Project 2 Thermal modeling of battery pack

AIM: To simulate 10cell series Lithium Ion battery model and to analyze thermal effects, life cycle performance at various temperatures, charge - discharge rates using MATLAB-SIMULINK.

PROCEDURE:

The following figure shows simulink model of 10 cells series Lithium-Ion battery model using an AC source with cyclic charge/discharge profile

The following are different block -explanation:

i. AC Current source:

The ideal AC current source maintains the sinusoidal current through it, independent of the voltage across its terminals. The output current is defined by

I = I0 * sin(2*pi*f*t + PHI),

where I0 is the peak amplitude, f is the frequency in Hz, and PHI is the phase shift in radians.

ii. 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.

iii. Temperature source:

This 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.

iv. Temperature sensor:

This block measures temperature is 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

v. Convective Heat transfer:

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.

Following blocks shows the Convection block values for different cells.

vi. Conductive Heat transfer:

This block models heat transfer in a thermal network by conduction through a layer of material. The rate of heat transfer is governed by Fourier's law and is proportional to the temperature difference, material thermal conductivity, area normal to the heat flow direction, and inversely proportional to the layer thickness.

The following blocks shows the Conductive transfer for different cells

vii. Rate transition:

Handle data transfer between different rates and tasks. It transfers data from output of a block operating at one rate to the input of another block operating at a different rate.

viii. Discrete time integrator:

This block implements Discrete-time integration or accumulation of the input signal.

ix. Cells:

For cells 01 to 04,

For Cell 5

For Cell 6-10

In workspace, certain parameters values are defined for the above parameters in table like:

The all temp values can be obtained from the excel file(uploaded) as below:

The simulation is run for 7200sec, the output results are:

1. Cells temperature:

• For Cells 1-4, the temperature is around 307k to 310k
• For Cell 5, the cell which is under fault condition, the temperature reached upto 323k
• For Cells 6-10, the temperature is around 308k to 310k
• Faulty cell reached maximum temperature

2. SOC:

• SOC reached from 0 to 0.97 in less than 350 sec
• SOC reached from 0.97 to 0 in around 350 sec

3. Ambient temperature:

Now input have to be changed instead of AC source, use any other current signal using signal builder. Here Iam using UDDS drive cycle:

UDDS signal is as below having a current profile

The simulation is run for 1400sec, the output results are:

i. Cell temperatures:

• For Cells 1-4, the temperature is around 293.15k to 293.19k
• For Cell 5, the cell which is under fault condition, the temperature reached upto 293.2k
• For Cells 6-10, the temperature is around 293.15 to 293.18k
• Faulty cell reached maximum temperature

ii. SOC:

• SOC reached from 0 to 0.97, for 1400sec

iii. Ambient temperature:

CONCLUSION:

Thermal modelling of battery pack is explained using two different types of sources i.e AC source and a Drive cycle source with signal builder.