PEM Fuel Cell Power System Research Articles

(Invited) The Fuel Cell Solution for Automobile Industry

Proton exchange membrane fuel cell (PEMFC) has been considered as an ideal power source of electric vehicle propulsion due to its high power and energy density, particularly when combined with high pressure hydrogen storage technology. After decades of R&D, the PEMFC technology has been improved to a commercially viable level. In the next five years, the automobile industry in China will invest substantially more efforts on fuel cell vehicles, and Chinese government has launched an attractive subsidy policy towards commercialization of fuel cell vehicles. Sunrise Power has focused on achieving fuel cell technology targets for automobile industry over fifteen years. Three generations of PEMFC power systems has been developed to enhance the power density, durability, and to reduce the cost.The 1st generation of PEMFC power system was developed for fuel cell vehicle demonstration during “2008 Beijing Olympic Games” and “2010 Shanghai EXPO” in China. And the fuel cell lifetime between 1000~2000 hours was demonstrated. The 2nd generation optimized the system and stack design following a fuel cell failure mode, which was disclosed via the degradation research on the 1st generation fuel cell systems. And it has been validated that the fuel cell lifetime can be improved to about 5000 hours. The 3rd generation eliminated air humidification via the adoption of a water management strategy to achieve higher power density and lower cost. Basing on the research, Sunrise Power has launched fuel cell product portfolio of HyMOD, HyMOD+ and HySYS to support the application of the fuel cell vehicle industry.

Design methodology for a PEM fuel cell power system in a more electrical aircraft

In recent years the concept of “more electric aircrafts” has established itself increasingly and the electrical power systems for aircrafts are in progress. In this context, fuel cells represent a valid source of electric power for the advantages in terms of pollution emissions, noise reduction and fuel consumptions.In this study, the authors analyzed the feasibility, from the specific energy point of view, in using a PEM fuel cell power system as APU unit in a more electrical aircraft with respect to a battery system installation. The proposed fuel cell system has a modular architecture and consists of fuel cell stacks, air compressors, heat exchangers, compressed hydrogen tanks and auxiliary batteries.The analysis has been performed by applying a design methodology based on an optimization procedure concerning the size and the efficiency of each power system component in order to reach the maximum specific energy (higher than 500Wh/kg).Moreover, a “black-box”-type model of the power system has been developed to support the optimization methodology in the evaluation of its performance in terms of electric power production, heat production, auxiliary systems consumption and hydrogen consumption.Results pointed out the advantages of the PEM fuel cell application in a more electric aircraft; as a matter of fact for assigned mission requirements, according to the specifications defined in the Long Endurance Demonstrator (LED) project promoted by CIRA (Italian Aerospace Research Centre), the specific energy of the designed power system results to be equal to 0.51kWh/kg. This value is very interesting if compared to the specific energy of commercial LiPo batteries characterized by 0.2kWh/kg.

Coordinated control design for a PEMFC power system using adaptive VRFT method

For a proton exchange membrane fuel cell (PEMFC) power system containing a methanol reformer and a DC–DC converter, it is necessary to coordinate the subsystem controllers to achieve effective power tracking control and prevent constraint violations. This study focuses on the controller design of coordinating control scheme for a PEMFC power system to maintain stable fuel utilization ratio and meet the load demand simultaneously. Because the system exhibits considerable nonlinear behavior, a process model is difficult to identify and is prone to modeling errors. Therefore, this study employs the virtual reference feedback tuning (VRFT) method to design the controllers directly using the process input–output data. To address the process nonlinearity, an improved adaptive VRFT method is developed and applied to the adaptive PID controllers design for a cascade control system. Furthermore, the design parameter of the fuel cell current controller is adaptively tuned according to the deviation of fuel utilization ratio, so that the coordinating control is realized by keeping the dynamics of the current loop consistent with that of the fuel flow loop. Simulation results show that this coordinated control design enables the PEMFC power system to track the load power demand effectively while maintaining the fuel utilization ratio constant.

Control of PEM fuel cell power system using sliding mode and super-twisting algorithms

Traditional sliding mode controller applied to a DC/DC boost converter for the improvement and optimization of the proton exchange membrane fuel cell (PEMFC) system efficiency, has the drawback of chattering phenomenon. Thus, based on the analysis of the mathematical model of PEMFC, this paper addresses the second order super twisting algorithm (STA) as a solution of chattering reduction, Stability of the closed loop system is analytically proved using Lyapunov approach for the proposed controller. The model and the controllers are implemented in the MATLAB and SIMULINK environment. A comparison of results indicates that the suggested approach has considerable advantages compared to the classical sliding mode control.

Fuel Cell Condition Monitoring System Based on Interconnected DC–DC Converter and Voltage Monitor

This paper presents a comprehensive solution for condition monitoring (CM) of proton exchange membrane (PEM) fuel cell systems. It comprises a modular dc-dc converter, a 90-channel fuel cell voltage monitor, and embedded diagnostics algorithms. Besides providing its basic functionality, the dc-dc converter is designed to perform diagnostic probing of fuel cells by injecting current excitation waveforms. The designed voltage monitor enables the precise voltage measurement of all individual cells in the stack. The interconnection between the dc-dc converter and the voltage monitor provides a platform for an embedded CM system. It employs a novel algorithm for fast electrochemical impedance estimation and automatic tuning of the thresholds used in the fault detection algorithm. The final output is a unit-free condition indicator that describes the overall condition of the fuel cell stack. As such, the designed CM system allows the seamless integration and optimal exploitation of fuel cell power systems. The complete solution has been evaluated on an 8.5-kW PEM fuel cell power system.

Nonlinear observer design for PEM fuel cell power systems via second order sliding mode technique

In this paper, a nonlinear observer is proposed for a PEMFC system, based on Second Order Sliding Mode (SOSM) techniques. The goal is to estimate the hydrogen partial pressure in the anode channel of the PEMFC, using the measurements of stack voltage, stack current, anode pressure and anode inlet pressure. The proposed observer employs a nonlinear error injection term, where the error is obtained from the difference between the system voltage output obtained from an experimental validated nonlinear model and estimated voltage output obtained from the designed observer. The robustness of this observer against parametric uncertainties and load variations is studied, and the finite time convergence property is proved via Lyapunov analysis. Simulation results illustrate the effectiveness and robustness of the proposed approach.

The development of a hybrid PEMFC power system

This paper describes the development of a stationary hybrid power system consisting of a 3 kW proton exchange membrane fuel cell (PEMFC) module, a battery set, and solar cells. We design PEMFC control and power managements for the hybrid system, and construct a simulation model based on experimental data. The simulation model is then used to analyze performance and efficiency of the system, employing different power management strategies. The study comprises three parts: PEMFC control, power management, and the simulation model. First, we apply robust control to regulate the PEMFC temperature and current, and achieve root mean square errors of 0.06 °C and 0.07 A, respectively. Second, we integrate the hybrid power system and design power management strategies for sustainable operation. Third, we develop a Matlab™ SimPowerSystem model based on experimental data. The simulation results are shown to match the experiments with a deviation of 0.21%. Last, we apply the simulation model to discuss the impacts of different power management strategies on system efficiency. Based on the results, the designed controllers and power management strategies are deemed effective at improving system performance and efficiency. In addition, the developed simulation model can be applied in the future to develop customized hybrid power system.

PEM fuel cell fault diagnosis via a hybrid methodology based on fuzzy and pattern recognition techniques

In this work, a fault diagnosis methodology termed VisualBlock-Fuzzy Inductive Reasoning, i.e. VisualBlock-FIR, based on fuzzy and pattern recognition approaches is presented and applied to PEM fuel cell power systems. The innovation of this methodology is based on the hybridization of an artificial intelligence methodology that combines fuzzy approaches with well known pattern recognition techniques. To illustrate the potentiality of VisualBlock-FIR, a non-linear fuel cell simulator that has been proposed in the literature is employed. This simulator includes a set of five fault scenarios with some of the most frequent faults in fuel cell systems. The fault detection and identification results obtained for these scenarios are presented in this paper. It is remarkable that the proposed methodology compares favorably to the model-based methodology based on computing residuals while detecting and identifying all the proposed faults much more rapidly. Moreover, the robustness of the hybrid fault diagnosis methodology is also studied, showing good behavior even with a level of noise of 20dB.

Dynamic Analysis of the Proton Exchange Membrane Fuel Cell

Hydrogen energy fuel cell is one of the clean/green energy solutions for the environmental pollution, global warming, and petroleum energy shortage. This study investigates the dynamic characteristic of the green hydrogen energy fuel cell: Proton Exchange Membrane Fuel Cell (PEMFC). PEMFC has been adopted to be the power supplier of the vehicle, small train, etc. A lot of researchers aim on pure electrical property analysis. However, to put PEMFC power system on the road, some mechanical properties of the system should also been examined. In this paper, the dynamic characteristic of a single PEMFC is studied. A single PEMFC (L112×W82×D6 mm) is set up and measured for the time and frequency response. Several fundamental modes are found experimentally which should be avoid during operation period of PEMFC especially in a moving vehicle.

An integrated simulation model for PEM fuel cell power systems with a buck DC–DC converter

Fuel cell powered systems generally have a high current and a low voltage. Therefore, the output voltage of the fuel cell must be stepped-down using a DC–DC buck converter. However, since the fuel cell and converter have different dynamics, they must be suitably coordinated in order to satisfy the demanded load. Accordingly, this study commences by constructing a MATLAB/Simulink model of a proton exchange membrane fuel cell (PEMFC) system comprising a PEMFC stack, an air/fuel supply system, and a temperature control system. The validity of the PEMFC model is demonstrated by comparing the simulation results obtained for the polarzation curves of a single fuel cell with the corresponding experimental curves. A model is then constructed of the DC–DC buck converter used to step-down the PEMFC output voltage. In addition, a sliding mode control (SMC) scheme is proposed for the DC–DC buck converter which guarantees a low and stable output voltage given transient variations in the output voltage of the PEMFC. Finally, a model is constructed of a DC–AC inverter with a pulse width modulated (PWM) control scheme which enables the PEMFC stack to supply the grid or power AC applications directly. Overall, the combined PEMFC/DC–DC buck converter/DC–AC inverter model provides a powerful and versatile tool for the design and development of a wide range of PEMFC power systems.

Derivation of a Fast Mathematical Model of PEM Fuel Cell With Two-Phase Water Transport

A physical model that accounts for the transportation of water in both vapor and liquid phases is useful for the design of water management scheme in a proton exchange membrane fuel cell (PEMFC) system. A 1-D, two-phase PEMFC model that offers both a very short simulation time and a realistic capture of the physical behavior of PEMFC is developed. The presence of liquid water in the cathode gas diffusion layer is modeled by using a simplified treatment of the mass balance of water. The simulation results are compared to the published experimental data and a satisfactory agreement is obtained. The proposed model is used to predict the cell performance under various operating conditions, and its capability to predict an abrupt fall in the cell voltage under flooding condition is demonstrated. The model equations developed, except for the average liquid water saturation, are analytical and require a minimal computational effort, hence reduces the overhead time in PEMFC power system simulations.

Mathematical analysis of hybrid topologies efficiency for PEM fuel cell power systems design

An efficiency mathematical analysis of the commonly used series and parallel hybrid topologies in distributed generation systems (DGS) is presented. The electrical architecture of the DGS consisting of PEM fuel cells, auxiliary storage devices and electrical loads allows regenerative power flow from the load bus. Criteria for a proper choice of the topology for a given load power profile are derived from the analysis and the inclusion of some practical considerations. A novel series-parallel hybrid topology for uncertain load power profiles is also disclosed. The proposed topology is compared with both series and parallel structures in terms of efficiency and number of converters under non-regenerative power conditions. The theoretical predictions of the mathematical analysis are verified by simulation using a Matlab/Simulink model that integrates a physical model of the PEM fuel cell with its control system, an electrical model of a battery with its state-of-charge regulator, and static models of DC/DC converters described in terms of efficiency.

Dynamic Simulator and Controls for a PEM Fuel Cell Power System

Controls of a PEM fuel cell stack are one of the crucial issues for securing efficient and durable operations of the stack. When the air is excessively supplied, the efficiency of the system drops. Conversely, insufficient supply of the air causes oxygen starvation at a dynamically varying load. In particular, proper cooling strategy ensures rejecting heat produced and prevents any thermal stress on thin layers of cells. Excessive cooling decreases the working temperature and consequently drops efficiency of the stack. In contrast, the thermal stress imposed by insufficient cooling may reduce the lifespan of the layers.Design of controls needs a model for the plant that sufficiently represents its dynamics. Current models available are either empirical or computationally intensive, which do not allow for analysis of a stack behavior and associated controls. The paper addresses development of a high dynamic model for a stack that is based on transport of charges, flow of fuels and byproducts taken into temperature effects. The stack is constructed with single cells composed of sandwiched multiple layers that are thermally and electrically coupled. Air is supplied by a blower, which voltage is regulated. Two representing control strategies for the air supply system are designed and compared. Heat is rejected by a thermal circuit that consists of a pump, a three-way valve, and a radiator with a fan and a reservoir. In order to control the coolant flow rate, a linear cascade and a state feedback control are designed and compared, which includes a feed-forward function that is derived from load profile. In addition, the temperature effect on air flow rate is compensated, so that a deviation of the oxygen excess ratio can be suppressed.The dynamics and performance of the designed controllers are evaluated and analyzed by simulations using dynamic fuel cell system models at a multi-step current and a current profile measured at the Federal Urban Driving Schedule. The results show that the control strategy proposed reduces not only temperature rise in the catalyst layer but also the parasitic power needed for operation of the air and coolant pumps maintaining the oxygen excess ratio set.

Methanol Steam Reforming for Hydrogen Production

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Methanol Steam Reforming for Hydrogen Production

Review article covering developments in methanol steam reforming in the context of PEM fuel cell power systems. Subjects covered include methanol background, use, and production, comparison to other fuels, power system considerations, militrary requirements, competing technologies, catalyst development, and reactor and system development and demonstration.

Glass fiber entrapped sorbent for reformates desulfurization for logistic PEM fuel cell power systems

Glass fiber entrapped ZnO/SiO 2 sorbent (GFES) was developed to remove sulfur species (mainly hydrogen sulfide, H 2S) from reformates for logistic PEM fuel cell power systems. Due to the use of microfibrous media and nanosized ZnO grains on highly porous SiO 2 support, GFES demonstrated excellent desulfurization performance and potential to miniaturize the desulfurization reactors. In the thin bed test, GFES (2.5 mm bed thickness) attained a breakthrough time of 540 min with up to 75% ZnO utilization at 1 ppm breakthrough. At equivalent ZnO loading, GFES yielded a breakthrough time twice as long as the ZnO/SiO 2 sorbent; at equivalent bed volume, GFES provided a three times longer breakthrough time (with 67% reduction in ZnO loading) than packed beds of 1–2 mm commercial extrudates. GFES is highly regenerable compared with the commercial extrudates, and can easily be regenerated in situ in air at 500 °C. During 50 regeneration/desulfurization cycles, GFES maintained its desulfurization performance and structural integrity. A composite bed consisting of a packed bed of large extrudates followed by a polishing layer of GFES demonstrated a great extension in gas life and overall bed utilization. This approach synergistically combines the high volume loading of packed beds with the overall contacting efficiency of small particulates.

Integrated modeling and control of a PEM fuel cell power system with a PWM DC/DC converter

A fuel cell powered system is regarded as a high current and low voltage source. To boost the output voltage of a fuel cell, a DC/DC converter is employed. Since these two systems show different dynamics, they need to be coordinated to meet the demand of a load. This paper proposes models for the two systems with associated controls, which take into account a PEM fuel cell stack with air supply and thermal systems, and a PWM DC/DC converter. The integrated simulation facilitates optimization of the power control strategy, and analyses of interrelated effects between the electric load and the temperature of cell components. In addition, the results show that the proposed power control can coordinate the two sources with improved dynamics and efficiency at a given dynamic load.

06/00959 Thermodynamic analysis of a PEM fuel cell power system: Hussain, M. M. et al. International Journal of Thermal Sciences, 2005, 44, (9), 903–911.

06/00959 Thermodynamic analysis of a PEM fuel cell power system: Hussain, M. M. et al. International Journal of Thermal Sciences, 2005, 44, (9), 903–911.

Teledyne wins Nasa contract option

Maryland-based Teledyne Energy Systems Inc has been awarded a $4.3m contract option to develop and deliver an ‘engineering model’ PEM fuel cell power system, rated at 7 kWe, to Nasa’s Glenn Research Center in Ohio. This is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news.

PEM fuel cell power system

PEM fuel cell power system