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This article introduces a single phase flux-reversal machine (FRM) and presents the design method to improve its starting torque. The effects of the design parameters on the characteristic and starting torque are analyzed by the finite element method. The design variables considered are tapered airgap, stepped airgap, slotted teeth, and asymmetric PM width. As a result, we can find the best model in producing starting torque of a single phase 2/3 FRM. [ABSTRACT FROM AUTHOR]

The large demagnetizing currents in brushless dc (BLdc) motor are generated by the short-circuited stator windings and the fault of a drive circuit. So, irreversible magnet demagnetization occurs due to the external demagnetizing field by these currents. In this paper, we deal with the effect of design variables on irreversible magnet demagnetization in BLdc motor through the modeling approach using a two-dimensional finite-element method (2D FEM). The nonlinear analysis of a permanent magnet is added to 2D FEM to consider irreversible demagnetization. As a result, it is shown that 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. [ABSTRACT FROM AUTHOR]

Flux-reversal machine (FRM) is a 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. In this paper, a design technique to improve the performance of FRM is proposed. The proposed techniques have a stator winding and a magnet arrangement method. The stator and rotor shapes of concave-type and a flux barrier are also proposed. According to the experimental results, it is shown that the proposed FRM has improved the performance. [ABSTRACT FROM AUTHOR]

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]

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]

This paper proposes a fuzzy speed tracking controller and a fuzzy rotor angular acceleration observer for a surface-mounted permanent magnet synchronous motor (SPMSM) based on the Takagi-Sugeno (T-S) fuzzy model. The proposed observer-based controller is robust to load torque variations since it utilizes rotor angular acceleration information instead of the load torque value. Linear matrix inequality (LMI) sufficient conditions are given to compute the gain matrices of the speed tracking controller and the observer. In addition, it is mathematically verified that the proposed observer-based control system is asymptotically stable. Simulation and experimental results are presented to confirm that the proposed control algorithm assures a better transient behavior and less sensitivity under model parameter variations than the conventional PI control method. [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]

This paper presents a nonlinear sliding mode control (SMC) scheme with a variable damping ratio for interior permanent magnet synchronous motors (IPMSMs). First, a nonlinear sliding surface whose parameters change continuously with time is designed. Actually, the proposed SMC has the ability to reduce the settling time without an overshoot by giving a low damping ratio at the initial time and a high damping ratio as the output reaches the desired setpoint. At the same time, it enables a fast convergence in finite time and eliminates the singularity problem with the upper bound of an uncertain term, which cannot be measured in practice, by using a simple adaptation law. To improve the efficiency of a system in the constant torque region, the control system incorporates the maximum torque per ampere (MTPA) algorithm. The stability of the nonlinear sliding surface is guaranteed by Lyapunov stability theory. Moreover, a simple sliding mode observer is used to estimate the load torque and system uncertainties. The effectiveness of the proposed nonlinear SMC scheme is verified using comparative experimental results of the linear SMC scheme when the speed reference and load torque change under system uncertainties. From these experimental results, the proposed nonlinear SMC method reveals a faster transient response, smaller steady-state speed error, and less sensitivity to system uncertainties than the linear SMC method. [ABSTRACT FROM AUTHOR]

This paper proposes an online gain tuning algorithm for a robust sliding mode speed controller of surface-mounted permanent magnet synchronous motor (SPMSM) drives. The proposed controller is constructed by a fuzzy neural network control (FNNC) term and a sliding mode control (SMC) term. Based on a fuzzy neural network, the first term is designed to approximate the nonlinear factors while the second term is used to stabilize the system dynamics by employing an online tuning rule. Therefore, unlike conventional speed controllers, the proposed control scheme does not require any knowledge of the system parameters. As a result, it is very robust to system parameter variations. The stability evaluation of the proposed control system is fully described based on the Lyapunov theory and related lemmas. For comparison purposes, a conventional sliding mode control (SMC) scheme is also tested under the same conditions as the proposed control method. It can be seen from the experimental results that the proposed SMC scheme exhibits better control performance (i.e., faster and more robust dynamic behavior, and a smaller steady-state error) than the conventional SMC method. [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]