School of Engineering EEE8155 Coursework Handout
Design and Analysis of Electrical Machines and Drives: Coursework Specification
Design and Analysis of Electrical Machines and Drives: Coursework Specification ……………………………………….1 Introduction ………………………………………………………………………………………………………………………………………….. 1 Introduction to FEA ………………………………………………………………………………………………………………………………… 1 Cordless Drill – Coursework Scenario ………………………………………………………………………………………………………… 2
3.1. Specification: Cordless electric drill …………………………………………………………………………………………………… 2
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3.2. Dimension measurements ……………………………………………………………………………………………………………….. 2
3.3. Experimental measurements ……………………………………………………………………………………………………………. 5
Coursework: Redesign of a motor ……………………………………………………………………………………………………………. 6
4.1. Design criteria ………………………………………………………………………………………………………………………………… 6
4.2. Report and Marking Scheme ……………………………………………………………………………………………………………. 7
Accessing MotorCAD………………………………………………………………………………………………………………………………. 8 5.1. On Campus access…………………………………………………………………………………………………………………………… 8 5.2. ………………………………………………………………………………………………………………………………………………………….. 8 Remote access is available via https://rdweb.wvd.microsoft.com/arm/webclient/index.html ……………………………. 8 5.3. License problems ……………………………………………………………………………………………………………………………. 9
Introduction
This document contains the details for the Assessment 2(Coursework).
You are set a design problem and have to produce a report detailing your final design and results from Motor-CAD. The final report (.pdf) is due Friday 25th April 2021 and must be uploaded to canvas, along with your optimum final design- a Motor-CAD file (.mot).
Please follow the name format for your submission of two documents.
Format: Last Name_First Name_Student ID_Report.pdf and Last Name_First Name_Student ID_FinalDesign.mot. For example, Deng_Daisy_B123456_Report.pdf and Deng_Daisy_B123456_FinalDesign.mot.
2 Introduction to FEA
Modern electrical machine design is heavily based on Finite Element Analysis (FEA) software. A number of commercially available packages exist based on the same working principle: the machine is split into a large number of small elements, and the magnetic and electric fields are analysed within each element. The machine geometry is drawn in a CAD like environment, and any machine geometry may be analysed. For more standard machine design, it is possible to use simplified versions of FEA, where the user selects the machine geometry from a library of pre-drawn options. This type of software can be used as a design tool, and in this coursework we are going to use Motor-CAD, as
School of Engineering EEE8155 Coursework Handout
shown in Figure 1. A tutorial of how to build and simulate a brushless PM motor is attached in Modules->Assessment 2 on canvas for your reference. Details of how to access the software are given in Section 5 below.
Figure 1. Default Brushless PM Motor when you open Motor-CAD for the first time.
3 Cordless Drill – Coursework Scenario
3.1. Specification: Cordless electric drill
This drill is used by professional builders. The manufacturer has received complaints about the design of the drill, many of which say they feel it is underpowered and does not last for a full day’s work. In this work, you have been tasked by the manufacturer to increase the peak torque of the machine so that it feels better to use, along with an increase in machine efficiency to extend the battery life of the product. The specification of the original product is shown in the Table 1 below.
Table 1. Specification of the original product
Manufacturer Model No-load speed Power
Drill Max torque
3.2. Dimension measurements
De CD778L2T-SFGB 0-500/1750 rpm (after gearbox) 340 W
Six photos below show the measurements of the original motor in the drill, which provide you a reference of geometries and winding connections when you start to build the original motor in Motor-CAD.
The motor has 6 slots and 4 poles and is powered by a three-phase six-step inverter. The magnets are embedded in the rotor, so it is an interior permanent magnet machine. The wires have an area of 0.28𝑚𝑚2 with 33 turns per coil. And the coils are connected in a delta configuration with 2 parallel paths.
School of Engineering EEE8155 Coursework Handout
School of Engineering EEE8155 Coursework Handout
School of Engineering EEE8155 Coursework Handout
3.3. Experimental measurements
Here are some useful testing results that you must use to validate a model of the motor you build in Motor-CAD.
1) Testing in the laboratory of the original motor was found to output a peak torque of 0.667N·m at 4067rpm. At this speed and torque the supplied line current had a peak value of 90A.
2) The DC link voltage supplied to the inverter was 18V.
3) The back EMF was found to have a peak of 8.5V, when unloaded, at a speed of 10000rpm before the gearbox.
School of Engineering EEE8155 Coursework Handout
4 Coursework: Redesign of a motor
Your project is to improve the design inline with the manufacturer’s feedback in section 3.1. The only stipulation is that the design must be a brushless permanent magnet machine driven by a six-step inverter. You must first model the original motor in Motor-CAD to re-create its operation and prove any improvements in the design.
Any aspect of the motor can be altered, along with any topology offered in Motor-CAD (i.e. surface mounted, buried or bread loaf), the choices of how you will alter the original design are yours however the overall dimension of the motor (i.e. Outer diameter and axial length) must remain mostly unchanged.
4.1. Design criteria
The ideal motor is light, efficient and cheap. Machine design is all about compromise, for example an efficient machine is likely to be more expensive. One way to get the ‘best’ design based on both cost and efficiency is to give these criteria relative importance e.g. if efficiency is more important than cost, the designs can be ranked based on a weighting of 80% efficiency and 20% cost.
e.g. design score = 0.8*efficiency (per unit)+0.2*cost (per unit)
This is only a suggestion you can use your own depending on what you deem to be most important.
The criteria typically used in machine design:
Mass (kg) – total mass of machine
magnet mass (kg) – total mass of magnets
cost (£) – based on mass of material
efficiency
volume (m3)
School of Engineering EEE8155 Coursework Handout Useful figures for cost and density are given in Table 2.
Table 2. Cost and density of some materials commonly used in electric motors cost Density
Copper 3.76957 8940 NdFeB 125.1282 7500
In your project you can use these ratings, or other referenced information sources, to guide design choices. You will have to propose and justify a method of incorporating these weightings into your design process.
4.2. Report and Marking Scheme
A number of sample design reports for completely different applications have been provided on Canvas. Do not copy the format, method or layout, but they might help you plan your own work. You must demonstrate that you have done some design work and you understand the results of the simulations. Your design must meet the required torque. The overall breakdown of marks is
20% Report:
Style / presentation / quality of language / use of references (it is acceptable to base designs on those
found papers etc. (e.g. papers from IEEE Xplore)) 80% Investigation:
Quality of investigation / data gathering / research / assessment of effort relating to
o Validated simulation results of the existing motor design, based on the original motor
provided. – 5%
o Atargetspecificationforyourproposeddesign,includingjustificationforthetorqueyouwish
to achieve, speed, target mass and new efficiency. – 5%
o Apreliminaryanalyticaldesignstudy(e.g.suggestedpolenumber,magnetheight,backiron
depth, tooth width etc.) using sensible assumptions/limits supported by relevant calculations
as to why the initial design parameters were chosen – 5%
o TheuseofMotor-CADtoinvestigateanumberofpotentialdesignsforyourapplicationand
analysis of these designs and a design study (e.g. pole number verses performance, motor
type verses performance, magnet type verses performance). -40%
o A discussion on how you have selected your final design based on the conflicting
performance criteria, and why you may have disregarded others -5%
o Summary details of the final design including a comparison of your re-design to the original
motor, and upload the Motor-CAD model to Canvas -10%
o Conclusion–summaryofkeyfindingsofreport,summaryofwhyyourchangeshaveresulted
in increased performance and a better product -10%
If your device requires a gear box, please state its ratio – but you do not need to design it.
The report must be less than 2000 words / 10 pages (excluding title / contents page, appendices and references)
£/kg kg/m^3
5.504834 4900
School of Engineering EEE8155 Coursework Handout
5 Accessing MotorCAD
The university does not have a licence to allow you to download the software to your own PC. You must either access it on campus or remotely as below.
5.1. On Campus access
AnsysMotorCAD is available in the first floor computing lab in Merz court (E1.13 / room 4.33). Access to this lab is 7:00-23:45 Monday – Friday.
Remote access is available via https://rdweb.wvd.microsoft.com/arm/webclient/index.html Select “tier 1” Desktop.
School of Engineering
EEE8155 Coursework Handout
You should then have a desktop where you can open ANSYS Motor-CAD
5.3. License problems
If you are confronted with a licence error, follow the below steps Please go into Licence>Configuration
Change License system to ANSYS
Change Licence INI file (lower box) to Tick PM, IM and Sync
Then update
School of Engineering EEE8155 Coursework Handout
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