Chang-Sung Jin

Influence of the Construction of Secondary Reaction Plate on the Transverse Edge Effect in Linear Induction Motor

In this paper, linear induction motor is analyzed by 3-D finite-element method (3-D FEM) to consider influence of construction of secondary reaction plate on the transverse edge effect. A effective 3-D analysis model for considering the transverse edge effect caused by the finite widths of the primary and the secondary is not only proposed, but also the simple method measuring the transverse edge effect by using the patterns of currents induced in the secondary reaction plate is proposed. With this effective analysis method, various models with overhang and cap have been analyzed to consider the relationship between the construction of secondary reaction plate and the transverse edge effect.

A Study on Improvement Magnetic Torque Characteristics of IPMSM for Direct Drive Washing Machine

This paper presents a research on magnetic torque improvement of interior permanent magnet synchronous motor (IPMSM) for a direct drive washing machine by considering various barrier shapes. For the direct drive of washing machine, the IPMSM must have high magnetic torque at low speed in the laundry mode. However, the magnetic torque of it is decreased and torque ripple is also increased at the same time, when current phase angle is increased. By using finite element analysis (FEA), several characteristics such as d-, q-axis inductance, back electromotive force (EMF), average torque, torque ripple, and cogging torque are presented. Besides, high-temperature demagnetization which can occur in manufacturing time is considered. Finally, the analysis results are compared with experimental results to verify the proposed design.

Inductance Calculation Method of Synchronous Reluctance Motor Including Iron Loss and Cross Magnetic Saturation

This paper presents the novel method inductance calculation of a synchronous reluctance motor (SynRM). Synchronous inductances (Ld and Lq) are exceedingly important factor of SynRM to drive. Because of self axis current as well as the other axis current, inductances of d-axis and q-axis of SynRM are varied. Using an equivalent circuit model for expressing d-axis and q-axis inductance variation, the authors elicit suitable equation considering iron loss and cross magnetic saturation. Parameters of motor to use calculation are gained by AC signal test.

Method of Current Compensation for Reducing Error of Holding Torque of Permanent-Magnet Spherical Wheel Motor

A permanent magnet spherical wheel motor, which consists of magnets on rotor and coils on spherical stator, is able to operate on 3-D space as using magnetic alignment torque generated from between coils and magnets. Especially the shaft can be tilted stably by optimized coil position on stator. Because, however, the spherical wheel motor has feature of 3-D structure as relative position between coils and magnets, stable holding torque for rotor position should be analyzed as function of the tilt degree of a shaft. The characteristic of stable holding torque can be changed nonlinearly by the alpha and beta degrees of a shaft. Therefore, when reference current is commanded at coils, the shaft cannot be tilted to the reference position exactly for the nonlinear characteristic. In this paper, for improving the nonlinear phenomenon of holding torque, the authors research and improve a current compensation function to increase stable operating range. Also, the compensation function was estimated by using torque ripple computed from torque simulation.

Proposal of Improved Winding Method for VR Resolver

The variable reluctance (VR) resolver is generally used instead of an optical encoder as a position sensor on motors for hybrid electric vehicles or electric vehicles owing to its reliability, low cost, and ease of installation. The commonly used conventional winding method for the VR resolver has disadvantages, such as complicated winding and unsuitability for mass production. This paper proposes an improved winding method that leads to simpler winding and better suitability for mass production than the conventional method. In this paper, through the design and finite element analysis for two types of output winding methods, the advantages and disadvantages of each method are presented, and the validity of the proposed winding method is verified. In addition, experiments with the VR resolver using the proposed winding method have been performed to verify its performance.

An Analytic Analysis of the Multi-Degree-of-Freedom Actuator

This paper discusses the analysis and simulation method and the test method for a two-degree-of-freedom (2-DOF) actuator torque. The previous studies on the analysis of 2-DOF motors tilting torque were carried out only by finite element method (FEM), not by analytic method. This paper describes the operating principles of and the processes of inducing a tilting torque and a holding torque both of which exist only in special purpose electric machines. This allowed us to establish a design process. By overcoming the limits of the 3-D FEM, this paper introduced the 2-D model analysis by considering a real coil shape. Finally, this paper manufactured and tested the 2-DOF actuator to verify the introduced analytic analysis method.

2D FE Analysis of hybrid stepping motor(HSM) using virtual magnetic barrier

In this paper, we describe the 2D finite element analysis of hybrid step motor (HSM) using virtual magnetic barrier.

Design and Analysis of a Regenerative Electromagnetic Brake

In this paper, a regenerative electromagnetic brake, which has the same structure as conventional electromagnetic brakes and the same principle as self-excited induction generators, is introduced, and a miniature model is designed. The most important part of the design stage is to choose proper equivalent circuit parameters for self-excitation within a given operating speed range. This paper describes a 3-D map, called a CN-map, that consists of the rotating speed, capacitance, and stator resistance to verify the possibility of self-excitation during the design stage. A miniature model is designed using the map, and the experimental results obtained with the miniature model confirm the feasibility of the design process.

Method for Analyzing Vibrations Due to Electromagnetic Force in Electric Motors

In this paper, a method for predicting vibrations due to an electromagnetic force from among the other types of vibrations that occur in an electric motor is proposed. Among electromagnetic forces, the forces applied in the radial direction were separated into their spatial and temporal harmonic components for developing the vibration-prediction method. Each separated radial force densities acts as a vibration source and generates vibrations combined with the mechanical characteristics of the motor. The separation of vibration sources makes it possible to predict the magnitude of the vibration velocity occurring in the motor. This enables optimal motor design considering vibration. To this end, a description explaining the characteristics of electromagnetic vibrations that occur in an eight-pole nine-slot permanent magnet synchronous motor has been provided in this paper as an example. In addition, the proposed method was verified by comparing the obtained vibration velocity with that obtained through electromagnetic-vibration coupled analysis.

Design of IPMSM to reduce cogging torque considering tapping the rotor and shape of barrier

Generally, cogging torque derives from motor using permanent magnet such as interior permanent magnet synchronous motor (IPMSM) and surface permanent magent synchronous motor (SPMSM). The cogging torque works for smoothness in rotation of the rotor, but it is a kind of root cause mechanical vibration and acoustic noise. Consequently, cogging torque must be reduced by all manner of means. There are various methods to reduce the cogging torque, but this paper deals with two ways in the IPMSM. One is tapping the rotor and the other is design of barrier shape. Besides, this paper proposes best design of the IPMSM to reduce cogging torque, and the analysis of cogging torque by using FEM is compared with experimental results to verify.