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Permanent-magnet-assisted salient-pole synchronous machines (PMa-SMs) are a new type of salient-pole synchronous machines that has PMs between the adjacent pole shoes. The PMs have the ability to improve the output power and the terminal voltage. In this paper, a simple magnetic circuit of PMa-SMs is presented. Using the magnetic circuit, the electric and magnetic basic characteristics of PMa-SMs are calculated. The results are compared with the results by measurements and finite-element analysis (FEA). They have shown that the magnetic circuit calculates the characteristics of PMa-SMs with satisfactory accuracy and that the computational time of the magnetic circuit is much smaller than that of FEA. Influence of the pole-shoe magnetic reluctances on the calculation accuracy by the magnetic circuit is also discussed, and some guidelines to enhance the accuracy have been presented. [ABSTRACT FROM PUBLISHER]

In this paper, the core losses that occur in a 4-kVA flux-modulating synchronous machine (SM) (FMSM) are investigated using 2-D finite-element analysis, and the results are supported by experiments. A method for reducing the core losses is also presented. The FMSM is a new type of multipole SM in which the stator field magnetomotive force is modulated by the air-gap permeance to generate the rotating field. A 2pa-pole three-phase armature winding and a 2pf-pole field winding are centrally wound around individual stator teeth, and a reluctance rotor with 2pr\ (= pa + pf) saliencies is used to provide a magnetic coupling between these windings. As a result of the investigation, it was found that, although the core losses occur in the rotor as well as in the stator, the rotor core loss can be effectively reduced by decreasing the height of the rotor poles. [ABSTRACT FROM AUTHOR]

This paper presents a new type of multipole synchronous machine (SM) in which 2pa-pole armature and 2pf-pole field windings are centrally wound around individual stator teeth. The proposed machine operates as a (2pa + 2pf)-pole SM by providing a magnetic coupling between the armature and field windings through a 2pr-pole reluctance rotor. A 4-kVA (32 + 48)-pole prototype machine was designed and built to validate the principle of this structure. Performance characteristics of the prototype machine were simulated using 2-D finite-element analysis (FEA) and were supported by experiments. In addition, the effects of the rotor pole shape on the performance characteristics were studied through 2-D FEA simulations. The results presented provide guidelines for the optimum design of the proposed machine. [ABSTRACT FROM PUBLISHER]

The characteristic improvements of salient-pole synchronous generators by inserting additional permanent magnets are investigated from both results of finite-element analyses and experiments. First, the assist effects of the magnets in a megavoltampere-class generator are analyzed by the finite-element method. It is clarified that the additional permanent magnets have the effects of reducing magnetic saturation at the rotor-pole bodies, as well as the effects of increasing the direct flux linkage of armature windings. It is also clarified that the output of the generator can be increased by more than 20% by inserting the magnets without any increase in total machine size and decrease in efficiency. Finally, the characteristic improvements are validated by the experiment of a small prototype generator. The experimental and calculated results are found to be in good agreement. [ABSTRACT FROM PUBLISHER]

In this paper, a new salient-pole synchronous generator (SG) termed the PMa-SG is presented. In the PMa-SG, permanent magnets (PMs) are placed between the pole shoes to reduce the magnetic saturation in the field poles. By using finite element analysis (FEA), the internal magnetic fields and basic characteristics of a 2.8-MVA PMa-SG are compared with those of a conventional SG of the same size, and the reduction effect of the magnetic saturation of the PMs is examined. The FEA simulations are also validated by experiments on a 2.0-kVA prototype machine. The PMs placed between the pole shoes reduce the magnetic saturation in the pole bodies and pole tips and effectively increase the terminal voltage and output power. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(4): 58-67, 2011; Published online in Wiley Online Library (). DOI 10.1002/eej.21132 [ABSTRACT FROM AUTHOR]

We propose a new method for analysis of the harmonic wave components of magnetic fields in rotating machinery. Using the magnetic permeability obtained by transient analysis of the nonlinear magnetic field, the harmonic wave components of the magnetic field are individually calculated in the spaces of both the rotor and stator subject to the boundary condition that the harmonic wave components obtained by the transient analysis are set on the sliding surface. Mode separation of the magnetic field will contribute to research on reducing harmful harmonic wave components for rotating machinery. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(2): 55–63, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20951 [ABSTRACT FROM AUTHOR]