AIM:
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.
OBJECTIVE:
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.
THEORY:
Now a days lithium ion battery are mostly used in electric vehicles we must know its charge and discharge rates to operate this battery in efficient manner and without damage when this battery in operations this temperature of it must be kept in limit we simulate the thermal effect of this cell, by knowing the how much temperature rise takes place we can provide efficient cooling to the battery so that the life cycle of the battery increases we will see a model on this issue below and explanation as follows
cells connected in series and one of the cell is faulty so what will be thermal effect. this example shows how to simulate abattery pack consisting of multiple series connected
cells in an efficient manner . it also shows hoe aa fault can be introduced into one of the cells to see the impact on battery performance and cell temperatures.for efficiency, identical series connected cells are not just simply modeled by connecting cell models in series. instead a single cell iss used and the terminal voltage scaled up by the number of cells.the fault is represented by changing the parameters for the cell 10 fault subsystem,reducing both capacity and open circuit voltage and increasing the resistance values.
CIRCUIT CONSTRUCTION AND WORKING:
In this circuit we use lithium ion cell 1 to 10, temperature sensors, ambient temp block,state of charge estimation scope,charge discharge profile given to circuit from and goto block matlab simulink.
cell subsystem is basically consist of a thermal model and lithium cell 1RC block which calculates the temperature and thermal effect for cells and overall calculate for the battery pack.
This block basically consists of capacitance value which depends on a external physsical signal inputs SOC and T. it is assumed that the capacitance value is slowly varying with time and hence the eqn i=C*dv/dt holds.
Resistance value(R) table which depends on an external physical signal inputs SOC and T.
Voltage value(EM) which implements the cells main branch voltage source and determines values for capacity(C) and state of cahrge(SOC).The defining equations depends on cell temperature(T).
output of the cell is connected with the SOC estimation whereas other output is connected with AC current source for cyclic charge/discharge profile.
The peak aamplitudes set to 50A for cyclic charge and discharge. A basic parameters of AC current source is as other block which are used in lithium ion battery pack are as :
TEMPERATURE SOURCE:
The Temperature Source block represents an ideal source of thermal energy that is powerful enough to maintain specified temperature at its outlet regardless of the heat flow consumed by the system.
The source generates constant absolute temperature, defined by the Temperature parameter value.
Connections A and B are thermal conserving ports that connect to the two points where temperature is being monitored. port T is a physical signal port that outputs the temperature differential value.the block positive directions is from port A to port B.the measured temp is determined as T=TA - TB.
The Temperature Source block represents an ideal source of thermal energy that is powerful enough to maintain specified temperature at its outlet regardless of the heat flow consumed by the system.
This block is used for ambient temperature which we can set and check results.
CONVECTIVE HEAT TRANSFER:
The Convective Heat Transfer block represents a heat transfer by convection between two bodies by means of fluid motion.the rate of heat transfer is proportional to the temperature difference ,heat transfer coefficient,and surface area in contact with the fluid. this used for 1-4 cells and 6-10 cells.
from and goto blocks
the goto block passes its input to its corresponding from blocks. the input can be a real or complex valued signal or vector of any data type.from and goto blocks allow you to pass a signal from one block to another without actually connecting them.from block accepts a signal from a corresponding goto block then passes it as output. the data type of the output is the same as that of the input from the goto block.from and goto blocks allow you to pass a signal from one block to another without actually connecting them.
STATE OF CHARGE ESTIMATION:
State of charge (SOC) is a crucial index used in the assessment of electric vehicle (EV) battery storage systems. Thus, SOC estimation of lithium-ion batteries has been widely investigated because of their fast charging, long-life cycle, and high energy density characteristics.
The coulomb counting method measures the discharging current of a battery and integrates the discharging current over time in order to estimate SOC.
This subsysstem takes current as input and gives the battery SOC % as output.A current sensor blockis used and connected for SOC estimation.
this circuit estimates the battery SOC% using coulomb counting method. it takes current as the input and gives SOC% as output. initial SOC of the battery is assumed to be 100%
RESULT EXPLANATION:
For a 10 cell series lithium ion battery model we imulate the thermal effects and compare life cycle performance at various temperatures,charge and discharge rates using ATLAB. results are as follows.
1-4 cells are normal cell 5th cell is faulty 6-10 cell is normal cell as we are simulating theral effect on we give cyclic charge/ discharge profile to circuit the waveform you can see aabove results all conditions it is same but when circuit is run on this drive cycle profile as 5th cell was faulty it will show temp is rise high than any other cell and the life cycle of cell get reduced and cell even can get damaged. so as we give temp of results at 300k i.e 26.85 degree celsius the 1-4 and 6-10 cell temperature is near to 316k.
but, 5th faulty cell temp goes to 330k ie 56.85 degree celsius and the drive cycle is shown which is cyclic charge/discharge drive cycle.
in condition two we give temp 310k i.e 36.85 degree celsius and 1-4 and 6-10 cell temp is near to 326k but 5th faulty cell temp goes to 340k i.e 66.85 degree celsius and the drive cycle is shown which is cyclic cahrge/discharge drive cycle
in condition two we give temp 324k ie 50.85 and 1-4 and 6-10 cell temp is near 340k but 5th faulty cell temp goes to 354k ie 80.85 degree celsius and the drive cycle is shown which is cyclic charge/discharge drive cycle.