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.     

Experimental investigation on the dynamic performance of a hybrid PEM fuel cell/battery system for lightweight electric vehicle application

A hybrid system combining a 2 kW air-blowing proton exchange membrane fuel cell (PEMFC) stack and a lead–acid battery pack is developed for a lightweight cruising vehicle. The dynamic performances of this PEMFC system with and without the assistance of the batteries are systematically investigated in a series of laboratory and road tests. The stack current and voltage have timely dynamic responses to the load variations. Particularly, the current overshoot and voltage undershoot both happen during the step-up load tests. These phenomena are closely related to the charge double-layer effect and the mass transfer mechanisms such as the water and gas transport and distribution in the fuel cell. When the external load is beyond the range of the fuel cell system, the battery immediately participates in power output with a higher transient discharging current especially in the accelerating and climbing processes. The DC–DC converter exhibits a satisfying performance in adaptive modulation. It helps rectify the voltage output in a rigid manner and prevent the fuel cell system from being overloaded. The dynamic responses of other operating parameters such as the anodic operating pressure and the inlet and outlet temperatures are also investigated. The results show that such a hybrid system is able to dynamically satisfy the vehicular power demand.     

Modeling and thermal management of proton exchange membrane fuel cell for fuel cell/battery hybrid automotive vehicle

The proton exchange membrane fuel cell (PEMFC) stack is a key component in the fuel cell/battery hybrid vehicle. Thermal management and optimized control of the PEMFC under real driving cycle remains a challenging issue. This paper presents a new hybrid vehicle model, including simulations of diver behavior, vehicle dynamic, vehicle control unit, energy control unit, PEMFC stack, cooling system, battery, DC/DC converter, and motor. The stack model had been validated against experimental results. The aim is to model and analyze the characteristics of the 30 kW PEMFC stack regulated by its cooling system under actual driving conditions. Under actual driving cycles (0–65 kW/h), 33%–50% of the total energy becomes stack heat; the heat dissipation requirements of the PEMFC stack are high and increase at high speed and acceleration. A PID control is proposed; the cooling water flow rate is adjusted; the control succeeded in stabilizing the stack temperature at 350 K at actual driving conditions. Constant and relative lower inlet cooling water temperature (340 K) improves the regulation ability of the PID control. The hybrid vehicle model can provide a theoretical basis for the thermal management of the PEMFC stack in complex vehicle driving conditions.     

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.     

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.     

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.     

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.     

Feasibility study and techno-economic analysis of an SOFC/battery hybrid system for vehicle applications

A feasibility study and techno-economic analysis for a hybrid power system intended for vehicular traction applications has been performed. The hybrid consists of an intermediate temperature solid oxide fuel cell (IT-SOFC) operating at 500–800 °C and a sodium–nickel chloride (ZEBRA) battery operating at 300 °C. Such a hybrid system has the benefits of extended range and fuel flexibility (due to the IT-SOFC), high power output and rapid response time (due to the battery). The above hybrid has been compared to a fuel cell-only, a battery-only and an ICE vehicle. It is shown that the capital cost associated with a fuel cell-only vehicle is still much higher than that of any other power source option and that a battery-only option would potentially encounter weight and volume limitations, particularly for long drive times. It is concluded that increasing drive time per day decreases substantially the payback time in relation to an ICE vehicle running on gasoline and thus that the hybrid vehicle is an economically attractive option for commercial vehicles with long drive times. In the case where the battery has reached volume production prices at £70 kWh⁻¹ and current fuel duty values remain unchanged then a payback time <2 years is obtained. For a light delivery van operating with 6 h drive time per day, a fuel cell system model predicted a gasoline equivalent fuel economy of 25.1 km L⁻¹, almost twice that of a gasoline fuelled ICE vehicle of the same size, and CO₂ emissions of 71.6 g km⁻¹, well below any new technology target set so far. It is therefore recommended that a SOFC/ZEBRA demonstration be built to further explore its viability.     

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.     

Hydrogen fuel cell hybrid scooter (HFCHS) with plug-in features on Birmingham campus

A commercially available ‘pure’ lead-acid battery electric scooter (GoPed) was converted to a hydrogen fuel cell battery hybrid scooter (HFCHS) in views of investigating the effect of hybridisation on driving duty cycles, range, performance, recharging times, well-to-wheel CO₂ footprint and overall running costs. The HFCHS with plug-in features consisted mainly of a 500 W hydrogen PEM Fuel Cell stack connected to four 12 V 9 Ah lead-acid batteries and two hydrogen metal-hydride canisters supplying pure hydrogen (99.999%) and also acting as heat sink (due to endothermic hydrogen desorption process). In this study, the HFCHS urban driving cycle was compared with that of a conventional petrol and ‘pure’ battery electric scooter. The energy consumed by the HFCHS was 0.11 kWh/km, with an associated running cost of £0.01/km, a well-to-wheel CO₂ of 9.37 g CO₂/km and a maximum range of 15 miles. It was shown that the HFCHS gave better energy efficiencies and speeds compared to battery and petrol powered GoPed scooters alone.     

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.     

Micro-generation systems and electrolysers for refuelling private bi-fuel cars at home

An assessment is presented of the prospective use of micro-generation systems in conjunction with electrolysers and hydrogen stores for refuelling private bi-fuel (gasoline/hydrogen) cars with hydrogen. For a range of system sizes and three power source operating modes, predictions are made of the annual travel range on hydrogen and the associated CO₂ savings. A basic system (Mode A) operating solely from the output of a photovoltaic array was found to generate sufficient hydrogen to allow a passenger vehicle with a fuel efficiency of 8.5 l/100 km (33 mpg) to travel 613 km annually per kW of PV installed. An alternative system (Mode B) that permitted network electricity to contribute to hydrogen production, provided that the CO₂ emission factor of the generated hydrogen was half that of gasoline, enabled an annual travel distance of 772 km per kW of PV installed. A hybrid micro-generation system comprising a PV and micro-CHP system (Mode C), where the electricity that would otherwise be exported from the dwelling was diverted to hydrogen production, achieved a more consistent hydrogen production rate across the year. This resulted in a lower on-site storage requirement; when compared with Mode A, it provided an additional annual travel distance on hydrogen of between 1285 and 1833 km. A utility factor was employed to indicate the extent to which a system design could deliver a given daily driving distance on hydrogen across the year. High utility factors (>70%) were only achievable for modest daily driving distances (10–17 km) for the considered range of PV sizes (1.7–8.5 kW).     

Modeling,control and power management of hybrid photovoltaic fuel cells with battery bank supplying electric vehicle

In this paper, modeling, control and power management (PM) of hybrid Photovoltaic Fuel cell/Battery bank system supplying electric vehicle is presented. The HPS is used to produce energy without interruption. It consists of a photovoltaic generator (PV), a proton exchange membrane fuel cell (PEMFC), and a battery bank supplying an electric vehicle of 3 kW. In our work, PV and PEMFC systems work in parallel via DC/DC converter and the battery bank is used to store the excess of energy. The mathematical model topology and it power management of HPS with battery bank system supplying electric vehicle (EV) are the significant contribution of this paper. Obtained results under Matlab/Simulink and some experimental ones are presented and discussed.     

Fuzzy control based engine sizing optimization for a fuel cell/battery hybrid mini-bus

The fuel cell/battery hybrid vehicle has been focused for the alternative engine of the existing internal-combustion engine due to the following advantages of the fuel cell and the battery. Firstly, the fuel cell is highly efficient and eco-friendly. Secondly, the battery has the fast response for the changeable power demand. However, the competitive efficiency of the hybrid fuel cell vehicle is necessary to successfully alternate the conventional vehicles with the fuel cell hybrid vehicle. The most relevant factor which affects the overall efficiency of the hybrid fuel cell vehicle is the relative engine sizing between the fuel cell and the battery. Therefore the design method to optimize the engine sizing of the fuel cell hybrid vehicle has been proposed. The target system is the fuel cell/battery hybrid mini-bus and its power distribution is controlled based on the fuzzy logic. The optimal engine sizes are determined based on the simulator developed in this paper. The simulator includes the several models for the fuel cell, the battery, and the major balance of plants. After the engine sizing, the system efficiency and the stability of the power distribution are verified based on the well-known driving schedule. Consequently, the optimally designed mini-bus shows good performance.     

Control design and power management of a stationary PEMFC hybrid power system

This paper develops robust control and power management strategies for a 6 kW stationary proton exchange membrane fuel cell (PEMFC) hybrid power system. The system consists of two 3 kW PEMFC modules, a Li–Fe battery set, and electrical components to form a parallel hybrid power system that is designed to supply uninterruptible power to telecom base stations during power outages. The study comprises three parts: PEMFC control, power management, and system integration. First, we apply robust control to regulate the hydrogen flow rates of the PEMFC modules in order to improve system stability, performance, and efficiency. Second, we design a parallel power train that consists of two PEMFC modules and one Li–Fe battery set for the uninterruptible power supply (UPS) requirement. Lastly, we integrate the system for experimental verification. Based on the results, the proposed robust control and power management are deemed effective at improving the stability, performance, and efficiency of the stationary power system.     

Test of hybrid power system for electrical vehicles using a lithium-ion battery pack and a reformed methanol fuel cell range extender

This work presents the proof-of-concept of an electric traction power system with a high temperature polymer electrolyte membrane fuel cell range extender, usable for automotive class electrical vehicles. The hybrid system concept examined, consists of a power system where the primary power is delivered by a lithium ion battery pack. In order to increase the run time of the application connected to this battery pack, a high temperature PEM (HTPEM) fuel cell stack acts as an on-board charger able to charge a vehicle during operation as a series hybrid. Because of the high tolerance to carbon monoxide, the HTPEM fuel cell system can efficiently use a liquid methanol/water mixture of 60%/40% by volume, as fuel instead of compressed hydrogen, enabling potentially a higher volumetric energy density.     

Directly connected series coupled HTPEM fuel cell stacks to a Li-ion battery DC bus for a fuel cell electrical vehicle

The work presented in this paper examines the use of pure hydrogen fuelled high temperature polymer electrolyte membrane (HTPEM) fuel cell stacks in an electrical car, charging a Li-ion battery pack. The car is equipped with two branches of two series coupled 1 kW fuel cell stacks which are connected directly parallel to the battery pack during operation. This enables efficient charging of the batteries for increased driving range. With no power electronics used, the fuel cell stacks follow the battery pack voltage, and charge the batteries passively. This saves the electrical and economical losses related to these components and their added system complexity. The new car battery pack consists of 23 Li-ion battery cells and the charging and discharging are monitored by a battery management system (BMS) which ensures safe operating conditions for the batteries. The direct connection of the fuel cell stacks to the batteries can only be made if the stacks are carefully dimensioned to the battery voltage. The experimental results of stationary fuel cell charging are presented, showing stable and efficient operation.     

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.     

An experimental study of a PEM fuel cell power train for urban bus application

An experimental study was carried out on a fuel cell propulsion system for minibus application with the aim to investigate the main issues of energy management within the system in dynamic conditions. The fuel cell system (FCS), based on a 20 kW PEM stack, was integrated into the power train comprising DC–DC converter, Pb batteries as energy storage systems and asynchronous electric drive of 30 kW. As reference vehicle a minibus for public transportation in historical centres was adopted. A preliminary experimental analysis was conducted on the FCS connected to a resistive load through a DC–DC converter, in order to verify the stack dynamic performance varying its power acceleration from 0.5 kW s⁻¹ to about 4 kW s⁻¹. The experiments on the power train were conducted on a test bench able to simulate the vehicle parameters and road characteristics on specific driving cycles, in particular the European R40 cycle was adopted as reference. The “soft hybrid” configuration, which permitted the utilization of a minimum size energy storage system and implied the use of FCS mainly in dynamic operation, was compared with the “hard hybrid” solution, characterized by FCS operation at limited power in stationary conditions. Different control strategies of power flows between fuel cells, electric energy storage system and electric drive were adopted in order to verify the two above hybrid approaches during the vehicle mission, in terms of efficiencies of individual components and of the overall power train.