Project 2 Thermal modeling of battery pack

                                                    EV - 21 PROJECT - 2

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.

Simulate the model and observe the thermal effect of various temperature and charge discharge rates 

Similarly observe the life cycle performance at various temperature and charge discharge rates 

BATTERY PACK:-

A battery pack is a set of any number of (preferably) identical batteries or individual battery cells. They may be configured in a series, parallel, or a mixture of both to deliver the desired voltage, capacity, or power density. The term battery pack is often used in reference to cordless tools, radio-controlled hobby toys, and battery electric vehicles

Components of battery packs include the individual batteries or cells, and the interconnects which provide electrical conductivity between them. Rechargeable battery packs often contain a temperature sensor, which the battery charger uses to detect the end of charging

nterconnects are also found in batteries as they are the part that connects each cell, though batteries are most often only arranged in series strings. When a pack contains groups of cells in parallel there are different wiring configurations that take into consideration the electrical balance of the circuit.

Battery regulators are sometimes used to keep the voltage of each individual cell below its maximum value during charging so as to allow the weaker batteries to become fully charged, bringing the whole pack back into balance

Simulink Model:-

the above figure shows the 1p10s configuration of lithium ion battery pack these are all battery cells connected in series this battery pack charges or discharges by using the controlled current source and square wave generator for this cell enable the temperature effect of the and agingg afect option for observing and estimating the temperature and signal effects so in this model estimate the age of the cell SOC of the battery pack and battery pack temperature , ambient temperature battery pack current by using bus selector from any one cell of the battery pack because this battery pack is made from connecting the cells in series so current temperature SOC and age of the cell is similar to the other cells the battery pack voltage is used to calculte the by using voltage measurement block and this block is connected across the battery pack first cell positive terminal connected to positive terminal of voltage measurement block and last cell negativeterminal connected to the negative terminal ofvoltage measurement block also by using constant block it provides ambient temperature to the all cells 

Signal Generator :-

the signal generator block can produce one of the four different waveforms sine, square , sawsooth , and random we can express signal parameters in herzts or radians per second for this model used square waveform and this signal is provided to the current controlled source 

Controlled Current Source :-

the controlled current source block converts the simulink input signal into a equivalent current source the generated current is driven by the input signal of the block the positive current direction is as shown by the narrow in the block icon we can intialize the controlled current source block with specific ac or dc current if you want to start the simulation in steady state the block input must be connected to the signal starting as sinusoidal waveform corresponding to the initial values 

Generic Battery :-

the battery block implements the generic dynamic model that represents the most popular types of rechargeable batteries for this model enables the temperature effect of and aging effect options so cell nominal volatge is 7.2V and capacity is 5.4Ah intial SOC is 100% in agng section the aging model sample time is 20sec aging characterstics at cell ambient temperature of 25oC and nominal charge and discharge current taken as 1and all other parameters are default values so all these blocks is cinnected as per shown in the above model figure 

Results :-

so this simulink model simulates the multiple times at various different ambient temperature and different charge and discharge current rate the ambient temperature varies by changing the ambient temperature constant block 

Case 1 :-

in this case ambient temperature is 10C and charge and discharge rates are keeps the 5.45ah the battery pack soc is same and voltage and cell temperature varies 

Case 2:-

Case 3:-

CONCLUSION 

from this case study conclude that when the ambient temperature increases the cell temperature increased also this ambient temperature adverse effect reflects the age of the battery pack and vice versa