Design and development of a small scale 12S 14P outer rotor HEFSM

SCALE 12S -14P OUTER ROTOR HEFSM

GADAFI BIN M.ROMALAN

DESIGN AND DEVELOPMENT OF A SMALL-SCALE 12S-14P OUTER ROTOR HEFSM

GADAFI BIN M.ROMALAN

A thesis submitted in

fulfilment of the requirement for the award of the Degree of Master of Electrical Engineering

Faculty of Electrical & Electronic Engineering Universiti Tun Hussein Onn Malaysia

To my beloved family.

Thank you for your prayer and support. I love you all.

ACKNOWLEDGEMENT

In the name of ALLAH, the most Gracious and the Most Merciful. Alhamdulillah, all praises to Allah Almighty for His grace and His blessings given to me for the successful completion of my master’s studies.

I also wish to express my gratitude to my supervisor, Dr. Erwan Sulaiman for his guidance, invaluable help, advice, and patience on my project research. Without his constructive and critical comments, continuous encouragement, and good humour while facing difficulties, I could not have completed this research. I am also very grateful to him for guiding me to think critically and independently.

I acknowledge, with many thanks, UTHM and KPM MyBrain15 for awarding me a scholarship for my master’s programme. I am much honoured to be the recipient

for this award. Receiving this scholarship has given me motivation, confidence, and willingness to achieve my goals.

Without support from technical staff and my lab fellows of FSM research group, this research would not have been undertaken. My sincere thanks to all my FSM group friends, especially Mr. Md Zarafi Ahmad, Mr. Faisal Khan, and Mr. Fairoz Omar. They helped me many times with their technical knowledge.

It has been a very pleasant and enjoyable experience to work in UTHM with a group of highly dedicated people, who have always been willing to provide help, support, and encourage me whenever needed. I would like to thank all my friends during my stay in UTHM. Life would never have been so joyful without you.

ABSTRACT

ABSTRAK

CONTENTS

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xii

LIST OF SYMBOLS AND ABBREVATIONS xv

LIST OF PUBLICATIONS xvii

LIST OF AWARDS xviii

CHAPTER 1 INTRODUCTION 1

1.1 Background Introduction 1

1.2 Problem Statement 2

1.3 Objectives 3

1.4 Scopes 3

1.5 Research Contribution 4

1.6 Thesis Outline 5

CHAPTER 2 LITERATURE REVIEW 7

2.1 Flux Switching Motor 7

2.1.1 Fundamental of Outer-Rotor HEFSM 8 2.1.2 Outer-Rotor HEFSM Design 9 2.2 Fabrication of Motor Design 12

2.3 Prototype Experimental 19

2.3.1 Measurement System 19

2.3.2 Weightage in Fabrication 21

2.4 Summary 22

CHAPTER 3 DESIGN AND ANALYSIS OF SMALL SCALE 12S-14P OR-HEFSM USING JMAG DESIGNER 23

3.1 Design of Small-Scale 12S-14P OR-HEFSM 23

3.1.1 Part 1: Main Component of Rotor and

Stator Design 24

3.1.2 Part 2: Excitation Element of PM, FEC

and armature coil 35

3.1.3 Part 3: Finite Element Analysis (FEA)

and Material Setup 37

3.1.4 Part 4: Circuit Setup 37

3.1.5 Part 5: Simulation 38

3.2 Simulation Using JMAG Designer Solver 40

3.2.1 No-Load Analysis of 12S-14P

OR-HEFSM 40

3.2.2 Load Analysis of 12S-14P OR-HEFSM 43

3.2 Summary 44

CHAPTER 4 PROTOTYPE DEVELOPMENT OF THE DESIGNED 12S-14P OR-HEFSM USING APA 45

4.1 Actual Prototype Analysis (APA) 45

4.1.1 Gathering and Stacking Approach 45 4.2 Development of Small Scale 12S-14P

OR-HEFSM Using APA 48

4.3 Development of Direct Drive Prototype 68

4.4 Summary 70

CHAPTER 5 EXPERIMENTAL ANALYSIS OF A SMALL

SCALE PROTOTYPE 71

5.1 Experimental analysis 71

5.2 Prediction of Motor Performances by

Analytical Sizing Equations 77

5.3 APA Weightage (W factor) 82

5.4 Summary 87

CHAPTER 6 CONCLUSION AND FUTURE WORK 88

6.1 Conclusion 88

6.2 Future Work 89

REFERENCES 90

APPENDIX A: Technical Drawing 99 APPENDIX B: Details of Silicon Steel 35H210

and 35A250 103

APPENDIX C: Details of Cooper Coil 105 APPENDIX C: Details of Permanent Magnet

Neodymium 35AH 106

LIST OF TABLES

1.1 Restriction and specification 4

3.1 Rotor design analysis 26

3.2 Analysis of rotor design D with different number

of rotor holders 28

3.3 Analysis of rotor holders width 32

3.4 Analysis of rotor holders height 32

3.5 Analysis of chamfer and fillet on 4 rotor holders design 33 3.6 Parameter specifications P1 to P19 35 3.7 Materials for the design of 12S-14P OR-HEFSM 37 3.8 Ia and Ie (Ampere) based on various current density 38

3.9 Condition for simulation decision 39 4.1 Example of gathering terms regarding fabrication process 46 4.2 Example of stacking process based on task 46

4.3 Legend stacking of task for APA 46

4.4 Example of material decision table for stator and rotor 55 4.5 Material list for prototype 12S-14P OR-HEFSM 56 4.6 Example of machine decision table 57 4.7 Number of turn and filling factor of armature

coil and FEC 63

5.1 Differences in percentage of experimental to simulation

back EMF 77

5. 2 Calculated magnetic flux density at various Ja

with constant PM and Je 81

5.3 Division Weightage (DW) for APA 83

5.4 Division Evaluate Mark (DEM) analysis 83

5.5 Weightage stage 1 APA 85

5.7 Weightage stage 3 APA 86

5.8 Weightage stage 4 APA 86

5.9 Weightage stage 5 APA 86

LIST OF FIGURES

2.2 Fundamental electromagnetic concept 8

2.3 Principle operation of OR-HEFSM 9

2.4 Design of 8S-4P OR-HEFSM 10

2.5 Performance of 8S-4P OR-HEFSM 10

2.6 Initial design of three-phase 12S-14P OR-HEFSM 11 2.7 Torque versus Jeof initial design 12S-14P OR-HEFSM 11

2.8 Comparison of 12S-14P OR-HEFSM 11

2.9 Torque versus Je of the improved design 12S-14P

OR-HEFSM 12

2.10 PM brushless prototype design using SMC 13 2.11 PM mini motor using low cost fabrication technic 14

2.12 PMSM design 14

2.13 PM design axial-flux direct drive for scooter 15

2.14 18S-12P SRM design for EV 15

2.15 FSM design based on TSFE 16

2.16 Electromagnetic wave of FSM design based on TSFE 16 2.17 Complete fabrication of 12S-10P WFFSM 17 2.18 Complete fabrication of outer-rotor PMSM 18 2.19 Complete 3-D design of outer-rotor PMFSM 18 2.20 Complete design of outer-rotor PMSM for wind turbine 19 2.21 No-load property measurement system 20 2.22 Load property measurement system 20 2.23 Experiment set up for motor measurement system [43] 21 2.24 Equivalent block diagram motor of measurement

system in Figure 2.23 21

3.1 Flowchart of JMAG geometry editor and design 24 3.2 Design A with initial small scale design 25 3.3 Design B with rectangular shape rotor 25

3.6 Design D with three holders 29

3.8 Design D with six holders 30

3.9 Design D with seven holders 30

3.10 Design D with eight holders 31

3.12 Chamfer on four rotor holders design 33 3.14 Small-scale design of 12S-14P OR-HEFSM 34

3.15 Parameter P1 to P19 35

3.16 Excitation element 36

3.17 Flowchart of simulation analysis 39 3.19 Comparison of magnetic flux distribution at

high current 41

3.20 Flux cancelation and losses in small scale design

of 12S-14P OR-HEFSM 41

3.21 Fundamental and harmonic Back EMF of 12S-14P

OR-HEFSM 42

3.22 Cogging torque of small scale design of 12S-14P

OR-HEFSM 42

3.23 Torque versus FEC current density at various

armatures current densities 43

3.24 Power and Torque versus speed characteristic 44 4.1 Actual Prototype Analysis (APA) flowchart 47

4.2 Complete 3-D design flowchart 49

4.3 Rotor design 50

4.4 Stator design 51

4.5 Permanent magnet design 51

4.6 3-D design armature coil and FEC 52

4.7 Winding coil case 53

4.8 Shaft and retaining clip 53

4.9 Motor housing 54

4.10 Holder rotor to shaft 54

4.11 Silicon electric steel 35A250 57

4.12 Wire cutting machine 58

4.13 Wire cutting fabrication (a) Stator, (b) Rotor 59

4.15 Milling machine fabrication 60

4.16 3-D printer 60

4.17 Separator coil case 60

4.18 Permanent magnet NICUNI grade 35 61 4.19 Assembling process for prototype 62 4.20 Assembly flow of prototype 12S-14P OR-HEFSM 64 4.21 Full stack prototype 65 4.22 Coil case assembly 65 4.23 Finishing windings 66 4.25 Prototype assembly through step 1 to 6 for internal assembly 66 4.26 Finishing step 7 and 8 for external assembly generated by SolidWorks 67 4.27 Finishing prototype 67 4.28 Assembly flow for direct drive prototype 12S-14P OR-HEFSM 68 4.29 Direct drive prototype 12S-14P OR-HEFSM 69 4.30 Rim to direct drive prototype application of 12S-14P OR-HEFSM 69 4.31 Finishing direct drive prototype 70 5.1 General experimental flowchart of stage 5 of APA 72 5.2 Block diagram motor measurement system 73 5.3 Motor measurement system 74 5.4 Experimental coil test analysis 74 5.5 Back EMF at 600 r/min 75

5.6 Back EMF at 1,200 r/min 75

5.7 Back EMF at 1,800 r/min 75

5.8 Back EMF at 2,400 r/min 75

5.9 Back EMF at 3000 r/min 76

5.11 Calculated back EMF based on Equation 5.4 78 5.12 Effective area for small scale 12S-14P OR-HEFSM 79 5.13 Calculated and simulation torque versus various

LIST OF SYMBOLS AND ABBREVATIONS

A Ampere

AC Alternating Current

B Flux Density [T]

f Frequency [Hz], [rad/s]

I Current [A]

J Current Density [A/m2]

L Length [m]

N Number of turns

P Number of Poles

S Slot area [mm2]

r Radius [m]

r/min Revolution Per Minute

T Torque [Nm]

t Time [s]

V Voltage [V]

EMF Electromotive Force FEA Finite Element Analysis FEC Field Excitation Coil

FEFSM Field Excitation Flux Switching Machine or Motor FSM Flux Switching Machine or Motor

HEFSM Hybrid Excitation Flux Switching Machine or Motor HEV Hybrid Electrical Vehicles

IMs Induction Motors PM Permanent Magnet

PMFSM Permanent-Magnet Flux Switching Machine or Motor SRM Switched Reluctance Machine or Motor

Kp Filling Factor Effective Area Kd Leakage Factor

Bg / Bpm Permanent-Magnet Magnetic Flux Density Rso Stator Outer Radius

Ф Magnetic Flux

trAC Total Radial Active Component

B Magnetic Flux Density Ae Effective Area

hPR Rotor Pole Height

DW Division Weightage

TP Total Phase

LIST OF PUBLICATIONS

Journals

(i) “Actual prototype analysis floor plan for general electric machine,” ARPN Journal of Engineering and Applied Sciences, Vol. 10, No. 16, pp. 7070-7074. (ii) “OR-HEFSM D-rive developed structure based on actual prototype analysis

(APA) process”, ARPN Journal of Engineering and Applied Sciences, -

(submitted and accepted)

(iii) “Development small scale direct drive 12s-14p OR-HEFSM” Jurnal Teknologi, IPECS 2015, - (submitted and accepted)

Proceeding

LIST OF AWARDS

(i) Silver medal at Malaysia Technology Expo (MTE), International Invention & Innovation, Kuala Lumpur, Malaysia 18 - 20 February 2016.

(ii) Silver medal at Pencipta 2015, Dewan Konvensyen Kuala Lumpur, 4 – 5 December 2015.

(iii) Bronze medal at Seoul International Invention Fair, Korea 26 - 29 November 2015

(iv) Bronze medal at Research & Innovation Festival, UTHM, Malaysia 16 - 17 November, 2015.

(v) Silver medal at Post Graduate Showcase IEEE CENCON 19 – 21 October 2015. (vi) Silver medal at Poster Competition Hari Transformasi Minda FKEE, UTHM

2015.

CHAPTER 1

INTRODUCTION

1.1 Background Introduction

Development of direct-drive motor for in-wheel electric vehicle (EV) has grown into an interesting research topic because of their advantages of direct torque control and elimination of the transmission gear system. At present, the major types of electric motors under serious consideration for EVs are the DC motor, induction motor (IM), permanent magnet synchronous motor (PMSM), and switched reluctance motor (SRM) [1,2]. Based on the extensive review on state-of-the-art electric propulsion systems, it may be observed that investigations on cage IMs and PMSMs are highly dominant [3-5].

In fact, from various types of motors, the flux switching motor (FSM) is a good design to fulfil direct-drive application due to high starting torque, constant power over a wide speed range, low torque ripple, and high durability. The FSM operating principle is quite interesting. This is due to the flux switches from stator pole to rotor tooth and vice versa that made researchers to develop a novel FSM design for various applications ranging from domestic appliances to heavy applications such as electric traction [6, 7].

12S-14P OR-HEFSM design generated torque and power of 335.08 Nm and 160.2 kW, respectively [11].

Theoretically, the design capability has been proven through finite element analysis (FEA) using computer-aided software, JMAG designer. Basically, the analysis is based on numerical input and operating principle without any compromise towards error factor from manufacturing such as mechanical deformation. Therefore, development and fabrication process are required to evaluate the motor performance through prototype units [12]. However, because of cost and tool constraints, the design dimension and volume have been rescaled by ratio 1:8.

To interpret the outer-rotor design into prototype unit, the design needs a few approaches to complete the whole process such as actual prototype analysis (APA) and FEA-based simulation. The APA is created to set a standard procedure to develop and fabricate the design via five stages – design, material selection, fabrication, assembly, and test. All stages of APA come with a specific objective to initiate the process guided by closed loop flow chart to reach high standards in fabrication. Through the last stage of APA, the experimental test has been conducted to finalise all aims in the development and fabrication process [13].

1.2 Problem Statement

In recent research of electric motor drives for EV propulsion, in-wheel direct drive is becoming more popular in diminishing transmission gearing system, and available cabin space can be occupied by more batteries. Thus, this application does not only provide optimal torque directly to the wheel, but also contributes for light vehicle and wider driving range per charge. In considering for higher torque and power densities for the in-wheel drive motors, outer-rotor machine configuration is among the good designs compared with conventional inner-rotor [11].

However, the proposed motor is yet to be validated experimentally. Thus, in this research, a complete process involving design and fabrication of a small-scale 12S-14P OR-HEFSM shall be carried out from the initial stage to the end of experimental validation before it goes for full scale or mass production.

1.3 Objectives

The objectives of this research are as follows:

(i) To optimise and analyse a small-scale design of 12S-14P OR-HEFSM rotor for direct drive structure.

(ii) To develop and fabricate a small-scale design of 12S-14P OR-HEFSM using actual prototype analysis (APA).

(iii) To validate a small-scale design of 12S-14P OR-HEFSM by analytical modelling and experimentation.

1.4 Scopes

The research focuses on optimising and analysing a small-scale prototype of three-phase 12S-14P OR-HEFSM, which will be evaluated by analytical modelling and experimentation. In achieving the research objectives, the followings scopes have been selected:

(i) Guided by a full-scale design of 12S-14P ORHEFSM [11], the design restriction and specification for a designated small-scale design of 12S-14P OR-HEFSM by a ratio of 1:8 are listed in Table 1.1. The FEA process is aided by JMAG Designer 14 software to design and analyse the load and no load conditions. (ii) In developing the small-scale prototype of 12S-14P OR-HEFSM, the APA

approach is used. The approach uses a conversion import file format .DWG from JMAG-Designer to .SLDPRT for SolidWorks V.2014. The 2-D projection from JMAG-Geometry will be ‘boss extruded’ into SolidWorks to generate the 3-D projection.

(iv) In determining whether the APA approach is acceptable for general electric motor fabrication, the collected data of simulation analysis and five stages of APA will be evaluated using subjective evaluation method [14]. The evaluation uses numeric score as weightage factor based on data feedback from motor performance and fabrication qualities.

Table 1.1: Restriction and specification

1.5 Research Contribution

Research contribution throughout this research study are described as follows:

(i) The rotor optimisation and analysis of a small-scale design of 12S-14P OR-HEFSM contributed to the idea on how the rotor design should be developed to suit with direct drive structure. Simultaneously, presenting the analysis of a small-scale 12S-14P OR-HEFSM in terms of back EMF, torque, speed, and power. (Structural and assembly design of outer-rotor hybrid excitation flux switching motor based on finite element analysis approach published in Energy

Conversion (CENCON), 2015 IEEE Conference)

(ii) The APA approach contributes to the systematic flowchart to develop and fabricate the electric motor. Moreover, the APA weightage factor could be used to determine the successfulness of the fabricated prototype. (Actual prototype analysis floor plan for general electric machine, published in ARPN Journal of Engineering and Applied Sciences)

RESTRICTION AND SPECIFICATION

DESCRIPTION OR-HEFSM

Electric

Max. DC-bus voltage inverter (V) 400 Max. DC-bus voltage inverter (V) 400

Max. inverter current (Arms) 50

Max. current density in armature coil, Ja (Arms/mm2)

30

Max. current density in FEC, Je

(A/mm2₎ 30

Motor

Motor radius (mm) 66

Motor stack length (mm) 35

Shaft/Inner motor radius (mm) 30

Air gap length (mm) 0.4

PM weight (g) 17

(iii) The mathematical modelling for OR-HEFSM using analytical sizing equation contributes to the motor performances prediction in terms of power and torque. (iv) The three-phase fabricated small-scale 12S-14P OR-HEFSM working principle

has been proven experimentally.

1.6 Thesis Outline

This thesis deals with the design studies on OR-HEFSM for HEV applications. The thesis is divided into five chapters. A summary of each chapter is as follows:

(i) Chapter 1: Introduction

This chapter introduces the research background of design and development of a small-scale 12S-14P OR-HEFSM. The contents focus on problems, objectives, scopes, and contributions of the research.

(ii) Chapter 2: Literature review

The review on developing and fabricating the 12S-14P ORHEFSM was divided into three sections. The first section is the introduction of flux switching motor (FSM) while focusing on hybrid excitation FSM. It is followed by the review of fabrication process, which is already established and used by other researchers. The review covers both motor concepts, from inner to outer rotor fabrication. At the end of the chapter is the review of measurement systems and weightage for experimental purpose.

(iii) Chapter 3: Design and analysis of small-scale 12S-14P OR-HEFSM using JMAG-Designer

(iv) Chapter 4: Prototype development of the designed 12S-14P OR-HEFSM using APA

This chapter clarifies the complete process and results based on the second research objective. It is divided into three sections namely development of APA approach, development of small-scale prototype, and development of direct drive prototype. The development of small scale and direct drive prototype has been developed by four stages of APA from 3-D design, material selection, fabrication, and assembly.

(v) Chapter 5: Experimental analysis of a small-scale prototype

This chapter elaborates the experimental analysis of a small-scale prototype of 12-14P OR-HEFSM with respect to simulation configuration. The tool and calculation process have been explained based on analysis. The analysis is divided into three sections namely experimental analysis for no load condition, prediction motor performances based on analytical sizing equation, and weightage analysis.

(vi) Chapter 6: Conclusion and future work

CHAPTER 2

LITERATURE REVIEW

2.1 Flux Switching Motor

The flux switching motor (FSM) incorporates the features of a conventional DC motor and switch reluctance motor (SRM). Similar with conventional motor, the rotor and stator combinations of FSM play a role to drive their operating principle as well as coming out with various designs probability. In 1950, the first FSM was introduced. Structurally it had a large value of permanent magnet usage with less slot area [15]. To overcome the large value of permanent magnet usage and to improve the FSM structure topologies, researchers have tried to figure out the best combination of FSM in terms of thestator-rotor structure and excitation component.

The general classification of FSMs is demonstrated in Figure 2.1, where the permanent magnet (PM) and field excitation (FE) FSMs consist of PM and DC field excitation coil, respectively as their excitation element. The hybrid excitation (HE) FSM consists of the combination of both PM and FE for their flux excitation.

Flux Switching Motor (FSM)

Permanent Magnet (PM)

FSM

Field Excitation (FE)

FSM

Hybrid Excitation (HE) FSM

2.1.1 Fundamental of Outer-Rotor HEFSM

The terminology of hybrid can be defined as a combination of two excitation sources, namely field excitation coil (FEC) and permanent magnet (PM) to excite and switch the generated flux from stator pole to rotor tooth, while armature coil as the main flux to interact with excitation source. The operating principle of OR-HEFSM slightly contrasts by modification for the inner rotor position and outer stator position. Even the design seems complex, as it presents a great mechanical advantage such as robust rotor structure that makes it suitable for high-speed applications. In addition, the FEC could be used to control flux with variable flux capabilities [16].

Figure 2.2 illustrates the fundamental electromagnetic concept or right hand screw rule in terms of magnetic field (B) behaviour as the current (I) flows with respect to the current direction. In contrast, the operating principle of OR-HEFSM is illustrated in Figure 2.3 [17, 18]. The single piece of rotor is shown in the upper part, while the stator consisting of PM, FEC, and armature coils are located in the lower part. The PM and FEC are placed between two stator poles to generate excitation fluxes that create the term “hybrid excitation flux”.

Figures 2.3 (a) and (b) demonstrate the flux generated by PM and FEC flow from the stator into the rotor and vice versa to produce a complete one flux cycle. The combined flux generated by PM and FEC establishes more excitation fluxes to generate high torque for motor. Moreover, when the rotor moves to the right as shown in Figures 2.3 (c) and (d), the rotor pole goes to the next stator tooth, switching the magnitude and polarities of the flux linkage. The flux shifts clockwise and counter clockwise in direction with each armature current reversal. This condition establishes less excitation flux and generates less torque [19].

Figure 2.2: Fundamental electromagnetic concept

Current (I)

Current (I) Magnetic field (B)

Figure 2.3: Principle operation of OR-HEFSM (a) θe = 0º (b) θe = 180º more excitation, (c) θe = 0º (b) θe = 180º less excitation

2.1.2 Outer-Rotor HEFSM Design

Several researches have been conducted with various probable designs involving the OR-HEFSM operating principle as illustrated in Figures 2.4 and 2.5. Figure 2.4 (a) shows the combination of single-phase 8S-4P OR-HEFSM, which produced a great result for the initial design [20], while Figure 2.4 (b) shows the design improvement [21] using optimisation process that successfully achieved much higher performances than the initial design. The torque and power performance of both initial and optimised designs are illustrated in Figure 2.5. It is obvious that the torque and power increased approximately 22.1% and 59.5%, respectively.

PM PM

Armature coil Armature coil Armature coil Armature coil

FEC FEC

N S N S

Stator Stator

Rotor Rotor

PM Armature coil Armature coil Armature coil Armature coil

FEC FEC

N S N S

Stator Stator

Rotor Rotor

(a) (b)

(c) (d)

PM flux flow

PM flux flow FEC flux flow

FEC flux flow FEC flux flow

FEC flux flow

PM flux flow

(a) (b)

Figure 2.4: Design of 8S-4P OR-HEFSM (a) Initial design, (b) Improved [21]

(a) (b)

Figure 2.5:Performance of 8S-4P OR-HEFSM (a) Torque, (b) Power [21]

In 2014, the initial three0phase 12S-14P OR-HEFSM was proposed, as illustrated in Figure 2.6. The proposed motor produced a great performance in terms of torque and power, as illustrated in Figure 2.7. Meanwhile, Figure 2.8 illustrates the structural comparison of the final design for the initial and optimised design of the proposed motor. It is obvious that the stator and rotor structures of the final design have improved the flux flow capability and magnetic flux density. Deterministic optimisation approach is used to improve the torque and power performances of the initial design. The torque characteristic at various Je and Ja of the final design is

Figure 2.6: Initial design of three-phase 12S-14P OR-HEFSM [22]

Figure 2.7: Torque versus Jeof initial design 12S-14P OR-HEFSM [22]

(a) (b)

Figure 2.8: Comparison of 12S-14P OR-HEFSM (a) Initial, (b) Improved [22]

Improved point Initial

Figure 2.9: Torque versus Je of the improved design 12S-14P OR-HEFSM [22]

2.2 Fabrication of Motor Design

The term fabrication has been defined as an act or process to construct something new or already in the market based on sketching. Electric motors are one of the great things fabricated by Moritz Jacobi in 1834. Designers have used a few elements such as copper wire winding isolated by shellac, square shaft iron, and magnet [23-27]. The basic structure for electric motor design is still used in modern times with a few improvements in design, concept, size, material, power source, and many more to achieve various targets in industrial civilisation.

There are two types of popular structure in motor design: inner-rotor and outer-rotor motors. However, research on motor design to date has been focusing mainly on general electromagnetic analysis and optimisation of the inner-rotor type, with hardly any attention given to the outer-rotor motor [28-30]. This happened because the market needed an inner-rotor design and the design is easy to be fabricated even with a complex design.

2.2.1 Prototype of Inner-Rotor Design

this design concept is the cheapest at the moment due to its simple design structure and ease of fabrication.

There are few inner rotor types such as interior permanent magnet synchronous motor (IPMSM), switch reluctant motor (SRM), and flux switching motor (FSM). The design in Figure 2.10 shows a PM brushless stator core made by the precision machining from a cylindrical piece of soft magnetic composite (SMC). The rotor consists of four arc-shaped with surface mounted by magnet segments with a solid mild steel back-iron. The prototype machine has an unusually large air gap of 6.5 mm compared with its 2.5 mm magnet thickness [31].

Figure 2.10: PM brushless prototype design using SMC [31]

Figure 2.11: PM mini motor using low cost fabrication technic [32]

Although the 3-D dimension has been developed, the complete process in fabrication is still vague due to secondary manufacturers’ usage such as in fabrication process for PM synchronous motor (PMSM) [33]. The PMSM design as depicted in Figure 2.12 shows the design process as initiated by taking the dimensions of an existing stator lamination of an induction motor. This was done to reduce tool cost and required time when developing the motor.

(a) (b)

Figure 2.12: PMSM design (a) Stator, (b) Rotor [33]

for EV with 18 stator poles, 12 rotor poles, and three-phase windings with 50 kW of power [35].

Figure 2.13: PM design axial-flux direct drive for scooter [34]

(a) (b)

Figure 2.14: 18S-12P SRM design for EV (a) Stator, (b) Rotor [35]

(a) (b)

Figure 2.15: FSM design based on TSFE (a) Stator, (b) Rotor [36]

Figure 2.16: Electromagnetic wave of FSM design based on TSFE [36]

(a) (b)

(c) (d)

Figure 2.17: Complete fabrication of 12S-10P WFFSM (a) Stator, (b) FEC winding, (c) Full assembly stator and rotor, (d) Prototype with water cooling jacket [37]

2.2.2 Prototype of Outer-Rotor Design

Figure 2.18: Complete fabrication of outer-rotor PMSM [38]

Figure 2.19: Complete 3-D design of outer-rotor PMFSM [39]

Figure 2.20: Complete design of outer-rotor PMSM for wind turbine [40]

Although the torque and power results shows close agreement between experimental and predicted results, it still has not satisfied the FEA performance. A few demerits include materials for fabrication and the method of fabrication itself, perhaps making the experimental prototype slightly come off from the FEA result. It is noteworthy that a proper consideration in material and fabrication process is needed for further experimentation.

Most of the prototypes that have been presented produced efficiencies above 90%, but there are also publications where the efficiency is rather low, mainly caused by various unfavourable aspects in the physical assembly of the prototype and the remaining loss was claimed to be mechanical loss [40-42].

2.3 Prototype Experimental 2.3.1 Measurement System

The motor measurement system consideration should abide by motor and measurement classifications. This consideration is mostly based on the motor capability measurement system to provide accurate and constant measurement as well as to avoid unexpected event. In fact, only the high-end motor measurement system is able to provide high-end results, which are quite expensive to begin with.

analyse and record the measurements. Indeed, the outcomes are precise in certain parts, but are still unable to measure a complete performance of PM brushless.

Meanwhile, Figures 2.21 and 2.22 show the brushless DC motor created by Koji Ikeda [42], which has been analysed using different measurement systems. The employed no-load load property systems in both figures are able to provide a complete result of the motor’s characteristics. The combination of both no-load and load analysis measurement systems will increase the measurement accuracy for certain applications.

Figure 2.21: No-load property measurement system [42]

Figure 2.22: Load property measurement system [42]

diagram for this type of measurement system has been illustrated in Figure 2.24 in terms of measurement device and connection.

Figure 2.23: Experiment set up for motor measurement system [43]

Figure 2.24: Equivalent block diagram motor of measurement system in Figure 2.23

2.3.2 Weightage in Fabrication

The weightage has been derived from a perspective view of a preliminary investigation to predict the final effect of fabrication either in objective or subjective point. Basically, in subtract or multiple variable into a weightage ratio, the mathematical modelling such as fuzzy systems is needed to obtain precise weightage calculation. In contrast, the weightage is derived subjectively or by interpolative decision making [44]. This method is used in weightage transformation from variable such as dimension deformation into a ratio.

Different product topology and application lead to new variables in a weightage calculation. So, a few considerations are needed to conclude the variables into a

Prime mover FEFSM

Controller

Armature Power

supply FE Power

supply Oscilloscope

qualitative or quantity ratio, which are used to calculate the weightage. By computing the weightage based on preliminary result the final performance of model can be predicted [45]. This technique is also useful to evaluate some model performances that cannot be measured such as flux distribution.

In motor design, a common weightage is usually used in winding calculation with respect to allocated winding space, known as filling factor. The ratio ranges between zero to one by considering one of them as a high filling factor in motor design. The factor is used to predict the outcome number for the turn of windings by multiplying the factor with the winding equation [46]. Simultaneously, the filling factor becomes one of the variables in fabrication weightage. The input and output of filling factor can be evaluated as winding variables in defining the full fabrication weightage [47].

2.4 Summary

CHAPTER 3

DESIGN AND ANALYSIS OF SMALL SCALE 12S-14P OR-HEFSM USING JMAG DESIGNER

3.1 Design of Small-Scale 12S-14P OR-HEFSM

Finite element analysis (FEA) based on JMAG Designer version 14.1 is used to design a small-scale 12S-14P OR-HEFSM before the analysis and fabrication process. The software can give the user substantially greater insight into design performance while providing versatility to support users from conceptual design to comprehensive analysis.

START Sketch of Rotor Sketch of Stator Sketch of Armature coil Sketch of FEC Set materials Set the conditions Set the circuits

Set the mesh & study properties Run and Simulate END Sketch of Permanent Magnet GEOMETRY EDITOR DESIGNER No-Load analysis:

a. Coil test

b. Flux strengthening / weakening

c. Flux distribution

d. Flux lines

e. Electromotive force (EMF)

f. Cogging torque

Load analysis:

a. Torque versus Je/Ja

b. Torque versus speed

c. Power versus speed

d. Iron loss, copper loss, eddy current lost

e. Efficiency

f. Mechanical strength

Success Simulation data YES NO Success YES NO 1 1

Figure 3.1: Flowchart of JMAG geometry editor and design

3.1.1 Part 1: Main Component of Rotor and Stator Design

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