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In this paper, we analyze the back electromotive force (BEMF) characteristics according to the magnetization pattern of irreversible demagnetization to determine the fault type for interior permanent-magnet (IPM) type brushless DC (BLDC) motors. We numerically model irreversible demagnetized PMs using space-harmonics analysis. In addition, we analyze the results using the finite element and analytical...
Stator slot magnetic wedges are used instead of conventional epoxy glass wedges in large, high output induction motors since the motor efficiency and power factor can be improved. However, cases of loose or missing magnetic wedges due to their weak mechanical strength have recently been increasingly reported. Although missing wedges can deteriorate motor performance and reliability, there currently...
This paper considers the electromagnetic and structural co-design of synchronous reluctance (SyR) machines for high-speed applications, with the aid of optimization algorithms. The aim of this work is twofold. First, three commercial electrical steel grades are compared to establish quantitatively how steel properties influence the performance of high-speed SyR machines. The considered steel grades...
During the mass production of surface-mounted permanent magnet motors the rotor and stator geometrical dimensions usually deviate from their nominal values due to manufacturing tolerances which impact machine performance. Radial misalignment in the placement of the permanent magnets on the rotor surface as well as slot opening variations are common deviations observables in the final product. As a...
This paper proposes a new senseless start-up method by using a terminal voltage/current without position sensor. A flux estimator consisting of field flux model, P controller and flux voltage model is proposed and rotor angle/speed is estimated by using a phase locked loop. Furthermore, initial rotor angle is estimated rapidly and accurately by using the same flux voltage model during the initial...
The main goal of this paper is to fundamentally address the behavior of the extra eddy current losses in a high speed/frequency synchronous reluctance machine (HS-SynRM). Both stator core and rotor eddy current solid losses, due to the current harmonics, under Variable Speed Drive (VSD) operation, have been studied. First, the root-cause of these losses is explained and developed through an analytical...
This paper presents a sensor-less vector control method which estimates the rotor angle and speed of a nine-phase, Interior Permanent Magnet (IPM) machine with concentrated stator winding, especially for use at starting, zero and low speed operations. The injection of unique high frequency voltage signals into a non-torque producing third sequence circuit of the machine provides current information...
Switched reluctance motors (SRMs) are popular due to their advantages of simple and robust construction, wide speed range, and fault tolerance. Commonly cited limitations of SRMs are acoustic noise and the need for a different inverter configuration. It has been reported that when the SRM phases are excited with sinusoidal bipolar currents, there is significant reduction in acoustic noise. Further,...
The purpose of this paper is to characterize the performance of a novel dual-stator six slot four pole (6/4) flux switching permanent magnet machine. The proposed dual-stator 6/4 topology eliminates even order harmonics in the flux linkage and back electromotive force, which are present in the conventional single stator topology. The resulting back electromotive forces of the proposed dual-stator...
A switched reluctance machine (SRM) is applicable to high speed applications due to its simple magnetic structure and mechanical robustness. During the operation of a converter, however, it causes high peak phase current which leads to a rise in the VA rating of an SRM system. Therefore, this paper investigates the reduction of peak phase current and describes the basic design procedure of an SRM...
This paper presents design process of the rotor to obtain a variable-flux flux-intensifying interior permanent magnet machine (VFI-IPM) with improved torque quality and reduced magnetization current. The VFI-IPMs have attracted much attention because the magnetization state of the permanent magnets can be adjusted according to load conditions. By applying a d-axis pulse current to magnetize the PMs...
PM temperature measurement/estimation in permanent magnet synchronous machines (PMSMs) is convenient both for torque control and monitoring purposes. Most of existing methods provide and averaged/punctual temperature. However, PM temperature distribution is not uniform, which can have unexpected adverse effects like reduced accuracy estimating the torque produced by the machine or local demagnetization...
This paper proposes a non-linear observer for Induction Machine (IM) drives which takes into consideration the saturation effects. The non-linear observer is based on an original formulation of the dynamic model of the IM taking into consideration the magnetic saturation of the iron core. A Lyapunov based convergence analysis is proposed in order to suitably compute the observer gain guaranteeing...
The cross-saturation inductance is a mutual inductance due to the saturation of portions of the magnetic circuit of one axis caused by the current of the other axis. In the sensorless drives, the differential cross-saturation inductance causes an error in the estimation of the rotor position when performed by means of the high frequency signal injection methods. The knowledge of the properties of...
A block commutation based position sensorless method for low speed regions has some advantages [6]-[11]. This method introduces "Induced Voltage caused by Magnetic Saturation (IVMS)". The IVMS based method can be applied to most permanent magnet synchronous motors (PMSM) with or without a saliency rotor structure. However, some motors that have a closed-slot stator structure cannot easily...
This paper proposes a dual-rotor, toroidal-winding, axial-flux vernier permanent magnet (VPM) machine. By the combination of toroidal windings with the rotor-stator-rotor topology, the end winding length of the machine is significantly reduced when compared with the regular VPM machine. Based on the airgap permeance function, the back-EMF and torque expressions are derived, through which the nature...
This paper proposes a detailed numerical model of a very narrow air gap of a permanent magnet synchronous machine without an imposed axial flow. The flow structure analysis and the convective heat transfer are carefully investigated using an axisymmetric model of two concentric cylinders where the inner cylinder is rotating and the outer cylinder is stationary. For the different cases, only isothermal...
Continuous online monitoring of electrical assets is critical for reducing the process downtime and the associated financial losses in industrial applications. Majority of large induction motors, which are critical to industrial applications, are mains-fed. Condition monitoring of these mains-fed motors is critical for reducing the failure rate of these motor systems. Motor relays, commonly used to...
A novel three-phase, concentrated winding, axial flux, segmental rotor, flux-switching synchronous motor is presented. The proposed topology has rotor segments made of only iron laminations and operates with flux-switching principle. Compared to existing axial flux permanent magnet (AFPM) topologies, the proposed machine contains reduced amount of permanent magnets located only in its stator. This...
This study is used to highlight the potentials of flux switching PM machines for medium-speed wind generator drives, considering among other things, that the rotor pole number is critical to the electromagnetic torque output. The initial result obtained by finite-element simulations and theoretical analyses of the pre-optimised 12/10 FSPM topology compared to its 12/14 counterpart show that with higher...
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