a potential growth trajectory – by overcoming the binding constraints of informality and by opening up new markets to operators. The life-cycle analysis also offers some insights into critical success factors that, if not met in the long run, could jeopardise the longevity and scalability of the formalisation project. The paper concludes with insights regarding the planning and management of BRT systems to maximise their potential for leveraging the formalisation of informal operators, both in South Africa and in other developing countries.