EEE6011 Electrical Machines & Power Electronic Drives Assignment One Brief | UOB

Introduction

The module aims to cover all fundamental areas of electrical machines and power electronics drives including their modern world applications. The module includes basic magnetic circuit theories, electromechanical systems and their conversions, transformers, DC machines including DC motors and DC generators, induction motors and drives, synchronous machines, special purpose motors such as stepper motors and their applications, AC power electronic drives and DC power electronic drives.

The assignment should be submitted as a report which consists of two parts. Assignment Part 1 is about characteristics and applications identification of synchronous generators. For this part of the assignment, you will have to use the knowledge you gained from this module related to synchronous generators part, as well as background studies and references. The necessary explanations need to be done using relevant equations, diagrams, tables etc. Moreover, the student should select 3 real world applications of synchronous generators and explain each of them as how they are related to the theoretical understanding of synchronous generators. The Assignment Part 2 is focused on assessing the students’ analytical and application ability of the theoretical knowledge. There, a real-world existing scenario of an induction motor is given so at first, the student will have to determine the equivalent circuit parameters of the induction motor through a MATLAB Code. For this, it is required to develop a MATLAB Code for finding the equivalent circuit parameters. After that, several calculation tasks are given which need to be done by developing MATLAB codes for each question separately. Finally, the student is asked to develop a MATLAB code for plotting the typical torque-speed characteristic of the given induction motor for the two scenarios given in part (b) and part
(d) of the question. In the Discussion section, which is the final part of the assignment, will assess the analytical thinking ability of the student. Furthermore, this will assess the basic principles of the above topics and the ability to apply the knowledge of induction motor applications and design.

Assignment Part 1

In this assignment, you will write about synchronous generators and their industrial applications. In your report you should specifically explain about synchronous generator construction, operating principle, equivalent circuit, mathematical modelling, parallel operation and their industrial applications. In composing the report by addressing the above-mentioned aspects, you may use equations, diagrams, tables and circuit arrangements as required. However, student should research in depth about the synchronous generators with relevant references so that the report should not be limited to the things learnt during the class. Also, the explanations should not be presented merely as diagrams/figures/screenshots and the explanations need to be presented in word format. You can refer to any source available (textbooks, application notes of manufacturers, internet etc). However, the writeup must be in your own words and all sources must be acknowledged. No marks will be given for similar/copied assignments. All information must be pertaining to present day applications only.

Assignment Part 2

Assume that you have been given a four pole, Y-connected cage rotor induction motor of Class C which operates at 480V, 30 horsepower, 50 Hz. It has a rated current of 33A. In order to determine the induction motor parameters, DC test, No Load test and Locked rotor tests were performed. The data extracted from the three tests are given as follows.

Table 1

(a) Write a MATLAB code for determining all the important induction motor parameters (i.e. 𝑅1, 𝑅2, 𝑋1, 𝑋2, 𝑋𝑀) by using the data given in Table 1. Present the values obtained separately.

(b) Write a MATLAB code for determining the maximum torque of this motor and the slip at that torque. Also write a code for finding the starting torque of this motor. Present the values obtained separately.

(c) Now, assume the rotor resistance is increased by 400%. Write a separate MATLAB code for determining the speed at which the maximum torque occurs. Present the values obtained separately.

(d) Modify the code you wrote for finding the starting torque in part (b) for calculating the new starting torque when the rotor resistance is increased by 400%. Present the values obtained separately.

(e) Calculate and thus plot the torque-speed characteristics of this motor both with the original rotor resistance and with the rotor resistance increased by 400%.

Discussion

1. Compare and contrast the two torque-speed characteristics obtained in part (e) of Assignment Part 2.
2. Now assume, rotor resistance is further increased as six times the original rotor resistance. Without using any MATLAB codes, predict and draw the torque-speed characteristic of the motor in this instance in comparison with the previously obtained two torque-speed characteristics.
3. Name 3 applications where single phase induction motors are used and briefly explain them.
4. Explain the technique of “Plugging” of induction motors.
5. Considering the full torque-speed characteristic of an induction motor, discuss about the induction motor “Generator region” and “Braking region”. Moreover, explain using two practical applications in which these two operation regions are being used.