# Engineering and Construction Electrical Principles

Engineering and Construction Electrical Principles

Project description

Your objective in this assignment is to analyse and design various electrical systems in a modern
automobile. In order to carry out this exercise you will need to use personalised values based on
number.
This assignment requires you to apply the knowledge and skills developed during EAT113. For each
question you should explai
n any calculations you use. The number of marks available is given for
each question. Zero marks will be awarded if:
?
No expla
nation of the calculations is presented
?
You fail to use the correct values for the calculations based on your student ID.
There is no requirement for you to perform any research for this exercise.
If material from the literature or the internet is used
and not correctly referenced this will be
reported to the Infringement Panel as a case of suspected plagiarism.
Your report should be submitted to the Assignment Desk in St Peter’s Library, in person or by post,
by
4pm on Friday 22
nd
August 2014.
Electro
nic Submission is not accepted for this assignment and work which is submitted late or via an
incorrect mode of submission will not be marked.
Any questions regarding this assignment should be addressed to
michael.knowles@sunderland.ac.uk
Part 1

Vehicle Lights
The vehicles light system consists of the following bulbs:
Lamp
Number
Wattage
2
45W
Running Lamp
2
30W
Indicator
2
20W
Fog Lamp
2
30W
Number Plate Lamp
2
5W
Brake Lamp
3
20W
Reversing Lamp
1
20W
Rear Lamp
2
10W
These lamps are to be replaced by a special type of Light Emitting Diode (LED). Three of these LEDs
are capable of producing the same light output as a 5W bulb. You may assume that the light output
of a higher wattag
e bulb can be obtained by multiplying this number accordingly, e.g. 10W
Conventional bulb can be replaced by 6 LEDs, 15W conventional bulb can be replaced by 9 LEDs etc.
The maximum current each LED can use is given by 1XX mA where XX is the last two digi
ts of your
student number, e.g. if your student number is
1236548
76
, the maximum current the LEDs can
operate at is 1
76
mA. When fully activated you should assume the LED voltage is 3V.
The vehicle
power supply system is 12V.
When the engine is not running a 40Ah battery is used to supply the
lights. This means that the battery can supply 40A for one hour, 20A for two hours etc.
Question 1.
The LEDs are to be wired in series combinations of three LEDs with a protec
tion resisto
r in place to
limit the current. Calculate the value of this protection resistor and explain your calculation. Include
references to any aspects of circuit theory you use.
(5 marks)
Question 2.
Calculate the power used in each LED circuit. Determine the
percentage reduction in power
when all
lights are activated compared to the original bulbs.
(5 marks)
Question 3.
Determine the increase in the time the lights can be powered from the battery before it becomes
discharged.
(5 marks)
Question 4
Make a reco
mmendation for the current rating of a fuse for the Headlight system and explain any
(5 marks)
Part 2

Air conditioning control unit.
A digital control system is used to control the air conditioning com
pressor for the climate control
system. The compressor runs if and only if a) the fans are turned on
and b
) if the temperature is too
high. The compressor will also run if ‘demist’ setting is activated.
The following digital inputs are
provided:
?
F

Fans
are turned on (1 = on, 0 otherwise)
?
T

Temperature too high (1 = too
high, 0 otherwise)
?
D

Demist
activated
(1 = activated, 0 otherwise)
Question 5
Use a combination of truth tables and Karnaugh maps to design a logic circuit to control the
compressor
Credit will be given for creating an efficient circuit using the smallest possible number of
logic gates.
(
1
0 marks)
Question 6
Describe the advantages and disadvantages of using a microprocessor for this application. Include
consideration of other comp
onents or functionality which could be included in the system
(5 marks)
Part 3

Pancake Generator
The auxiliary power supply for the vehicle is generated using a pancake generator driven by the
engine. A coil rotates into and out of a magnetic field
once
per revolution
.
The magnetic field
strength is 0.1T.
The number of turns on the coil
is given by 2YY where YY represents the first two
digits of your student number. The area of the coil is 0.1 m
2
.
Question 7
Calculate the required rotational speed i
n Hz for the generator to produce a voltage whose average
magnitude is 12V.
You may assume that the flux witnessed by the coi
l drops to zero momentarily
each time it leaves the field.
(20 marks)
Part 4

Regenerative Braking
A regenerative braking system is installed in the vehicle. This will use supercapacitors to store energy
captured during deceleration and use this to support the acceleration of the vehicle.
Question 8
Calculate the maximum amount of energy which can be h
arvested when a vehicle slows from
40km/h to a standstill. Assume the vehicle
mass
is given by 1XX0 kg where XX are the last two
(5 marks)
Question 9
A bank of 100 supercapacitors is to be used to store the energy. Each sup
ercapacitor has a
capacitance of 1.5F. Assuming 80 percent of the available energy is captured, and assuming that the
capacitors have an initial voltage of 12V, determine the voltage t
o which they must be charged to
store the captured energy.
You should
sp
ecify
how the capacitors are connected and justify your
reasoning.
(15
marks)
Question 10
Determine the amount of charge which is transferred and estimate the average current which must
flow to achieve this if it takes 10s for the vehicle to slow down
(10
marks)
Question 11
The capacitors used are parallel plate devices where the plates are 2mm apart and separated by a
material whose relative perimittivity is 5. Determine the Electric Field Strength in each capacitor.
(10 marks)
Question 12
Identify any potential safety issues with such a system and describe measures which may be taken to
mitigate against these.
(5 marks) 