RFOC Induction Machine

Tài liệu Induction Machines pptx

... This is the normal operating state of a slip-ring induction machine The second type of induction machines are so-called squirrel-cage induction machines Rotor winding is in this case cast into ... exclusively by electromagnetic induction; therefore asynchronous machines are called induction machines End ring Rotor winding bars Fig – Squirrel-cage winding of a squirrel cage induction machine Rotating ... is the case in synchronous machines, there is no way of exciting the induction machine in a manner similar to synchronous machines This is one of the main reasons why induction machine is mainly...
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electric machine Chapter 6 Polyphase Induction Machines

... rotor resistance 6. 2 Currents and Fluxes in Polyphase Induction Machines 6. 3 Induction- Motor Equivalent Circuit Only machines with symmetric polyphase windings exited by balanced polyphase voltages ... Tmech − Trot ωs = ωm (6. 24) (6. 25) (6. 26) (6. 27) (6. 28) Figure 6. 11 Equivalent circuits with the core-loss resistance Rc neglected corresponding to (a) Fig 6. 9 and (b) Fig 6. 10 6. 5 Torque and Power ... for a polyphase induction motor at slip frequency ˆ ˆ I 2s = I E s = sE ˆ ˆ E s = sE ˆ ˆ E s sE = = Z s = R2 + jsX ˆ ˆ I 2s I2 ˆ E R Z = = + jX ˆ s I2 (6. 12) (6. 13) (6. 14) (6. 15) (6. 16) Fig 6. 9...
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Chapter 6 symmetrical induction machines

... 220 460 2300 2300 1710 1705 1773 17 86 11.9 198 1.98 × 103 8.9 × 103 5.8 46. 8 93 .6 421.2 0.435 0.087 0. 262 0.029 0.754 0.302 1.2 06 0.2 26 26. 13 13.08 56. 02 13.04 0.754 0.302 1.2 06 0.2 26 0.8 16 0.228 ... 2⎞ pWm = −Te ⎜ ⎟ pθ r ⎝ P⎠ (6. 6-11) Therefore, (6. 6 -6) can be written as ⎛ 2⎞ ⎛ 2⎞ ⎜ ⎟ pWe = pW f + Te ⎜ ⎟ pθ r ⎝ 3⎠ ⎝ P⎠ (6. 6-12) If we compare (6. 6-12) with (6. 6-8), and if we equate coefﬁcients ... ′ ′ (6. 6-8) Comparing (6. 6-8) with (6. 6 -6) , it is clear that the right-hand side of (6. 6-4) is pWf − pWm Now TORQUE EQUATION IN ARBITRARY REFERENCE-FRAME VARIABLES pWm = −Te pθ rm 231 (6. 6-9)...
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Chapter 9 unbalanced operation and single phase induction machines

... (9. 5-21)– (9. 5-23) and solving the result for νng yields 350 UNBALANCED OPERATION AND SINGLE- PHASE INDUCTION MACHINES vng = 1 (egb + egc ) + vas 2 (9. 5-24) Substituting (9. 5-24) into (9. 5-22) and (9. 5-23) ... (9. 5-8)– (9. 5-10), and we have vng = − ias z( p) (9. 5-11) 348 UNBALANCED OPERATION AND SINGLE- PHASE INDUCTION MACHINES Equation (9. 5-11) is valid as long as ega + egb + egc is zero Substituting (9. 5-11) ... only ωe 346 UNBALANCED OPERATION AND SINGLE- PHASE INDUCTION MACHINES 9. 5 TYPICAL UNBALANCED STATOR CONDITIONS OF INDUCTION MACHINES Although it is not practical to consider all stator unbalanced...
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the induction machine handbook chuong (1)

... equations) around 1860 The knowledge was ripe for the invention of the induction machine which has two fathers: Galileo Ferraris (1885) and Nicola Tesla (1886) Their induction machines are shown ... manufacturing and testing for induction machines Integral induction motors: induction motors with the PWM converter integrated into one piece 1.3 INDUCTION MACHINES IN APPLICATIONS Induction motors are, ... invented the induction motor with the wound rotor and subsequently the cage rotor in a topology very similar to that used today He also invented the double-cage rotor Thus, around 1900 the induction...
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the induction machine handbook chuong (2)

... cases the internal primary is the mover and the external secondary is at a standstill In most rotary IMs, the primary is the stator and the secondary is the rotor Not so for linear induction machines ... fact, it is 25 to 60% of the rated current depending on the machine airgap g to pole pitch τ ratio The higher the ratio τ/g, the smaller the magnetization current in p.u The stator and rotor currents ... (Figure 2.9) The slip rings are visible to the right The stator-placed brush system is not Single-phase-supply IMs have, on the other hand, in general, two windings on the stator The main winding...
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the induction machine handbook chuong (3)

... to this combination The insulation of the coil conductors (turns) is applied before inserting the coils in slots The coils are vacuum also impregnated outside the machine The slot insulation ... All these insulation accelerated life tests involve the ageing of insulation test specimens until they fail at temperatures higher than the operating temperature of the respective motor The logarithms ... motor The logarithms of the accelerated ageing times are then graphed against their reciprocal Kelvin test temperatures (Arhenius graph) The graph is then extrapolated to the planed (reduced) temperature...
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the induction machine handbook chuong (4)

... 6K1 + 2(4) and 2p2 = 6K2 + 1, respectively, the mmf waves for the two pole counts travel in the same direction On the other hand, if 2p1 = 6K1 + 2(4) and 2p2 = 6K2 + 4(2), the mmf waves for the ... layer and the other side in the second layer They are connected observing the inward (A, B, C) and outward (A’, B’, C’) directions of currents in their sides Connecting the coils per phase The Ns/2m ... ……… For the fundamental, ν = 1, we obtain the maximum amplitude The higher the order of the harmonic, the lower its amplitude in (4.8) While in principle such a primitive machine works, the harmonics...
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the induction machine handbook chuong (5)

... and the mutual stator/rotor inductances are calculated for the fundamental airgap flux density This information prepares the ground to define the parameters of the equivalent circuit of the induction ... replaced by the actual (designed) maximum flattened flux density Bgm, at an angle θ = 30°/p1, which makes the length of the flux lines in the back core 2/3 of their maximum length Then finally the calculated ... have consequences in the phase current waveforms for the two connections Finally, the saturation produced third and other harmonics influence, notably the core loss in the machine This aspect...
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the induction machine handbook chuong (6)

... respectively As the pole pitch of the harmonics is τ/ν, their fields not reach the back cores and thus their saturation factor Ksν is smaller then Ks The higher ν, the closer Ksν is to unity In a ... fields The airgap flux does not reach the other slotted structure (Figure 6.10a) while the zig-zag flux “snakes” out through the teeth around slot openings In general, they may be treated together ... rotor phases In reality the flux in the rotor varies at Sf1 frequency, while in the stator at f1 frequency The amplitude is the same and, with respect to each other, they are at stall Now we...
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the induction machine handbook chuong (7)

... S.A.Nasar………… ……… The lower the power factor at ideal no-load, the lower the core loss in the machine (the winding losses are low in this case) In general, when the machine is driven under load, the value ... the value of Pelm is zero, so the machine driven at that speed absorbs power in the stator to cover the winding and core loss Motor no-load mode is when there is no-load torque at the shaft The ... means that either n < and n1(f1) > or n > and n1(f1) < In both cases, as S > (S > 0), the electromagnetic power Pelm > and thus flows from the power source into the machine On the other hand, with...
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the induction machine handbook chuong (8)

... constant under steady state and the machine behaves like a synchronous machine with the torque dependent on the power angle δ (S = f2/f1 = ct) On the other hand, the frequency f2 may be varied ... frequency f1 and the other at frequency f2 from a limited power frequency converter The machine speed n is n= f1 ± f p1 + p (8.71) The smaller f2, the smaller the rating of the corresponding ... single induction motions If the induction motor remains at stall for a long time, the rotor and stator temperatures become too large, so there is a maximum stall time for each machine design On the...
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the induction machine handbook chuong (9)

... IN THE END RINGS VIA THE MULTILAYER APPROACH As the end rings are placed in air, although rather close to the motor laminated stack, the skin effect in them is routinely neglected However, there ... On the other hand, if slot leakage saturation occurs only on the teeth top and the teeth, additional saturation due to skewing does not influence the flux lines distribution within the slot, the ... calculate the final values of leakage inductances Now if the skewing flux occurs both in the stator and in the rotor, when the leakage inductance is calculated, the rotor one will include the skewing...
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the induction machine handbook chuong (10)

... components close their flux lines axially through the stator frame then radially through the end frame, bearings, and axially through the shaft (Figure 10.3) The factor ch accounts for the magnetic ... order is a multiple of the number of slots (10.12) The stator (rotor) mmfs may produce harmonics of the same order either as sourced in the mmf or from the interaction with the first airgap magnetic ... in general, 6c1 ± 1, while the stator slotting introduces harmonics of the order c1 N s ± The higher the harmonic order, the lower its mmf amplitude The slip p1 Sν of the νth harmonic is Sν =...
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the induction machine handbook chuong (11)

... when the IM is static converter fed, and thus the voltage time harmonics content depends on the type of the converter and the pulse width modulation used with it The space harmonics in the stator ... associated with them, but the higher frequency flux harmonics may lead to larger core loss On the other hand, the commutation losses in the PWM converter increase with carrier frequency The optimum ... means that the skin effect is not significant Therefore we may neglect the rotor lamination-induced current reaction to the stator field That is, the airgap field harmonics (11.6) penetrate the rotor...
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