Design and Voltage Supply of High-Speed Induction - Aaltodoc

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10 ξν ρ Material density σ Leakage factor σmax τ Pole pitch Φ l Ωm Ωs Winding factor of a ν th harmonic Maximum stress allowed Magnetic flux through current loop Mechanical speed Synchronous speed ω Angular frequency ωc First bending critical speed Abbreviations AC Alternating current AMB Active magnetic bearing CFD Computational fluid dynamics CMS Cross magnetic structure DC Direct current emf Electromotive force FEM Finite element method FFNF Free-free natural frequency GA Genetic optimization algorithm GTO Gate-turn-off thyristor IGBT Insulated-gate bipolar transistor LC Inductance - capacitance mmf Magnetomotive force PAM Pulse amplitude modulation pf Power factor pphc Pulses per half cycle PWM Pulse width modulation rms Effective (root mean square) value TEFC Totally enclosed fan cooled THD Total harmonic distortion VSI Voltage source inverter UPS Uninterruptible power supply
1 INTRODUCTION The need for high rotational speed is a built-in requirement in some industrial applications. Compressors, pumps and machine tools can often achieve better performance at higher speeds. The energy efficiencies of pump and compressor drives improve at higher speeds. The rate of material removal in a spindle tool is increased by an increase in speed. The sizes of the machines and drives are reduced when the rotational speed is increased. The Laboratory of Electromechanics has taken part in a project for the development of high-speed drive systems. In the Laboratory, electric high-speed machines and active magnetic bearing systems have been studied. On the machines side, emphasis has been on high-speed induction motors. At the beginning of the project, frequency converters had to be specially made as there were no suitable products on the market. 1.1 High speed electric drive systems Traditionally, a drive consists of a load machine, a power source and a gearbox. Nowadays, electric induction motors are the most common source of mechanical power. Induction motors are low cost, reliable and easily operated. Electric motors, which are supplied by the electricity distribution network, have a supply frequency of 50 or 60 Hz. Thus, these motors have a maximum operating speed of 3000 or 3600 1 /min. A gearbox in a traditional drive changes that speed into one more suitable for a load machine. Another way to have a high rotational speed is to use a frequency converter, also called as an inverter. The frequency converter transforms the 50/60 Hz supply frequency and voltage into a desired frequency and voltage. High rotational speeds can be achieved and the sizes of the motor and the drive can be reduced. There are fewer components subject to wear and tear if active magnetic bearings are used. Lubrication is not needed anymore. Table 1.1 and Fig. 1.1 show the difference between these two approaches and the benefits of high-speed technology. Fig. 1.2 illustrates a high-speed compressor drive and a rotary compressor drive. The development of power electronics has made inverters available at the large power vs. speed region. A voltage source inverter and simple scalar control are usually suitable for feeding a highspeed induction motor in the applications considered. Newer power semiconductors can operate at 11
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: Rn Resistance of a parallel conduct
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 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
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6.1 Comparison of PAM and PWM for 6
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h d = , (6.2) I I h, PAM where Ih,P
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Fig. 6.4 Phase-to-phase voltage and
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Temperature rise [K] 120 100 80 60
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Machines loss [W] 12000 10000 8000
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considerably higher than expected.
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In order to improve the performance
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l = + , (7.2) sλs 2leλ e l wλ w
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gap of 1 mm would yield an effectiv
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Table 7.1 Calculated effective leng
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Input current [A] 170 160 150 140 1
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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
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Because Φ l is approximately at th
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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,
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Height of bar slot [mm] 8 6 4 2 0 R
Page 115 and 116:
The different rotor topologies were
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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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