Project 2
Aim :- Using MATLAB/simulink and the drive cycle from the attached excel sheet, find-
- The max heat generation of the battery
- The SOC of the battery at 2 *104second of the battery operation
| Time | Time Step | Battery Current |
| 00:00.4 | 0.1 | -0.9632 |
| 00:00.5 | 0.2 | -0.952 |
| 00:00.6 | 0.3 | -0.9072 |
| 00:00.7 | 0.4 | -0.9632 |
| 00:00.8 | 0.5 | -1.0304 |
| 00:00.9 | 0.6 | -0.9632 |
| 00:01.0 | 0.7 | -1.0304 |
| 00:01.1 | 0.8 | -1.008 |
| 00:01.2 | 0.9 | -0.9856 |
| 00:01.3 | 1 | -0.9632 |
| 00:01.4 | 1.1 | -0.9184 |
| 00:01.5 | 1.2 | -0.9296 |
| 00:01.6 | 1.3 | -0.9296 |
| 00:01.7 | 1.4 | -0.9296 |
| 00:01.8 | 1.5 | -0.9184 |
| 00:01.9 | 1.6 | -0.9408 |
| 00:02.0 | 1.7 | -0.896 |
| 00:02.1 | 1.8 | -0.9072 |
| 00:02.2 | 1.9 | -0.9072 |
| 00:02.3 | 2 | -0.9408 |
| 00:02.4 | 2.1 | -0.9296 |
| 00:02.5 | 2.2 | -0.9296 |
| 00:02.6 | 2.3 | -0.9968 |
| 00:02.7 | 2.4 | -0.9968 |
| 00:02.8 | 2.5 | -0.9408 |
| 00:02.9 | 2.6 | -0.9408 |
| Battery resistance | 2 milli ohm |
Consider the battery resistance is 0.5 mOhm, delta time is 0.1 and entropic factor is 2
Solution : Based on the aim given this battery related details should be answered in two parts. First part would be the calculations related to heat generated and second part Simulink model to calcuate the SOC. Let us go ahead with part one.
Part 1 : To find out the max heat generation of the battery
We have been given data related to battery and its parameters,
Maximum Current, I = -1.0304
Total Time, t = 2.6
Entropic factor is 2
Battery Resistnace , R1 = 2 mOhm & R2= 0.5 mOhm
As we know that ,
Heat Generated = Joule Heat + Entropic Heat
Now calculating the Joule Heat,
Maximum Joule Heat = I2⋅R⋅t
Maximum Joule Heat = [ -1.0304 ^2]*[2*10^-3]*2.6
Maximum Joule Heat = 0.0055 Joule
Heat Generated = Joule Heat + [ 2*Joule Heat]
Heat Generated = 0.0055 + [2*0.0055]
Max. Heat Generated = 0.0165 Joule
Similarly for R = 0.5 mOhm,
Now calculating the Joule Heat,
Maximum Joule Heat = I2⋅R⋅t
Maximum Joule Heat = [ -1.0304 ^2]*[0.5*10^-3]*2.6
Maximum Joule Heat = 0.0013 Joule
Heat Generated = Joule Heat + [ 2*Joule Heat]
Heat Generated = 0.0013 + [2*0.0013]
Max. Heat Generated = 0.0039 Joule
Part 2 : To find the SOC of the battery at 2 *104second of the battery operation
Here a specific MATLAB/Simulink model is developed to track the SOC of battery while charging. While charging mode the current & voltage are supplied to battery so that it get recharged for electric Vehicle's further operations. A typical Simulink model is build which is shwon in below fig 1.
Parameter configuration of Model -
1] Signal Builder : This block contains the actual signal which is supplied to battery for its charging operation. This os connected through a controlled current source to battery block. A given drive cycle data is imported to this block and signal is generated, the data considered is step time which is 26 nos & battery current data which were provided in aim itself. Below fig2 shows the signal builder block configuration,
fig 2- Signal Builder block Parameter
2] Battery : To achieve the aim a must needed block is battery choose which belongs to simscape library. The connection is visible in fig 1 where positive terminal is connected to Negative terminal of controlled current source and Negative is to positive of controlled current source to achieve the charging output from battery. The parameters are shown in fig 3 in which battery SOC % is selected to 30% , Ah capacity is selcted as 2.5 from standard datasheet of cell & voltage as well.
3] Controlled Current Source : By using Controlled Current Source the battery is going to charge or discharge based on the connection made and input given Also there no specific parameter setting for this block.
4] Bus Selector : This block is used to opt the measurement of required paramaters of battery like voltage , current & SOC.
5] Scope : Scope is used to check the output or results from the battery model and to do the further analysis.
Result / Output of Model -
Fig 3 - Scope output with same time period as input signal
Fig 4 - Scope output with same time period as per given condition 2*104 Seconds
Conclusion - The conclusion is drawn in two parts which is given below,
Part 1 : To find out the max heat generation of the battery
- From the calculated maximum heat generated values it can be observed that for if resistance value is more then the more heat will be genarate, so resitance of battery is important factor while desiging of battery pack.
Part 2 : To find the SOC of the battery at 2 *104second of the battery operation
- A typical Simulink model is build successfully and simulated as per the given data. Battery charging mode is selected in this model and observed the parameters of battery block.
- SOC % is found to be increasing from 30% when the model is simulated which means that model is working fine as per the design. Althogh, the model us simulated for two different time intervals.
- For 4 seconds, The model is simulated for the actual signal builder time which is around 2.5 seconds just to observe the behaviour of the SOC and other associated parameters. All found to be exactly in order.
- For 208 Seconds, As the aim condition is given to check the SOC % of model at this particular time period hence the model is simulated and observed the SOC % it shows increasing but with higher percentage than above condition.
- Current & voltage both following the input signal behaviour.
(Enclosed - MATLAB Model file & excel file