Detailed Proposal Of Project Engineering Essay

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The goal of this research is to design and analysis of 3-phase brushless permanent magnet (PM) motor. Brushless PM motors become an interest as it widely used in robotics, automotive, machine tools, high-performance industry applications and variety of industrial application. The main reasons why brushless PM machines are so widely used due to their high efficiency and torque density which are higher to that of induction, switched reluctance and synchronous reluctance machines. The project will involve two main phases: the designing of the machine using Finite Element Analysis and the analysis of the simulation result. Simulation study can greatly facilitate to designing the machine while keeping the desired hardware aspect in mind. The designed machine should be capable to meet performance specification such as high-power density, high efficiency and low cogging torque. Torque density and back EMF are two of the most crucial parameter to be determined in brushless machine design, changes in winding arrangement, slot and pole number will potentially affect the back EMF, and torque derived for the brushless PM motor. To meet the requirement, some issue need to be consider such as selection of pole number, winding arrangement, rotor topology, motor shape, permanent magnet material and machines size.


Detailed proposal of project:

(a) Problem statement *motivation

The design of brushless PM motors is not a simple task. Generally, knowledge of magnetics, electronics, mechanics, thermodynamics and material science is required. Thus, the electrical and mechanical relationships are important and should be taken into account in designing the brushless PM motor. Torque density and back EMF are two of the most crucial parameter to be determined in brushless machine design. Changes in winding arrangement, slot and pole number will potentially affect the fundamental relationships such magnetomotive force (MMF), back EMF, and torque derived for the brushless PM motor. For these reasons, it is important to design a machine with less parasitic torque, to ensure it will produce smooth mechanical rotation.

(b) Objective (s) of the Project

Design and analysis of 3-phase brushless permanent magnet motor are the aims of the research. The machine should be capable to meet performance specification such as high-power density, high efficiency, low cogging torque and flux-weakening capabilities. To achieve these aims, the objectives of this research are formulated as follows:

To assess a 3-phase brushless PM motor with consequent pole and inset-mounted permanent magnet rotor.

To investigate the parasitic effect presence in the machine.

To perform the simulation study for the design using Finite Element Analysis.

(c) Project Scope

This research covers the analysis, design and development of rotational 3-phase brushless permanent magnet (PM) motors. Brushless PM motors can be divided into the PM synchronous AC motor (PMSM) and PM brushless DC motor (PM BDCM), depending on the back EMF waveform. The materials recited in this research project emphasis on brushless PM synchronous motor with sinusoidal back EMF and are driven by sinusoidal currents. Radial-flux laminated motors are considered since this constitute are the most common shape of brushless PM motors. This project is focuses more on electromagnetic and mechanical design instead of thermal aspects. Rotor topology in this research project was confined to two types, which is inset permanent magnet and consequent pole rotor. 2-D Finite Element Analysis will be used to create a truly customized modeling of motor structure and to investigate the behaviour of the designed motor.

(d) Literature Review

Currently, the brushless PM motors offer an attractive solution in the variety of application due to their high efficiency and power density. All brushless PM motors are constructed with electrical windings on the stator and permanent magnets on the rotor [1]. Since only the stator having coil, this motor has solved the problem on the motor with brunch. Lack of brush and commutator in these motor lead to no mechanical contact, hence, can reduces friction, increases reliability, and decreases the cost of maintenance.

Brushless PM motors can be divided into two classes, which is AC or DC, depending on the back EMF waveform. PM synchronous AC motor (PMSM) are type of AC motor since it have a sinusoidal back EMF and are driven by sinusoidal currents. PM brushless DC motor (PM BDCM) with trapezoidal-induced emf and driven by rectangular pulse currents are categorized as DC machine. Stator windings and how the number of turns and their arrangement in the stator laminations greatly influence the fundamental relationships such as magnetomotive force (mmf), back EMF, and torque for both class of machines [1], [2].

Brushless PM motor is like an induction motor and all other motor that comprise of two main part. The non-moving part that includes the coils of wire is called stator and the moving or rotating part that caries the permanent magnet is called rotor. In between rotor and stator there is an air-gap that separates the two parts. Usually, the rotor is placed inside the stator. This construction is safer because the stator outside can act as a shield to the rotating part. However, it is also possible for the rotor to perform on the outside of the stator. This type often called as exterior rotor or inside-out rotor. It proves to have higher efficient than interior rotors [2].

Brushless PM motor can be constructed in two basic shape; radial-flux or axial-flux type. In radial-flux type, the stator windings and permanent magnets are structured radially. Thus, the magnetic field is distributed in radial direction between the stator and rotor. This type of motor is the most common shape of motor and more favourable due to minimization of electric loading caused by the presence of stator slots. For radial-flux motor, the magnetic field are traveling in axial direction across the air-gap inside the motor. This motor resembles a pancake shape. Small size and rugged construction features make this type of motor preferred for in many applications. In these motor, the number of copper used are limited caused stator windings tend to be air-gap windings. Consequently, amount of loading possibility can be confined [8].

There are many ways to place permanent magnets on the rotor [2]. Mostly, there are three basic topologies of brushless PM machine. Surface-mounted permanent magnet (SPM) rotor has magnets mounted on the rotor surface and facing the air gap, while interior permanent magnet (IPM) rotor has buried magnets inside the rotor. SPM rotors offer higher air-gap flux density because the magnet directly faces the air-gap. Magnetization direction for this configuration is only in radial. Disadvantages of SPM rotor configuration are lower robustness as they are not closely fitted into the rotor laminations to their entire thickness. Therefore, SPM rotors are not preferred for high-speed applications. IPM rotor is ideal for high speed application because of the construction is designed to be mechanically robust. There is another type of rotor topologies referred as surface-inset rotor which is combine some advantages of both surface mounted and interior permanent magnet motors [7]. This arrangement is more mechanically robust compared to SPM rotor as the magnets do not prominent out of the rotor laminations giving it mechanical strength from flying out [2].

Winding arrangement is one of the important components to be considered in designing a brushless machine. Its arrangement will determine the motor back EMF whether it is sinusoidal or trapezoidal back EMF. Winding arrangements which are most commonly used for 3-phase radial-flux brushless PM motor can be classified as overlapping and non-overlapping [3]. Distributed and concentrated is type of overlapping winding and often utilized for ac operation due to sinusoidal back EMF produced. Concentrated winding with either all teeth or alternate teeth wound is a type of non-overlapping winding that aim to obtain trapezoidal back EMF waveform. The correct winding for a machine is very much a function of the pole number and slot number and whether there is single-layer or double-layer winding [3].

The type of magnet used will have a great effect on the motor performance and cost [3]. There are four classes of modern magnetic materials, each based on their material composition. Within each class is a group of grades with their own magnetic properties. These general classes are; Neodymium Iron Boron, samarium cobalt, ceramic and alnico. Amongst the available PM materials, Alnico magnets can have flux densities equivalent to soft magnetic irons but they get easily demagnetized due to lower values of coercive force as compared to ceramic magnets [5]. Ceramic magnets are economical but their maximum energy density product is low due to lower values of retentivity. Rare earth and samarium cobalt alloys have relatively good magnetic properties, but they are expensive. Other than polymer bonded rare earth magnets, for example, ferrite and cobalt based metallic magnets are physically hard and brittle. Therefore, selection of the particular PM material is application specific; however, Neodymium-Iron-Boron (Nd-Fe-B) rare earth magnets are more in demand because they provide the highest energy density and higher residual flux density than others.

(e) Methodology

Phase 1: Literature Review

Researching through books, articles, journals and internet sources to review the design issues and technique for brushless PM motors. Find out what the available technology in the market, and what the best approach to meet design requirement.

Phase 2: Designing of Project

Modelling, and hence simulation study can greatly facilitate to designing the machine while keeping the desired hardware aspect in mind.

2-D Finite Element Analysis is used for the designing.

Typical design step for brushless PM motor is:

Review requirements

Select the permanent magnet material for the rotor.

Select the soft iron for the stator lamination.

Match the mechanical parameters as input to the program (size, volume, weight).

Select the number of rotor poles and stator slots

Using the software, match the torque and speed requirements with the electrical inputs and change the internal motor geometry as required.

Select the winding configuration and optimize turns, wire size, and stator winding slot fill.

Check the software outputs for validity.

Run other solutions varying certain parameters for optimization such as add and remove a winding turn, change air gap between rotor and stator, change magnet thickness and check the software solutions until meet the requirements and select the best match.

This phase is important to check whether the motor can work as desired before implementing it on hardware.

Phase 3: Analysis of the Design

The outputs of the simulation being observe and analyze. The simulation is to see whether the output produced is same with desired output in term of speed and torque.

Phase 4: Preparation for presentation and report writing

Preparation for the presentation for Seminar 2 and writing the report's draft.

Handing in of the completed thesis after presentation.

(f) Milestones

Project task

Expected Date

Literature Review

Motor design and simulation

Simulation testing

Analysis and discussion

Report writing

(g) References

[1] D. C. Hanselman, Brushless Permanent Magnet Motor Design. Lebanon, OH: Magna Physics, 2006.

[2] R. Krishnan, Permanent Magnet Synchronous and Brushless DC Motor Drives. Boca Raton, FL: CRC, 2010.

[3] D. G. Dorrell , M.-F. Hsieh , M. Popescu , L. Evans , D. A. Staton and V. Grout  "A review of the design issues and techniques for radial-flux brushless surface and internal rare-earth permanent magnet motors",  IEEE Trans. Ind. Electron.,  2011.

[4] M. S. Ahmad, N. A. A. Manap, and D. Ishak, "Permanent magnet brushless machines with minimum difference in slot number and pole number," in Proc. IEEE Int. PECon, Johor Baharu, Malaysia, Dec. 1-3, 2008, pp. 1064-1069.

[5] F. Magnussen and H. Lendenmann, "Parasitic effects in PM machines with concentrated windings," IEEE Trans. Ind. Appl., vol. 43, no. 5, pp. 1223-1232, Sep./Oct. 2007.

[6] A. M. EL-Refaie, "Fractional-slot concentrated-windings synchronous permanent magnet machines: Opportunities and challenges," IEEE Trans. Ind. Electron., vol. 57, no. 1, pp. 107-121, Jan. 2010.

[7] S. Van Haute, G. Terörde, K. Hameyer and R. Belmans. Modelling and implementation of a permanent magnet Synchronous motor drive using a DSP development environment. Katholieke Universiteit Leuven, Belgium.

[8] K. Sitapati and R. Krishnan, "Performance comparisons of radial and axial field permanent-magnet, brushless machines," IEEE Trans. Industry Appl, vol. 37, no. 5, pp. 1219-1225, Sept./Oct. 2001.

[9] A.M. EL-Refaie and T.M. Jahns, "Optimal flux weakening in surface PM machines using fractional-slot concentrated windings," IEEE Trans. Ind. Appl., vol. 41, no. 3, pp. 790-800, May/Jun. 2005.

[10] N. Bianchi, S. Bolognani, and G. Grezzani, "Design considerations for fractional-slot winding configurations of synchronous machines," IEEE Trans. Ind. Appl., vol. 42, no. 4, pp. 997-1006, Jul./Aug. 2006.

[11] D. Ishak, Z. Q. Zhu, and D. Howe, "Comparison of PM brushless motors, having either all teeth or alternate teeth wound," IEEE Trans. Energy Convers., vol. 21, no. 1, pp. 95-103, Mar. 2006.

[12] D. Ishak, Z. Q. Zhu, and D. Howe, "Permanent magnet brushless machines with unequal tooth widths and similar slot and pole numbers," IEEE Trans. Ind. Appl., vol. 41, no. 2, pp. 584-590, Mar./Apr. 2005.

[13] O Ronghai, M Aydin and T A Lipo. 'Performance Comparison of Dualrotor Radial-flux and Axial-flux Permanent-magnet BLDC Machines'. Proceedings of IEEE IEMDC'03, 2003, pp 1948-1954.

[14] S Hwang, J Eom, Y Jung, Dee and B Kang. 'Various Design Techniques to Reduce Cogging Torque by Controlling Energy Variation in Permanent Magnet Motors'. Transactions on Magnetics, vol 37, no 4, July 2001, pp 2806-2809.









Please indicate your estimated budget for this project

Sila nyatakan anggaran bajet bagi cadangan projek ini

Budget details

Butiran belanjawan

Amount requested by applicant

Jumlah yang dipohon

oleh pemohon

Comment by panel







E (i)

Project Materials & Supplies

Bekalan dan Bahan Projek

E (ii)

Maintenance and Minor Repair Services

Baik pulih kecil dan ubahsuai

E (iii)

Professional Services

Perkhidmatan Ikhtisas

E (vi)

Accessories and


Aksesori dan Peralatan




Declaration by candidate / Akuan Calon

(Please tick ( √ )): / (Sila tanda ( √ )):

I hereby confess that:

Saya dengan ini mengaku bahawa:

All information stated here are accurate, Supervisor and panel has right to reject or to cancel this proposal without prior notice if there is any inaccurate information given.

Semua maklumat yang diisi adalah benar, Penyelia dan panel berhak menolak permohonan atau membatalkan tawaran cadangan ini pada bila-bila masa sekiranya keterangan yang dikemukakan adalah tidak benar.

Application of this Project Proposal is presented for a FYP 1 seminar.

Permohonan cadangan projek projek ini dikemukakan untuk Seminar PSM 1.

Date : Candidate's Signature :

Tarikh : Tandatangan Calon : ___________________________


Recommended by FYP Supervisor

Perakuan Penyelia PSM

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A. Highly Recommended

Sangat Disokong

B. Recommended


C. Not Recommended (Please specify reason)

Tidak Disokong (Sila Nyatakan Sebab)











Name: Signature:

Nama: Tandatangan:



Appendix A: Flow Chart of Project Activities


Literature Review and specify requirement

Simulation study and Motor design


Simulation Testing


Analysis and Report Writing


Appendix B: Project Schedule of Project Activities (Gantt chart)

Project task

Final Year Project 1

Final Year Project 2











Literature Review and theory understanding

Motor design and simulation

Simulation testing

Analysis and discussion

Report writing

Appendix C: TURNITIN Report must be attached