Design and Voltage Supply of High-Speed Induction - Aaltodoc

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94 Fig. 8.5 Strand currents in the two parallel paths for phase W in complex coordinate system. Circles show the amplitude of the average strand current. Line shows the direction of average current.
8.2 Impedance of the circulatory current loop The impedance of a circulatory current loop was also measured as a function of frequency. This was done in order to see whether the frequency of the circulatory current would affect the load impedance it sees. The impedance was measured by selecting two individual strands. The strands were disconnected from the terminal end. Thus, the current had a path from one strand end to the star connection and back along the other strand. A sinusoidal test signal was produced with an arbitrary waveform generator, a Sony/Tektronics AWG2005. The signal was amplified with a Kepco bipolar operational amplifier. Voltage, current and phase shift between them was measured. The phase shift was read from a HP 54600A scope. The current amplitude of the signal was selected to correspond roughly to the strand current in a nominal operation point of the high-speed motor. The measurement setup is illustrated on the right hand side of Fig. 8.6. Fig. 8.7 shows the measured impedance and load angle or the phase shift between voltage and current of the circulatory current loop. The result shows that the impedance is mainly resistive up to the frequency of 10 kHz. For the 60 kW 60000 1 /min high-speed motor, a significant part of the harmonics spectrum lies within this region. As the emf inducing the currents is proportional to the frequency and the impedance can be assumed constant up to 10 kHz, the circulatory current loss produced becomes proportional to the square of the frequency. The result implies that moving the harmonic components of the supply voltage and current up in the frequency range will increase the loss relative to the current because of the circulatory currents. This may degrade the benefits of using pulse width modulation as opposed to pulse amplitude modulation. This will be discussed more in Section 8.5. Synchronous generator 15 - 450 Hz NORMA D 6100 I in P in f in MBC-11 u ref i n Stator Tektronix tm502a i n Tektronics AWG2005 10 Hz - 50 kHz Kepco amplifier HP 54600A Fig. 8.6 On the left, the measurement setup for strand currents. On the right, the measurement setup for impedance and load angle of a circulatory current loop. u n i n α n 95
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El 108 ACTA POLYTECHNICA SCANDINAVI
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PREFACE This thesis is the result o
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5 Comparison of rotors for 60 kW 60
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LIST OF SYMBOLS a Number of paralle
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Rn Resistance of a parallel conduct
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1 INTRODUCTION The need for high ro
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Conventional (high-speed) drive Hig
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Chapter 5 reports the comparison of
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Some penetration depth values are c
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2.2 Stator windings for high-speeds
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⎛ π ⎞ sin⎜ν ⎟ ⎛ π ⎞
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Table 2.3 Air gap characteristics o
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Cooling of the stator could need ax
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f sw N p = (2.9) fs The switching f
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3 ROTOR CONSTRUCTIONS Starting from
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and eddy-currents traveling on the
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support the squirrel cage winding,
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3.1.3 Rotor loss and friction loss
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Table 3.1 High-speed induction moto
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critical speeds are passed relative
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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 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: Fig. 8.4 Strand currents in the two
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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