Design and Voltage Supply of High-Speed Induction - Aaltodoc

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20 Fig. 2.1 On the left, one phase of a full pitch (one layer) winding for a 36 slot stator. On the right, one phase of a 5/6 pitch (double layer) windings for the same stator. Table 2.2 Winding factors ξν for three phase windings with one pole pair up to a harmonic number 37. Slot harmonics are shown in italics. m=3, p=1 ν Q=24 W/τ =1 Q=24 W/τ =5/6 Q=36 W/τ =1 Q=36 W/τ =5/6 1 0.958 0.925 0.956 0.924 5 0.205 0.053 0.197 0.051 7 0.158 0.041 0.145 0.038 11 0.126 0.122 0.102 0.098 13 0.126 0.122 0.092 0.089 17 0.158 0.041 0.084 0.022 19 0.205 0.053 0.084 0.022 23 0.958 0.925 0.092 0.089 25 0.958 0.925 0.102 0.098 29 0.205 0.053 0.145 0.038 31 0.158 0.041 0.197 0.051 35 0.126 0.122 0.956 0.924 37 0.126 0.122 0.956 0.924 σδ,ν ≤ 1000 0.0088 0.0062 0.0051 0.0029
⎛ π ⎞ sin⎜ν ⎟ ⎛ π ⎞ ⎝ 2m ⎠ ⎛ π W ⎞ ξν = sin⎜ν ⎟ sin⎜ν ⎟ , (2.2) ⎝ 2m ⎠ ⎛ π ⎞ ⎝ 2 ⎠ qsin⎜ν ⎟ ⎝ 2mq ⎠ where m is the number of phases, q is the number of slots per pole per phase, W is the coil span, τ is the pole pitch and ν is the order of harmonic: ν = 2km + 1, k ∈ N (2.3) The leakage factor σ describing the harmonics content of the mmf is: 2 ⎛ ξν ⎞ σ = ∑ ⎜ ⎟ (2.4) ν ≠1 ⎝νξ1 ⎠ The high frequency currents and stray flux may cause considerable skin effect and eddy-current loss in the windings. To avoid this, random wound windings consisting of thin conductors are used. Mekhiche et al. (1999) have used Litz wire. This kind of a filamentary conductor is used in high frequency transformers and inductors. Litz wire yields low power loss but it can be more expensive than conventional enamel coated conductors. Another design problem related to windings is that rotor dynamic limitations often suggest quite short but wide constructions for the rotor and for the stator accordingly. For a two pole motor, this means relatively long end windings resulting in relatively higher ohmic loss and leakage inductance. A four pole motor would be better in this sense but it would mean a double supply frequency, higher iron loss, increased skin effect and higher switching loss for the inverter. Consequently, another trade-off situation must be solved herein. 2.3 Air gap and slot opening In addition to reduced winding harmonics, a decrease in the permeance harmonics is needed in order to have a smooth sinusoidal air gap flux at the rotor side. Perhaps the most important single parameter in the whole design of a high-speed motor, the air gap, affects the air gap permeance variation a lot. A long air gap is needed to dampen the harmonic components of the magnetic flux seen by the solid rotor surface. As mentioned in previous section, the harmonics can induce most of the losses at the rotor side. For an induction motor, the long air gap is a problem because the rotor has to be magnetized from the stator side. This means a high magnetization current, increased ohmic loss in stator windings 21
Page 1 and 2: El 108 ACTA POLYTECHNICA SCANDINAVI
Page 3 and 4: PREFACE This thesis is the result o
Page 5 and 6: 5 Comparison of rotors for 60 kW 60
Page 7 and 8: LIST OF SYMBOLS a Number of paralle
Page 9 and 10: Rn Resistance of a parallel conduct
Page 11 and 12: 1 INTRODUCTION The need for high ro
Page 13 and 14: Conventional (high-speed) drive Hig
Page 15 and 16: Chapter 5 reports the comparison of
Page 17 and 18: Some penetration depth values are c
Page 19: 2.2 Stator windings for high-speeds
Page 23 and 24: Table 2.3 Air gap characteristics o
Page 25 and 26: Cooling of the stator could need ax
Page 27 and 28: f sw N p = (2.9) fs The switching f
Page 29 and 30: 3 ROTOR CONSTRUCTIONS Starting from
Page 31 and 32: and eddy-currents traveling on the
Page 33 and 34: support the squirrel cage winding,
Page 35 and 36: 3.1.3 Rotor loss and friction loss
Page 37 and 38: Table 3.1 High-speed induction moto
Page 39 and 40: critical speeds are passed relative
Page 41 and 42: Table 3.2 The free-free natural fre
Page 43 and 44: Table 3.3 The free-free natural fre
Page 45 and 46: 4 COMPARISON OF ROTORS FOR 65 KW 30
Page 47 and 48: Temperature [ºC] 110 109 108 107 1
Page 49 and 50: Temperature rise [K] 120 100 80 60
Page 51 and 52: improve the laminated design, more
Page 53 and 54: The copper coated solid steel rotor
Page 55 and 56: As reported in Lähteenmäki et al.
Page 57 and 58: Temperature rise [K] 100 80 60 40 2
Page 59 and 60: Temperature rise [K] 140 120 100 80
Page 61 and 62: 6. The rest of the loss is defined
Page 63 and 64: Temperature rise [K] 100 80 60 40 2
Page 65 and 66: 5.2.7 About the mechanical robustne
Page 67 and 68: 6.1 Comparison of PAM and PWM for 6
Page 69 and 70: h d = , (6.2) I I h, PAM where Ih,P
Page 71 and 72:
Fig. 6.4 Phase-to-phase voltage and
Page 73 and 74:
Temperature rise [K] 120 100 80 60
Page 75 and 76:
Machines loss [W] 12000 10000 8000
Page 77 and 78:
considerably higher than expected.
Page 79 and 80:
In order to improve the performance
Page 81 and 82:
l = + , (7.2) sλs 2leλ e l wλ w
Page 83 and 84:
gap of 1 mm would yield an effectiv
Page 85 and 86:
Table 7.1 Calculated effective leng
Page 87 and 88:
Input current [A] 170 160 150 140 1
Page 89 and 90:
8 CIRCULATORY CURRENTS IN A STATOR
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Table 8.1 Circulatory current loss
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Fig. 8.4 Strand currents in the two
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8.2 Impedance of the circulatory cu
Page 97 and 98:
Because Φ l is approximately at th
Page 99 and 100:
Table 8.2 Circulatory current loss
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Power loss [W] 3500 3000 2500 2000
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k cc 600 500 400 300 200 100 0 0 50
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9 OPTIMIZATION OF SOLID STEEL ROTOR
Page 107 and 108:
whole solution space determined by
Page 109 and 110:
the average time saving is 39 %. Th
Page 111 and 112:
Fig. 9.3 Cross sections of the 16,
Page 113 and 114:
Height of bar slot [mm] 8 6 4 2 0 R
Page 115 and 116:
The different rotor topologies were
Page 117 and 118:
possible. The coating practically v
Page 119 and 120:
Table 9.3. Optimization results for
Page 121 and 122:
Fig. 9.11 Initial (left) and opt. (
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high-speed induction machine. Accor
Page 125 and 126:
Foelsch K. 1936. Magnetfeld und Ind
Page 127 and 128:
Pyrhönen J. and Kurronen P. 1994.
Page 129 and 130:
APPENDIX 129
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currents in the solid iron flow mor
Page 133 and 134:
where the C sw E is the loss coeffi
Page 135 and 136:
B. CALCULATION OF THERMAL CHARACTER
Page 137 and 138:
Axial cooling duct Frame R fr3 Stat
Page 139 and 140:
Linear equalities Ax = b, (C3) wher
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Design and Voltage Supply of High-Speed Induction - Aaltodoc

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