Design and Voltage Supply of High-Speed Induction - Aaltodoc

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56 5.2.1 Temperature rise in the stator winding The temperature rise of the stator winding is considered first. Lower temperature rise in the stator winding indicates smaller loss, at least at the stator side of the motor. Also, a lower temperature rise makes it possible to increase the utilization of the motor, i.e., to get more power out from the same motor size. This argument is based on the assumption that the temperature rise of the rotor is not a problem. Fig. 5.4 shows the temperature rise of the winding with different rotors as a function of the input power. At 835 Hz, the input power of 50 kW corresponds approximately to the nominal torque and power. It can be seen that the temperature rise of the copper coated rotor is 5 per cent higher than that of the 16 bar rotor. The difference is about 8’% at no-load. From the Figure, it can be seen that the temperature curve for the 26 bar rotor ends at around 47 kW. This is because the temperature rise of a rotor surface became a limiting factor for the loading of the motor. As mentioned in Section 3.5, the maximum allowed temperature for the squirrel cage rotors was 150 °C. At no-load, the temperature rise of the stator winding for the 26 bar rotor was similar to that of the 16 bar rotor. When loaded, the temperature rise approached the values recorded with the copper coated rotor. The difference in results of the different rotors is much smaller than in the previous case for the laminated and solid steel rotor. 5.2.2 Input current and power factor The input current of a motor was chosen to be another characteristic to be compared. A lower input current and a better power factor mean that a smaller frequency converter could be selected in some cases. Fig. 5.5 shows that compared to the 16 bar rotor, the input current of the copper coated rotor is 10 per cent higher at 50 kW input power. The difference is over 30 per cent at no-load. Figs. 5.3 and 5.4 indicate that the squirrel cage rotor with 16 bars is somewhat better than the copper coated rotor in the way that it can be more heavily loaded in this respect. The effect of the large airgap for the copper coated rotor is the main reason for this comparison result. Fig. 5.6 shows the difference in power factors for the different rotors. The values are quite low for all the rotors. This is due to the relatively large air gap, which is common to high-speed induction machines, as shown in Section 2.3. The iron-to-iron airgap for the copper coated rotor is 80 % larger than for the others. This is clearly seen in the results.
Temperature rise [K] 100 80 60 40 20 0 Coated 26 bars 16 bars 0 10 20 30 Input power [kW] 40 50 60 Fig. 5.4 Measured average temperature rise in the stator winding. Input current [A] 160 140 120 100 80 60 40 20 0 Coated 16 bars 26 bars 0 10 20 30 Input power [kW] 40 50 60 Fig. 5.5 Measured input current. Power factor 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 16 bars 26 bars 0 10 20 30 Input power [kW] 40 50 60 Fig. 5.6 Measured power factor. Coated 57
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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 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: As reported in Lähteenmäki et al.
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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