Project 2 Thermal modeling of battery pack

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.

Blocks needed in making simulink model:

1. Battery (Table based)

This block models a battery based on tabulated characteristics as functions of state of charge (SOC) and optional temperature (T).

Here we made the ports to instrumented and show thermal port.

here we made the soc measurment port to yes 

And also the thermal port to model  so that the thermal port and soc port is showing in the model.

Here we made same 10 battery block.And the parametres are same as default nothing i made changes.

   2. Controlled Current Source 

The block represents an ideal current source that is powerful enough to maintain the specified current through it regardless of the voltage across it. The output current is I = Is, where Is is the numerical value presented at the physical signal port.

   3. Current Sensor:

The block represents an ideal current sensor, that is, a device that converts current measured in any electrical branch into a physical signal proportional to the current.Connections + and - are conserving electrical ports through which the sensor is inserted into the circuit. Connection I is a physical signal port that outputs current value.

  4. Temperature Source:

his block represents an ideal energy source in a thermal network that can maintain a constant absolute temperature at the port regardless of the heat flow rate.

Here its default value is  293.15k, we are going to varry the temperature value to see the charge and discharge at various temperature.

  5. Temperature Sensor:

This block measures temperature in a thermal network. There is no heat flow through the sensor. The physical signal port T reports the temperature difference across the sensor. The measurement is positive when the temperature at port A is greater than the temperature at port B.

  6.Thermal reference:

This block represents a reference point in a thermal network where the temperature is equal to absolute zero.

  7. Convective heat transfer block:

This block models heat transfer in a thermal network by convection due to fluid motion. The rate of heat transfer is proportional to the temperature difference, heat transfer coefficient, and surface area in contact with the fluid.

Here the area of contact and heat transfer coefficient is having default vlue but we shall change it at the time of simulation.

  8. Voltage Sensor:

The block represents an ideal voltage sensor, that is, a device that converts voltage measured between any electrical connections into a physical signal proportional to the voltage.Connections + and - are conserving electrical ports through which the sensor is connected to the circuit. Connection V is a physical signal port that outputs voltage value.

  9. Signal Builder:

   (UDDS )

The US FTP-72 (Federal Test Procedure) cycle is also called Urban Dynamometer Driving Schedule (UDDS) or LA-4 cycle (CFR 40, 86. App. I) [2656]. This cycle should not be confused with the UDDS schedule for heavy-duty vehicles. The cycle simulates an urban route of 7.5 mi (12.07 km) with frequent stops. The maximum speed is 56.7 mph (91.25 km/h) and the average speed is 19.6 mph (31.5 km/h). 

The cycle consists of two phases: (1) 505 s (5.78 km at 41.2 km/h average speed) and (2) 867 s. The first phase begins with a cold start. Weighting factors of 0.43 and 0.57 are applied to the first and second phases, respectively. Emissions are expressed in g/mile or g/km. The same engine driving cycle is known in Australia as the ADR 27 (Australian Design Rules) cycle and in Sweden as A10 or CVS (Constant Volume Sampler) cycle. In Sweden, both phases have the same weighting factors.

• In axis select the change time range

• Change the time range to 1369

• Select under signal block-new-custom.

• provie the data from the given and press ok

• This is the udds data curve in signal builder.

  10. Electrical Reference:

Electrical reference port. A model must contain at least one electrical reference port (electrical ground).

  11. Integrator block:

All the input parametres are same as default we did not made changes here.

  12. Solver configuration:

Defines solver settings to use for simulation.

  13. Goto Block:

Send signals to From blocks that have the specified tag. If tag visibility is 'scoped', then a Goto Tag Visibility block must be used to define the visibility of the tag. The block icon displays the selected tag name (local tags are enclosed in brackets, [], and scoped tag names are enclosed in braces, {}).

  14. From block:

Receive signals from the Goto block with the specified tag. If the tag is defined as 'scoped' in the Goto block, then a Goto Tag Visibility block must be used to define the visibility of the tag. After 'Update Diagram', the block icon displays the selected tag name (local tags are enclosed in brackets, [], and scoped tag names are enclosed in braces, {}).

  15. Scope:

Show the results of the simulation in the form of plot.

SIMULINK MODEL:

Working of simulink model:

• Firstly we took the table based battery and then made it as instrumented and show thermal port and rest all the parametres as default,we are using matlab default data not from anyu data sheet.And then we conected 10 such cell in series with same configuration.so the voltage across the pack is multplied by 10 and the capacity is same through out the pack.
• Now we conected a voltage sensor to the 2 torminal negative from the first and positive from the last and a goto block is conected through ps to simulink converter to the voltage sensor to take the output voltage and a from block is connected to the scope to recieve the voltage signal.
• The controlled current source is connect to the battery to take the current from the battery and there  a current sensor is connected to sense how much current is drawn from the battery and that current is again connected to go to block through ps to simulink converter and a from block is there to recieve the signal and give it to the scope.
• The same current is now integrated through integrator block and then divided by total capacity of the pack which is 27Ah(27*3600) to make it in ampre second,that is now substracted from one so that it will give the soc of the battery. and a goto block is conected to take the output SOC and a from block is connected to the scope to recieve the SOC signal.
• A signal builder is taken to give the input to the controlled current sensor and UDDS drive cycle data is used in the form of current with respect to time.
• Now at the thermal port the temperature source is connected to give the external temperature and it is not connected directly it is connected through the convective heat transfer block so that the area of contact we increase and as we give the temperatue input to  the temperature source block. There a temperature sensor is connected to sense the temperature of thr battery pack and one port is connected to thermal reference.
• The output of the temperature sensor is connected to goto block throught ps to simulink converter block and a from block is connected to the scope to take the temperature signal to the scope.
• finally a electrical reference is connected the the electrical side of the model for ground and also a solver configuration is connected.
• And we run the simulation for 1369sec as the input current is only for the 1369 sec if we go beyond the graph will so constant because no load current is drawn from it.

Simulation result:

• Here all the default value is given to the the blocks and the simulation results are here.In the first graph the current drawan is there and it is same as the the drive cycle because we used it same and se there the maximum vaue is goes upto 8 and the minimum is -5 which shows of charging regen braking.
• The second graph is of soc which is in the decreasing form but in linear, it is some time charging and some time it is discharging as per the current goes positive or negative.it starts from 1 which is full charge after the whole simulation it is at 0.992 which is aproxx full.
• Third graph is Temperaturewhich is default one i didn't made any changes,so it is increasing from 298.1 to 298.5 which not much rising.
• Finally at the last it is voltage fluctuation with respect to time and it starts from 41.9v and ends at same 48.9 and in between it is increasing and decresing as the battery is charge or discharge or as per the current drawn or supplied.The max voltage drawn is42.2v and minimum is 41.2v.

Now we are changing the temperature data:

Here from the temperature source we change the  temperature to 350k.

And in convective heat transfer,the area we made from 1e-1 to 1m^2.

lets se the result the simulation time and rest all parametres are same.

• Here we can see the first graph of current is same because we didn't made changes on the load side.The graph is same as above.
• The second graph is soc where also we are not seing any difference because th runing time is very low we can se any changes here.
• The 3rd graph which is temprature with respect to time here it is changed like first it starts from 300 and it increases upto 350 and hen it goes constant after 200 sec.So yes we have seen the hude difference from the prvious one.
• The last is voltage graph which is also very much similar to previous one.

Now i am change agiain the temperature parametre to negative lets see what is happening: 

here we made the temperature to 200k which is aproxx equal to -73.15°C 

And the area in the convective heat transfer made to 50m^2,and th coefficient to 1.

Lets see the result:

•  Here as above the current is same because no changes made on load side.
• The second graph is soc as i told previous  where also we are not seing any difference because th runing time is very low we can se any changes here.
• The 3rd graph which is temprature with respect to time here it is changed like first and second it is different totaly starts from 300 and it decreases down upto 200 and then it goes constant after 200 sec.So yes we have seen the hude difference from the prvious one and the first one.

Conclusin:

Due to temperature difference the cycle of charge dicharge is not much varriying here but in real life it must be vary and the temperature of the battery changes by variying the outside teemperatur suplied.