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The phenomenon of the irreversible magnet demagnetization is described by using two-dimensional finite-element method (2-D FEM). The nonlinear analysis of a permanent magnet is added to 2-D FEM for considering irreversible demagnetization and the design methods effective in avoiding irreversible demagnetization are described.

The effects of the magnetization direction on the various characteristics are examined. The results have shown that the radial magnetization direction has more advantage in terms of the irreversible magnet demagnetization.

A single phase flux-reversal machine is presented and a design method to improve its starting torque is proposed. Analysis of the design variables such as airgap, stepped airgap, slotted teeth, and asymmetric permanent magnet width suggests that tapered air gap, or stepped airgap is the most appropriate, and either can be chosen, depending on the application.

A design technique to improve the performance of flux-reversal machine (FRM), which is a doubly salient stator permanent magnet (PM) with flux linkage reversal in the stator concentrated windings, is proposed. The proposed FRM that has the stator and rotor shapes of concave-type, and a flux barrier is found to improve the performance.

The effect of design variables on irreversible magnet demagnetization in brushless dc (BLdc) motor through the modeling approach using a two-dimensional finite-element method (2D-FEM) is discussed. The magnet thickness, teeth surface width, and rotor back yoke thickness are the most important geometrical dimensions of BLdc motor in terms of irreversible magnet demagnetization.

Flux-reversal machine (FRM) is a new doubly salient stator-permanent magnet (PM) machine with flux linkage reversal in the stator concentrated windings. It can operate in both motoring and generating modes. Its simple structure makes it cost effective and suitable for mass production. However, there is notable permanent magnet flux leakage which deteriorates the torque ability of the FRM. In this paper, a novel design to improve the performance of an FRM is proposed. The proposed FRM has permanent magnets parallel to the stator magnet flux lines and thus is much more difficult to demagnetize. To analyze the characteristics of the proposed FRM, a two-dimensional finite-element method (2-D FEM) is used. The prototype FRM is also built to prove the advantage of the new design method. From the analysis and experimental results, it is shown that the proposed FRM has an improved performance. [ABSTRACT FROM AUTHOR]

A flux-reversal machine (FRM) is a new doubly salient stator-permanent magnet (PM) machine with flux linkage reversal in the stator concentrated windings. It can be driven by 1200 square-wave voltage and use pulse-width modulation (PWM) patterns in two-phase feeding schemes to control the speed of the machine. This paper introduces four PWM modes that used the FRM control system and analyzes the effects of four different PWM modes on the iron loss using a 2-D time-stepped voltage source finite-element method. The iron loss is calculated from the time variation of the magnetic field distribution. [ABSTRACT FROM AUTHOR]

In this paper, we deal with the magnetic field analysis of a magnetron composed of axisymmetric and rectangular structures using hybrid type finite element method. The magnetron used in microwave oven has cylindrical permanent magnet and rectangular iron plate to generate magnetic field. By comparing with the experimental results, we show that the proposed computational method is suitable to analyze a magnetron composed of axisymmetric and rectangular structures. [ABSTRACT FROM AUTHOR]

This paper describes the effect of pulsating current generated by back-electromotive force (BEMF) current of switch-off phase in flux-reversal machine (FRM) which is driven by 120° square wave voltage sources. A two-dimension time-stepped voltage source finite element analysis using a direct convergence method is proposed to analyze an electromagnetic field and the BEMF current. To prove the propriety of the proposed analysis method, we build the prototype FRM and a digital signal processor (DSP) installed controller as a set for the experiment. [ABSTRACT FROM AUTHOR]

The flat-type vibration motor has an axial-gap structure. Analyzing axial-gap motors with the two-dimensional (2-D) finite-element method is very difficult because we have to define the analysis surface as a cylindrical surface In order to simulate the flat-type vibration motor, we have developed new equations of calculation for the torque of the motor, which is uses a 2-D grid model. We have measured the load torque of the vibration motor which is used for the motion transient analysis. The simulated vibration characteristic is compared with experimental value. [ABSTRACT FROM AUTHOR]

In this paper, we introduce the analysis method of Brushless DC Motor (BLDCM) with long commutation period and large DC link voltage ripple using time-stepped voltage source Finite Element Method (FEM), and investigate the influence on motor performance such as torque ripple and radial force due to signal distortion of the position sensor and DC link voltage ripples. Simulation and experimental results are also presented to verify the proposed analysis method. [ABSTRACT FROM AUTHOR]

A novel permanent-magnet flux-concentration-type linear oscillatory actuator (LOA) for a compressor is analyzed in this paper. The losses of a flux-concentration-type LOA which is driven by sinusoidal and rectangular-shaped current are compared using finite-element method (FEM). In this computation, the equation of magnetic field is coupled with the equation of the driving electric circuit and the equation of motion. The results are compared with respect to iron losses. The eddy-current loss and hysteresis loss of both the sinusoidal current and rectangular current was calculated using two-dimensional FEM. [ABSTRACT FROM AUTHOR]

The cogging torque of the flux-reversal machine (FRM) may cause some problems like noise and vibration of the motor. By FEM analysis of the cogging torque of FRM, a noticeable feature was found that the rotor teeth width increases, phase and magnitude of the cogging torque varies. So, the rotor teeth pairing method is proposed for reducing the cogging torque of FRM. In this method, we made a rotor which has two different tooth widths and measured the cogging torque of the motor. From the result, we can see that the simulation result is well matched with the measured result and the proposed method is feasible. [ABSTRACT FROM AUTHOR]

The paper introduces a set of static and dynamic experiments to more fully characterize a linear permanent magnet (PM) oscillatory machine. The proposed set of tests was performed on a PM brushless linear oscillatory machine with surface PM and PM flux concentration movers, respectively. Though the testing arrangement allows for it, temperature, noise and vibration have not been investigated in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes the single-phase flux-reversal motor for a vacuum cleaner. The circuit parameters are determined by using both finite-element method and experimental measurements while a simulation was done by using an equivalent circuit model to derive the dynamic characteristics. Due to the inductance of the coil of high-speed drives, a phase difference occurs between the current and the electromotive force which produces a negative torque that degrades the output. Through simulation, the turn-on angle and turn-off angle that minimize the negative torque are found and simulation results will be compared with the results of the experiment. [ABSTRACT FROM AUTHOR]

A novel permanent magnet (PM) flux concentration-type linear oscillatory actuator (LOA) for a compressor is proposed in this paper. The proposed LOA has an embedded PM structure and the structure is effective in magnet flux concentration. The flux concentration has a positive influence on the flux linkage, cogging force, and electromotive force. The superiority of the proposed LOA has been confirmed by comparing the performances between the proposed and conventional LOA. [ABSTRACT FROM AUTHOR]

The three-phase flux reversal machine (FRM) is a doubly-salient stator-permanent magnet machine with flux linkage reversal in the stator three-phase concentrated windings. It can operate in both motoring and generating modes. In this paper, we identify stator/rotor geometrical design variables that influence the cogging, interaction torques, and winding flux linkage using a two-dimensional finite-element method and the flux-magnetomotive force diagram technique. Also, the novel design to improve the performance of the FRM is studied both theoretically and experimentally. [ABSTRACT FROM AUTHOR]