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.     

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.     

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.     

新型燃料电池和超级电容器混合动力车

石油资源并非用之不竭,作为汽车的主要燃料,它总会有被替代的一天。虽然在寻找新能源的过程中,世界各大汽车公司纷纷研制各种新能源汽车,包括燃料电池车、电动汽车、混合动力汽车、代用燃料汽车等。但由于燃料电池汽车和纯电动汽车还存在不少问题,目前还不具备产业化条件,只能进行研制开发、示范运行。而今全球各大汽车公司已纷纷推出各种混合动力汽车,并先后推出了各自的量产车型。     

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.     

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.     

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.     

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。     

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.     

Analysis on fuel economy and advanced systems of hybrid vehicles

Basic ideas on operation of hybrid vehicles were discussed from a view point of energy saving. Almost double fuel economy of series–parallel–hybrid vehicles was estimated on condition of no engine idling during vehicle stop, energy saving in acceleration using brake energy recovery and high efficiency operation on low load condition using series–hybrid system. From the discussion of overall efficiency, involving fuel cycle, under both low and high load conditions, both series–parallel–hybrid vehicles with internal combustion engine and fuel cell are supposed to have a high potential for the future.     

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。     

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。     

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.     

Electrochemical battery model and its parameter estimator for use in a battery management system of plug-in hybrid electric vehicles

This paper reports the development of a battery model and its parameter estimator that are readily applicable to automotive battery management systems (BMSs). Due to the parameter estimator, the battery model can maintain reliability over the wider and longer use of the battery. To this end, the electrochemical model is used, which can reflect the aging-induced physicochemical changes in the battery to the aging-relevant parameters within the model. To update the effective kinetic and transport parameters using a computationally light BMS, the parameter estimator is built based on a covariance matrix adaptation evolution strategy (CMA-ES) that can function without the need for complex Jacobian matrix calculations. The existing CMA-ES implementation is modified primarily by region-based memory management such that it satisfies the memory constraints of the BMS. Among the several aging-relevant parameters, only the liquid-phase diffusivity of Li-ion is chosen to be estimated. This also facilitates integrating the parameter estimator into the BMS because a smaller number of parameter estimates yields the fewer number of iterations, thus, the greater computational efficiency of the parameter estimator. Consequently, the BMS-integrated parameter estimator enables the voltage to be predicted and the capacity retention to be estimated within 1 % error throughout the battery life-time.     

质子交换膜燃料电池在电动车辆上的应用

本文分别介绍并讨论了国内外质子交换膜燃料电池(PEMFC)在电动汽车上的应用现状,描述和总结了各类电池汽车的前景和各自的竞争力量,分析了当前燃料电池汽车商业化需要解决的问题,如氢气的供应、成本以及存在的技术问题。     

Fuel consumption parameters for realizing and verifying fuel consumption prospect algorithm of vehicle driving route information system

Emissions of CO₂, as the main component of greenhouse gases, and high fuel consumption rates are worldwide problems. To solve them, most car manufacturers have concentrated on developing various techniques to improve the efficiencies of engines and transmissions and ECO-ROUTEs to meet environmental regulations. In this study, an algorithm for determining routes that cause the least fuel consumption was developed. The core of this algorithm is a specific EEC (energy efficiency constant) map containing logic that is able to predict fuel consumption. The accuracy of the algorithm was confirmed by vehicle tests for various driving patterns. Parameters affecting vehicle fuel economy were studied and verified. Improvement in the accuracy of this algorithm was confirmed by applying these parameters to ECO-ROUTE logic.     

Combined power management/design optimization for a fuel cell/battery plug-in hybrid electric vehicle using multi-objective particle swarm optimization

In this paper, the combined power management/design optimization problem is investigated for a fuel cell/Liion battery PHEV. Formulated as a constrained multi-objective optimization problem (MOP), the combined optimization problem simultaneously minimizes the vehicle cost and fuel consumption subject to the vehicle performance requirements. With an emphasis on developing a generic optimization algorithm to find the Pareto front for the synthesized MOP, the Pareto based multi-objective particle swarm optimization (PMOPSO) algorithm is developed, which solely depends on the concept of Pareto dominance. Three approaches are introduced to the PMOPSO method to address the constrained MOP. They are: (i) by incorporating system constraints in the original objective functions, the constrained MOP is transformed to an unconstrained MOP; (ii) to avoid being trapped in local minima, a disturbance operator with a decaying mutation possibility is introduced; (iii) to generate a sparsely distributed Pareto front, the concept of crowding distance is utilized to determine the global guidance for the particles. Finally, under the Matlab/Simulink software environment, simulation results are presented to demonstrate the effectiveness of the PMOPSO in the derivation of the true Pareto front.     

Study of fuel consumption improvement of the car with the dry hybrid belt CVT

By reducing transmission loss in the speed-change control system and optimizing the transmission ratio using an electronically controlled DC motor, the authors were able to prove that the dry hybrid belt CVT is more fuel efficient than manual transmissions. This paper describes the results of the transmission-loss analysis and the control method used for the speed-change ratio.     

混合动力城市客车燃料电池系统总体设计

讨论了某型城市客车燃料电池系统设计中的关键问题,包括燃料电池、超级电容、电机等关键零部件的参数匹配.通过合理匹配和布置,从而提高了行车可靠性和安全性.     

SAE氢燃料电池车新技术标准或推动普及

<正>为了加快燃料电池车的普及进程以及相关补给设施的建设,美国SAE燃料电池标准工作组(Fuel Cell Standards Task Force)制定了两项新的技术标准:SAE J2601-轻型气态氢汽车的燃料协议。SAE-J2799-氢燃料汽车补给站软件及硬件标准。这两项标准的诞生使得全球两种氢燃料罐气压规格(35兆帕和70兆帕)得以协调。