2024-25 Semester 2 - Coursework 1
Undergraduate – Year 2
MFE108TC - Introduction to Mechatronics
Submission Deadline: 24:00 18 May 2025 (Sunday Week 13) on LMO
Part A
Questions
(70 Marks)
QUESTIONS 1 (25 MARKS)
Figure 1 Schematic of the electrical-magnetic coil layout.
A core with three legs is shown in Figure 1. Its depth is 8 cm, and there are 400-turn coil on the center leg. The core is composed of a steel having the magnetization curve shown in Figure 2. Answer the following questions:
(a) What current is required to produce a flux density of 0.5T in the central leg of the core? （ 4 marks）
(b) What current is required to produce a flux density of 1 T in the central leg of the core? Is it twice the current in part (a)? （5 marks）
(c) What are the reluctances of the central and right legs of the core under the conditions in part (a) （8 marks）
(d) What are the reluctances of the central and right legs of the core under the conditions in part (b) （8 marks）
Figure 2 Magnetization intensity vs Flux density for the selected core.
QUESTION 2 (25 MARKS)
Figure 3 Circuit diagram for question 3.
A linear machine shown in Figure 3 has a magnetic flux density of 1.5 T directed into the page, a resistance of 0.5 Ω , a bar length l=1.5m, and a battery voltage of 200 V.
(a) Find the initial force on the bar at starting? What is the initial current flow? (4 marks)
(b) Find the no-load steady-state speed of the bar? （5 marks）
(c) If the bar is loaded with force of 50 N opposite to the direction of motion, what is the new steady state speed?（8 marks）
(d) What is the efficiency of the machine under these circumstances? (8 marks)
QUESTION 4 (20 MARKS)
A 460V, 60Hz, 25-hp, four-pole, Y-connected wound-rotor induction motor has the following impedances in ohms per phase referred to the stator circuit:
R1 = 0.641 Ω , R2 = 0.332 Ω , X1 = 1. 106 Ω; X2 = 0.464 Ω , XM = 26.3 Ω
Figure 4 Induction motor diagram for Question 4.
Obtain results for the following questions. For each question, detailed solution procedure is required with all the necessary equations and calculations.
(a) At what speed and slip does this occur? (5 marks)
(b) What is the maximum (pullout) torque of this motor? (5 marks)
(c) What is the starting torque of this motor? (5 marks)
(d) Calculate the rated current (full load current)? (5 marks)
Part B
PLC Demonstration
(30 Marks)
PART B (30 MARKS)
According to the Lab Manual, students are required to use PLC-based programming to design control logic for the system as shown below.
Figure 5. Electromagnetic-relay based control system for Y-Delta starter.
Now, design a PLC-based control system that can achieve the same functionality as the above control system. Detailed requirements are:
1. Sketch the PLC-based Electrical Control Circuit Schematic Diagram (10 Marks) :
In your sketch, indicate different parts of the circuit, e.g. where is the power circuit and where is the control circuit (and where is this control circuit drawing power from?) as well as your additional design.
2. Give a table detailing I/O allocation for the PLC (10 Marks).
3. Draw flowcharts and explain the PLC logic control process (10 Marks).
Submission Deadline: 24:00 18 May 2025 (Sunday Week 13) on LMO