Simulation of a SOFC/Battery powered vehicle

Solid oxide fuel cells (SOFCs) have received attention in the transport sector for use as auxiliary power units or range extenders, due to the high electrical efficiency and fuelling options using existing fuel infra structure. The present work proposes an SOFC/battery powered vehicle using compressed natural gas (CNG), liquefied natural gas (LNG) or liquefied petroleum gas (LPG) as fuels. A model was developed integrating an SOFC into a modified Nissan Leaf Acenta electrical vehicle and considering standardized driving cycles. A 30 L fuel tank and 12 kW SOFC module was simulated, including a partial oxidation fuel reformer. The results show a significant increase of the driving range when combining the battery vehicle with an SOFC. Ranges of 264 km, 705 km and 823 km using respectively CNG, LNG and LPG compared to 170 km performed by the original vehicle were calculated. Furthermore, a thorough sensitivity analysis was carried out.     

Energy distribution analyses of an additional traction battery on hydrogen fuel cell hybrid electric vehicle

Hydrogen is the most abundant element in the world and produces only water vapor as a result of chemical reaction that occurred in fuel cells. Therefore, fuel cell electric vehicles, which use hydrogen as fuel, continue its growing trend in the sector. In this study, an energy distribution comparison is carried out between fuel cell electric vehicle and fuel cell hybrid electric vehicle. Hybridization of fuel cell electric vehicle is designed by equipped a traction battery (15 kW). Modeled vehicles were prepared under AVL Cruise program with similar chassis and same fuel cell stacks for regular determining process. Numerical analyses were presented and graphed with instantaneous results in terms of sankey diagrams with a comparison task. WLTP driving cycle is selected for both vehicles and energy input/output values given with detailed analyses. The average consumption results of electric and hydrogen usage is found out as 4.07 kWh and 1.125 kg/100 km respectively for fuel cell electric vehicle. On the other hand, fuel cell hybrid electric vehicle’s average consumption results figured out as 3.701 kWh for electric and 0.701 kg/100 km for hydrogen consumption. As a result of this study, fuel cell hybrid electric vehicle was obtained better results rather than fuel cell electric vehicle according to energy and hydrogen consumption with 8% and 32%, respectively.     

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.     

Energy management of a fuel cell hybrid ultra-energy efficient vehicle

This paper focuses on energy management in an ultra-energy efficient vehicle powered by a hydrogen fuel cell with rated power of 1 kW. The vehicle is especially developed for the student competition Shell Eco-marathon in the Urban Concept category. In order to minimize the driving energy consumption a simulation model of the vehicle and the electric propulsion is developed. The model is based on vehicle dynamics and real motor efficiency as constant DC/DC, motor controllers and transmission efficiency were considered. Based on that model five propulsion schemes and driving strategies were evaluated. The fuel cell output parameters were experimentally determined. Then, the driving energy demand and hydrogen consumption was estimated for each of the propulsion schemes. Finally, an experimental study on fuel cell output power and hydrogen consumption was conducted for two propulsion schemes in case of hybrid and non-hybrid power source. In the hybrid propulsion scheme, supercapacitors were used as energy storage as they were charged from the fuel cell with constant current of 10 A.     

Fuel processor-battery-fuel cell hybrid drivetrain for extended range operation of passenger vehicles

Power required to run auxiliary systems on a passenger car, such as those for air conditioning and advanced vehicle control, reduces the driving range of a vehicle equipped with a hybrid drive train. Under practical driving conditions, a significant amount of additional energy is required at low power levels compared to the rated power of the drive unit. In the present study, we consider a fuel cell-battery drive train augmented by an on-board fuel (ethanol) processor to provide the motoring power requirements of a car. Using systematic driving cycle simulations that take account of power-to-weight, energy-to-weight and power-to-efficiency factors of on-board power sources under simulated load conditions, we show that a combination of steadily-operated compact ethanol reformer, a low-power battery continuously charged by excess reformer capacity and a high-power fuel cell powered by conservatively-used hydrogen from cylinder can increase the range of hybrid fuel cell drivetrains to about 750 km. Although the overall energy consumption of the three-way hybrid is more than that of fuel cell-battery hybrid, lesser use of stored hydrogen improves the fuel economy of the hybrid drivetrain. While the system complexity is increased, long-range distressed mode operation becomes feasible with the added fuel processor.     

Control strategy of a fuel-cell power module for electric forklift

Fuel cell-battery hybrid systems for the powertrain, which have the advantage of emission-free power generation and adapt to material transport and emission reduction, are investigated. Based on the characteristics of the fuel cell system and the characteristics of the electric forklift truck powertrain system, this work defines the design principle of the control strategy to improve overall performance and economy. A simulation platform for fuel cell and electric vehicles has been established. The optimal performance of the fuel cell stack and the battery capacity were defined for the specific application. An energy control strategy was defined for different operating cycles and operating conditions. Model validation involved comparing simulation results with experimental data obtained during VDI60 test protocol. The main parameters that influence the forklift performance were defined and evaluated, such as energy loss, fuel cell operating conditions and different battery charging cycles. The optimal size of the fuel cell stack of 11 kW and the battery of 10 Ah was determined for the specific load profile with the proposed control strategy. The results obtained in this work forms the basis for an in-depth study of the energy management of fuel cell battery drive trains for forklift trucks.     

Design and development of a multipurpose utility AWD electric vehicle with a hybrid powertrain based on PEM fuel cells and batteries

This paper presents the results obtained on the research project CIT-370000-2008-11, entitled “Multi-purpose remote-controlled all-wheel-drive tool-vehicle powered by fuel cells” funded by the Spanish Ministry of Science and Technology. A new concept multipurpose electric vehicle has been designed and manufactured, based on three basic features: a hybrid power system consisting in PEM fuel cells + batteries, an all-wheel-drive traction system, and the capability of being either on-site driven or remote-controlled. The vehicle is formed by two frames connected by a two-degree of freedom joint, and is powered by two 2.5 kW DC motors, one in each axle. All the electric circuits for the suitable control of the power hybrid system have been developed in our Laboratory, allowing a large flexibility. After the different tests performed, it has been verified that the vehicle presents good maneuverability, a good traction performance in off-road driving, as well as a good slope-climbing capability. Under the experimental conditions tested, the vehicle reached a maximum speed of 11 km/h on flat surface, keeping the maximum power consumption always around 3 kW.     

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.     

Experimental assessment of fuel cell/supercapacitor hybrid system for scooters

This paper presents an experimental assessment of fuel cell hybrid propulsion systems for scooters based on a modular 1.2 kW PEM fuel cell. The tests of the hybrid system are carried out using a programmable electronic load. Different configurations of the fuel cell/battery and the fuel cell/supercapacitor hybrid systems are explored. Both systems demonstrate their ability to deliver the requested load satisfactorily. The distributions of the fuel cell power delivery, although different between the two systems, are within the region where the fuel cell efficiency is approximately constant. As a result, the rates of fuel consumption show no discernable difference between the two systems for all three driving cycles considered. In addition to the fuel consumption, considerations including bus voltage, cost and packaging issues suggest that the supercapacitor has advantages over the battery for the use as secondary energy storage in fuel cell hybrid propulsion system for scooters.     

Fuel cell hybrid powertrains for use in Southern Italian railways

This paper analyses the use of a fuel cell hybrid powertrain for different uses on rail. Four vehicles are numerically tested on suitable tracks. The implemented model calculates the vehicle power demand, starting from track altitude, train speed and vehicle characteristics. For each track, a powertrain composed of a fuel cell system and an energy storage system, battery and/or supercapacitor, is used, suitable for the purpose. Each component is modelled separately and is validated. It should be underlined that the whole system is validated, by means of experimental data found in the literature. A comparison analysis between the simulation results is done: the H₂ consumption varies between 5 kg/cycle and 160 kg/cycle, according to the track energy consumption, while the fuel cell efficiency is between 50% and 47%, since the fuel cell works at different power rates.     

Hybrid polymer electrolyte membrane fuel cell–lithium‐ion battery powertrain testing platform – hybrid fuel cell electric vehicle emulator

A testing and validation platform for hybrid fuel cell (FC)–lithium‐ion battery (LIB) powertrain systems is investigated. The hybrid FC electric vehicle emulator enables testing of hybrid system components and complete hybrid power modules up to 25 kW for application in electric light‐duty vehicles, light electric vehicles and so forth. A hybrid system comprising a 10‐kW_el low‐temperature polymer electrolyte membrane FC stack and an 11.5‐kWh LIB pack is installed. The system supplies power to a 20‐kW permanent magnet synchronous motor and a 25‐kW alternating current asynchronous, electrically programmable dynamometer is used to simulate the vehicle load during testing at dynamic drive cycle. The steady‐state performance tests of the direct current (DC) motor, DC/DC converter, low‐temperature polymer electrolyte membrane FC stack and LIB are performed as well as dynamic tests of the complete hybrid system. The Economic Commission for Europe driving cycle is selected as a reference cycle to validate the investigated hybrid FC–LIB powertrain. An efficiency of 83% and 95% is measured for electric motor and DC/DC converter, respectively. An average stack efficiency of 50% is achieved. An average hydrogen consumption of 3.9 g * km^?1 is reached during the Economic Commission for Europe driving cycle test. Copyright © 2017 John Wiley & Sons, Ltd.     

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.     

Fuel cell-battery hybrid powered light electric vehicle (golf cart): Influence of fuel cell on the driving performance

A light electric vehicle (golf cart, 5 kW nominal motor power) was integrated with a commercial 1.2 kW PEM fuel cell system, and fuelled by compressed hydrogen (two composite cylinders, 6.8 L/300 bar each). Comparative driving tests in the battery and hybrid (battery + fuel cell) powering modes were performed. The introduction of the fuel cell was shown to result in extending the driving range by 63–110%, when the amount of the stored H₂ fuel varied within 55–100% of the maximum capacity. The operation in the hybrid mode resulted in more stable driving performances, as well as in the increase of the total energy both withdrawn by the vehicle and returned to the vehicle battery during the driving. Statistical analysis of the power patterns taken during the driving in the battery and hybrid-powering modes showed that the latter provided stable operation in a wider power range, including higher frequency and higher average values of the peak power.     

Comparison of fuel economies of high efficiency diesel and hydrogen engines powering a compact car with a flywheel based kinetic energy recovery systems

Coupling of small turbocharged high efficiency diesel engines with flywheel based kinetic energy recovery systems is the best option now available to reduce fuel energy usage and reduce green house gas (GHG) emissions. The paper describes engine and vehicle models to generate engine brake specific fuel consumption maps and compute vehicle fuel economies over driving cycles, and applies these models to evaluate the benefits of a H₂ICEs developed with the direct injection jet ignition engine concept to further reduce the fuel energy usage of a compact car equipped with a with a flywheel based kinetic energy recovery systems. The car equipped with a 1.2 L TDI Diesel engine and KERS consumes 25 g/km of fuel producing 79.2 g/km of CO₂ using 1.09 MJ/km of fuel energy. These CO₂ and fuel energy values are more than 10% better than those of today’s best hybrid electric vehicle. The car equipped with a 1.6 L DI-JI H₂ICE engine consumes 8.3 g/km of fuel, corresponding to only 0.99 MJ/km of fuel energy.     

Development of integrated fuel cell hybrid power source for electric forklift

A hybrid drivetrain comprising a 16 kW polymer electrolyte membrane fuel cell system, ultracapacitor modules and a lead-acid battery was constructed and experimentally tested in a real counterweight forklift application. A scaled-down version of the hybrid system was assembled and tested in a controlled laboratory environment using a controllable resistive load. The control loops were operating in an in-house developed embedded system. The software is designed for building generic control applications, and the source code has been released as open source and made available on the internet. The hybrid drivetrain supplied the required 50 kW peak power in a typical forklift work cycle consisting of both loaded and unloaded driving, and lifting of a 2.4 tonne load. Load variations seen by the fuel cell were a fraction of the total current drawn by the forklift, with the average fuel cell power being 55% of nominal rating. A simple fuel cell hybrid model was also developed to further study the effects of energy storage dimensioning. Simulation results indicate that while a battery alone significantly reduces the load variations of the fuel cell, an ultracapacitor reduces them even further. Furthermore, a relatively small ultracapacitor is enough to achieve most of the potential benefit.     

Size optimization of a hybrid photovoltaic/fuel cell grid connected power system including hydrogen storage

This paper describes the size optimization of a hybrid photovoltaic/fuel cell grid linked power system including hydrogen storage. The overall objective is the optimal sizing of a hybrid power system to satisfy the load demand of a university laboratory with an unreliable grid, with low energy cost and minimal carbon emissions. The aim is to shift from grid linked diesel power system to a clean and sustainable energy system. The optimum design architecture was established by adopting the energy-balance methods of HOMER (hybrid optimization model for electric renewables). Analysis of hourly simulations was performed to decide the optimal size, cost and performance of the hybrid system, using 22-years monthly averaged solar radiation data collected for Ambrose Alli University, Ekpoma (Lat. 6°44.3ʹN, Long. 6°4.8ʹE). The results showed that a hybrid system comprising 54.7 kW photovoltaic array, 7 kW fuel cell system, 14 kW power inverter and 3 kW electrolyzer with 8 kg hydrogen storage tank can sustainably augment the erratic grid with a very high renewable fraction of 96.7% at $0.0418/kWh. When compared with the conventional usage of grid/diesel generator system; energy cost saving of more than 88% and a return on investment of 41.3% with present worth of $308,965 can be derived in less than 3 years. The application of the optimally sized hybrid system would possibly help mitigate the rural-to-urban drift and resolve the electricity problems hindering the economic growth in Nigeria. Moreover, the hybrid system can alleviate CO₂ emissions from other power generation sources to make the environment cleaner and more eco-friendly.     

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.     

The effect of battery temperature on total fuel consumption of fuel cell hybrid vehicles

In order to consider the effect of battery temperature on the total fuel consumption when a Pontryagin's Minimum Principle (PMP)-based power management strategy is applied to a fuel cell hybrid vehicle (FCHV), this paper designates the battery temperature as a second-state variable other than the battery state of charge (SOC) and defines a new costate for the battery temperature in the control problem. The PMP-based power management strategy is implemented in a computer simulation and the relationship among the final values of the two state variables and the total fuel consumption is illustrated based on the simulation results. This relationship is defined as an optimal surface in this research. Using the optimal surface, it can be concluded that considering the battery temperature effect in the PMP-based power management strategy improves the fuel economy of the FCHV. Potential fuel economy gains attributed to consideration of the battery temperature effect are also determined based on the optimal surfaces.     

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.     

Performance and cost of fuel cells for off-road heavy-duty vehicles

Replacing hydrocarbon-powered off-road vehicles with hydrogen fuel cell-powered off-road vehicles can reduce carbon dioxide and criteria pollutant emissions in the agriculture, construction, and mining industries. Off-road vehicles perform challenging work in harsh environments that complicate deployment of their fuel cell-powered counterparts. Customers and vehicle manufacturers recognize the health and environmental benefits of emissions reductions but are compelled by the total cost of ownership of their vehicles. This study provides a novel technoeconomic comparison of hydrogen fuel cell + battery hybrid powertrains to traditional diesel powertrains for three hallmark off-road vehicles: tractors, wheel loaders, and excavators. Performance metrics include fuel cell engine power, hydrogen consumption rate, hydrogen storage system volume, energy-regenerative drivetrain efficiency, cost of capital, operating and maintenance cost, fuel cost, and fuel storage cost. Results demonstrate that state-of-the-art fuel cell-powered wheel loaders and excavators are currently cost competitive with diesel platforms by total cost of ownership: compact wheel loaders are 19% less expensive, large wheel loaders are equally expensive, mini/compact excavators are 11% more expensive, and standard/full excavators are 9% less expensive. If targeted improvements to cost, performance, and durability of fuel cell stacks and storage systems are achieved, fuel cell systems would be cost competitive for tractors and significantly lower total cost of ownership options for wheel loaders and excavators. This study also elucidates the relationship between performance, cost, and vehicle duty cycle and provides guidance for optimal deployment of fuel cell off-road vehicles.