Seung-Chan Park

Novel topology of unequal air gap in a single-phase brushless DC motor

Most single-phase brushless DC (BLDC) motors have unequal air gaps to eliminate the dead point where the developed torque value is zero. These unequal air gaps deteriorate the motor characteristics in cogging torque. Thus in this paper a new topology of the unequal air gaps is proposed to solve this problem. As a result, it is proved by the finite element analysis and experimental results that the proposed air gap topology is very effective in reducing the cogging torque.

Design of single-sided linear induction motor using the finite element method and SUMT

This paper describes the optimization of design variables of SLIM using finite element method and SUMT sequential unconstrained minimization technique). Thrust is taken as objective function in order to maximize thrust under constant current drive, and seven independent design variables and nine constraints are chosen. As the result, g/r and dal/T of good criteria in SLIM design are determined.

Characterization of a single-phase induction motor due to the effect of slot opening

This work investigates the effect of the slot opening on the torque and efficiency of a single-phase induction motor. The time-stepping finite element method is used to solve the electromagnetic coupled field in a single-phase induction motor, and then, the Maxwell stress tensor is used to investigate the mechanism of torque production and, eventually, to improve the efficiency. It shows that torque is produced in the vicinity of the slot opening as the rotating magnetic field revolves. It also shows that double layer slots, which have the main and auxiliary windings together, produce a significant amount of negative torque. This research designs the slots of the stator by controlling the slot opening as well as by appropriately introducing slot closure in such a way as to minimize negative torque so that it increases the efficiency of a single-phase induction motor.

Prediction of the electromechanical faults in a single phase squirrel cage induction motor

In this paper, we characterizes how broken rotor bars and rotor eccentricity affect the electromechanical parameters such as input current, magnetic force and vibration of a rotor in order to effectively diagnose the faults of a single phase squirrel cage induction motor.

Analysis of exterior-rotor BLDC motor considering the eddy current effect in the rotor steel shell

This paper describes the effect of eddy currents generated in the rotor steel shell of an exterior-rotor type permanent magnet brushless DC motor of which the rotor is revolving at a high speed. A two dimensional time-stepped finite element method is used to analyze the electromagnetic field and compute motor performance. The conductivity of the rotor steel shell is modified to consider the transverse edge effect. As a result, the effect of eddy currents is shown by comparing the analysis results between when the proposed method is used and when the method it is not.

Forward converter analysis by the method of coupling electromagnetic field with hysteresis and circuit equations

This paper presents a new method to analyze a forward converter. A high frequency transformer is coupled with the forward converter electric circuit and then the finite element analysis considering a hysteresis phenomenon of magnetic core is carried out when the primary or the reset winding conducts current. The analytical method is used to reduce the computation time when the reset winding circuit of the transformer turns off. As a result, the simulation results show a good agreement with experimental ones.

Influence on brushless DC motor performance due to unsymmetric magnetization distribution in permanent magnet

The real brushless DC motor has different permanent magnet pole magnetization levels due to the influence of the magnetizer geometry. Therefore, this paper discusses the influence of change in the magnetic parameter on brushless DC motor performances. As a result, the unbalanced magnetic force acting on the rotor, cogging torque and torque ripple are examined for spindle motor with unsymmetric magnetization distribution.

Analysis of axially non-uniform loss distribution in 3-phase induction motor considering skew effect

This paper discusses the phenomena of the axially nonuniform distribution of magnetic flux densities and losses in a three-phase squirrel cage induction motor of which the rotor bars are skewed. A 2-D complex finite element method, taking account of the effects of the skewed rotor bars, is utilized for the analysis of characteristics such as copper and iron losses and the loss distributions are examined. The summing up values of nonuniform losses resulted from the finite element analysis are compared with measurements.

Experimental investigations and simulations using FEM for the direct field oriented control of linear induction motor

In the vector control of a linear induction motor (LIM), it is difficult to calculate air gap field vector exactly because of end effects of LIM. So, this paper shows the longitudinal end effect and the transverse edge effect of LIM by experiment and determines the position of the sensor for detecting the air gap field vector. The direct vector control scheme is utilized to control the speed of LIM. As a result, simulation values by finite element analysis and experimental values of direct vector control using DSP are compared, and investigated.

Electromechanical analysis of a HDB spindle motor considering electromagnetics, thermal analysis, hydrodynamic bearing, and rotor dynamics

This research presents a finite element method to analyze the electromechanical coupled field of a hydrodynamic-bearing (HDB) spindle motor of computer hard disk drives considering electromagnetics, thermal analysis, HDB, and rotor dynamics to investigate the coupling effect. Simulation results are verified by the experiments, and it shows that it is essential to include the appropriate coupled fields to predict the performance accurately. This research also investigates the electromechanical characteristics of a HDB spindle motor due to the electromechanical coupling effect.