Prevention of harmonic torques in squirrel cage induction motors by means of soft ferrite magnetic wedges

Anazawa, Yoshihisa; Kaga, Akio; Akagami, Hideo; Watabe, S.; Makino, M.

doi:10.1109/tmag.1982.1062116

Cited by 24 publications

(11 citation statements)

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“…For a long time, the beneficial effect of ferrite magnetic wedges, in terms of reduction of air-gap flux density pulsations, has been known to designers of classical induction and synchronous machines, [10]- [12]. In more recent years, soft magnetic composite (SMC) wedges have been proposed for PM machines, [7] and [13]- [15]; however, a detailed study on the possible shapes of these wedges and on the influence that these have on PM machine performance has not yet been carried out.…”

Section: Introductionmentioning

confidence: 99%

No-Load Performance of Axial Flux Permanent Magnet Machines Mounting Magnetic Wedges

Donato

Capponi

Caricchi

2012

IEEE Trans. Ind. Electron.

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Axial flux permanent magnet (AFPM) machines are being increasingly used in a variety of industrial, direct drive applications which benefit from their extreme axial compactness. In particular, slotted AFPM machines are of great interest, since they allow to achieve high torque densities together with an adequate constant power speed range. This paper analyzes a particular aspect related to the design of such machines, i.e. the use of soft magnetic composite (SMC) wedges to close stator slots. Magnetic circuit-based analyses and 2-D and 3-D finite-element analyses are performed on a 10 kW AFPM machine; various magnetic wedge configurations are adopted; the no-load performance is compared with that of the same machine using nonmagnetic wedges in terms of flux linkage, cogging torque, and no-load losses. Finally, experimental tests and results on a full-scale prototype machine mounting magnetic wedges are reported

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Section: Introductionmentioning

confidence: 99%

No-Load Performance of Axial Flux Permanent Magnet Machines Mounting Magnetic Wedges

Donato

Capponi

Caricchi

2012

IEEE Trans. Ind. Electron.

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“…It has been shown in the literature that switching to a semi-magnetic slot wedge with a low, but >1 relative permeability in the range 2 < < 10 can act to reduce the harmonic content in the airgap by modulating the flux paths -therefore assisting in reducing torque pulsations. Semi-magnetic slot wedges have also used in hydro-generators [15] to improve the EMF harmonic content and in induction machines to improve the losses [16].…”

Section: Use Of Semi-magnetic Slot Wedgesmentioning

confidence: 99%

Electromagnetic Analysis of a Synchronous Reluctance Motor With Single-Tooth Windings

2017

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“…Semi magnetic slot wedges has been used for induction machines in order to reduce torque harmonics [41] and iron losses [40]. The same concept has been used in axial flux PM machines; in [42] slot wedges was used successfully to reduce iron losses and cogging torque.…”

Section: Redesign Based Leakage Flux Variationmentioning

confidence: 99%

“…As a result of insertion of semi magnetic slot wedges the cogging torque was reduced by 60% in [41]. As the machine rotates the flux from the permanent magnets leads to flux pulsations in the iron powder cores.…”

Section: Redesign Based Leakage Flux Variationmentioning

confidence: 99%

Sensorless control of permanent magnet synchronous machines

Øvrebø¹

2013

IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society

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As the cost for permanent magnets are decreasing and the quality of the magnets are increasing the Permanent Magnet Synchronous Machine (PMSM) are becoming more popular. The PMSM is superior to induction machines both in torque per kilograms and efficiency. Typical applications for these machines are applications where machine volume or efficiency is important. In order to control a PMSM the rotor position needs to be known. This can be obtained by usage of sensor or by usage of a sensorless control scheme. Sensorless Control schemes typically divide into two categories; schemes that give good controllability from 2-5 Hz and schemes that gives good controllability at all speeds including zero speed. The focus for this thesis is sensorless control schemes with good controllability at low and zero speeds. Sensorless control is a multi physics challenge where the machine, inverter and control scheme are equally important for the quality of the drive system. In order to describe the saliency in the machine a new saliency machine model is developed in this thesis. The model includes yoke saturation, teeth saturation and induced currents in magnets. In injection based sensorless control the high frequency flux distribution in the machine is of great interest. In this thesis the frequency dependency in inductance is estimated in two machines by using injection of test signals in a large frequency range. Based on the measurements and the new saliency model the high frequency flux distribution is estimated and the frequency dependency of the saliency is described. A variety of different sensorless schemes are published over the last two decades. As the publications uses different test criteria it is challenging to determine the characteristics for the different schemes: three different control schemes are evaluated in terms of determining the scheme characteristics. A new scheme based on [1,7] is presented in this thesis. The new scheme enables integration of transient excitation and position estimation in every switching period. The continuous injection based schemes evaluated in this work is rotating high frequency carrier injection [2,13,39] and pulsating high frequency carrier injection [3,26]. The different schemes sensitivity to the inverter non linearity is modelled and evaluated. A comparison of the three schemes is presented. Surface mounted PMSM typically has a small saliency. The saliency in a surface mounted PMSM can be increased in several ways. The last part of this thesis presents a redesign approach for an axial flux PMSM. Several approaches are evaluated in terms of synergy effects with the machine cost and performance. An approach based on insertion of semi-magnetic slot wedges are realised in a prototype. iv ACKNOWLEDGMENTS

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Prevention of harmonic torques in squirrel cage induction motors by means of soft ferrite magnetic wedges

Cited by 24 publications

References 1 publication

No-Load Performance of Axial Flux Permanent Magnet Machines Mounting Magnetic Wedges

No-Load Performance of Axial Flux Permanent Magnet Machines Mounting Magnetic Wedges

Electromagnetic Analysis of a Synchronous Reluctance Motor With Single-Tooth Windings

Sensorless control of permanent magnet synchronous machines

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