Design and Voltage Supply of High-Speed Induction - Aaltodoc

More documents

Recommendations

Info

78 Input current THD [%] 60 50 40 30 20 10 0 3 pulses 9 pulses PAM 15 pulses 0 10 20 30 Input power [kW] 40 50 60 Fig. 6.15 Measured total harmonic distortion of input current for the motor. Harmonic loss [W] 2500 2000 1500 1000 500 0 3 pulses 9 pulses 15 pulses PAM 0 10 20 30 Input power [kW] 40 50 60 Fig. 6.16 Measured harmonic loss for the motor. Eff. harmonics resistance 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 15 pulses 9 pulses 3 pulses PAM 0 10 20 30 Input power [kW] 40 50 60 Fig. 6.17 Effective harmonics resistance relative to the resistance for PAM at no-load.
In order to improve the performance of the PWM inverter, some modifications must be made. One option would be to optimize the pulse waveform. This would be done by determining the switching instants for the individual pulses in order to have the lowest harmonic loss (Zach 1989). The switching instants for each pulse number and modulation index could be stored in the memory of the modulator. The optimization could be started using the same theoretical approach as presented in Section 6.1.1. More accurate results would require the use of a full model for the motor and possibly also for the inverter. This could be a challenging task because the model should include, for example, the effect of circulatory currents in the stator winding. The PWM waveform having 9 pulses per half a cycle could be selected for the optimization. According to the results, it seems to generate a reasonable compromise between the inverter and motor loss, yielding a decent loss level for the drive system. Another way to improve PWM and also PAM waveforms would be to put a LC filter between the inverter and the induction machine. This approach is used by Huppunen and Pyrhönen (2000) for a 12 kW 13500 1 /min high-speed solid rotor induction motor. The losses of the motor would decrease without increasing the losses in the frequency converter. Another advantage stated in the study is that the filter can compensate some of the reactive load of the induction motor. This may have a beneficial impact on inverter sizing. 6.2 Conclusion The results of the measurements show that the idea of moving the harmonic content of voltage and current upwards in spectral scale by increasing the switching frequency does not apply well for the high-speed induction machine. The currents of higher harmonic order produce more loss than the same amount of lower order harmonics. This result, together with the consideration of inverter and drive loss, implies that PAM should be preferred as a voltage waveform for high-speed induction machines. 79
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 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: considerably higher than expected.
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
show all

Design and Voltage Supply of High-Speed Induction - Aaltodoc

Create successful ePaper yourself

Delete template?

Save as template?