Project 2

Aim of the project:

1. To calculate The max heat generation of the battery the drive cycle from the attached excel sheet
2. Design Using MATLAB/Simulink, The SOC of the battery at 2 *104second of the battery operation

Theory:

Heat generation and SOC estimation techniques

(a) Heat Generation Calculation:

There are two heat sources for battery heat generation

• Joule’s heat
• Entropy heat

Heat generated = joules heat + entropy heat

Joule’s heat

From ohms law we know that

V = IR

when the current flowing through a resistance, there is a heat dissipated in the resistor this heat dissipation is called joules heat.

The joules heat also known as Ohmic heat

We know,

Power P = V*I

P = I^2*R

Heat H= integration P.dt with respect to limits of time 0 to t

H = I^2*R*t

Joule heat

H = I^2*R*t

Where,

P = Power in watts

V = Voltage in Volt

I = Current in Ampere

R = Resistance in Ohms

H = Heat in Joule

The heat is produced in a resistor is-

• It is directly proportional to the square of current flowing through it.
• It is directly proportional to resistance.
• Directly proportional to time for which current flows through it.

Entropy heat:

The heat generation due to entropy change inside a battery occurs when electrochemical reactions are performed. The entropy heat is reversible heat resulting from changes in open circuit voltage with respect to temperature at two electrodes.

The given below table to calculate the maximum heat generated.

Time	Time Step	Battery Current
00:00.4	0.1	-0.9632
00:00.5	0.2	-0.952
00:00.6	0.3	-0.9072
00:00.7	0.4	-0.9632
00:00.8	0.5	-1.0304
00:00.9	0.6	-0.9632
00:01.0	0.7	-1.0304
00:01.1	0.8	-1.008
00:01.2	0.9	-0.9856
00:01.3	1	-0.9632
00:01.4	1.1	-0.9184
00:01.5	1.2	-0.9296
00:01.6	1.3	-0.9296
00:01.7	1.4	-0.9296
00:01.8	1.5	-0.9184
00:01.9	1.6	-0.9408
00:02.0	1.7	-0.896
00:02.1	1.8	-0.9072
00:02.2	1.9	-0.9072
00:02.3	2	-0.9408
00:02.4	2.1	-0.9296
00:02.5	2.2	-0.9296
00:02.6	2.3	-0.9968
00:02.7	2.4	-0.9968
00:02.8	2.5	-0.9408
00:02.9	2.6	-0.9408

Battery resistance

2 milli ohm

Heat generation = joule heat + entropy heat

As entropic heat is twice the joule heat

The formula will be as shown below for Maximum:

Maximum heat generated = Maximum joule heat + 2 *(maximum joule heat)

(maximum current, Battery internal resistancce and time is taken as total time should be taken from the table)

Imax = -1.0304 Amp

Tmax = 129 sec

Rbat = 0.002 ohm

Maximum joule heat = (Imax)^2*R*tmax

Maximum joule heat = (-1.0304)^2*0.002*129

= 1.06172416*0.002*129

= 0.27392483328 J

Maximum heat generated = Maximum joule heat + 2 *(maximum joule heat)

= 0.27392483328 + 2 * (0.27392483328)

= 0.27392483328 + 0.54784966656

= 0.82177449984 J

Maximum heat generated = 821.77449984 mJ

b) The SOC of the battery at 2 *104second of the battery operation

Consider the battery resistance is 0.5 mOhm, delta time is 0.1 and entropic factor is 2

Answer:

The state of charge (SOC) is a measurement of the amount of energy available in a battery at a specific point in time expressed as a percentage.

SoC is usually expressed as percentage (0% = empty; 100% = full)

SOC = Q / Qmax

Where,

Q = Available capacity

Qmax = Overall capacity

The total time for the run time is taken as 2*104 = 208 sec. as the simulation time.

Simukink Model:

Signal Builder: In the Signal Builder window, we can create signals and define the output waveforms.

Controlled current source: Controlled Current source is to Converts the Simulink input signal into an equivalent current source.

Resistor : this is taken from RLC series Branch, in that we select R which is act as Load for this model.

Battery: The Battery block implements a generic dynamic model that represents most popular types of rechargeable batteries.

Bus selector: The Bus Selector block outputs the elements you select from the input bus

Powergui : The powergui block allows you to choose one of these methods to solve in our model:

Continuous, Discretization

scope: This block shows the output result in waveform.

Signal builder:

we take on X-axis time in sec and on Y- axis Battery current.

Scope Result:

• SOC: here, the SOC of the battery fall from 100% to 98%, so load consumed the battery energy 2% from it full charge of the battery.
• Current : The current of the battery is following to the source of the input Signal Builder.
• Voltage : Voltage of the battery is also decrease upto 208 sec.

Conclusion:

• The max heat generated in which the current flowing in and out i.e., charge and dischare due to internal resistance and chemical reaction during charging and discharging of the battery the heat generates of 821.77449984 mJ.
• The SOC of the battery at 2 *104 = 208 second of the battery operation is 100% to 98%, the load is consumed 2% of the Battery energy.