Project 2 Thermal modeling of battery pack

Introduction :-

Lithium-ion batteries are widely used as an energy source in various hybrid systems, but the operating characteristics of the batteries in such systems are highly dependent on operating temperature, so a good thermal control system is needed for improvement. must be used. these features. A hybrid electric vehicle (HEV) battery pack modeling thermal management system that provides the ability to control pack operating temperature for different duty cycles and ambient temperatures.

In this project, the requirement that we need to simulate the thermal effect and life cycle performance of lithium ion battery pack at various temperature , charge , discharge rate. Following are the model of lithium ion battery pack with fault :-

In these model, the 3 battery pack connect in series. The first pack of battery contain cell 01 to cell 09 it means pack having 9 cell connect in series and third pack contain cell 11 to cell 20 it means it having 10 cell connect in series.The second pack contain cell 10 which is at fault condition bacause of thermal effect from system. the electrical parameter of first and third battery pack are set such as its capacity,open ckt voltage, cell resistance, capacitance shown in below :-

The second pack having at fault so it having reduce electrical parameter such as capacity ,open ckt voltage and capacitance and increases the terminal resistance and cell resistence which shown in following:-

In these model , the different block are used suh as ( temperature source , convection heat transfer , conduaction heat transfer ,temperature sensor , thermal referance , scope , bus selector , heat sensing subsystem ) :-

Temperature source:- These temperature source block are use to set the ambient temperature and it also allow to change the temperature. it provide the source of tempertaure to battery through convection and coduction process.

Convection heat transfer:- These is convection heat transfer plate which work on the convection process and transfer the ambient temperature to battery pack.

Conduction heat transfer:- It also the heat transfer plate by the conducting process. it conduct heat from temperature source to the battery packs.

Temperature sensor:- In these simulation the second and third pack provide the their own subsystem to measure temperature. These subsystem include the temperature sensor block and thermal reference. Temperature sensor sense the temperature of pack with respect to thermal reference

Scope :- scope are use to display the graph of temperature across battery pack.

Mux Block :-

Temperature sensing subsystem:-

The cyclic charge and discharge current applies to battery pack at peak amplitude 50 and having frequency 1/100 act as a load to all battery pack system.

Modification in simulink model as per requirement :-

• The Simulink model is modified according to your requirements. In the model above, the first battery pack has 9 cells in series, the second pack has 1 cell, the third pack has 10 cells, but now we need 10 cells in series, so the first of the 5 cells in series is I need a pack. Change 1 to 5, 2nd pack of 6 cells and 3rd pack of 4 cells from 6 to 10. Package naming remains the same as it affects temperature and SOC chart

• The second modification is to create a temperature sensing model for the first battery pack. We can measure the temperature of the second and third packs, but we need to check the cell temperature of the first battery pack. Models are created by components such as temperature sensors, thermal references, oscilloscopes, and Simulink PS converters.) This model measures the temperature of the first battery pack.

Cycle configuration:-

Bug model battery pack, but now with some changes. In these models the load is present in the form of AC current provided by the AC power block. This load connects the positive terminal to the battery pack and the negative terminal to the electrical reference. This load is the cyclic charging and discharging of the battery pack with a specific frequency and charging/discharging current.

This cyclic charge discharge current block parameter are set such as the frequency value is 1/600 Hz and the peak current is taken as 50 A and simulation time is taken as 7200 s.

Result:- The result of the cyclic charge and discharge load on the battery pack are shown below:-

Temperature at 300K:-

From the temperature-time graph above, we can see that the temperature of the three packs gradually increases. First, the triple pack starts at the same temperature of 300K. Looking at the charts, after a few seconds, the temperature of the second pack has risen compared to his other first and his third packs. At 300 seconds: the temperature of the third pack is 340K, the temperature of the second pack is 392.5K, which means the temperature rise while the battery is working. At 2000:- 3rd pack temperature is about 365K, 2nd pack temperature is 435K. 5000s: 3rd pack temperature is 365K, 2nd pack temperature is 435K. Temperature rising packs result from continuous loading and unloading loads. The second pack contains error cells whose temperature spikes and remains at a much higher level compared to the other packs.

Temperature of first battery pack cell at 300 K:-

The temperature of first pack is start with 300 K. At 2000s:- the temperature of first pack is 369K these temperature is higher than that of third pack because the first pack having more cell than the third pack. Temperature at 310 K:-

Temperature at 310 k:

From the temperature-time graph above, we can see that the temperature of the three packs gradually increases as in the case above. Initially, 3 packs are started at the same temperature of 310K. Looking at the charts, after a few seconds, the temperature of the second pack has risen compared to his other first and his third packs. At 300 seconds: the temperature of the third pack is 350K, the temperature of the second pack is 401.5K, which means the temperature rise while the battery is working. At 2000 seconds:- The temperature of the third pack is about 376.5 K, the second pack is 441 K. At 5000 seconds: the temperature of the third pack is 378 K, the temperature of the second pack is 443.6 K. In general, temperature rise in all three packs can be attributed to continuous charge/discharge loads. The second pack contains error cells whose temperature spikes and remains at a much higher level compared to the other packs. Compared to the 300K above, the temperature of each battery pack rises slightly. This is because as the ambient temperature rises, more heat is transferred to the cells in the battery pack through conduction and the hot plate.

Temperature of first battery pack at 315K:-

The temperature of first pack is start with 315 K. At 2000s:- the temperature of first pack is 382K these temperature is higher than that of third pack because the first pack having more cell than the third pack. At 5000s:- the temperature is 388K.

State of charge :-

From th SOC result graph, we can see that the SOC can be accelerate from 40% to 65% through out the whole simulation period . The continuous decrease and increase in the SOC correspond to charge and discharge load provide by AC current source block. From SOC graph observation the cell 10 which is design to fault cell due to its reduce capacity , capacitance and open circuit voltage and increase in terminal and cell resistance. This causes the SOC of the second pack fall slightly greater than the other two pack.

Drive cycle configuration:-

In this configuration, i remove the AC current block which provide cyclic charge /discharge load to battery pack .Now instead of these i place the set of block for drie cycle load to applied battery pack.these block are as follows:-

1. Signal builder block
2. Controlled current source block
3. Simulink Ps converter block
4. Electrical reference block

In signal builder block contain the drive cycle with the current profile. These signal builder block connected to the controlled current source through the simulink ps converter. The current signal is provide to the controlled current source and these source is connect to battery pack terminal and another terminal of battery connect to the electrical reference. From these manner apply the load to battery pack. The drive cycle plot image as shown below :-

The drive cycle configuration is shown in the image below:-

Result:-

Temperature at 300K:-From the temperature result, we can see that the three battery pack all start out with same initial temperature at 300. At 1125 s :- the temperature of second pack rises noticeably as compare to third pack. The temperature of third pack is below the range of temperature 300.02K and then rises to 300.08K and the second pack temperature is between 300.25K and then shoot up 300.40K. At 1215s :- The temperature of battery pack decrease. the second pack temperature 300.043K and then decrase upto 300.033K.Similarly the third pack temperature decrease 300.02 and decrase to 300.0018K. In general the vehicle accelerate rapidly and current having high value this reflect th temperature of second pack increases sharply and other two battery pack temperature increase but not more than second pack.

Temperature at 315K:-

Temperature at 315K:-From the temperature result, we can see that the three battery pack all start out with same initial temperature at 315K. At 601 s :- the temperature of second pack rises noticeably as compare to third pack. The temperature of third pack is 315.030K and then rises to 315.035K and the second pack temperature is 315.05K and then shoot up 315.055K. After that the temperature start to decrease. the second pack temperature decrase from 315.055 to 315.0455K.and thirdpack temperature decrease 315.035 to 315.0325. At 802s :- The temperature of battery pack decrease. the second pack temperature at 315.0520K and then decrase upto 315.045K.Similarly the third pack temperature at 315.03K and decrase to 315.025K. In general the vehicle accelerate rapidly and current having high value this reflect th temperature of second pack increases sharply and other two battery pack temperature increase but not more than second pack. compare to ambient temperature 300K, the overall temperature of pack are higher at an ambient temperature 315K causing more heat transfer through conduction and convection plate to battery pack.

Temperature of first battery pack at 315 K:- The first battery pack temperature is higher because of it contain more cell that's why it generte more heat.

State of charge :-

From the SOC graph, We can see that there is an increase the SOC. Initially , the second pack SOC start with 40.2% which is very low value as compare to other two pack. First and third pack start with 43.5%. At 20 min :-The SOC is start to increase upto the 20 min and after 20 min the SOC has constant level. The reduce capacitance and capacity and increase resistance causes the second pack get charged more quickly than the other two pack.

Conculsion:-

In conculsion, the thermal modelling of a 10 cell series arrangement has been perform at different temperature level such as 300K , 310K ,315K for three charging and discharging condition. For each configuration , the load can be change AC current source and drive cycle load applied to battery pack. the temperature and state of charge of each pack at each ambient temperature level for each load application was plotted ,analyzed and explained.