Why do the Simulation of Fuel Cell System and Fuel Cell I-V Characteristics examples not work in R2024b Update 7?

After installing MATLAB R2024b Update 7, the 'Simulation of Fuel Cell System' and 'Fuel Cell I-V Characteristics' examples throw an error. Why do these examples no longer work, and is there a workaround to allow me to use these workflows in R2024b after Update 7?

Answer 1

[MathWorks Support Team]

To fix non-physical current-voltage characteristics, the equations and parameters of the Fuel Cell block have changed. However, the current versions of the Fuel Cell System and Fuel Cell I-V Characteristics examples continue to use non-physical model constraints and parameter values to produce meaningful results, which cause simulation failures.

Any models that you created using these examples as a starting point might also include non-physical constraints and parameter values and therefore experience similar simulation issues. 

Workaround

To prevent this issue, arrange the blocks and connections in your Simulink models to match the configuration of blocks and connections used in the Simulink models of these examples provided in R2025b Update 1 or later.

Then, update these parameters:

Inside the FuelCellSystemData.m script:

Eoc = 65; % Open-circuit voltage [V]
A = 0.024; % Tafel slope [V]
Ri = 0.078; % Internal resistance [Ohm]
i0 = 0.3; % Nominal exchange current [A]
i_lim = 225; % Collapse current [A]
N_cell = 65; %Number of cells per module
number_unit = 10; %Module units (Series)
pH2_nom = 1.5e5; % Nominal H2 pressure [Pa]
pO2_nom = 1.0e5; % Nominal O2 pressure [Pa]
thermal_mass = 15000; % Thermal mass [J/K]
T_init = 338.15; % Initial stack temperature [K]
T_nom = 338.15; % Nominal stack temperature [K]
Qfuel0 = 2.0; % Initial fuel flow rate [lpm]
Rload = 62.5;
Vset = 0.9*N_cell*number_unit; % Setpoint voltage = 0.9 V per cell
pH2 = 2.5; % Pressure_H2

Inside the FuelCellIVCharacteristicData.m script:

Tsim = 360;
I_array = [1 5 15 26 37 48 62 76 86 97 110 124 138 155 170 188 202];
V_array = [64 61 58 56.5 55 53.5 52 50.5 49.5 48.5 47.2 45.7 44.5 43 41.5 40 39];
FuelCell.OpenCircuitVoltage = 65; % Open-circuit voltage [V]
FuelCell.TafelSlope = 0.024; % Tafel slope [V]
FuelCell.InternalResistance = 0.078; % Internal resistance [Ohm]
Nu = 1;
pAir = 1.0; pH2 = 1.5;
FuelCell.ExchangeCurrent = 0.3;
FuelCell.CollapseCurrent = 225;
FuelCell.NomH2_Pressure = 1.5e5;
FuelCell.NomAir_Pressure = 1.0e5;
FuelCell.InitVoltage = 65;
FuelCell.InitTemperature = 338.15;
FuelCell.NomTemperature = 338.15;
FuelCell.Qfuel = 90;
FuelCell.Qair = 375;
FuelCell.Concentration = [99 21 1]; %[H2 O2 vapor]
Ncell = 65; % Number of elementary cells