Se-Hyun Rhyu

Newly Structured Double Excited Two-Degree-of-Freedom Motor for Security Camera

This paper proposes a newly structured double excited two-degree-of-freedom (DOF) motor with tilt/pan motion to use in a security camera. For applications in active vision, a tilt/pan mechanism should be accurate, fast, small, inexpensive, and have low power requirements. We have designed a new type of motor meeting these requirements, which incorporates both tilt and pan into a single, two-degree-of-freedom device. The focus of the research is to design the improved 2-DOF motor which can eliminate the drawbacks as manufacturing, complicated control, and difficulty in lamination in conventional model. Additionally, to effectively improve the torque characteristic, the main pole pitch and the auxiliary pole shape are determined by the pan motion and the tilt motion, respectively. The validity of proposed structure will be shown in the computer simulation of the newly structured double excited 2-DOF motor for security cameras.

Hysteresis Torque Analysis of Permanent Magnet Motors Using Preisach Model

This paper deals with the computation of hysteresis torque in electric machines by means of the hysteresis Preisach model in finite element methods. In most cases, core loss is divided into hysteresis loss and eddy current loss. However, this component experiences mostly hysteresis loss at low speed. This hysteresis loss acts on the braking torque with cogging in the permanent magnet motor. In order to analyze the hysteresis torque, the Preisach hysteresis model is applied to the post-processor using the finite element method. In this method, computation errors can occur more than with the existing analysis method, but this method can compute hysteresis torque without complex nonlinear analysis. The hysteresis torque that is bearing friction is compared with test results. Both simulations and experiments are performed to verify the validity of the proposed method.

Three dimensional characteristic analysis of micro BLDC motor according to slotless winding shape

A distributed current model of various shapes with a finite length in axial direction by Fast Fourier Transform is developed and a new calculation numerical method based on the model is presented to analyze the performance due to winding shape in the SLBLDC motor.

Development and control of BLDC Motor using fuzzy models

This paper presents the design and control of a small brushless DC (BLDC) motor. In order to control the developed BLDC motor, an adaptive fuzzy control (AFC) scheme via parallel distributed compensation (PDC) is developed for the multi- input/multi-output plant model represented by the Takagi-Sugeno (TS) model. The alternative AFC scheme is proposed to provide asymptotic tracking of a reference signal for systems with uncertain or slowly time-varying parameters. The developed control law and adaptive law guarantee the boundedness of all signals in the closed-loop system. In addition, the plant state tracks the state of the reference model asymptotically with time for any bounded reference input signal. The suggested design technique is applied to velocity control of a developed small BLDC motor.

Design of axial flux permanent magnet brushless DC motor for robot joint module

Joint modules for robot system require actuators with high torque and slim topology for easy loading. Axial flux permanent magnet (AFPM) machine with high torque density is proposed and manufactured. Magnetic design is executed by numerical analysis and analytic model. Manufactured motor is tested and verified characteristics. Through the comparison with radial flux BLDC motor, we confirm the output performance is adequate for robot joint module.

Exciter Design and Characteristic Analysis of a Written-Pole Motor

This paper deals with a design of the exciter which is a self-magnetizing apparatus of a written-pole motor (WPM). For a given rotor of 0.2 hp WPM, the pole shape and winding specifications of the exciter which is driven by a general voltage are optimally designed. Then, with consideration of hysteresis characteristics of a magnetic layer, the magnetization waveform is investigated with Preisach model. To validate the results calculated in design and analysis, the experimental test is carried out and comprehensive test results are suggested.

A Study on the Novel Coefficient Modeling for a Skewed Permanent Magnet and Overhang Structure for Optimal Design of Brushless DC Motor

A novel coefficient modeling technique, using a coefficient estimation method, is introduced for a brushless DC (BLDC) motor with a skewed permanent magnet and overhang structure. To construct the novel coefficient, the 3-D FEM and a design of experiment (DOE) are utilized along with the moving least square method (MLSM). Also, to verify the accuracy of the novel coefficient modeling, the conventional coefficient modeling using LSM is constructed and compared. Then the novel coefficient is combined with an approximate model constructed by 2-D FEM for use with an optimal design algorithm. For the searching process to obtain an optimal point, the genetic algorithm (GA) is used. Three-dimensional FEM simulation is used to verify the accuracy of the novel coefficient for the optimal design.

Novel Hybrid Radial and Axial Flux Permanent-Magnet Machine Using Integrated Windings for High-Power Density

This paper presents a design and analysis method for a novel hybrid flux permanent-magnet (PM) machine for a high-power density. By combining radial and axial flux machines with integrated windings, the air-gap flux density is increased, and an overhang structure of the PM and additional magnetic cores are applied to increase the power density. For the analysis and design of the proposed motor, a time-consuming 3-D finite-element analysis (FEA) is required owing to its unique structure. To address this problem, a correct and rapid novel analysis method is proposed using an equivalent 2-D conversion method. The accuracy of the proposed analysis method and the usefulness of the proposed motor are confirmed via the 3-D FEA and experimental results.

Design of the Rotary Magnetic Position Sensor with the Sinusoidally Magnetized Permanent Magnet

This paper proposes a rotary magnetic position sensor (RMPS) which has a sinusoidally magnetized permanent magnet (PM) with a small number of poles. To make the sinusoidal magnetic flux density distribution from the PM, a magnetizing fixture is designed by adjusting its pole shape. The magnetization process is analyzed using the Preisach model and two-dimensional finite-element method (FEM). The simulation result of the magnetization is compared with the experimental one. Also, the ability of position detection from two sinusoidal signals is shown

A Novel Cogging Torque Reduction Method for Single-Phase Brushless DC Motor

Single-phase, brushless DC (BLDC) motors have unequal air-gaps to eliminate the dead-point where the developed torque is zero. Unfortunately, these unequal air-gaps can deteriorate the motor characteristics in the cogging torque. This paper proposes a novel design for a single-phase BLDC motor with an asymmetric notch to solve this problem. In the design method, the asymmetric notches were placed on the stator pole face, which affects the change in permanent magnet shape or the residual flux density of the permanent magnet. Parametric analysis was performed to determine the optimal size and position of the asymmetric notch to reduce the cogging torque. Finite element analysis (FEA) was used to calculate the cogging torque. A more than 28% lower cogging torque compared to the initial model with no notch was achieved.