Design and Voltage Supply of High-Speed Induction - Aaltodoc

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40 Fig. 3.3 Measurement of the bending critical speeds of the laminated rotor. On the right, an Acceleration [g] Amplitude [1] acceleration sensor is attached. The rotor lies on an air bubble matrix. 4 2 0 -2 -4 0 0.2 0.4 0.6 0.8 Time [s] 1 1.2 1.4 1.6 1.8 10 4 10 3 10 2 10 1 10 0 0 100 200 300 400 500 600 700 800 900 1000 Frequency [Hz] Fig. 3.4 The output signal from the acceleration sensor and the corresponding spectrum.
Table 3.2 The free-free natural frequencies (FFNF) measured and calculated. Measured FFNF [Hz] Calculated FFNF [Hz] 1 st zero speed 2 nd zero speed 1 st zero speed 2 nd zero speed Solid rotor 1040 2270 1040 2282 Solid rotor system 828 1520 837 1527 Laminated rotor 678 1495 526 – 678 1) – 998 1391 – 1657 1) – 2122 Laminated rotor system 530 847 457 – 530 2) – 788 1164 – 1258 2) – 1528 Solid steel: Copper: Lamination: Compressor wheel: E = 210 GPa, ρ = 7800 kg /m3, νP = 0.3 E = 120 GPa, ρ = 8930 kg /m3, νP = 0.33 E = 0 GPa, ρ = 7600 kg /m3, νP = 0.3 E = 0 GPa, ρ = 2630 kg /m3, νP = 0.33 1) 1 st FFNF fitted ⇒ E = 40 GPa for lamination stack and squirrel cage combined. FFNF values: 0 – 40 – 210 GPa 2) 1 st FFNF fitted ⇒ E = 22 GPa for lamination stack and squirrel cage combined. FFNF values: 0 – 22 – 210 GPa As Table 3.2 shows, the measured and calculated results for the solid steel rotors were almost the same. Based on this, the effective stiffness of the combined lamination and cage was approximated. The stiffness was set as a free parameter and it was adjusted so that the first natural frequency matched the measured result. A comparison of the measured and calculated results indicates that there is some stiffness achieved by a careful manufacture. However, the calculated stiffness was different in the cases of a rotor alone or the rotor with the compressor and cooling propellers. This would indicate that the stiffness of the combined lamination stack and the squirrel cage is not constant. In this case, the error in the estimation of the second natural frequency raised doubts about correct modeling. The laminated rotor was then compared against the commercially used solid steel rotor with a copper coating. The stator was the same and only the rotors were changed during the comparison. As the effective air gap for the laminated rotor was only 48 % of the air gap for the solid steel rotor, a lower stator current and a better power factor was expected. The actual compressor was used as a load machine. The results of the comparison are presented in Chapter 4. 3.5 Solid rotors with a squirrel cage for a 60 kW 60000 1 /min motor As a part of the project, a new type of rotor was tested for a 60 kW 60000 1 /min motor. The rotor has a squirrel cage mounted at the surface of the solid steel rotor. Two such rotors were made. One rotor has 16 bars and the other 26 bars. The rotors were compared against the commercially used copper coated solid steel rotor presented in Section 3.2. The actual design of the rotors are not part of this work. The cross sections of the motors are illustrated in Fig. 3.5. 41
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: critical speeds are passed relative
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 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 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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