%% Battery Module Parameters and Documentation % % This document details various options available for use in the Battery % Module Simscape(TM) custom component. % % Copyright 2020-2026 The MathWorks, Inc. %% Battery Module Overview % % A Battery Module is defined as a collection of a number of cells in % series and / or parallel. A Battery (Table-based) block from the Simscape % Electrical library models the battery cell. You can specify the cell-to-cell % variations by modifying the relevant parameters inside the custom % component. Each module has six sides and you can choose from four % different thermal options for each side. % %% *Model Fidelity* % % * *Select Model Fidelity* — Modeling compexity of the Battery Module % component, specified as |Detailed|, |Grouped|, or |Lumped|. |Detailed| % model tracks each and every cell in the system. |Lumped| model tracks the % whole module as a single unit or as lumped. |Grouped| model tracks the % best and the worst cell in the module. The best and the worst cell is % determined based on the cell-to-cell variation specified in *Effective % rate of coolant heat transfer from each cell*, *Cell terminal resistance % R0 variation from baseline*, *Cell Ahr rating variation*, *Cell Self- % discharge resistance variation from baseline Rleak*, or *External heat*. % For more information on the model fidelity, see table in the Appendix-A % section. |Grouped| model working principle is shown in the image below. % For more information on the |Grouped| model fidelity, see Appendix-B. % % <> % % %% Battery *Cell Electrical* Parameters % % For the Battery Cell (Table-based) block in the Simscape Electrical % library, you can specify these parameters: % % * *Vector of temperatures, T* — Temperatures at which the cell or module % data for temperature-varying properties are tabulated, specified as a % vector. % % * *Single cell Ahr rating, baseline* — Cell capacity at the temperatures % defined in the *Vector of temperatures, T* parameter, specified as a % vector. % % * *Vector of state of charge values, SOC* — Range of values between 0 and % 1 at which the cell electrical parameters are defined, specified as a % vector. % % * *No load voltage, V0* — Cell open-circuit potential values at different % *Vector of state of charge values, SOC* and *Vector of temperatures, T* % points, specified as a matrix. % % * *Current directionality* — Current directionality, specified as % |Enabled| or |Disabled|. This parameter defines hystersis during charge % and discharge cycles. % % * *Terminal resistance, R0* — Cell ohmic resistance values at different % *Vector of state of charge values, SOC* and *Vector of temperatures, T* % points, specified as a matrix. % % * *Self-discharge* — Cell self discharge option, specified as |Disabled| % or |Enabled|. If you set this parameter to |Enabled|, you must then % specify the value of the *Self-discharge resistance, Rleak(T)* parameter. % The parameter, specified as resistance, defines a resistance for cell % leakage at all points defined in the *Vector of temperatures, T* % parameter. % % * *Charge dynamics* — Options to select cell dynamics, specified as % |no dynamics|, |one time-constant dynamics|, |two time-constant dynamics|, % |three time-constant dynamics|, |four time-constant dynamics| or |five % time-constant dynamics|. % % * *Polarization resistance* — Polarization resistance values at different % *Vector of state of charge values, SOC* and *Vector of temperatures, T* % points, specified as a matrix. You must specify the value of % *Polarization resistance* parameter based on the value of *Charge % dynamics* parameter. % % * *Time constant* — Time constant at different *Vector of state of charge % values, SOC* and *Vector of temperatures, T* points, specified as a % matrix. You must specify the value of *Time constant* parameter based on % the value of *Charge dynamics* parameter. % %% Battery *Cell Capacity Fade* Parameters % % If you set the *Fade characteristics* parameter of the Battery (Table- % based) block to |Equations|, specify the parameters *Number of discharge % cycles, N*, *Change in no-load voltage after N discharge cycles (%)*, % *Change in terminal resistance after N discharge cycles (%)*, *Change in % ampere-hour rating after N discharge cycles (%)* and the *Change in % polarization resistance after N discharge cycles (%)*. % %% Battery *Cell Thermal* Parameters % % * *Cell thermal mass* — Thermal mass of a single cell, specified as a % scalar. % % * *Cell thermal conductivity* — Cell through-plane conductivity for |pouch| % and |can| cells, or the radial conductivity for |cylindrical| cells, % specified as a scalar. % %% Battery *Module Electrical* Parameters % % * *Number of series connected cells Ns* — Number of strings in series, % specified as an integer. % % * *Number of parallel connected cells Np* — Number of parallel-cells in % a string, specified as an integer. % % * *Choose cell type* — Type of cell, specified as either |Pouch|, |Can|, % |Compact cylindrical|, or |Regular cylindrical|. % % <> % % <> % % * *Cell height* — Cell height, specified as a scalar. % % * *Cell width* — Cell width for |Pouch| and |Can| cells, specified as a % scalar. % % * *Cell thickness* — Cell thickness for |Pouch| or |Can| cells, specified % as a scalar. % % * *Cell diameter* — Cell diameter for |Compact cylindrical| or |Regular % cylindrical|, specified as a scalar. % % * *Number of cylindrical cells in a straight line* — Number of cylindrical % cells arranged in a straight line for packaging, specified as an integer. % % * *Accessory total resistance* — Resistance that combines all inline % resistance in a module, specified as a scalar. This resistance is the % sum of cell tab, busbar, cable and/or weld resistances, specified as a % scalar. % % * *Cell balancing* — Cell balancing method, specified as either |none| or % |passive|. In this example, this parameter is set to |passive|. Upon % selection of |passive| cell balancing, four parameters become visible. % These parameters are: *Shunt resistor*, *Switch closed resistance*, % *Switch open conductance* and *Switch operation threshold*. Passive cell % balancing is shown schematically in the figure below: % % <> % %% Battery *Module Thermal* Parameters % % * *Select module thermal management* — Whether to activate thermal % management in the module, specified as either |None| or |Active|. If % you select *Select module thermal management* to |Active|, the option to % specify heat transfer on the six sides of the module is visible. If you % select *Select module thermal management* to |None| is selected, then *Heat % transfer coefficient to ambient* is visible. All sides of the module lose % heat at a rate defined by this heat transfer coefficient value. % % The figure shows the labels of the six sides of the module. Each side of % the module has four options for heat transfer — |Detailed thermal % output|, |Lumped thermal port|, |Thermal lookup table|, or |Convection % boundary|. % % <> % % * |Detailed thermal output| enables thermal node of each cell to be % connected to other thermal components and is provided through a output % node. This is useful when detailed thermal analysis and information for % every cell is required. Each cell then loses heat at a different rate. % You can connect a detailed fluids component to the output port of the % battery to help in design optimization studies (example : cell-to-cell % cooling variation). % % * |Lumped thermal port|, connects every cell to the same thermal node % externally. % % * |Convection Boundary| specifies a convection boundary condition % on the module face, with its own heat transfer coefficient. % % * |Thermal lookup table| method specifies the heat transfer from battery % cells to the coolant using a lookup table method. The lookup table, for % thermal resistance (W/K) values at multiple temperature and flowrate % points, is defined for all the cells in the module. The range of % temperature and flowrate for coolant are defined in *Vector of % temperatures for LUT thermal model, Tc* and *Vector of coolant flow rates, % L*, respectively. The *Effective rate of coolant heat transfer from each % cell* is a 3-D matrix of size [T,F,C] where, *T* is the size of *Vector % of temperatures for LUT thermal model, Tc*, *F* is the size of *Vector of % coolant flow rates, L* and *C* is equal to the number of cells in the % module, *Ns* X *Np*. The values of the matrix are calculated using % |Detailed thermal output| or 3-D methods such as computational fluid % dynamics. The values of the matrix depend on the actual hardware design % of the cooling system or cold plates in the module. The 3D matrix is % described schematically in the figure below: % % <> % % The 3D matrix defines thermal resistance values at multiple temperature % and flowrate points. During the simulation, the actual value is picked % based on *FlwR* and *FlwT*. *FlwR* and *FlwT* specify coolant flowrate % and inlet temperature based on the values set. % % *FlwR* — Value between 0 and 1, specified as a scalar. The *FlwR* input % value is used to dynamically choose the right value of the flow rate % during the simulations. The value of the *FlwR* input defines the actual % flow rate in the module. In the *Vector of coolant flow rates, L* % parameter, *FlwR* equal to 0 means no flow, while *FlwR* equal to 1 means % highest flow rate value. % % *FlwT* — Positive or negative value that, when summed to the ambient % temperature, equals the coolant inlet temperature. A value of +15 for the % *FlwT* input and 273.15 K at the *Amb* port makes the coolant inlet % temperature equal to 273.15 + 15 = 288.15K. A value of -15 for the *FlwT* % input and 273.15 K at the *Amb* makes the coolant inlet temperature equal % to 273.15 - 15 = 258.15 K. % % <> % % % To open the above example, run the command on MATLAB command prompt: % uiopen('Overview/batteryModuleDoc_example.slx',1) % % % * *External heat* — External heat input to each cell in a module due to a % hot component placed near the module, specified as a vector. % % %% Battery Module *Cell-to-Cell Variation* Parameters % % * *Vector of initial cell temperature* — Cell initial temperature, % specified as a vector. % % * *Vector of initial cell state of charge* — Cell initial state of % charge, specified as a vector. % % * *Cell Ahr rating variation* — Cell-to-cell variations in cell capacity % at all *Vector of temperatures, T* points for each cell, specified as a % vector of scalar values. If you set this array to 1, all cell capacity % is the same. The array values for a cell are multiplied with the value % specified in the *Single cell Ahr rating, baseline* parameter to % calculate the actual capacity or the Ahr rating of the cell. % % * *Cell terminal resistance R0 variation from baseline* — Cell-to-cell % variations in cell terminal resistance, specified as a vector of scalar % values. If you set this array to 1, all cell terminal resistance values % are the same. The array values for a cell are multiplied with the value % specified in the *Terminal resistance, R0* parameter to calculate the % actual terminal resistance value for the cell. % % * *Cell Self-discharge resistance variation from baseline Rleak* — Cell- % to-cell self-discharge, specified as a vector of scalar values. This % parameter is visible if *Self-discharge* is |Enabled|. If you set this % array to 1, all cell self discharge values are the same. The array values % for a cell are multiplied with the value specified in the *Self-discharge % resistance, Rleak(T)* parameter to calculate the self-discharge % resistance value for the cell. % %% Appendix-A % % <> % %% Appendix-B % % The best and the worst cell is automatically selected based on the user % input for: % % * *Effective rate of coolant heat transfer from each cell* (if the % |Thermal lookup table| is selected on a module side for the battery % thermal management), % * *Cell terminal resistance R0 variation from baseline*, % * *Cell Ahr rating variation*, % * *Cell Self-discharge resistance variation from baseline Rleak* and % * *External heat* % % If the module thermal management does not use the option |Thermal lookup % table|, the best and the worst cells cannot be selected based on the % same. The cooling effect variation and best/worst cell cannot be found % out or determined if |Detailed thermal output| or the |Lumped thermal % port| is used for module thermal management. In that case, the best and % worst cells are decided based on: % % * *Cell terminal resistance R0 variation from baseline*, % * *Cell Ahr rating variation*, % * *Cell Self-discharge resistance variation from baseline Rleak* and % * *External heat* % % The code checks for cell-to-cell variation in the data for these % parameters and skips the ones that have no variation present. If multiple % parameters are defined with cell-to-cell variations, the best ad the % worst cells are decided based on cell indices as per the parameter % preference list above. These details are present in file % |getGroupedModelIndexFinal.m|. % % In scenarios where multiple parameters are defined with cell-to-cell % variations, it is important that the cell indices for the best and worst % cells are same for all parameters, else the variation effect would be % smoothed out in averaging and group-creation (|Grouped| model fidelity) % for large modules. You will be able to simulate with warning messages if % the cell indices for the best and worst cells differ for different % parameters. %