ABSTRACT
Fuel cells have been studied for use in stationary power generation and vehicle propulsion systems. The fuel cell thermal management subsystem is coupled and nonlinear, posing challenges for modeling and temperature control. This paper aims to integrate the physical models of the fuel cell stack, pump, thermostat, and other components combined with intelligent algorithms into an efficient system-level thermal management model framework and develop a model predictive controller to solve the temperature control problem. First, a physics-based nonlinear model of the fuel cell system is developed and used as a basis to identify the linearized model for different operating points. Then, the global model is obtained by fusing the local models with Gaussian validity functions using the local linear model tree method. Third, a multi-step prediction model is derived based on the local model networks, and a parameterized linear state space form is obtained and used for controller design. Furthermore, an online correction method is developed to reduce the model discrepancy. Finally, the accuracy of the system model and the performance of the proposed controller are verified by open-loop experimental data and a series of closed-loop simulation cases.
Nomenclature
Abbreviations | = | |
MPC | = | Model Predictive Control |
ANN | = | Artificial Neural Network |
SVR | = | Support Vector Regression |
KNN | = | K-nearest neighbor |
PEMFC | = | Proton Exchange Membrane Fuel Cell |
CHP | = | Combined heat and power |
BP | = | Bipolar plate |
MEA | = | Membrane Electrode Assembly |
LMN | = | Local model network |
NARX | = | Nonlinear auto-regression with exogenous input |
NFIR | = | Nonlinear Finite Impulse Response |
MISO | = | Multi-input single-output |
LoLiMoT | = | Local Linear Model Tree |
Symbols | = | |
Cst | = | Heat capacity of the fuel cell stack |
ΔH | = | Heat value of hydrogen |
nst | = | Cell number |
Ist | = | Load current |
F | = | Faraday constant |
= | Flow rate of coolant | |
Vcell | = | Output voltage of a single cell |
PH2 | = | Partial pressure of hydrogen |
PO2 | = | Partial pressure of oxygen |
Dpump | = | Diameter of pump |
Npump | = | Pump speed |
ρcol | = | Coolant density |
Ppump,out | = | Outlet pressure of pump |
Ppump,in | = | Inlet pressure of pump |
= | Coolant flow rate of the major-cycle | |
= | Coolant flow rate of the minor-cycle | |
α | = | Thermostat opening |
Tminor | = | Coolant temperature of the minor-cycle |
Cminor | = | Heat capacity of the minor-cycle |
Pptc | = | Power of PTC |
Tm | = | Mixing temperature of minor-cycle and major-cycle |
Tex | = | Heat exchanger outlet temperature |
Φi | = | Validity function |
φ | = | Scheduling vector |
r | = | Input variable of the local model |
Llm | = | Number of the local models |
θi. | = | Parameter vector |
C | = | Control horizon |
P | = | Prediction horizon |
Q | = | The weight of cost function |
= | Energy generated by the chemical reaction | |
= | Electrical energy | |
= | Heat lost to the environment | |
= | Heat removed by the cooling water |
Disclosure statement
No potential conflict of interest was reported by the author(s).