Project 2

Using MATLAB/Simulink and the drive cycle from the attached Excel sheet, find-

1. The max heat generation of the battery
2. The SOC of the battery at 2 *104second of the battery operation

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

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

Ans-

heat generated = joules heat + entropy heat

joules heat

from ohms law, we know that

V=IR

when the current flows through a resistance, there is a heat dissipated inn the resistor this heat dissipation is called joules heating.

joules heating is also known as ohmic heating

power

P=V*I=I^2*R

heat

H=∫P.dt with the limits of time 0 to t

H=I^2*R*t

where,

P=power

V=voltage

I=current

R=resistance

H=heat

T=time

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 change in open circuit voltage concerning temperature at two electrodes.

batterry resistance = 0.5m ohm = 0.0005ohm.

1. a) Maximum heat generated = maximum joule heat + 2(maximum joule heat)

Imax = -0.896 A

tmax = 1.7 sec

Rint = 0.0005 ohm

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

maximum joule heat = (-0.896)^2 * 0.0005 * 1.7 = 0.000682393J

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

Maximum heat generated = 0.000682393J+2=2.000682393J

1. 2. The SOC of the battery at 2 *104second of the battery operation:

   The SoC refers to the State of Charge of the battery, which is the capacity percent left in the battery which can be used. It a very improtent thing which teles about the battery status which helps in using the battery in a proper manner.

   The SoC can be measued in different ways. Some of them are listed below

   • Voltage Translation Method (VT)
   • Coulamb counting method (CC)
   • Combination of VT and CC

   The VT and CC has its own advantages ad disadvantages so to get accurate value we have to use the Combination of VT and CC.

   Voltage Translation Method (VT):

   It is measued by Open Circut Voltge of the battery and compared it with the Data sheet of the battery and SoC is estimated. It cannot used while the battery is in operation.

   Coulamb counting method (CC):

   It is calculated by the formula

   SoC = total charge input / Max capacity of the battery

   Total charge input = charge current * time (H)

   Or

   Z(t) = Z(0) - 1/Cn ∫ Ni*i(t) dt with thw limits of 0 to t

   where, Cn = Battery Nominal Capacity

   Z(t) = State of charge

   i(t) = Instantansous cell current

   t = time

   Ni = coulomb efficiency

   Z(0) = initial state of charge

   + for discharging

   - for charging

   Due to Faid in the battery capacity over the time it shows error

   Combination of VT and CC:

   To avoid the calculation of SoC both the Voltage Translation Method (VT) and Coulamb counting method (CC) are used combinedly.