PEMFC Optimization Strategy with Auxiliary Power Source in Fuel Cell Hybrid Vehicle

one of the present-day implementation of fuel cell is acting as main power source in Fuel Cell Hybrid Vehicle (FCHV). This paper proposes some strategies to optimize the performance of Polymer Electrolyte Membrane Fuel Cell (PEMFC) implanted with auxiliary power source to construct a proper FCHV hybridization. The strategies consist of the most updated optimization method determined from three point of view i.e. Energy Storage System (ESS), hybridization topology and control system analysis. The goal of these strategies is to achieve an optimum hybridization with long lifetime, low cost, high efficiency, and hydrogen consumption rate improvement. The energy storage system strategy considers battery, supercapacitor, and high-speed flywheel as the most promising alternative auxiliary power source. The hybridization topology strategy analyzes the using of multiple storage devices injected with electronic components to bear a higher fuel economy and cost saving. The control system strategy employs nonlinear control system to optimize the ripple factor of the voltage and the current and using the AOC-EMS system to improve the hydrogen consumption rate. ECMS and BERS strategy based on Time-Triggered Controller Area Network (TTCAN) also promoted to optimize hydrogen consumption rate from recovered kinetic energy while in braking regeneration mode

Integrated Li-Ion Ultracapacitor with Lead Acid Battery for Vehicular Start-Stop

Advancements in automobile manufacturing aim at improving the driving experience at every level possible. One improvement aspect is increasing gas efficiency via hybridization, which can be achieved by introducing a feature called start-stop. This feature automatically switches the internal combustion engine off when it idles and switches it back on when it is time to resume driving. This application has been proven to reduce the amount of gas consumption and emission of greenhouse effect gases in the atmosphere. However, the repeated cranking of the engine puts a large amount of stress on the lead acid battery required to perform the cranking, which effectively reduces its life span. This dissertation presents a hybrid energy storage system assembled from a lead acid battery and an ultracapacitor module connected in parallel. The Li-ion ultracapacitor was tested and modeled to predict its behavior when connected in a system requiring pulsed power such as the one proposed. Both test and simulation results show that the proposed hybrid design significantly reduces the cranking loading and stress on the battery. The ultracapacitor module can take the majority of the cranking current, effectively reducing the stress on the battery. The amount of cranking current provided by the ultracapacitor can be easily controlled via controlling the resistance of the cable connected directly between the ultracapacitor module and the car circuitry

Modeling of electrical behavior of graphene-based ultracapacitors

Graphene has been identified as a promising material for energy storage, especially for high performance ultracapacitors. Graphene-based ultracapacitors show high stability, significantly-improved capacitance and energy density with fast charging and discharging time at a high current density, due to enhanced ionic electrolyte accessibility in deeper regions. The surface area of a single graphene sheet is 2630 m2/g, substantially higher than values derived from Brunauer Emmett Teller (BET) surface area measurements of activated carbons used in the current electrochemical double layer capacitors. In an ultracapacitor cell, chemically modified graphene (CMG) materials demonstrate high specific capacitances of 135 and 99 F/g in aqueous and organic electrolytes, respectively. In addition, high electrical conductivity gives these materials consistently good performance over a wide range of voltage scan rates. This paper reports a modeling methodology to predict the electrical behavior of a 2.7 V/650 F ultracapacitor cell. The ultracapacitor cell is subject to the charge/discharge cycling with constant-current between 1.35 V and 2.7 V. The charge/discharge current values examined are 50, 100, 150, and 200 A. A three resistor-capacitor (RC) parallel branch model is employed to calculate the electrical behavior of the ultracapacitor. The simulation results for the variations of the cell voltage as a function of time for various charge/discharge currents are in good agreement with the experimental measurements

The Application of Regenerative Braking System to the Commercial Hybrid Vehicles with All-Wheel Drive System

The growing issues of energy shortage and the environmental crisis has resulted in new challenges for the automotive industry. Conventional commercial vehicles, such as refuse trucks and delivery vehicles, consume significantly more energy than other on-road vehicles since they have the characteristic of frequent start/stop with high moment of inertia and drive at low speeds on designated city routes. It is important to make these vehicles more fuel efficient and environmentally friendly. The hybrid commercial vehicle is a promising solution to reduce emissions and to meet the future vehicle emission standard since it is generally equipped with braking energy regeneration systems to recover the kinematic loss from frequent braking. This paper introduces a type of all-wheel drive hybrid concept suggested by Dr. Leo Oriet; the new concept allows commercial vehicles to have a significant improvement in kinetic braking energy recovery without sacrificing braking safety. Without mechanical connection involved to transfer energy within the powertrain, greater powertrain efficiency can be achieved. The research is based on the all-wheel drive with a two-axles regenerative braking strategy and driveline control unit. The vehicle model and driveline control unit were executed using AVL CRUISE to demonstrate its reliable braking energy regeneration system, effective energy management and emission reduction. Finally, the power system and engine operating condition, as well as vehicle driving mode, were analyzed after simulation to ensure the whole powertrain component functions together with high efficiency and significant reliability

Heavy-Duty Vehicles Modeling and Factors Impacting Fuel Consumption.

A conventional heavy-duty truck PSAT model was validated and incorporated into the Powertrain System Analysis Toolkit (PSAT). The truck that was modeled was a conventional over-the-road 1996 Peterbilt tractor, equipped with a 550 hp Caterpillar 3406E non exhaust gas circulation (EGR) engine and an 18-speed Roadranger manual transmission. A vehicle model was developed, along with the model validation processes. In the engine model, an oxides of nitrogen (NOx) emissions model and a fuel rate map for the Caterpillar 3406E engine were created based on test data. In the gearbox model, a shifting strategy was specified and transmission efficiency lookup tables were developed based on the losses information gathered from the manufacturer. As the largest mechanical accessory model, an engine cooling fan model, which estimates fan power demand, was integrated into the heavy-duty truck model. Experimental test data and PSAT simulation results pertaining to engine fuel rate, engine torque, engine speed, engine power and NOx were within 5% relative error. A quantitative study was conducted by analyzing the impacts of various parameters (vehicle weights, coefficients of rolling resistance and the aerodynamic drag) on fuel consumption (FC) for the Peterbilt truck. The vehicle was simulated over five cycles which represent typical vehicle in-use behavior. Three contributions were generated. First, contour figures provided a convenient way to estimate fuel economy (FE) of the Peterbilt truck over various cycles by interpolating within the parameter values. Second, simulation results revealed that, depending on the circumstances and the cycle, it may be more cost effective to reduce one parameter value (such as coefficient of aerodynamic drag) to increase FE, or it may be more beneficial to reduce another (such as the coefficient of rolling resistance). Third, the amount of the energy consumed by auxiliary loads was found to be highly dependent upon the driving cycles. The ratios between average auxiliary power and average engine power were found to be 71.0%, 17.1%, 15.3%, 12.4% and 11.43% for creep, transient, UDDS, cruise and HHDDT_s cycles, respectively. A hybrid electric bus (HEB) also was modeled. The HEB that was modeled was a New Flyer bus with ISE hybrid system, a Cummins ISB 260H engine and a single-reduction transmission. Information and data were acquired to describe all major components of the HEB. The engine model was validated prior to modeling of the whole vehicle model. The load-following control strategy was utilized in the energy management system. Experimental data and PSAT simulated results were compared over four driving schedules, and the relative percent of errors of the FC, FE, CO2 and NOx were all within 5% except for the FE and NOx of the Manhattan cycle, which were 6.93% and 7.13%, respectively. The high fidelity of this model makes it possible to evaluate the FE and NOx emissions of series hybrid buses for subsequent PSAT users

Toward Holistic Energy Management Strategies for Fuel Cell Hybrid Electric Vehicles in Heavy-Duty Applications

The increasing need to slow down climate change for environmental protection demands further advancements toward regenerative energy and sustainable mobility. While individual mobility applications are assumed to be satisfied with improving battery electric vehicles (BEVs), the growing sector of freight transport and heavy-duty applications requires alternative solutions to meet the requirements of long ranges and high payloads. Fuel cell hybrid electric vehicles (FCHEVs) emerge as a capable technology for high-energy applications. This technology comprises a fuel cell system (FCS) for energy supply combined with buffering energy storages, such as batteries or ultracapacitors. In this article, recent successful developments regarding FCHEVs in various heavy-duty applications are presented. Subsequently, an overview of the FCHEV drivetrain, its main components, and different topologies with an emphasis on heavy-duty trucks is given. In order to enable system layout optimization and energy management strategy (EMS) design, functionality and modeling approaches for the FCS, battery, ultracapacitor, and further relevant subsystems are briefly described. Afterward, common methodologies for EMS are structured, presenting a new taxonomy for dynamic optimization-based EMS from a control engineering perspective. Finally, the findings lead to a guideline toward holistic EMS, encouraging the co-optimization of system design, and EMS development for FCHEVs. For the EMS, we propose a layered model predictive control (MPC) approach, which takes velocity planning, the mitigation of degradation effects, and the auxiliaries into account simultaneously

A SC/battery Hybrid Energy Storage System in the Microgrid

The major challenges in power systems are driven by the energy shortage and environmental concerns, namely facilitating the penetration of renewable energy and improving the efficiency of the renewable powers. Due to the variable nature of renewables, the generated power profile may not be able to match the load requirement. Accordingly, much attention has been focused on the development of energy storage technologies to guarantee renewable power penetrations. Recently, advances in the supercapacitor (SC) have made the SC and battery hybrid energy storage systems (HESS) technically attractive. Compared with other energy storage technologies the principal advantages of SC are: the high power density, high cycling life, and high peak current handling capacities. However, SC is also deficient in low energy density. The battery is characterised by large energy density but low in power capacity. In the microgrid systems, high-frequency power fluctuations will cause a significant degree of battery power cycling. This, in turn, has been shown to lead to a significant reduction in battery service life. Therefore, the concept of the SC and battery hybrid scheme is proposed. A case study of the HESS based on a microgrid is introduced in this paper. A simplified microgrid system is established to test the performance of the proposed design

Theoretical dimensioning and sizing limits of hybrid energy storage systems

Aim of a storage hybridisation is a beneficial usage or combination of different storage technologies with various characteristics to downsize the overall system, decrease the costs or to increase the lifetime, system efficiency or performance. In this paper, the point of interest is a different ratio of power to energy (specific power) of two storages to create a hybrid energy storage system (HESS) with a resulting specific power that better matches the requirements of the application. The approach enables a downsizing of the overall system compared to a single storage system and consequently decreases costs. The paper presents a theoretical and analytical benchmark calculation that determines the maximum achievable hybridisation, i.e. possible spread in specific power, while retaining the original total energy and power capacities of an equivalent single storage system. The theory is independent from technology, topology, control strategy, and application and provides a unified view on hybrid energy storage systems. It serves as a pre-dimensioning tool and first step within a larger design process. Furthermore, it presents a general approach to choose storage combinations and to characterize the potential of an application for hybridisation. In this context, a Hybridisation Diagram is proposed and integral Hybridisation Parameters are introduced