Effects of key operating parameters on the efficiency of two types of pem fuel cell systems (High-Pressure and Low-Pressure operating) for Automotive Applications

The proton exchange membrane (PEM) fuel cell system consisting of stack and balance of plant (BOP) was modeled in a MATLAB/Simulink environment. High-pressure operating (compressor type) and low-pressure operating (air blower type) fuel cell systems were considered, The effects of two main operating parameters (humidity and the pressure of the supplied gas) on the power distribution characteristics of BOP and the net system efficiency of the two systems mentioned above were compared and discussed. The simulation determines an optimum condition regarding parameters such as the cathode air pressure and the relative humidity for maximum net system efficiency for the operating fuel cell systems. This study contributes to get a basic insight into the fuel cell stack and BOP component sizing. Further research using multiobject variable optimization packages and the approach developed by this study can effectively contribute to an operating strategy for the practical use of fuel cell systems for vehicles.     

Optimal operation strategy development for fuel cell hybrid vehicle

An overall simulation model for fuel cell hybrid vehicle (FCHV) power train in parallel configuration using MATLAB/Simulink programming is constructed in this study. The model runs on power control strategy by using logic-threshold approach, achieved by the hybrid control unit (HCU) and fuel cell stack number. Using accelerator and decelerator pedal positions deduced from the driving schedule as the primary input, the simulation implements power flow and distribution under different vehicle operating modes. The HCU control strategy also incorporates regenerative braking and recharge for battery capacity recovery. Using the D-optimality method for experiment points selection and sequential quadratic programming (SQP) algorithm for obtaining the optimal operational parameters, three control threshold variables of HCU and optimal stack cell number are selected for hydrogen fuel economy under certain driving cycles. The proposed method provides optimized configurations of the FCHV model and the fuel cell stack, which has the capability in satisfying drive power request while satisfying vehicle driving schedule and battery state of charge (SOC) recovery with lower fuel consumption.     

燃料电池汽车动力系统功率平衡控制策略

燃料电池汽车动力总成控制的主要目的是平衡各个动力总成部件如燃料电池发动机、动力蓄电池和电动机之间的功率流向和能量平衡,使车辆保持较好的动力性和经济性。依据燃料电池汽车动力系统基本拓扑结构,提出了基于DC/DC变换器电流控制方式和基于模糊决策的蓄电池恒荷电状态控制的动力系统功率平衡控制算法,在MATLAB环境中进行了离线仿真,并用快速控制原型方法进行了实车试验验证。     

考虑燃料电池耐久性的FCHV复合能量管理策略

针对燃料电池混合动力汽车(Fuel Cell Hybrid electric Vehicle,FCHV)在频繁变载、启停、连续低载和怠速工况下燃料电池寿命衰减的现状,提出基于模糊控制与开关控制的滑动平均滤波复合能量管理策略,该复合能量管理策略以整车需求功率与燃料电池高效区下限之差和蓄电池SOC为模糊输入量,在有效避免燃料电池启停、连续低载和怠速工况的同时,通过开关控制可避免蓄电池过充产生的安全问题,通过滑动平均滤波控制可以改善燃料电池在频繁变载工况下耐久性差的问题。采用AVL Cruise软件和Matlab/Simulink软件进行联合仿真,仿真结果表明,提出的复合能量管理策略在保证蓄电池安全性的情况下,减少了引起燃料电池寿命衰减的工况,提升了燃料电池的耐久性。     

Operation algorithm for a parallel hybrid electric vehicle with a relatively small electric motor

In this paper, operation algorithms for a parallel HEV equipped with a relatively small motor are investigated. For the HEV, the power assist and the equivalent fuel algorithms are proposed. In the power assist algorithm, an electric motor is used to assist the engine which provides the primary power source. In the equivalent fuel algorithm, the electric energy stored in the battery is considered to be an equivalent fuel, and an equivalent brake specific fuel consumption for the electric energy is proposed. From the equivalent fuel algorithm, distribution of the engine power and the motor power is determined to minimize the fuel consumption for a given battery state of charge (SOC) and a required vehicle power. It is found from the simulation results that the fuel economy and the final battery SOC depend on the motor discharge energy and it is the best way to charge the battery only by the regenerative braking, not by the engine to improve the overall fuel efficiency of the HEV with the relatively small motor.     

A fuel cell/battery hybrid power system for an unmanned aerial vehicle

A hybrid propulsion system composed of a homemade Polymer electrolyte fuel cell (PEFC) with a Lithium polymer (LiPo) battery in parallel connection was developed for Unmanned aerial vehicles (UAVs). The characteristics and performance of the system were evaluated considering its dynamic load responding capability and energy efficiency. A homemade PEFC stack composed of 36-unit cells and Balance of plant (BOP) was used to construct the fuel cell system directly connected to the propulsion system. Ten cells of a 3300-mAh 40C LiPo battery were combined with the PEFC system in parallel, and the LiPo battery was only switched on when high power was required for takeoff, acceleration and landing. The independent use of the homemade PEFC system and battery for the UAV showed a good load responding capability and a high fuel cell system efficiency of approximately 45%, which was obtained during cruising. The parasitic loss and the amount of unreacted hydrogen gas discharged outside of PEFC were nearly 3.91% and 0.89%, respectively. Results of the field test flights confirmed that the hybrid propulsion system based on the parallel connection of a PEFC system and a battery power is extremely effective in operating a UAV.

     

燃料电池城市客车能量分配算法研究

高效、清洁已使燃料电池混合动力汽车成为人们关注的焦点。燃料电池多能源的分配控制是其中的一个关键技术,其对汽车经济性、动力性及部件寿命有很大影响。分析比较了四种能量分配控制策略,即恒压浮充策略、基于母线电压的MAP图分配策略、基于电池荷电状态(State of charge,SOC)修正的分配策略和基于SOC和电动机需求功率的模糊分配控制策略,并结合国家863燃料电池城市客车项目进行了仿真分析,比较了各种能量分配控制策略的优缺点。分析结果认为基于SOC和电动机需求功率的模糊分配控制策略具有较强的鲁棒性,工况适应性好,是一种值得研究和应用的控制策略。     

燃料电池电动汽车控制策略的仿真研究

以燃料电池为混合动力装置的新一代电动汽车已经成为世界各大汽车公司竞相开发的产品。燃料电池电动汽车系统庞大复杂,需要的成本高,而建立其数学模型并应用适合的控制策略进行仿真分析,不仅便于灵活地调整设计方案、优化设计参数,而且可以降低科研费用、缩短开发周期。因此为了更好地研究燃料电池的整车性能,有必要研究其控制策略。提出了应用于燃料电池电动汽车的控制策略,分别实现了汽车驾驶时对电机和功率总线能量分配的控制;通过分析部件模型的动态特性,验证了应用于该系统模型的控制策略的正确性。     

压缩空气动力汽车的研究与发展

在对多种替代燃料汽车和电动汽车进行比较综述的基础上,介绍了压缩空气动力汽车的工作原理、结构特点和性能特性。从能量利用的角度分析了压缩空气动力汽车的效率问题和可行性,比较了压缩空气动力能源与电池能源、燃料能源的特性,并与目前最为看好的氢燃料电池电动汽车的多种特性进行了全面的对比。结合浙江大学所开展的初步研究工作,指出了压缩空气动力汽车项目需进行的主要研究内容,认为压缩空气动力汽车是一种真正“零污染”的、有广阔市场前景的新概念的“绿色汽车”。     

Heating performance characteristics of stack coolant source heat pump using R744 for fuel cell electric vehicles

The objective of this study is to investigate the performance characteristics of a stack coolant source heat pump using R744 with a stack coolant heat source for fuel cell electric vehicles under cold weather conditions. Electric heaters are currently used in fuel cell electric vehicles, and the high levels of energy consumption involved lead to lower fuel efficiency and a reduction in the vehicle??s driving range. In order to improve the efficiency of the fuel cell electric vehicles in this study, a heat pump using R744 as a refrigerant and making use of wasted heat from the stacks is developed to cover the heating capacity. This heat pump is tested and performance optimized for stack coolant heat recovery under the compressor speeds, air temperatures, and flow rates of the interior heat exchanger, as well as the coolant flow rates of the CO₂-coolant heat exchanger. In addition, the heating capacity of the tested system was sufficiently attained over 5.0 kW at the coolant flow rate of 5.0 l/min under extremely cold weather conditions of ?20°C.     

新软件技术在燃料电池客车控制系统中的应用

燃料电池城市客车的部件繁多,结构复杂,包括燃料电池发动机、蓄电池、DC/DC和电动机等多个部件节点,其控制系统多采用复杂的分布式控制系统.该控制系统信息流量大、控制任务复杂、实时性要求高,在开发与运行过程当中对数据监控、故障诊断、程序在线更新、数据传输等都提出了更高的要求.在燃料电池城市客车控制系统研发与装备过程中,采用了OSEK/VDX标准的实时操作系统、硬件在环实时仿真、时间触发控制器局域网(Controller area network, CAN)以及无缝自动代码生成等最新的软件技术,这些新技术的应用,有效地提高了燃料电池客车控制系统的开发效率,降低了系统故障率,并为燃料电池客车的优化控制构建了一个开放的技术平台.     

并联混合动力电动汽车的模糊能量管理策略

为进一步优化并联的经济性，增强其能量管理策略的鲁棒性，针对高混合率，分析了常用的发动机最优曲线能量管理策略的不足，提出了以功率差、电池组荷电状态和电机转速为输入，以决定电机功率的比例系数为输出的模糊逻辑功率分配策略，在线计算电机所应承担的功率，达到了优化发动机工作点、电机效率和电池组荷电状态平衡的目的。通过整车循环工况前向仿真验证了该模糊策略对车辆经济性和工况适应性的改善。     

Synthetical efficiency-based optimization for the power distribution of power-split hybrid electric vehicles

Now the optimization strategies for power distribution are researched widely, and most of them are aiming to the optimal fuel economy and the driving cycle must be preknown. Thus if the actual driving condition deviates from the scheduled driving cycle, the effect of optimal results will be declined greatly. Therefore, the instantaneous optimization strategy carried out on-line is studied in this paper. The power split path and the transmission efficiency are analyzed based on a special power-split scheme and the efficiency models of the power transmitting components are established. The synthetical efficiency optimization model is established for enhancing the transmission efficiency and the fuel economy. The identification of the synthetical efficiency as the optimization objective and the constrain group are discussed emphatically. The optimization is calculated by the adaptive simulated annealing （ASA） algorithm and realized on-line by the radial basis function （RBF）-based similar models. The optimization for power distribution of the hybrid vehicle in an actual driving condition is carried out and the road test results are presented. The test results indicate that the synthetical efficiency optimization method can enhance the transmission efficiency and the fuel economy of the power-split hybrid electric vehicle （HEV） observably. Compared to the rules-based strategy the optimization strategy is optimal and achieves the approximate global optimization solution for the power distribution. The synthetical efficiency optimization solved by ASA algorithm can give attentions to both optimization quality and calculation efficiency, thus it has good application foreground for the power distribution of power-split HEV.     

基于车速跟踪的商用车燃油经济性建模与仿真

针对燃油经济性仿真模型仅能计算车辆在模态工况下的燃油消耗量的问题,提出了一种基于车速跟踪的燃油经济性仿真模型的建模方法。在建立车辆纵向动力学模型、驾驶意图模型和发动机与传动系统模型的基础上,利用MATLAB/Simulink搭建了商用车燃油经济性仿真模型,并以某客车为例进行了试验与仿真对比。对比结果表明：所建模型能对商用车的任意行驶工况进行较好的车速跟踪,并能对商用车在该行驶工况下的燃油消耗量进行较为准确的仿真计算。通过更改仿真模型中的相关车辆参数,可以方便快速地进行不同动力总成配置的商用车的燃油经济性仿真计算。     

基于双转子电动机的混合四轮驱动系统

在研究现有混合动力驱动系统的基础上,提出一种基于双转子电动机的机－电桥间混合四轮驱动系统。该系统由机械桥和电动桥构成,通过桥间动力综合控制,两桥可以单独或共同驱动车辆行驶,其中电驱动桥由双转子电动机加上减速换向机构组成,可以实现驱动、差速、能量回收等功能。在分析双转子电动机工作原理的基础上,建立其数学模型,并进行模拟负载突变及车辆转弯下的性能仿真。以某运动型多功能汽车为例,利用Matlab/Simulink软件进行原型车和新方案的对比性能仿真。仿真表明：在保持动力性相当的前提下,新混合动力方案在经济性方面有较好的改善,百公里油耗比原型车在高速、城市工况下能够分别下降10.58%、21.87%。     

Evaluation of fuel economy for a parallel hybrid electric vehicle

In this work, the fuel economy of a parallel hybrid electric vehicle is investigated. A vehicle control algorithm which yields operating points where operational cost of HEV is minimal is suggested. The operational cost of HEV is decided considering both the cost of fossil fuel consumed by an engine and the cost of electricity consumed by an electric motor. A procedure for obtaining the operating points of minimal fuel consumption is introduced. Simulations are carried out for 3 variations of HEV and the results are compared to the fuel economy of a conventional vehicle in order to investigate the effect of hybridization. Simulation results show that HEV with the vehicle control algorithm suggested in this work has a fuel economy 45% better than the conventional vehicle if braking energy is recuperated fully by regeneration and idling of the engine is eliminated. The vehicle modification is also investigated to obtain the target fuel economy set in PNGV program.     

氢燃料电池客车动力传动系统参数匹配研究

基于传动系部件参数直接影响车辆性能的事实,以车辆项目开发参数为目标,对某款氢燃料电池客车的动力传动系统进行了参数匹配研究;综合CRUISE与MATLAB软件的优点,通过软件交付的方法建立了该车型动力传动系统仿真模型,对整车进行在线仿真分析及试验验证。仿真结果表明:氢燃料电池客车最高车速、加速度、峰值扭矩等参数满足氢燃料电池客车所需的目标动力性能,客车动力传动系统的经济性能在满足要求的前提下并保留一定的裕量;氢燃料电池堆工作点发电策略有效,动力传动系统参数匹配合理,验证了氢燃料电池客车零部件参数选型的匹配策略。     

基于驾驶意图的插电式混合动力公交车控制策略*

为了充分挖掘插电式混合动力公交车(Plug-in hybrid electric bus, PHEB)的节油潜力、增强车辆对不同类型驾驶员的自适应性,在基于规则类的控制策略基础上,增加驾驶员意图识别模型。对驾驶风格及加速意图进行模糊识别,通过驾驶员在环的半实物仿真验证了识别模型,以驾驶风格和加速意图识别结果为输入,建立转矩修正系数k的模糊控制器,反模糊化输出k值,对需求转矩进行修正。用system test工具将模糊控制器生成对应的模糊查询表。仿真及试验结果表明：有驾驶员意图识别控制策略较无驾驶员意图识别控制策略更加适应PHEB的运营、用电机制且燃油经济性进一步提高了1.8%。     

汽车动力系统匹配设计及发展趋势展望

介绍汽车动力系统匹配设计相关机制,并重点对混合动力汽车、智能网联汽车、燃料电池汽车的未来发展趋势进行了展望。随着计算机技术的不断发展,针对汽车动力系统进行的匹配设计过程也得以相应优化,由此显著提升了汽车技术水平及整车销量。考虑到我国汽车工业现状,仍需持续开展相关研究,逐步缩小与世界领先水平的差距。     

Method of electric powertrain matching for battery-powered electric cars

The current match method of electric powertrain still makes use of longitudinal dynamics, which can’t realize maximum capacity for on-board energy storage unit and can’t reach lowest equivalent fuel consumption as well. Another match method focuses on improving available space considering reasonable layout of vehicle to enlarge rated energy capacity for on-board energy storage unit, which can keep the longitudinal dynamics performance almost unchanged but can’t reach lowest fuel consumption. Considering the characteristics of driving motor, method of electric powertrain matching utilizing conventional longitudinal dynamics for driving system and cut-and-try method for energy storage system is proposed for passenger cars converted from traditional ones. Through combining the utilization of vehicle space which contributes to the on-board energy amount, vehicle longitudinal performance requirements, vehicle equivalent fuel consumption level, passive safety requirements and maximum driving range requirement together, a comprehensive optimal match method of electric powertrain for battery-powered electric vehicle is raised. In simulation, the vehicle model and match method is built in Matlab/simulink, and the Environmental Protection Agency (EPA) Urban Dynamometer Driving Schedule (UDDS) is chosen as a test condition. The simulation results show that 2.62% of regenerative energy and 2% of energy storage efficiency are increased relative to the traditional method. The research conclusions provide theoretical and practical solutions for electric powertrain matching for modern battery-powered electric vehicles especially for those converted from traditional ones, and further enhance dynamics of electric vehicles.