Electrical Machines and Drives

P24727- Electrical Machines and Drives

Coursework-Second Attempt

Deadline For Submission: The submission deadline is as published on the Moodle drop

box associated with this submission

Submission Instructions A report containing the information required in the

assignment should be uploaded to Moodle

Instructions for completing the

assessment:

Once completed, the report should be saved as a pdf file and

uploaded to Moodle.

Examiners: Richard Walters and Branislav Vuksanovic

P24727: Electrical Machines and Drives

Lab Assignment

1. Introduction

In this project you are required to analyse and report back on an electrical machine and drive.

2. Requirements- Drives

 The drive system you are to analyse is a three phase H-bridge inverter driving a ‘star’

connected load.

 You should assume that the power supply voltage VS is 50V DC and that the power

devices are FET transistors. The transistors are ‘off’ when 𝑣𝐺𝑆 = 0𝑉 and is ‘on’ when

𝑣𝐺𝑆 > 5𝑉.

 The circuit diagram is shown in figure 1, VQn is the input to transistor Qn. The output

voltages of each phase are VR1, VR2 and VR3, and the currents through each resistor

are IR1, IR2 and IR3.

Figure 1: Three-Phase Inverter Circuit Diagram

 You should analyse two cases of the circuit during one complete cycle (360o). For each

change of input you should determine the values of VR1, VR2 and VR3, and the size

and direction of the currents IR1, IR2 and IR3. You can assume that the transistors

have zero on resistance and zero voltage drop when on. The switching of the transistors

for each case are shown in tables 1 and 2 respectively.

 Having completed the analysis, you should comment of the differences between the two

cases.

Q1

2SK2553S

Q2

2SK2553S

Q3

2SK2553S

Q4

2SK2553S

Q5

2SK2553S

Q6

2SK2553S

V1

50V

R1

10Ω

R2

10Ω

R3

10Ω

VQ1

VQ2

VQ3

VQ4

VQ5

VQ6

IR2

A

IR1

A

IR3

A

VR1

V

VR2

V

VR3

V

 Finally, comment on any particular issues relating to the switching of Q2, Q4 and Q6.

Angle Q1 Q2 Q3 Q4 Q5 Q6

0-120o On On

120-240o On On

240-360o On On

Table 1: Transistor Switching for Case 1

Angle Q1 Q2 Q3 Q4 Q5 Q6

0-60o On On On

60-120o On On On

120-180o On On On

180-240o On On On

240-300o On On On

300-360o On On On

Table 2: Transistor Switching for Case 1

3. Requirements- Machines

 You should produce a short report on the methods of protection of distribution

transformers in transformer substations.

 Your report should include a short introduction to the problem, listing and explaining

the possible types of faults and failures encountered with transformers.

 In the main section of the report you should explain and discuss the methods and

technology used to protect transformers and other equipment in transformer substations

from those failures. You can choose a particular fault type and discuss it in more details

or alternatively, you can briefly describe and list the main failure and fault types and

methods as well as equipment for the protection. You can use schematic or calculations

to illustrate the problems you are discussing.

 Your report should also have a short conclusion section where summary of discussion

and some conclusions about transformer protection methods and equipment will be

made.

 Report should not be longer than 4 pages and should be written in IEEE paper format.

4. Reporting and Assessment

A typed report of the project should be submitted

 The report should be divided into two halves, one for the drives exercise and one for

the machines exercise.

 Each half should contain a short introduction to the exercise- no more than 10 linessetting

out what is expected.

 Each part of the task should then be clearly presented in a separate section.

 A final summary section for each half should be presented where further comments and

analysis should be presented.

Marking

Drives Case 1 10 marks

Drives Case 2 20 marks

Drives Further comments 10 marks

Drives Presentation 10 Marks

Machines - Transformer Protection Report –

Introduction

15 Marks

Machines - Transformer Protection Report -

Protection Methods and Technology

20 Marks

Machines - Transformer Protection Report -

Conclusions

15 marks