Design and Voltage Supply of High-Speed Induction - Aaltodoc

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48 4.2.2 Input current A lower input current indicates lower magnetization current and better efficiency at partial loads. A smaller frequency converter could be selected in some cases. Because the resistive loss in the stator winding is the main loss component to determine the temperature rise in the winding, the input current and the temperature rise are assumed to go hand in hand. This can be seen in Fig. 4.5, which shows that the input current of the laminated rotor is 11 per cent lower at the input power of 65 kW. The difference is over 50 per cent at no-load. Thus, the laminated rotor is superior to the copper coated rotor in this respect. This is mainly due to a smaller air gap in the case of the laminated rotor as stated in Section 3.4. 4.2.3 Slip of the rotor The slip of the rotor was chosen as a third characteristic for the comparison. The slip s does not relate to the total loss of the rotor but it gives the minimum load loss Ptl needed to produce the electromechanical power Pm from the airgap power Pδ. The operation principle of an induction machine dictates that the loss related to the torque producing components of power is the air gap power times the slip: ( 1 s) P ⎛ ⎜ ⎞ ⎟ ⎛ ⎜ − ⎞ ⎟ − ⎝ ⎠ ⎝ ⎠ m s m = Pδ ⎜ ⎟ = Pδ ⎜ ⎟ = Pδ − sPδ = Pδ Ptl , (4.1) s s where Ωm and Ωs are the mechanical and synchronous speeds of the rotor. Ptl is a resistive loss mainly generated in the copper coating or in the squirrel cage. The slip depends on the impedance of the rotor. The smaller the impedance or resistance, the smaller the slip and the load loss Ptl: P s = P tl 2 r (4.2) δ Rr I ∝ P δ Fig. 4.6 shows that the comparison of slip goes against the laminated rotor. At the input power of 65 kW, the slip of the laminated rotor is 52 % higher than the slip of the copper coated rotor. The rotor current in the laminated rotor seems to face a higher resistance. The amount of copper in the rotor cross section was the same in both of the rotors, but there was 27 per cent less copper at the end rings of the laminated rotor.
Temperature rise [K] 120 100 80 60 40 20 0 Coated Laminated 0 10 20 30 40 50 60 70 Input power [kW] Fig. 4.4 Comparison of the measured average temperature rises in the stator windings. Input current [A] 160 140 120 100 80 60 40 20 0 Coated Laminated 0 10 20 30 40 50 60 70 Input power [kW] Fig. 4.5 Comparison of the measured input currents. Slip [%] 2.00 1.50 1.00 0.50 0.00 Laminated Coated 0 10 20 30 40 50 60 70 Input power [kW] Fig. 4.6 Comparison of the measured slips. 49
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 and 20: 2.2 Stator windings for high-speeds
Page 21 and 22: ⎛ π ⎞ sin⎜ν ⎟ ⎛ π ⎞
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: Temperature [ºC] 110 109 108 107 1
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
Page 91 and 92: Table 8.1 Circulatory current loss
Page 93 and 94: Fig. 8.4 Strand currents in the two
Page 95 and 96: 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
Page 101 and 102:
Power loss [W] 3500 3000 2500 2000
Page 103 and 104:
k cc 600 500 400 300 200 100 0 0 50
Page 105 and 106:
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. (
Page 123 and 124:
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
Page 131 and 132:
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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