Design_of_Direct-driven_Permanent-magnet_Generators

amfk2006

Table of Contents
Abstract 3
Preface 3
' m( f" r- c. C- R1 [Table of Contents 4
  x4 v2 K) }) o7 }  dList of Symbols 6
1 Introduction 11
1.1 Why Use Direct-driven Wind-turbine Generators 11
3 B5 @/ ^8 R3 e* O* a& l1.2 Differences Compared with Conventional Generators 12
( d$ U0 c1 W6 L& G3 v3 y3 N1.3 Proposed Generator Types 12
; ], T- }( e3 Y$ |1.3.1 Sector Induction Generator 12
* Y: Z) Z. C1 h& D  G$ e1.3.2 Electrically Excited Synchronous Generator 13
1 A6 @7 q3 R9 C0 O7 f1.3.3 Switched Reluctance Generator 14
9 _! L& e' x5 X+ s  i; Y/ K/ q1.3.4 Permanent-magnet Radial-flux Synchronous Generator 14
1.3.5 Axial-flux Generators 16
1.3.6 Transversal-flux Variable-speed Generator 17
1.4 Discussion of Earlier Research 19
; T- g" Q2 g) {8 X6 E. h7 O1.5 Goal and Outline of the Thesis 19
8 n+ ]/ Q: ^; \; v( K2 Generator Specification and Cost Function 21
2.1 Specification 21
( V* w. y1 ~, z5 @/ C+ ]8 Q2.2 Generator Cost Function 23
: n  k  j6 l5 d: v; k9 N2.2.1 Cost of Active Parts 24
2.2.2 Cost of Structure 24
2.2.3 Cost of Average Losses 24
# T4 J$ t7 a7 ]6 O# F2.2.4 Total Cost Function 26
3 Calculation Method for the Average Losses 27
3.1 Average Losses 27
3.2 Average Efficiency and Average Power 29
3.3 Determining Average Loss Factors 30
4 m+ A7 p; U; {6 O$ S+ [4 Generator Types 37
4.1 Electrical Excitation or Permanent Magnets 37
4.2 Direct Grid Connection or Frequency Converter 39
! ~4 B) k4 {* Z4.3 Surface Magnets or Flux Concentration 40
4 h$ Z' [2 D* b" @0 b2 p4.4 Slot Winding or Air Gap Winding 41
4.5 Radial-, Axial- and Transversal-flux Machines 42
: o. y) J2 p6 n8 @" S% I4.6 Forced-commutated Rectifier or Diode Rectifier 44
6 {1 x6 L0 [; }1 |5 ^8 E1 @4.6.1 Generator Model 45
4.6.2 Diode Rectifier 45
, Y8 {) x2 j5 ^- Y( a! l8 {3 s4.6.3 Forced-commutated Rectifier 46
8 ?3 _" B2 E7 l% f& q4 E- @2 t4.6.4 Rectifier Comparison 48
4.7 Chosen Generator Type 51
0 _0 ]9 R" z) @! T/ R4.7.1 Basic Generator Concept 51
4.7.2 Details of the Chosen Generator 51
7 [$ J0 y3 e" m4.7.3 Materials 52
: g  d: B" }# z. O5 Design Method for a Permanent-magnet Generator 55
) ~5 f6 n# |# |  M5.1 Design Variables 55
5.2 Design Equations 58
5.2.1 General Definitions 58
5.2.2 Magnetic Circuit 60
5.2.3 Stator Inductance and Resistance 61
5.2.4 Material Volume and Weight 63
5.2.5 Losses 64
5.2.6 Voltage, Power and Efficiency 67
5.2.7 Thermal Model and Temperature Rise 68
5.2.8 Irreversible Demagnetization 69
' U- Q+ G$ w7 k# a$ F; b5.3 Calculation Procedure 71
5.4 Test of the Design Method 72
! J* e! |/ b7 A* q8 d. s5.4.1 Comparison with Finite Element Calculations 72
5.4.2 Test of Thermal Model 73
7 \; f4 l' o( D* M% x1 ^: i7 h* Z! Z6 Generator Optimization 77
6.1 Optimum 500 kW Generators 77
6.1.1 Optimized Reference Generator 77
6.1.2 Optimized Generators for 50 Hz and 200 % Peak Power 80
6.1.3 Optimization Using the Losses at Rated Load 82
6.2 Sensitivity to Variable Changes 84
: L% `2 y) w; \2 @, V8 |) h6.3 Sensitivity to Cost Function Changes 86
# k# z: c. f6 C7 B7 ]* S2 P6.3.1 Cost of Losses 86
6.3.2 Cost of Iron and Copper 87
6.3.3 Cost of Permanent Magnets 88
& B! C6 u3 J# |. _( k6.3.4 Cost of the Structure 89
6.4 Optimum Generator Diameter 90
6.5 Typical 500 kW Permanent-magnet Generator 92
7 Design and Comparison 95
7.1 Generators from 30 kW to 3 MW 95
7.1.1 Generator Data 95
7.1.2 Optimum Variables and Parameter Values 97
: T7 q9 K: M  k4 `3 P( P$ X1 x  l7.1.3 Power Limits For the Direct-driven Generators 100
7.2 Comparisons 102
& G" b# ?; E& j$ r; l. s7.2.1 Comparison with Conventional Generators and Gears 102
7.2.2 Comparison with Other Direct-driven Generators 104
8 Conclusions 107
6 m+ H. K2 a3 @1 c' S& x8.1 Different Generator Types 107
! V' R( K9 a$ `' \8.2 Generator Design and Optimization 108
8.3 Designed Generators and Comparison with Other Generators 108
8.4 Further Work 109
References 111
3 g; q  T9 Q1 Y6 z1 A" t4 t/ QAppendix A   Magnetizing Inductance 115
Appendix B  Thermal Model of the Generator 119
Appendix C   Average Efficiencies 131