37 References

Jones, Using the New Lamination Steels Database in Motor Design, Proceedings of SMMA-2000 Fall Conference in Chicago, pp.1-12. 2. M. Birkfeld, K.A. Hempel, Calculation of the Magnetic Behaviour of Electrical Steel Sheet Under Two Dimensional Excitation by Means of the Reluctance Tensor, IEEE Trans. Vol. MAG-33, No. 5, 1997, pp.3757-3759. 3. I.D. Mayergoyz, Mathematical Models for Hysteresis, Springer Verlag, 1991. 4. H.H. Saliah, D.A. Lowther, B. Forghani, A Neural Network Model...

77 Generating To Power Grid

As shown in paragraph 7.2, with S < 0 the electromagnetic power travels from rotor to stator (Peml < 0) and thus, after covering the stator losses, the rest of it is sent back to the power grid. As expected, the machine has to be driven at the shaft at a speed n > f1 p1 as the electromagnetic torque Te (and Pelm) is negative (Figure 7.8). Figure 7.8 Induction generator at power grid Figure 7.8 Induction generator at power grid The driving motor could be a wind turbine, a Diesel motor, a...

Dual System In Civil Engg

Notice that the current has both components. The main advantage of this variable transformation - to be done off line through a PC - is that it provides instantaneous power values without requiring averaging over a few integral electrical periods. 15 Consequently, while the machine travels from nmin to nmax and back, the active and (reactive) instantaneous power travel a circle when shown as a function of speed. (Figure 22.11) 15 Basically, the machine works as a...

146 Matching Ims To Variable Speedtorque Loads

IMs are, in general, designed for 60(50) Hz when used for variable speed with variable V f supply, they operate at variable frequency. Below the rated frequency, the machine is capable of full flux linkage, while above that, flux weakening occurs. For given load speed and load torque with variable V f supply, we may use IMs with 2pi 2, 4, 6. Each of them, however, works at a different (distinct) frequency. Figures 14.9 show the case of quadratic torque (pump) load with the speed range of 0 to...

96 Leakage Flux Path Saturationa Simplified Approach

Semi Closed Slots Induction Motors

Leakage flux path saturation occurs mainly in the slot necks zone for semiclosed slots for currents above 2 to 3 times rated current or in the rotor slot iron bridges for closed slots even well below the rated current (Figure 9.20). Consequently, a a + (Tss - aos) . T nDi aor'_ aor .0. Tsr _ (9.54) The slot neck geometrical permeances will be changed to a'os hos, a'or hor, or a'or hor dependent on stator (rotor) current. Figure 9.20 Leakage flux path saturation conditions With ns the number of...

Rotor bar skin effect reduction

The skin effect is a direct function of the parameter The slot shape also counts. But once the slot is rectangular or circular, only the slot diameter, and respectively, the slot height counts. Rounded trapezoidal slots may also be used to secure constant tooth flux density and further reduce the skin effects (Figure 17.2). Figure 17.2 Rotor bar slots with low skin effect a.) round shape b.) rectangular c.) pear-shape For given rotor slot (bar) area Ab (Figure17.2 a,b,c), we have , 2 j n5 2 h...

Linze Indction Motom Hz 87 Rpm 2500

Figure 1.6 Dual cage rotor induction motors for large starting torque (source ABB) Figure 1.6 Dual cage rotor induction motors for large starting torque (source ABB) There are applications (such as overhead cranes) where for safety reasons, the induction motor should be braked quickly, when the motor is turned off. Such an induction motor with integrated brake is shown on Figure 1.7. Figure 1.7 Induction motor with integrated electromagnetic brake (source ABB) Figure 1.7 Induction motor with...

92 The Skin Effect

As already mentioned, skin effects are related to the flux and current density distribution in a conductor (or a group of conductors) flowed by a.c. currents and surrounded by a magnetic core with some airgaps. Easy to use analytical solutions have been found essentially only for rectangular slots, but adaptation for related shapes has also become traditional. More general slots with notable skin effect (of general shape) have been so far treated through equivalent multiple circuits after...

V

gt Low space harmonic content windings Fractional pitch windings have been, in general, avoided for induction motor, especially due to low order sub or fractional harmonics and their consequences parasitic torques, noise, vibration, and losses. However, as basic resources for IM optimization are exhausted, new ways to reduce copper weight and losses are investigated. Among them, fractional windings with two pole symmetry q 2l 1 2 are investigated thoroughly 9,12 . They are characterised by the...

60

With A1 the specific stator current load A1 A m , We might separate the volume utilization factor C0 Esson's constant as C0 is not a constant as both the values of A1 A m and airgap flux density Bg increase with machine torque and with the number of pole pairs. The Dis2-L output coefficient may be calculated from 14.17 with Sgap from 14.6 and 14.11 . Typical values of C0 as a function Sgap with pole pairs p1 as parameter for low power IMs is given in Figure 14.14. The Dis2-L internal output...

Modeling Of Losses Induction Motor With Dual Stator Windings

1 Induction Machines an Introduction 1.1 Electric Energy and Induction Motors 1.3 Induction Machines in Applications 2 Construction Aspects and Operation Principles 2.1 Construction Aspects of Rotary IMs 2.2 Construction Aspects of Linear Induction Motors 2.3 Operation Principles of IMs 3 Magnetic, Electric, and Insulation Materials for IM 3.5.1 Random-Wound IM Insulation 4 Induction Machine Windings And Their M.M.Fs 4.2 The Ideal Traveling M.M.F. of A.C. Windings 4.3 A Primitive Single-Layer...