Project 2 Thermal modeling of battery pack
For a 10 cell series lithium ion battery model, simulate the thermal effects and compare life cycle performance at various temperatures, charge & discharge rates using MATLAB.
Below is the Simulink model of the 10 cells connected in series
Bus selector
This block accepts a bus as input which can be created from a Bus Creator, Bus Selector or a block that defines its output using a bus object. The left listbox shows the signals in the input bus. Use the Select button to select the output signals. The right listbox shows the selections. Use the Up, Down, or Remove button to reorder the selections. Check 'Output as virtual bus' to output a single bus signal.
Goto
Send signals to From blocks that have the specified tag. If tag visibility is 'scoped', then a Goto Tag Visibility block must be used to define the visibility of the tag. The block icon displays the selected tag name (local tags are enclosed in brackets, [], and scoped tag names are enclosed in braces, {}).
Cell
Implements a generic battery model for most popular battery types. Temperature and aging (due to cycling) effects can be specified for Lithium-Ion battery type.
Controlled Current Source
Converts the Simulink input signal into an equivalent current source. The generated current is driven by the input signal of the block.You can initialize your circuit with a specific AC or DC current. If you want to start the simulation in steady-state, the block input must be connected to a signal starting as a sinusoidal or DC waveform corresponding to the initial values.
Square wave Generator
Used to geerate square wave with the amplitude of 2.5 V with frequency (1/3600*2) Hz.
Stair Generator
Generate a signal changing at specified times. Output is kept at 0 until the first specified transition time.
Results:
The simulation is run for 200000 seconds, below is the plot of stair generator and the square wave generator output.
The stair generator the temperature is set to 25 degree celcius from 0 to 50000 seconds,temperature is set to 10 degree celcius from 50000 to 10*10^4 seconds,temperature is set to 45 degree celcius from 10*10^4 to 150000 seconds and temperature is set to 25 degree celcius from 150000 to 20*10^4 seconds.
The square wave generator has the amplitude of 2.5 V.
SoC is charging the cell to the 100% and discharging the cell to the 0%.One cycle consists of one complete charging and the discharging cycle.
From the graph it can be observed that the temperature spikes is reached to peak 35 degree celcius from 0 to 50000 seconds,temperature spikes is reached to peak 25 degree celcius from 50000 to 10*10^4 seconds,temperature spikes is reached to peak 51 degree celcius from 10*10^4 to 150000 seconds and temperature is set to 35 degree celcius from 150000 to 20*10^4 seconds.
Age cycles from 0 to 50000 seconds is small change,from 50000 to 10*10^4 seconds again very small change compared to the previous value, larger range from 10*10^4 to 150000 seconds and from 150000 to 20*10^4 seconds again the value is reduced. Voltage peaks are reduced during the higher temperature values and the with high peaks during the small temperature.The current has peak to peak value of 5V. it charges for 2.5A and discharges for 2.5A.