Tae Heoung Kim

A study of the design for the flux reversal machine

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.

Geometric and electrical optimization design of SR motor based on progressive quadratic response surface method

This paper presents an approximate optimization that is able to determine optimal geometric and electrical design variables of switched reluctance motor. In order to reduce torque ripple that causes noise and vibration, the approximate optimum design has been investigated by means of combining a progressive quadratic response surface method (PQRSM) and a time-stepping finite element method considering drive circuit. The PQRSM is more effective than conjugate gradient method in torque ripple minimization.

A Study on the Design of an Inset-Permanent-Magnet-Type Flux-Reversal Machine

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.

Development of a flux concentration-type linear oscillatory actuator

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.

Comparison of the iron loss of a flux-reversal machine under four different PWM modes

Flux-reversal machine (FRM) is a new brushless doubly salient permanent magnet machine. It can be driven by 120deg square wave voltage and use PWM pulse patterns in two-phase feeding scheme to control the speed of the machine. This paper introduces four PWM modes used FRM control system, and analyzes the effects of four different PWM modes on the iron loss using a two dimensional time-stepped voltage source finite-element method (FEM). The iron loss is calculated from the time variation of the magnetic field distribution

The finite element analysis of switched reluctance motor considering asymmetric bridge converter and DC link voltage ripple

This paper presents a characteristic analysis of switched reluctance motor (SRM) considering hard chopping and dc link voltage ripple by using time-stepped voltage source finite element method in which the magnetic field is combined with drive circuit. We also examine the influence of freewheeling diodes and dc link voltage ripple on the performance of a SRM such as torque ripples and radial force on the surface of the teeth. The freewheeling diodes and dc link voltage ripples must be taken into account in predicting the performance of the SRM.

Finite-element analysis of brushless DC motor considering freewheeling diodes and DC link voltage ripple

This paper deals with the characteristic analysis of a brushless dc motor (BLDC) taking into consideration the freewheeling diodes and dc link voltage ripple using a time-stepped voltage source finite-element method. By comparing the experimental results, the authors show that the proposed computational method is useful for the analysis and design of a BLDC motor. They also examine the influence of freewheeling diodes and dc link voltage ripples on the performance of a BLDC motor such as torque ripples and radial force on the surface of the teeth.

A study on the irreversible magnet demagnetization in single-phase line-start permanent magnet motor

The large demagnetizing currents in a single-phase line-start permanent magnet motor are generated by a starting and locked rotor condition. Thus, irreversible magnet demagnetization occurs due to the external demagnetizing field by these currents. In this paper, we present the phenomenon of the irreversible magnet demagnetization using two-dimensional finite-element method (2-D FEM). The nonlinear analysis of a permanent magnet is added to 2-D FEM to consider irreversible demagnetization. As a result, design techniques which are effective in avoiding irreversible demagnetization are proposed.

Effect of design variables on irreversible permanent magnet demagnetization in flux-reversal machine

Research interest in the switched reluctance motor (SRM) has grown significantly in recent years because of their apparent advantages such as simple construction, fault tolerance and mechanical robustness. In this paper, we deal with the effect of design variables on irreversible magnet demagnetization in the FRM using two-dimensional finite-element method (2-D FEM). The nonlinear characteristic of the permanent magnet is considered as well as that of a magnetic core on each B-H curve. From the analysis results, the most important geometrical dimensions are suggested in terms of irreversible magnet demagnetization.

Influences of PWM mode on the performance of flux reversal machine

The flux reversal machine (FRM) is a new brushless doubly salient permanent-magnet machine. Its operation is similar to that of the brushless dc motor, so it can be driven by 120/spl deg/ square wave voltage and use pulsewidth modulation (PWM) pulse patterns in two-phase feeding scheme to control the speed. This paper introduces PWM modes used in FRM control system, and analyzes their different influences on the performances of the FRM using a time-stepped voltage source finite-element method. To prove the propriety of the proposed analysis method, digital signal processor (DSP) installed experimental devices are equipped and the experiment is performed.