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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

your student ID

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

Headlamp

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

calculations you have used and justify your answer.

(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

numbers of your student number.

(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)