Fuel economy evaluation of fuel cell hybrid vehicles based on optimal control

The fuel economy of a fuel cell hybrid vehicle (FCHV) depends on its power management strategy because the strategy determines the power split between the power sources. Several types of power management strategies have been developed to improve the fuel economy of FCHVs. This paper proposes an optimal control scheme based on the Minimum Principle. This optimal control provides the necessary optimality conditions that minimize the fuel consumption and optimize the power distribution between the fuel cell system (FCS) and the battery during driving. In this optimal control, the final battery state of charge (SOC) and the fuel consumption have an approximately proportional relationship. This relationship is expressed by a linear line, and this line is defined as the optimal line in this research. The optimal lines for different vehicle masses and different driving cycles are obtained and compared. This research presents a new method of fuel economy evaluation. The fuel economy of other power management strategies can be evaluated based on the optimal lines. A rule-based power management strategy is introduced, and its fuel economy is evaluated by the optimal line.     

Improvement of drivability and fuel economy with a hybrid antiskid braking system in hybrid electric vehicles

When braking on wet roads, Antilock Braking System (ABS) control can be triggered because the available brake torque is not sufficient. When the ABS system is active, for a hybrid electric vehicle, the regenerative brake is switched off to safeguard the normal ABS function. When the ABS control is terminated, it would be favorable to reactivate the regenerative brake. However, recurring cycles from ABS to motor regenerative braking could occur. This condition is felt to be unpleasant by the driver and has adverse effects on driving stability. In this paper, a novel hybrid antiskid braking system using fuzzy logic is proposed for a hybrid electric vehicle that has a regenerative braking system operatively connected to an electric traction motor and a separate hydraulic braking system. This control strategy and the method for coordination between regenerative and hydraulic braking are developed. The motor regenerative braking controller is designed. Control of regenerative and hydraulic braking force distribution is investigated. The simulation and experimental results show that vehicle braking performance and fuel economy can be improved and the proposed control strategy and method are effective and robust.     

Modeling and simulation of fuel cell hybrid vehicles

A comprehensive procedure for mathematical modeling and validation of a fuel cell hybrid vehicle (FCHV) is presented in this paper. The subsystems are modeled based on lab testing and in-field vehicle testing results from the Tongji University Start prototype vehicle. An FCHV-SIM (fuel cell hybrid vehicle simulation) model is then developed based on the experimental data. Model validation results confirm that the FCHV-SIM model is reasonably accurate and suitable for model-based control development.     

Stability enhancement and fuel economy of the 4-wheel-drive hybrid electric vehicles by optimal tyre force distribution

In this paper, vehicle stability control and fuel economy for a 4-wheel-drive hybrid vehicle are investigated. The integrated controller is designed within three layers. The first layer determines the total yaw moment and total lateral force made by using an optimal controller method to follow the desired dynamic behaviour of a vehicle. The second layer determines optimum tyre force distribution in order to optimise tyre usage and find out how the tyres should share longitudinal and lateral forces to achieve a target vehicle response under the assumption that all four wheels can be independently steered, driven, and braked. In the third layer, the active steering, wheel slip, and electrical motor torque controllers are designed. In the front axle, internal combustion engine (ICE) is coupled to an electric motor (EM). The control strategy has to determine the power distribution between ICE and EM to minimise fuel consumption and allowing the vehicle to be charge sustaining. Finally, simulations performed in MATLAB/SIMULINK environment show that the proposed structure could enhance the vehicle stability and fuel economy in different manoeuvres.     

发展柴油车是汽车行业节能减排的重要选择

伴随着中国经济的高速增长，能源短缺、环境污染等问题已成为中国能否实现可持续发展所面临的重大挑战。在今年初的十一届全国人大代表大会上，温家宝总理在政府工作报告中再次强调了十一五规划大纲中的节能减排目标，即万元GDP能耗降低20％左右和主要污染物排放减少10％，并提出今年是实现目标的关键性的一年。     

Comparison of PMP and DP in fuel cell hybrid vehicles

Pontryagin’s Minimum Principle (PMP) and Dynamic Programming (DP) are both from the optimal control theory and can both achieve optimal trajectories when they are applied to power management strategies of hybrid vehicles. However they have totally different control concepts. In order to select the superior one, the PMP-based and the DP-based power management strategies are introduced and compared for a fuel cell hybrid vehicle (FCHV) in this paper. The two power management strategies are applied to the FCHV in a computer simulation environment, and the simulation results from the two strategies are compared when the control variable for the PMP is fuel cell system (FCS) net power and for the DP is battery power. As a result, the superiority of the PMP-based power management strategy is proved.     

Modeling and control strategy development for fuel cell hybrid vehicles

Using MATLAB/Simulink, we constructed a comprehensive simulation model for the fuel cell hybrid vehicle (FCHV) power train in parallel with a power control strategy that uses a logic threshold approach implemented with a hybrid control unit (HCU). The simulation implements power flow and power distribution under different vehicle operating modes using the accelerator and decelerator pedal positions deduced from the driving schedule as primary inputs. The HCU control strategy also incorporates regenerative braking and recharging for recovery of battery capacity. Using the D-optimality method for selection of the optimal experiment values, three control threshold variables for the HCU are selected to maximize the hydrogen fuel economy under certain driving cycles. The proposed method provides the optimal configuration of the FCHV model, which has the capability of achieving the requested drive power while also meeting the vehicle driving schedule and recovery needs of the state of charge (SOC) battery, with lower fuel consumption levels.     

混合动力客车 低碳节油别是一个传说

＂除了价格高企、节油率不高只是其中的典型问题。更现实的是,我们所采购的混合动力公交客车只能在非高峰时段上路运行。＂业内人士表示,目前国内投入运行的混合动力客车确实有很多问题,故障率很高。     

Development of equivalent fuel consumption minimization strategy for hybrid electric vehicles

Power distribution between an internal combustion engine and electric motors is one of main features of hybrid electric vehicles that improves their fuel economy. An equivalent fuel consumption minimization strategy can instantaneously identify the optimal power distribution by converting the battery power into the equivalent fuel power and minimizing the overall fuel consumption. To guarantee the effectiveness of the strategy, it is essential to find the proper value of the conversion factor used to obtain the equivalent fuel power. However, finding the proper value is not a straightforward process because it is necessary to consider the overall power conversion efficiencies and battery charge sustaining strategy for the target driving cycle in advance. In this study, a model-based parameter optimization method is introduced to find the optimal conversion factor. A hybrid electric vehicle simulation model capable of estimating fuel consumption was developed, and the optimal conversion factor was discovered using a genetic algorithm that evaluates its population members using the simulation model. A series of simulations and vehicle tests was conducted to verify the effectiveness of the optimized strategy, and the results show a distinct improvement in fuel economy.     

Fuel consumption of fuel cell hybrid vehicles considering battery SOC differences

Fuel cell hybrid vehicles (FCHVs) have become one of the most promising candidates for future transportation due to current energy supply problem and environmental problem. Fuel economy is an important factor in FCHVs. In order to properly evaluate the fuel economy of an FCHV, the initial battery state of charge (SOC) and the final battery SOC have to be identical so that the effect of the battery energy usage on the fuel economy is neglected. In the simulation or in the real driving, however, the final battery SOC is usually different from the initial battery SOC, and the final battery SOC often depends on the power management strategy. To consider the difference between the two battery SOC values, the concept of equivalent fuel consumption is presented by two methods. One is based on the relationship between delta SOC and delta fuel consumption, and the other is based on the optimal control theory. Two rule-based power management strategies for an FCHV are presented, and for each strategy, the fuel economy is evaluated based on the two methods. The characteristics of the two methods are discussed and compared, and the superior one is selected based on the comparison.     

Novel evaluation method of fuel consumption and emission for heavy-duty hybrid electric vehicles

This paper is a continuation of a previous paper titled “A novel way to calculate energy efficiency for rechargeable batteries” published on Journal of Power Sources/2012 describing a new method to calculate energy efficiency for rechargeable batteries. The present paper further describes the application of energy efficiency model on the evaluation of fuel consumption and emission for the heavy-duty hybrid electric vehicles (HD-HEVs). A more accurate calculation method of net energy change for power battery pack is proposed based on energy efficiency model of power battery pack. A more simplified and accurate correction method of fuel consumption and emission is also presented based on equivalent mileage. The fuel consumption and emission on chassis dynamometer are measured in the HD-HEVs. The experiment results show that relative errors of fuel consumption and emission between equivalent mileage correction results and linear regression correction results are less than 3%, which verifies accuracy and validates the proposed evaluation method for HD-HEVs fuel consumption and emission.     

Design methodology of hybrid electric vehicle energy sources: Application to fuel cell vehicles

This paper presents a methodology to optimize the sizing of the energy and power components in a fuel cell electric vehicle from the driving mission (which includes driving cycles, a specified acceleration and autonomy requirements). The fuel cell and the Energy Storage System associated (battery or/and ultra capacitor) design parameters are the numbers of series and parallel branches respectively Nsi and Npi. They are set so as to minimize the objective function that includes mass, cost, fulfilling the performance requirements and respect the technological constraints of each power component through a penalty function. The methodology is based on a judicious combination of Matlab-Simulink® for the global simulation and a dedicated software tool Pro@Design®. Both are well suited to treat inverse problems for the optimization. An application for a fuel cell/battery powertrain illustrates the feasibility of the proposed methodology.     

新能源汽车发展得失对燃料电池汽车的启示

新能源汽车是我国战略性新兴产业之一,2009年以来,我国逐步建立了以财税政策为主的支持政策体系,推动了我国新能源汽车产业从无到有,逐步发展壮大。新能源汽车产业政策对推动我国产业快速发展起到了关键性作用,但也面临“干预市场”、“干预技术路线”、“透支消费”等质疑,出现了“骗补谋补”、“补贴依赖症”等问题。目前我国燃料电池汽车仍处于市场起步期,大规模推广的条件尚未成熟,产业发展离不开国家政策的支持。如何继续发挥新能源汽车领域的先发优势,吸取前期产业发展经验教训,在下一步推广燃料电池汽车时少走弯路,加快推动产业发展,是当前燃料电池汽车产业发展面临的重大课题。     

驾驶技巧对节约燃料的影响

本文通过对当今世界燃油危机分析引出燃料节约的重要性及意义，分析影响燃料消耗的五大因素，重点分析驾驶员的操作技，了对节约燃料的影响，提出驾驶员如应如何规范操作车辆和进行爱车例保的作业，以节约燃料消耗，减少企业的运营成本。     

关于汽车节油与驾驶技巧探讨

目前,随着家用轿车的快速增加,关于汽车节油的问题显得更为敏感。汽车的节油是一项系统工程,影响汽车耗油量的因素很多,本文通过从分析节油技术以及汽车的驾驶和使用技巧两方面,总结出一套切实易行的汽车节油措施和建议。     

燃料电池电动汽车的能源问题

电动汽车是21世纪清洁、高效和可持续发展的交通工具，是以蓄电池，燃料电池和超级电容器等电化学能源储存与转换装置为动力系统的交通运输工具的通称，包括纯电动汽车（BHE），混合动力电动汽车（HEV）和燃料电池电动汽车（FCEV）。由于石油危机的出现，人类能否在石油，天然气和煤炭资源被耗尽前就开发出可大量获取能量的新能源，已成为影响人类后代生存和发展的严峻问题，因此汽车的新能量源研究被提上日程。     

能源技术与汽车燃油经济性

1 汽车燃油经济性发展现状 汽车的发明极大程度地改变了人们的生活方式,然而,在您面前呼啸而过的汽车其油箱中的能源只有15%左右为汽车的运行及辅助需要(如舒适性、操纵简便性等方面的需要)做了有用功.     

燃料电池汽车发展的研究与分析

本文描述了欧洲、美国、日本等世界发达国家及中国燃料电池汽车的发展动态,对各国现阶段对于燃料电池汽车采取的态度、技术选择、发展规划和政府支持等情况进行了详细的分析和研究。     

固体氧化物燃料电池在电动汽车中的应用

本文主要论述了燃料电池混合动力电动汽车相对于传统内燃机汽车及其他电动汽车的优势,固体氧化物燃料电池相对于其他的燃料电池的优势。若将其应用于电动汽车上,可以有效地增加电动汽车的行驶里程,提高燃油经济性。     

用于电动和混合动力交通工具的功率模块

对减少CO2排放的急迫呼吁,已使主要的汽车制造商致力于开发新的电动和混合动力驱动交通工具解决方案。为这些应用开发功率半导体模块,需要新的模块集成和封装解决方案。