Project 5

AIM: For a 10 cell series, calculate the voltage, current and SOC. Also simulate the aging and thermal effects at different charge and discharge rates. Comment on the battery pack’s capacity.

Block used: Power gui,MOSFET ,battery ,constant,bus selector ,voltage measurement, Current measurement, scope, display, Resistor, Relationship operator.

THEORY:

The battery pack is a set of cells or modules which are connected in either series or parallel based on the required voltage and current capacity ratings. The main thing we gave to observe is that in the battery pack each have to be in the same voltage and capacity ratings whether it having different type of connections to get good efficiency and perfect SOC.

It is an important part in the electrical vehicle because of it runs on this battery cells only. The baseline battery pack produced by the plant is sufficient for 20 miles of vehicle travel at 70% of the pack energy for a vehicle with an energy use of 300 Wh/mile. Due to running by this means it gets in charging and discharging the cells when the vehicle is in running condition which will generates some heat in the cells itself. By this it will gets heat of its continuous working, also by this charging and discharging.

The heat that forms inside of the cells and the heat absorbs by the battery through outside also shown affects on the battery pack which leads to reduce the efficiency and also its life be affected at some conditions if it’s increased it get explode. The effects that come in the battery by the heat are called as thermal effects. To avoid these heat losses in the battery we use the material called the battery management system (BMS) which protect the battery pack from the thermal forms by the cooling systems as well as by some electronic gadgets.

Battery:

The battery cells that we used in here is the model are located in the Simulink library at Simscape / Electrical / Specialized Power Systems / Electric Drives / Extra Sources

It is called as a Generic battery model.

This battery is also called as a generic battery model. It is used to act as same as a real battery, we can use this as different model like 18650, by changing the parameters of the battery and also, we can change based on our requirement in the parameters block, we can also add the temperature that is internal temperature and aging based on our requirement in the parameters block.

Voltage Measurement:

It is located at Simscape / Electrical / Specialized Power Systems / Fundamental Blocks / Measurements in the library.

It is the measurement block which is used to measure the voltage that passes through controlled current source and the battery cells. It is placed in parallel with the battery pack to measure the exact value of voltage. The value from the measurement block is given to the display and the scope through the v in the measurement block to see the results in the form of digital and the graph.

Bus Selector:

The bus selector is used to collect the output of the all the values of the battery block and used to get the output values based on our requirement. It’s like a selector which is used to select based on our choice. Here we selected all values that is SOC, Current, Voltage from the battery which is used to observe the results of the battery from one side. For another side we used to observe the graphs are cell temperature, ambient temperature, aging and maximum capacity. To see the results, we use the scope.

Display:

It is located in the Simulink library at Simulink / Sinks

It is used to see the output of the values in the form of digital way

Scope:

It is used to see the output in the form oof a graphical representation that is used to observe each and every sec output to identify or understand easily.

Constant:

It is used to give the input values in the form of a physical value that is in the form of number.

Powergui:

It is used to sole the simulation functions in the model while running. The simulation that we used type is the continuous type. It is located in library at Simscape / Electrical / Specialized Power Systems / Fundamental Blocks.

MOSFET:-

MOSFET and internal diode in parallel with a series RC snubber circuit. When a gate signal is applied the MOSFET conducts and acts as a resistance (Ron) in both directions. If the gate signal falls to zero when the current is negative, the current is transferred to the antiparallel diode.

SIMULINK MODEL:

In this project we make a battery model which can allow to simulate Battery charge/discharge characteristics along with aging and temperature effect of 10 series connected cell. For this purpose we use Generic battery model in simulink environment and simulate aging and temperature effect. take a look at this model first.

Here we connect 10 series Battery having 7.2V nominal voltage and 4.4Ah capacity, this is the inbuit data of the battery pack that will open when you first introduce the block, and we're not changing the model except for Battery response time(2) and Aging model sampling time(10s) but we adjust all other parameters of our model to observe aging efffect of battery in different ambient temperature, Charging/Discharging rate. The parameters of Battery pack is given below.

BLOCK PARAMETERS:

OUTPUT:

VOLTAGE OUTPUT:

CURRENT OUTPUT:

The TEN batteries or cells are connected in series with the load resistance. When the cells are connected in series the voltage of each cell will be added. The nominal voltage of each cell is 3.7 V and thus the total voltage of the battery pack is varies between 38-40 volts.

Conclusion:-

From these results we can conclude that by changing the ambient temperature the battery SOC voltage and current are not gone be affected or as much but its internal cell temperature aging and mac capacity changes are gone be affected. Which will reduce the life and the capacity.

By changing the charging and discharging values that is the C rate its total values all are have to be change that is its SOC be changes as well as voltage and current also be. At the same time, it going to be effect on temperature even though its ambient is not changed. This change is caused by the temperature effecting by internal value that is internal temperature. As the same its shows effect on the aging and the mac capacity as well. Its overall voltage also going to be change.

Here we observe that if we charge and discharge the battery with less C rate its life and max capacity increase as well as temperature is going to down.