Heung-Kyo Shin

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

A study on irreversible permanent magnet demagnetization in flux-reversal machines

Flux-reversal machine (FRM) is a new doubly-salient stator-permanent magnet (PM) machine with flux linkage reversal in the stator concentrated windings. The simple structure makes it cost effective and suitable for mass production. Also, the FRM has permanent magnets parallel to the stator magnet flux lines and thus is much more difficult to demagnetize. However, in actual application fields such as factory automation and a home appliance, the FRMs adopt permanent magnets with a low intrinsic coercivity and a narrow thickness. In this paper, we especially concentrate on the irreversible demagnetization characteristic of the permanent magnet. To analyze the characteristics of the FRM, a two-dimensional finite-element method (2D FEM) considering the nonlinear analysis of the permanent magnet is used.

The optimum design of interior permanent magnet synchronous motor for the vibration reduction

In this paper, for the high efficiency and vibration reduction of IPMSM(Interior Permanent Magnet Synchronous Motor), Design of the rotor and stator shapes was carried out. The validity of the study was verified through the efficiency and the vibration characteristics comparison with the experiment ones.

A study on the power LEDs drive circuit design with asymmetrical half-bridge resonant converter

Recently white light-emitting diode (LED) has very attractive attention as a backlight for LCD display and lighting sources. The series-parallel connected LEDs must be driven from a current source because their forward voltage varies, as a result the brightness changes depending on the forward current increases. In this paper, the suitable LED driving system is proposed for LED lighting sources. The driving system is consist of high power factor correction circuit and isolated constant current DC-DC converter with high efficiency.

The estimation of torque ripple according to parameters considered with time varying in voltage equation

Torque calculation using the d-q axis has the advantage of faster execution time; however, the torque ripple cannot be considered in torque calculation using the d-q axis equivalent circuit because the time-dependent component is removed. In this work, with d-q transformation, the characteristics of some parameters were identified. These characteristics were considered for representing torque ripple. Calculation with d-q axis transformation and finite-element analysis (FEA) was performed, and the results obtained using these two approaches were compared. It was verified that the calculated torque can be expressed with ripple.

Study on the improvement of power utilization efficiency of industrial consumers using small scale microgrid

In this study, we collected actual demand power data for small and medium sized industrial customers(SMEs) with high power consumption. Based on these collected data, a small microgrid system including a photovoltaic system and a battery system is constructed at a factory in a customer to improve power consumption efficiency. This system also includes a peak demand power controller to reduce the peak power, and a method for reducing the maximum demand power and the amount of power consumption is proposed in this study.

Analysis of IPMSM temperature characteristics based on stator parameters

In this paper, the effect of changes in the width of teeth and yoke on stator temperature characteristics was analyzed. An initial model of fill factor 45% was produced. The validity of the temperature analysis using the thermal equivalent circuit method was experimentally verified. A basic model was selected as the initial model. Also, a temperature characteristic analysis was performed for various widths of stator teeth and yoke, and the effects were analyzed.

The shape design of IPMSM for the efficiency improvement

The operating characteristics was calculated through a finite element analysis (Maxwell). Iron loss and copper loss was estimated through the calculation and the mechanical loss is the result of the experiment for the calculation of the efficiency. In this paper, the shape design of IPMSM(Interior Permanent Magnet Synchronous Motor) for improving the efficiency was carried out. As a result, Back EMF of the improved model is increased. So, copper loss was reduced comparing to the same output. Through the shape design for avoidance of the magnetic saturation, iron loss was reduced to improve efficiency.