Model-based analysis for the thermal management of open-cathode proton exchange membrane fuel cell systems concerning efficiency and stability

In this work we present a dynamic, control-oriented, concentrated parameter model of an open-cathode proton exchange membrane fuel cell system for the study of stability and efficiency improvement with respect to thermal management. The system model consists of two dynamic states which are the fuel cell temperature and the liquid water saturation in the cathode catalyst layer. The control action of the system is the inlet air velocity of the cathode air flow manifold, set by the cooling fan, and the system output is the stack voltage. From the model we derive the equilibrium points and eigenvalues within a set of operating conditions and subsequently discuss stability and the possibility of efficiency improvement. The model confirms the existence of a temperature-dependent maximum power in the moderate temperature region. The stability analysis shows that the maximum power line decomposes the phase plane in two parts, namely stable and unstable equilibrium points. The model is capable of predicting the temperature of a stable steady-state voltage maximum and the simulation results serve for the design of optimal thermal management strategies.     

Modeling and control of a PEM fuel cell system: A practical study based on experimental defined component behavior

In this contribution, the dynamical behavior of a polymer electrolyte membrane (PEM) fuel cell system is modeled; related control approaches are developed. The system model used for experimental and modeling purposes describes a 1.2 kW PEM fuel cell stack and an air blower. Due to the dynamical fuel cell–blower interaction the fuel cell stack and the blower model are validated to real systems respectively. Additionally, a feedback based on PI-control is used for hydrogen pressure control with an anode inlet valve. This controller is able to eliminate a stationary error between the anode and cathode pressures. For principal investigations three control approaches, a classical static feed-forward control approach, a state-space feedback control, and a novel gain-scheduling approach are developed, applied, and compared. As result, it can be shown that the feed-forward approach lacks in performance recovering the excess oxygen ratio to the desired level. The state-space feedback control shows stationary error. The introduced gain-scheduling control approach leads to a fast excess oxygen ratio recovery without stationary deviations.     

微通道重整器的动态特性建模与仿真

燃料电池通常需要根据负载的变化而调整工作状态,因此其动态特性是关系到系统性能的关键因素.而重整器作为燃料电池系统的一个重要部件,其动态特性的研究显然就十分必要.选用结构紧凑、性能优良的微通道重整器,通过机理建模得到其集总参数动态数学模型,然后在Matlab平台上构建了其仿真模型.根据燃料电池实际运行过程中负荷变化的特点,分别对重整器的主要调控参数,如流量、温度和压力在发生动态变化的情况下进行了动态响应的仿真.仿真结果与参考文献结论一致,表明该模型能预估重整器动态特性,从而为重整器乃至燃料电池的控制系统设计提供参考.     

基于变论域模糊增量理论的质子交换膜燃料电池温度控制

质子交换膜燃料电池(PEMFC)内部的电化学反应过程直接表现为温度的变化,所以有效的温度控制是保证燃料电池可靠性和耐久性的关键.本文将模糊增量控制用于PEMFC热管理系统中,将PEMFC的温度和电堆出入口温度差保持在设定值.首先,建立PEMFC热管理系统的动态模型,包括PEMFC电堆模型和辅助散热设备模型.然后,基于建立的系统模型,设计了一种变论域的模糊增量控制器.该控制器通过伸缩因子来动态调节模糊控制器中的量化因子和比例因子,实现对模糊论域的调节,从而提高控制的灵敏性和精确度.最后,将该温度控制方法用于10 kW燃料电池系统中,实验结果表明变论域模糊增量控制器相比于其他模糊控制方法,不仅具有更快的动态响应速度,还具有更强的鲁棒性和更高的控制精度.     

Control‐oriented fault detection of solid oxide fuel cell system unknown input on fuel supply

As the solid oxide fuel cell (SOFC) system work environment is a high‐temperature environment for a long time, it is difficult to obtain the SOFC stack internal state change directly. When the fault occurs, it is difficult to determine where the fault occurs. Moreover, the existing literature ignores the impact of faults, which creates many problems for SOFC system control. Therefore, a state observer‐based fault detection method, which is used to detect the input flow sensor fault and the fuel input fault, is proposed. Their advantage is that they do not need data processing. To realize the fault detection, the observer is used to track the changes of SOFC stack chamber temperature. To obtain the observer estimation parameter, an approach from the actual stack structure parameters is employed to approximate the observer parameters. The results show the proposed fault detect method can judge fuel input fault type quickly and shield the disturbances signals from the sensor effectively. The proposed method also can be used to other operating points or air input fault.     

Modelling,dynamics and control of a portable DMFC system

A dynamic model for a direct methanol fuel cell and its ancillary units is presented, in which all ancillary units perform only one operation each. The system’s losses and main dynamics (cathodic oxygen fraction, anodic methanol concentration, stack temperature, system water holdup) are analysed for stability and time constants. The system is found to be stable in all of its dynamics except for that of water holdup. The influence of external conditions, such as temperature and humidity, on system feasibility is analysed; the capability of system autonomous operation depends essentially on environmental conditions and on the chosen air excess ratio. Decoupled single-input, single-output controllers, some of which employing feedback, are applied to maintain the system at a certain set point. System simulations are performed, confirming the performance of the proposed controllers, their ability to stabilise the water holdup, and the absence of interaction-induced oscillations; the system can be started up in about ten minutes with the presented parameters.     

Modeling and cycling control of carbonate fuel cell power plants

A mathematical process model for an internal reforming molten carbonate fuel cell power plant is discussed in this paper. The dominant thermal and chemical dynamic processes are modeled for the cell stack array and balance-of-plant, including cathode gas preparation, heat recovery, and fuel processing. Physical data is obtained from a 2 MW system design that was a precursor to a demonstration plant operated at the City of Santa Clara, CA, USA. Steady state validation for several load points is provided for the cell stack array and a load cycling control system is described and tested under ramping operation between load points.     

PEM燃料电池堆单片电压检测系统设计

根据电池堆性能测试及其控制系统研发需要,设计了一种燃料电池堆单片电压检测系统.该系统精度高、实时性好、稳定性强,而且电路简单、成本低、体积小、易布局.实验证明该系统能够有效地完成燃料电池单片电压实时采集、显示和保存.已成功应用于200W常温常压空冷质子交换膜燃料电池(PEMFC)电源控制系统.     

Output Tracking Control of a Hydrogen-air PEM Fuel Cell

Hydrogen-air proton exchange membrane (PEM) fuel cell is a promising clean energy. However, the stack output tracking control is still a challenging problem due to the soft characteristic of the stack. Both over-and less-control will cause the stack flooding or oxygen lacking which dramatically decreases the life of stacks. Traditional control methods rely on the accurate model of the fuel cell system, which is a high-order nonlinear system, and involve a complex controller design process. This paper combines the data-based fuzzy cluster modeling technology with the sliding mode control and the integral actions. The sliding mode controller tracks the dynamic changes of the fuel cell system and the integral controller eliminates the steady-state errors. Simulation results demonstrate good performance of the proposed control method.      

燃料电池温度模糊自适应控制

如何控制燃料电池温度性能是燃料电池的一个重要问题。首先基于模糊辨识建模方法建立质子交换膜燃料电池温度性能的T-S模型。模型结构简单,精度高,方便地应用于质子交换膜燃料电池系统控制中。其次针对该模型设计电堆温度的模糊自适应控制器。最后在Matlab平台进行仿真,模糊自适应控制器在较大幅度变化的系统参数下都得到较好的控制性能,证明模糊自适应控制系统具有很好的鲁棒性和良好的控制品质,能够满足质子交换膜燃料电池温度控制系统的要求。     

阳极焙烧燃油供给温度的模糊预测函数控制

阳极焙烧燃油供给温度的精确控制是一个具有非线性特性的流体加热供给控制问题,实际测试表明,现有的PID控制很难实现对燃油供给温度的动态跟踪控制,影响燃油的充分喷射、雾化及其与空气的混合,使部分燃油得不到充分燃烧,造成了能源浪费和环境污染。提出基于粒子群优化模糊预测函数控制（PSO-F-PFC）的油料燃烧供给温度控制方法,通过与PID控制方法的比较,以及对阳极焙烧炉重油燃烧供给温度的动态跟踪控制表明,该方法优于原有燃油燃烧系统的PID控制,实现了燃油供给温度的动态跟踪精确控制。     

质子交换膜燃料电池建模与动态仿真

对质子交换膜燃料电池（PEMFC）电堆进行电输出特性研究,有助于改善燃料电池的设计,提高其性能。运用MATLAB的Simulink仿真工具对PEMFC建立仿真模型,通过所建立的电堆参数模型,就能够研究主要运行参变量对电堆动态输出性能和电堆非线性内阻产生的影响。当电堆输出电流出现阶跃变化时,对电堆电压,输出功率,消耗功率,电堆效率,非线性内阻的动态响应,进行了仿真和结果分析。仿真结果符合文献[7]实验数据,表明此参数模型是可操作和有效的,并可方便地用于PEMFC控制方法研究。     

水冷型PEMFC温湿度建模与智能控制

当负载电流一定时,质子交换膜燃料电池(PEMFC)的工作温度和质子膜的相对湿度是影响电池输出性能的主要因素.分析电池电流密度与最优工作温湿度的关系,建立基于温湿度耦合模型的最优温湿度操作条件的电压模型.通过对冷却水流量和阴阳极气体加湿度进行综合控制,保持电堆的工作温湿度在最佳状态,不仅保证了电池最优的输出性能,还可以延...     

CO detection in H2 reducing atmosphere with mini fuel cell

A prototype of a miniaturized fuel cell has been studied in order to detect carbon monoxide in hydrogen-rich atmosphere for PEMFC (proton exchange membrane fuel cell) applications. It consists on a single PEMFC (membrane-electrode-assembly supplied by CEA/LITEN) directly fed by the hydrogen-carbon monoxide mixture while the cathode is exposed to ambient air. Experiments have been carried out on a laboratory testing bench with simulated reforming gas. Two working modes have been studied. For low CO concentrations (≤20 ppm), the amperometric mode is suitable but a regeneration in air is necessary to obtain a good reversibility of the sensor response. On the contrary, for higher CO concentrations (250-4000 ppm), a good reversible response is observed without air regenerating by using a potentiometric or quasi-potentiometric mode. Therefore, this prototype of mini fuel cell sensor seems to be convenient for monitoring reformed gases either for low temperature PEMFC which are poisoned by very low traces of CO or for high temperature PEMFC which can operate at higher CO concentrations.     

基于模糊逻辑与遗传算法的燃料电池热管理方法研究

有效的质子交换膜燃料电池(Proton Exchange Membrane Fuel Cell,PEMFC)热管理是提升氢燃料电池汽车安全性、耐久性以及运行效率的关键因素之一.该文提出一种PEMFC电堆热管理控制方法,使电堆出入口温度保持在设定值.该方法以PEMFC热管理系统模型中电堆出入口温度的变化为依据,设计一种二...     

Nonlinear modeling and adaptive fuzzy control of MCFC stack

To improve availability and performance of fuel cells, the operating temperature of molten carbonate fuel cells (MCFC) stack should be controlled within a specified range. However, the most existing models of MCFC are not ready to be applied in synthesis. In this paper, a radial basis function neural networks identification model of MCFC stack is developed based on the input–output sampled data. A novel adaptive fuzzy control procedure for the temperature of MCFC stack is also developed. The parameters of the fuzzy control system are regulated by back-propagation algorithm, and the rule database of the fuzzy system is also adaptively adjusted by the nearest-neighbor-clustering algorithm. Finally using the neural networks model of MCFC stack, the simulation results of the control algorithm are presented. The results show the effectiveness of the proposed modeling and design procedures for MCFC stack based on neural networks identification and the novel adaptive fuzzy control.     

Nonlinear MPC Controller Design for AIR Supply of PEM Fuel Cell Based Power Systems

The air supply system, which provides the oxygen for the fuel cell stack, is one of the most important subsystems of the proton exchange membrane fuel cell (PEMFC). In order to improve the performance of the air supply, a small rechargeable lithium‐ion battery is utilized to start up the PEMFC system and provide buffer power supply for the load demand. With energy consumption of the compressor considered, a power coordinating algorithm utilizing a virtual potential field approach is presented to manage the power demand for the PEMFC and the battery while maintaining the battery's state of charge. A nonlinear observer is designed to estimate the unmeasurable states of the air supply system and its convergence is proven. A nonlinear MPC method is proposed to control the air flow and ensure the adequate oxygen supply. Simulation results are provided to validate the performance of the power management algorithm and the air supply control method. Compared with the results of the MPC algorithm and the nonlinear MPC method for the PEMFC system without an auxiliary battery, the method designed here has better performance.     

Active disturbance rejection control for voltage stabilization in open-cathode fuel cells through temperature regulation

Temperature regulation is an important control challenge in open-cathode fuel cell systems. In this paper, a feedback controller, combined with a novel output-injection observer, is designed and implemented for fuel cell stack temperature control. The first functionality of the observer is to smooth the noisy temperature measurements. To this end, the observer gain is calculated based on Kalman filter theory which, in turn, results in a robust temperature estimation despite temperature model uncertainties and measurement noise. Furthermore, the observer is capable of estimating the output voltage model uncertainties. It is shown that temperature control not only ensures the fuel cell temperature reference is properly tracked, but, along with the uncertainty estimator, can also be used to stabilize the output voltage. Voltage regulation is of great importance for open-cathode fuel cells, which typically suffer from gradual voltage decay over time due to their dead-end anode operation. Moreover, voltage control ensures predictable and fixed fuel cell output voltages for given current values, even in the presence of disturbances. The observer stability is proved using Lyapunov theory, and the observer's effectiveness in combination with the controller is validated experimentally. The results show promising controller performances in regulating fuel cell temperature and voltage in the presence of model uncertainties and disturbances.     

Design and experimental validation of a constrained MPC for the air feed of a fuel cell

Fuel cells represent an area of great industrial interest due to the possibility to generate clean energy, especially PEM (Polymer Electrolyte Membrane or Proton Exchange Membrane) fuel cells for their use in stationary and automotive applications. The oxygen excess ratio expressing the proportion between oxygen reacting in the cells and oxygen entering the stack is widely used to guarantee safety and to reach a high performance. To control the oxygen excess ratio a model predictive control (MPC) has been developed using the compressor motor voltage to manipulate the air flow rate entering the fuel cell. The design of the MPC is carried out with a commercial fuel cell. The proposed MPC is implemented and validated in experiments and compared with the original built-in controller. The behaviour of the system and the controller is illustrated by means of experimental results.     

安全操控下5 kW固体氧化物燃料电池电堆预测控制器设计

基于5 kW固体氧化物燃料电池(SOFC)电堆,考虑建模仿真—2温度层模型在模型精度与复杂度上做了更好的折中,可以更有效地应用于控制器设计.本文首先对2温度层模型在常用稳态工作点附近采用泰勒级数展开,获得其状态空间方程.然后考虑其安全操作特性,设计了两种带约束的预测控制器:即面向SOFC电堆的快速负载跟踪与燃料亏空控制...