Shark -new motor design concept for energy saving- applied to - VBN

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20 Chapter 2 Linear analysis of the Shark switched Reluctance Motor coils, which means an equal number of turns per pole, the same conductor diameter and consequently the same quantity of copper. The geometric conditions of the analysis may be summarised as follows: • the two motors have identical stack lengths • the two motors have identical main dimensions (see Fig.2.4 and Fig.2.5) • the two motors have identical lengths of the air gap • the two motors contain the same amount of material (iron and copper) Methodology of the Analysis The geometrical pattern, which is longitudinally translated to form the Shark air gap, is called Shark tooth/profile/segment and it may adopt various shapes. A study of the effect of applying these shapes was performed for the aligned rotor position in this section. The sections considered are illustrated in: Fig.2.6, Fig.2.7, Fig.2.8 and Fig.2.9. Each of these Shark profiles is defined by the following dimensions: lshk – Shark tooth pitch, hshk – height of the Shark profile, angle and g – the air gap length. The air gap length is assumed to be constant for all Shark profiles considered. For some configurations, e.g. as the square wave, the length of the air gap may have different values in the radial and longitudinal directions, as shown in Fig.2.8. The trapezoidal version requires an additional parameter, ltop, expressed as a fraction k of the tooth pitch, lshk. Fig. 2. 4 Saw-toothed profile showing characteristic dimensions g1 lshk lshk hshk Fig. 2. 6 Square-wave profile showing characteristic dimensions g g2 Fig. 2. 5 Elliptical profile showing characteristic dimensions Fig. 2. 7 Trapezoidal profile showing characteristic dimensions This study is performed using on the theory of the equivalent magnetic circuit [53]. The differential permeance of a layer of thickness dy with flux crossing the area l ⋅ dy , shown in Fig.2.8 is given by the expression: hshk lshk g lshk ltop hshk g l1 g1
( y) Chapter 2 Linear analysis of the Shark switched Reluctance Motor l ⋅ dy dG = µ ⋅ (2.2) w Fig. 2. 8 Illustration for differential permeance calculation Using equation (2.2), the permeance of the magnetic circuit may be calculated in the aligned position for each of the Shark profiles considered. All these calculations are valid under specific assumptions, which are discussed in the following paragraph. Assumptions used in the magnetic circuit calculations The objective of this chapter is, as stated to make a linear analysis and comparison of various Shark profiles. In order to achieve this objective some assumptions were made. First of all the iron was considered to have linear magnetic properties. This means that the BH curve is linear and no saturation is taken into account. Secondly fringing of flux at the ends of the magnetic circuit was neglected. This admits a very simple geometry, whose parameters may be determined by the above method. These assumptions simplify expression (2.2) and facilitate calculation of the air gap permeance. Evaluation criteria dy l w(y) The comparison of the performances of the various Shark profiles was based on the following criteria: • inductance gain in the aligned rotor position. This is determined as the ratio of the inductance value calculated for the Shark SRM to the same variable calculated for the CSRM • energy gain. The energy conversion in an SRM may simply be estimated by the difference of the coenergy between the aligned and the unaligned rotor positions. This quantity was determined for both Shark and cylindrical air gap SRM. The improvement of the energy conversion process in the Shark SRM may now be evaluated by observing the ratio of the energy converted in the Shark SRM during a single stroke to the energy converted in the CSRM during a single stroke. 2.2 Linear analysis of various Shark profiles The magnetic performances of various Shark profiles were analysed under the conditions and assumptions discussed in the previous section. The analysis starts with the CSRM and continues 21
Page 1: Shark -new motor design concept for
Page 6 and 7: Abstract The aim of this thesis is
Page 8 and 9: i instantaneous current Ψ ϕ flux
Page 13 and 14: Table of contents Preface………
Page 15 and 16: Chapter 1 Introduction Chapter 1 In
Page 17 and 18: Chapter 1 Introduction Table 1.1 Fu
Page 19 and 20: Chapter 1 Introduction The magnetic
Page 21 and 22: Chapter 1 Introduction Fig.1.7 Illu
Page 23 and 24: [Wb] O Wf Wconv Fig. 1.9 Conversion
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Page 31 and 32: Chapter 2 Chapter 2 Linear analysis
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Page 45 and 46: ksquare Lsquare L0 Chapter 2 Linear
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Page 79 and 80: flux linkage [Wb] Chapter 3 Finite
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Chapter 3 Finite Element modeling o
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Chapter 3 Finite Element modeling o
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Chapter 4 Chapter 4 Analytical mode
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Chapter 4 Analytical modelling of t
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N s because there are ph Chapter 4
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where where λ ( , θ ) 102 Chapter
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104 energy gain Chapter 4 Analytica
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106 Chapter 4 Analytical modelling
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112 radial force [N] 1900 1800 1700
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114 radial force [N] Chapter 4 Anal
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120 Chapter 5 Measurement and compa
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turn on angle [deg] 128 10 8 6 4 2
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140 copper loss [W] Chapter 5 Measu
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142 d. Power factor Chapter 5 Measu
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144 f. Specific torque Chapter 5 Me
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148 Chapter 6 Manufacturing conside
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158 Chapter 7 Summary and Conclusio
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Appendix A Design data of Induction
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170 Appendix B Definition of the ai
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178 air gap flux density [T] Append
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Appendix C 180 Appendix C Analytica
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A A A w1 w2 w3 182 = w ⋅ v = w =
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Appendix C.4 184 Appendix C Analyti
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Appendix C.5 Permeance ratio 186 Ap
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Appendix D Appendix D.1 188 Appendi
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190 References [16] T.J.E. Miller,
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192 References Conference, , 27 Jul
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194 Volume: 2 , 1996 , Page(s): 715
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196 References [96] F. Abrahamsen,
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188 References
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Shark -new motor design concept for energy saving- applied to - VBN

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