Battery Module Parameters and Documentation

This document details various options available for use in the Battery Module Simscape™ custom component.

Contents

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

Battery Cell Electrical Parameters

For the Battery Cell (Table-based) block in the Simscape Electrical library, you can specify these parameters:

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

Battery Module Electrical Parameters

Battery Module Thermal Parameters

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.

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)

Battery Module Cell-to-Cell Variation Parameters

Appendix-A

Appendix-B

The best and the worst cell is automatically selected based on the user input for:

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:

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.