基于价值损耗的燃料电池混合动力能量管理策略评价

为了评价燃料电池混合动力系统能量管理策略的经济性,对基于状态机和模糊逻辑2种能量管理策略的燃料电池混合动力叉车的价值损耗进行分析。首先,通过分析燃料电池和锂电池的工作特性,分别构建依赖实际工况的燃料电池单体电压衰减率模型和锂电池容量衰减率模型;同时定义计及燃料电池氢耗量的燃料电池混合动力系统的综合价值损耗指标。其次,通过测试叉车极限工况,计算燃料电池功率和锂电池容量,并根据母线电压确定锂电池SOC范围。最后,设计基于状态机和模糊逻辑的2种燃料电池混合动力叉车能量管理策略,并通过仿真分析在叉车一次循环工况下2种能量管理的价值损耗。研究结果表明:相较于模糊逻辑策略,采用状态机策略造成燃料电池寿命损耗提高7.81%,氢耗量提高1.89倍,锂电池寿命损耗减小21.33%。     

Simulation for the analysis of a hybrid electric scooter powertrain

This paper describes the mathematical modelling, analysis and simulation of a novel hybrid powertrain used in a scooter. The primary feature of the proposed hybrid powertrain is the use of a split power-system that consists of a one-degree-of-freedom (dof) planetary gear-train (PGT) and a two-dof PGT to combine the power of two sources, a gasoline engine and an electric motor. Detailed component level models for the hybrid electric scooter are established using the Matlab/Simulink environment. A simple rule-based power control strategy is then established with the primary objective to optimize the fuel economy of the hybrid electric scooter. The performance of the proposed hybrid powertrain is studied using the developed model under four driving cycles. The simulation results verify the operational capabilities of the proposed hybrid system and show both the engine and the electric motor work in an optimal state under various operating conditions.     

Experimental assessment of energy-management strategies in fuel-cell propulsion systems

The limitations of electric vehicles equipped with electrochemical batteries justify strong research interest for new solutions, based on hydrogen fuel-cell technology that are able to improve vehicle range, and reduce battery recharging time, while maintaining the crucial advantages of high efficiency and local zero emissions. The best working of a fuel-cell propulsion system, in terms of optimum efficiency and performance, is based on specific strategies of energy management, that are designed to regulate the power flows between the fuel cells, electric energy-storage systems and electric drive during the vehicle mission. An experimental study has been carried out on a small-size electric propulsion system based on a 2.5-kW proton exchange membrane fuel cell stack and a 2.5-kW electric drive. The fuel-cell system has been integrated into a powertrain comprising a dc–dc converter, a lead–acid battery pack, and brushless electric drive. The experiments are conducted on a test bench that is able to simulate the vehicle behaviour and road characteristics on specific driving cycles. The experimental runs are carried out on the European R40 driving cycle using different energy-management procedures and both dynamic performance and energy consumption are evaluated.     

Performance simulation and analysis of a fuel cell/battery hybrid forklift truck

The performance of a forklift truck powered by a hybrid system consisting of a PEM fuel cell and a lead acid battery is modeled and investigated by conducting a parametric study. Various combinations of fuel cell size and battery capacity are employed in conjunction with two distinct control strategies to study their effect on hydrogen consumption and battery state-of-charge for two drive cycles characterized by different operating speeds and forklift loads. The results show that for all case studies, the combination of a 110 cell stack with two strings of 55 Ah batteries is the most economical choice for the hybrid system based on system size and hydrogen consumption. In addition, it is observed that hydrogen consumption decreases by about 24% when the maximum speed of the drive cycle is decreased from 4.5 to 3 m/s. Similarly, by decreasing the forklift load from 2.5 to 1.5 ton, the hydrogen consumption decreases by over 20%.     

A robust online energy management strategy for fuel cell/battery hybrid electric vehicles

Traditional optimization-based energy management strategies (EMSs) do not consider the uncertainty of driving cycle induced by the change of traffic conditions, this paper proposes a robust online EMS (ROEMS) for fuel cell hybrid electric vehicles (FCHEV) to handle the uncertain driving cycles. The energy consumption model of the FCHEV is built by considering the power loss of fuel cell, battery, electric motor, and brake. An offline linear programming-based method is proposed to produce the benchmark solution. The ROEMS instantaneously minimizes the equivalent power of fuel cell and battery, where an equivalent efficiency of battery is defined as the efficiency of hydrogen energy transforming to battery energy. To control the state of charge of battery, two control coefficients are introduced to adjust the power of battery in objective function. Another penalty coefficient is used to amend the power of fuel cell, which reduces the load change of fuel cell so as to slow the degradation of fuel cell. The simulation results indicate that ROEMS has good performance in both fuel economy and load change control of fuel cell. The most important advantage of ROEMS is its robustness and adaptivity, because it almost produces the optimal solution without changing the control parameters when driving cycles are changed.     

Simulation research on a novel control strategy for fuel cell extended-range vehicles

Adapting to urban transportation and emission reduction in China, fuel cell extended-range commercial vehicles are advocated and studied, which have the advantages of no pollution and long continued driving mileage. According to the features of fuel cell extender and characteristics of the powertrain system of the electric commercial vehicle, the design principle of the extender control strategy is determined in this paper, in order to improve the power and economic performance. A simulation platform for fuel cell plus electric vehicles was established. By comparing and analyzing the characteristics of on-off control strategy, power following control strategy and fuzzy logic control strategy, an on-off power following control strategy is put forward and built which is used for extender controller, and a fuzzy algorithm of following control strategy is studied. By Simulating and analyzing on the platform, the results show that the power following fuzzy algorithm can improve the power performance with the 8.9s accelerating time (0–50 km/h) and better total mileage continued 286.7 km for the powertrain system of fuel cell extended-range commercial vehicles. The research in this paper provides a basis for the in-depth study of the energy management of electric vehicles.     

Cost-optimal design and energy management of fuel cell electric trucks

Road freight transport on hilly routes represents a significant challenge for the advancement of fuel cell electric trucks because of the high-performance requirements for fuel consumption, vehicle lifetime, and battery charge control. Therefore, it is essential to optimize the vehicle design and energy management, which greatly influence the driving performance and total cost of ownership. This paper focuses on the cost-optimal design and energy management of fuel cell electric trucks, considering five key influencing factors: powertrain component sizing, driving cycle, vehicle weight, component degradation, and market prices. The cost optimization relies on a novel predictive energy management scheme based on dynamic programming and the systematic calibration of control parameters. The paper analyzes the simulation results to highlight three main findings for fuel cell electric trucks: 1) cost-optimal energy management is essential to define the best trade-off between fuel consumption and component degradation; 2) the total cost of ownership is significantly influenced by component sizing, driving cycles, vehicle weight, and market prices; 3) predictive energy management is highly beneficial in challenging road topographies for substantial cost-saving and lower component size requirements.     

Model-based power control strategy development of a fuel cell hybrid vehicle

An integrated procedure for math modeling and power control strategy design for a fuel cell hybrid vehicle (FCHV) is presented in this paper. Dynamic math model of the powertrain is constructed firstly, which includes four modules: fuel cell engine, DC/DC inverter, motor-driver, and power battery. Based on the mathematic model, a power control principle is designed, which uses full-states closed-loop feedback algorithm. To implement full-states feedback, a Luenberger state observer is designed to estimate open circuit voltage (OCV) of the battery, which make the control principle not sensitive to the battery SOC (state of charge) estimated error. Full-states feedback controller is then designed through analyzing step responding of the powertrain and test data. At last of the paper, the results of simulation and field test are illustrated. The results show that the power control strategy designed takes into account the performance and economy characteristics of components of the FCHV powertrain and achieves the control object excellently.     

Optimal energy management strategy of fuel-cell battery hybrid electric mining truck to achieve minimum lifecycle operation costs

Proton exchange membrane fuel cell (PEMFC) electric vehicle is an effective solution for improving fuel efficiency and onboard emissions, taking advantage of the high energy density and short refuelling time. However, the higher cost and short life of the PEMFC system and battery in an electric vehicle prohibit the fuel cell electric vehicle (FCEV) from becoming the mainstream transportation solution. The fuel efficiency-oriented energy management strategy (EMS) cannot guarantee the improvement of total operating costs. This paper proposes an EMS to minimize the overall operation costs of FCEVs, including the cost of hydrogen fuel, as well as the cost associated with the degradations of the PEMFC system and battery energy storage system (ESS). Based on the PEMFC and battery performance degradation models, their remaining useful life (RUL) models are introduced. The control parameters of the EMS are then optimized using a meta-model based global optimization algorithm. This study presents a new optimal control method for a large mining truck operating on a real closed-road operation cycle, using the combined energy efficiency and performance degradation cost measures of the PEMFC system and lithium-ion battery ESS. Simulation results showed that the proposed EMS could improve the total operating costs and the life of the FCEV.     

An innovative optimal power allocation strategy for fuel cell, battery and supercapacitor hybrid electric vehicle

An optimal design of a three-component hybrid fuel cell electric vehicle comprised of fuel cells, battery, and supercapacitors is presented. First, the benefits of using this hybrid combination are analyzed, and then the article describes an active power-flow control strategy from each energy source based on optimal control theory to meet the demand of different vehicle loads while optimizing total energy cost, battery life and other possible objectives at the same time. A cost function that minimizes the square error between the desired variable settings and the current sensed values is developed. A gain sequence developed compels the choice of power drawn from all devices to follow an optimal path, which makes trade-offs among different targets and minimizes the total energy spent. A new method is introduced to make the global optimization into a real-time based control. A model is also presented to simulate the individual energy storage systems and compare this invention to existing control strategies, the simulation results show that the total energy spent is well saved over the long driving cycles, also the fuel cell and batteries are kept operating in a healthy way.     

Optimal sizing of a fuel processor for auxiliary power applications of a fuel cell-powered passenger car

The present study considers the optimal sizing of a three-way hybrid powertrain consisting of a compact reformer, a compact battery and a low temperature PEM fuel cell stack serving as the main power unit. A simulation model consisting of the relevant characteristic parameters of the three power sources has been developed and has been used to study the fuel utilization features of the hybrid powertrain while going through the NEDC driving cycle with a given auxiliary power requirement. The optimality is based on minimizing fuel cost while having an assured range of 500 km under practical driving conditions and a further 100 km under reduced auxiliary power usage. It is shown that for performance characteristics of Toyota Mirai and for average auxiliary power consumption of 5 kW, a smaller NiMH battery size of 1.3 kWh together with a fuel processor of 5.6 kW constant output would be optimal with a further requirement of 25% more hydrogen and 33 kg of ethanol to be carried on-board. Substantial reductions in vehicle mass and fuel load can be achieved for more modest performance characteristics and auxiliary power consumption.     

Investigation of battery end-of-life conditions for plug-in hybrid electric vehicles

Plug-in hybrid electric vehicles (PHEVs) capable of drawing tractive energy from the electric grid represent an energy efficient alternative to conventional vehicles. After several thousand charge depleting cycles, PHEV traction batteries can be subject to energy and power degradation which has the potential to affect vehicle performance and efficiency. This study seeks to understand the effect of battery degradation and the need for battery replacement in PHEVs through the experimental measurement of lithium ion battery lifetime under PHEV-type driving and charging conditions. The dynamic characteristics of the battery performance over its lifetime are then input into a vehicle performance and fuel consumption simulation to understand these effects as a function of battery degradation state, and as a function of vehicle control strategy. The results of this study show that active management of PHEV battery degradation by the vehicle control system can improve PHEV performance and fuel consumption relative to a more passive baseline. Simulation of the performance of the PHEV throughout its battery lifetime shows that battery replacement will be neither economically incentivized nor necessary to maintain performance in PHEVs. These results have important implications for techno-economic evaluations of PHEVs which have treated battery replacement and its costs with inconsistency.     

An improved thermal control of open cathode proton exchange membrane fuel cell

Proton exchange membrane fuel cell is a well-known technology that has shown high efficiency and performance as a power system compared to conventional sources such as internal combustion engines. Especially, open cathode proton exchange membrane is growing more popular thanks to its simple structure, low cost and low parasitic losses. However, the open cathode fuel cell performance is highly related to the operating temperature variation and the airflow rate which is adjusted through the fan voltage. In this regard, the present study investigates the thermal management of an open cathode proton exchange membrane fuel cell. The objectives are the stack performance improvement and the stack degradation prevention. Indeed, a safety and optimal operating zone governed by the load current, the stack temperature and the air stoichiometry, is designed. This optimal operating zone is defined based on the system thermal balance and the operating constraints. Hence, the proposed control strategy deals concurrently with the stack temperature regulation and the air stoichiometry adjustment to guarantee the goals achievement. The performance of the proposed control strategy is verified through experimental studies with different operating conditions and results prove its efficiency. To properly design an appropriate control strategy, a multiphysic fuel cell model is developed based on acausal approach by mean of Matlab/Simscape and experimentally validated.     

A comparison of real-time energy management strategies of FC/SC hybrid power source: Statistical analysis using random cycles

This paper presents a comparative study of two promising real-time energy management strategies for fuel cell electric vehicle applications: adaptive equivalent consumption minimization strategy (A-ECMS), and stochastic dynamic programming (SDP). An off-line algorithm –classic dynamic programming - provides reference results. On-line and off-line strategies are tested both in simulation and using a dedicated test bench completely consistent with an electric scooter powertrain.The hybrid power source combines a fuel cell, a supercapacitor pack and two related power converters. The system model is carefully calibrated using experimental data. This allows meaningful identification of parameters of the various strategies. The model data is determined using a motorcycle certification driving cycle.The robustness of each strategy is then analyzed using a large number of random driving cycles. Experimental and simulation results show that a specific SDP approach, based on Markov chain modeling, has the best overall performance in real-world driving conditions. It achieves the minimum average hydrogen consumption while respecting the state-sustaining constraint. Conversely, the A-ECMS results lack robustness and show poor performance indexes when facing unknown real world power demand profile. In conclusion, the present results indicate SDP is an interesting approach for future hybrid source energy allocation.     

A hierarchical energy management strategy for fuel cell/battery/supercapacitor hybrid electric vehicles

In this paper, a hierarchical energy management strategy (EMS) based on low-pass filter and equivalent consumption minimization strategy (ECMS) is proposed in order to lift energy sources lifespan, power performance and fuel economy for hybrid electrical vehicles equipped with fuel cell, battery and supercapacitor. As for the considered powertrain configuration, fuel cell serves as main energy source, and battery and supercapacitor are regarded as energy support and storage system. Supercapacitor with high power density and dynamic response acts during great power fluctuations, which relives stress on fuel cell and battery. Meanwhile, battery is used to lift the economy of hydrogen fuel. In higher layer strategy of the proposed EMS, supercapacitor is employed to supply peak power and recycle braking energy by using the adaptive low-pass filter method. Meantime, an ECMS is designed to allocate power of fuel cell and battery such that fuel cell can work in a high efficient range to minimize hydrogen consumption in lower layer. The proposed EMS for hybrid electrical vehicles is modeled and verified by advisor-simulink and experiment bench. Simulation and experiment results are given to confirm effectiveness of the proposed EMS of this paper.     

Dynamic behaviour of Li batteries in hydrogen fuel cell power trains

A Li ion polymer battery pack for road vehicles (48 V, 20 Ah) was tested by charging/discharging tests at different current values, in order to evaluate its performance in comparison with a conventional Pb acid battery pack. The comparative analysis was also performed integrating the two storage systems in a hydrogen fuel cell power train for moped applications. The propulsion system comprised a fuel cell generator based on a 2.5 kW polymeric electrolyte membrane (PEM) stack, fuelled with compressed hydrogen, an electric drive of 1.8 kW as nominal power, of the same typology of that installed on commercial electric scooters (brushless electric machine and controlled bidirectional inverter). The power train was characterized making use of a test bench able to simulate the vehicle behaviour and road characteristics on driving cycles with different acceleration/deceleration rates and lengths. The power flows between fuel cell system, electric energy storage system and electric drive during the different cycles were analyzed, evidencing the effect of high battery currents on the vehicle driving range. The use of Li batteries in the fuel cell power train, adopting a range extender configuration, determined a hydrogen consumption lower than the correspondent Pb battery/fuel cell hybrid vehicle, with a major flexibility in the power management.     

A novel predictive power flow control strategy for hydrogen city rail train

Hydrogen-based vehicular traction has already reached a mature technological level and can replace the more polluting diesel engines. The adoption of this technology can also alleviate the carbon footprint issue of the rail trains running on non-electrified lines.This study presents a model and a numerical performance analysis of an electric hybrid train in an urban context. The train uses hydrogen as fuel and operates over non-electrified lines with zero local emission.The electric traction motors of the train are fed by a hybrid power unit consisting of several hydrogen fuel cell stacks operating independently in on/off mode and a set of flywheel energy storage devices.Each component of the power train is modeled separately and its operating limits are chosen on the base of technical literature.An innovative predictive logic to manage power flows is defined and proposed with the aim to minimize the fuel consumption. Furthermore, this approach uses a regenerative electrical braking and eliminates dissipative devices, like rheostats, which are commonly utilized onboard electric trains.This predictive approach is based on the optimal management of the power unit components according to the advanced knowledge of the data of the rail vehicle, the characteristics of path, drive cycle and payload for an established route.The fuel cell stacks operate accordingly to the average traction power requirement in each railway line section, whereas the flywheel energy storage system manages the dynamic power.A parametric model of the system and a respective software tool have been developed; this implementation, that incorporates many tunable parameters of the train and rail path, is able to simulate the rail train operating on a specific railway path by implementing the novel control strategy.An existing single track non-electrified line, designed again for urban service, has been selected as a case study to evaluate the performance of the proposed system.The specific fuel consumptions obtained with the novel control strategy and with a single fuel cell system operating at constant power are compared under the same operating conditions.The results highlight that significant fuel savings can be achieved.     

Active fault tolerance control system of fuel cell hybrid city bus

With ever growing concerns on energy crises and environmental issues, Proton Exchange Membrane Fuel Cell is favored in automotive applications because it is clean, efficient and low noise. A fuel cell hybrid powertrain is composed of a fuel cell system as the primary power source, a battery as the secondary power source and an electric motor. In order to improve the reliability, a distributed control system that can be preserved even under faulty cases is necessary. This paper presents an active fault tolerance control system (AFTCS) for a fuel cell/battery hybrid powertrain applied to a city bus. The AFTCS consists of a system for fault detection and diagnose and a reconfigurable controller. Algorithms to detect and isolated three kinds of important faults are introduced. The real-time applicable reconfigurable controller is exploited to recover the pre-fault system performance as much as possible. Experimental results show the effectiveness of the proposed system.     

Fuel cell/battery passive hybrid power source for electric powertrains

The concept of passive hybrid, i.e. the direct electrical coupling between a fuel cell system and a battery without using a power converter, is presented as a feasible solution for powertrain applications. As there are no DC/DC converters, the passive hybrid is a cheap and simple solution and the power losses in the electronic hardware are eliminated. In such a powertrain topology where the two devices always have the same voltage, the active power sharing between the two energy sources can not be done in the conventional way. As an alternative, control of the fuel cell power by adjusting its operating pressure is elaborated. Only pure H₂/O₂ fuel cell systems are considered in this approach. Simulation and hardware in the loop (HIL) results for the powertrain show that this hybrid power source is able to satisfy the power demand of an electric vehicle while sustaining the battery state of charge.     

Multi-objective optimization of hybrid PEMFC/Li-ion battery propulsion systems for small and medium size ferries

Hybrid Polymer Electrolyte Membrane Fuel Cells/Lithium-ion battery powertrains are a promising solution for zero-local-emissions marine propulsion. The present study aims to optimize the design and operation of such hybrid powertrain for small-size passenger ferries, taking into account the performance degradation of both fuel cells and batteries. A Mixed-Integer Linear-Programming approach and a hierarchical method are adopted to concurrently minimize the fuel cells degradation, the capital expenditure and the operating expenditure, while constraints are included in the model to limit the battery degradation. The results show that the proposed multi-objective optimization can lead to a reduction of fuel cells degradation by up to 65% compared to a cost-minimization only. However, this can imply an increase in the battery capacity by up to 136%. The proposed method has general validity, and it is a useful tool for both preliminary design and choice of the optimal energy management strategy for ships energy systems.