In-Soung Jung

Analysis of forces in a short primary type and a short secondary type permanent magnet linear synchronous motor

This paper presents the analysis of the static thrust, the detent force and the normal force of a permanent magnet linear synchronous motor (PMLSM) using the finite element method (FEM). The forces of a short primary type PMLSM and a short secondary type PMLSM are compared. To reduce the force ripple, the characteristics according to the width of the PM and the effect of the primary core shape were studied.

Performance analysis of skewed PM linear synchronous motor according to various design parameters

This paper deals with the performance variation of permanent magnet linear synchronous motor (PMLSM) with skewed magnet according to various design parameters. The detent force, thrust and normal force characteristics are analyzed according to the variation of air-gap length, thickness of PM, overhang length of PM, width of PM and length of skew. And, the optimal length of skew that the detent force is minimized is determined. For the analysis, a 3-D equivalent magnetic circuit network (EMCN) method is used. To verify the analysis results, the results are compared with the measured ones.

Development and Analysis of Interturn Short Fault Model of PMSMs With Series and Parallel Winding Connections

In this study, interturn short fault models of permanent magnet synchronous motors (PMSMs) employing series and parallel winding connections are developed using deformed flux models based on both fault winding flux information and inductance variations caused by cross flux linkages that depend on the distribution of same phase windings. As these models take into account fault winding within a three-phase winding dynamics analysis, they constitute fourth-order assessments. In the parallel-winding model, an additional dynamical analysis is used to describe variations in current distribution caused by the parallel connection between fault and healthy windings. Based on deformed flux modeling and positive sequence current assumptions, the proposed model is derived in both positive and negative sequence synchronous reference frames. A finite-element method-based simulation is applied to validate the proposed PMSM model.

Robust shape optimization of electromechanical devices

This paper presents the robust shape optimization of electromechanical devices considering the uncertainties of design variables based on numerical optimization technique and finite element method (FEM). In the formulation of robust optimization, the multiobjective function is composed of the mean and the standard deviation of original objective function, while the constraints are supplemented by adding a penalty term to the original constraints. The sequential quadratic programming (SQP) is applied to solve the robust optimization problem. The results of robust shape optimization considering manufacturing errors are compared with those of conventional shape optimization.

3-D analysis of permanent magnet linear synchronous motor with magnet arrangement using equivalent magnetic circuit network method

In this paper, the fields and forces of permanent magnet linear synchronous motors (PMLSM) with segmented or skewed magnet arrangement are analyzed according to length of segment or skew. And, the effects according to the lateral overhang of magnet are investigated. For the analysis, 3-dimensional equivalent magnetic circuit network (3-D EMCN) method is used. The analysis results are compared with the experimental ones and show a reasonable agreement.

Design and Analysis of Slotless Brushless DC Motor

This paper presents a design method for a small-sized slotless brushless dc motor. Distributed hexagonal windings are employed for achieving a high torque density and for ease of manufacture. Numerical approaches with an analytic model are used to analyze the magnetic and output characteristics of the motor. The proposed motor is manufactured, and the empirical results are compared with the results of the simulation.

Lateral characteristic analysis of PMLSM considering overhang effect by 3 dimensional equivalent magnetic circuit network method

This paper represents the lateral characteristics of a permanent magnet linear synchronous motor (PMLSM) according to changes of overhang length. In order to analyze the overhang effect of a PMLSM with large airgap and finite width considering lateral displacement, a new 3-dimensional equivalent magnetic circuit network method (3-D EMCN) taking into account movement of the secondary in the lateral direction is introduced, which supplements the magnetic equivalent circuit by using a numerical technique. The 3-D EMCN can consider secondary movement without remeshing the elements because it uses the initial mesh continuously. The authors analyzed the characteristics for three overhang-type cases which must be problems in 3-D. The results are compared with experimental data and show reasonable agreement.

Dynamic Analysis Of A Reciprocating Linear Actuator For Gas Compression Using Finite Element Method

This paper presents the dynamic analysis of a reciprocating actuation system based on moving magnet actuator for gas compression. For the analysis of the linear actuator, an axisymmetric finite element method (FEM) considering the saturation effect of the magnetic material is used, and electrical circuit equation, mechanical dynamic equation and pressure dynamics are coupled. In the FE analysis, we adopt a moving line technique to save computation time and to perform the process efficiently. The pressure dynamics of the gas in the compressor is modeled by using the law of thermodynamics. The analysis results compare fairly well with experimental ones.

Start-Up Current Control Method for Three-Phase PWM Rectifiers with a Low Initial DC-Link Voltage

When a PWM rectifier has a low DC-link voltage during startup, the output voltage vector cannot be high enough to regulate the input current. This lack of a PWM rectifier output voltage vector can cause an unregulated inrush current when the rectifier operation starts. This paper presents a PWM rectifier start-up current control algorithm for when it starts operation with a lower DC-link voltage than unloaded condition case. To avoid the unregulated inrush current caused by a lack of DC-link voltage, the proposed control scheme regulates the one phase current with one switch chopping and it generates the current command considering the uncontrolled current magnitude information, which is calculated in advance. Simulation and experiment results support the validity of the proposed method.

Robust DC-link voltage control scheme for photovoltaic power generation system PCS

A power conversion system (PCS) for photovoltaic power generation system is composed of the DC/DC converter and the DC/AC inverter. To maximize power generation, DC/DC converter operated with MPPT (Maximum Power Point Tracking) algorithm and the PCS has been developed by the method of transformer tab change. DC/AC inverter controls DC-link voltage and grid current. But, single phase grid has 120Hz (Grid voltage frequency is 60Hz.) power ripple which arise DC-link voltage ripple. This paper presents a robust DC-link voltage control scheme. The control scheme utilizes a widow averaged DC-link voltage as a feedback signal. Experiment performed with 3kW PCS and the results support the validity of the control scheme.