Kyeong-Ho Choi

Support Vector Machine Based Bearing Fault Diagnosis for Induction Motors Using Vibration Signals

In this paper, we propose a new method for detecting bearing faults using vibration signals. The proposed method is based on support vector machines (SVMs), which treat the harmonics of fault-related frequencies from vibration signals as fault indices. Using SVMs, the cross-validations are used for a training process, and a two-stage classification process is used for detecting bearing faults and their status. The proposed approach is applied to outer-race bearing fault detection in threephase squirrel-cage induction motors. The experimental results show that the proposed method can effectively identify the bearing faults and their status, hence improving the accuracy of fault diagnosis.

A High Performance Position Control System of Switched Reluctance Motor

This paper presents a high performance position control system of switched reluctance motor (SRM). Recently, the variable-speed and servo drive systems have been developed because of industrial automation. One of the possible electrical machines in modern servo drive system is the SRM. The control of SRM drive system requires several controllers including switching angle and current controller. Generally switching angle controller is used to increase the drive efficiency, while current controller is adapted to control the electromagnetic torque and to prohibit the over-current. Due to the development of high performance micro-controllers, such as TMS320F2812 Digital Signal Processor (DSP), many complicated control algorithms can be realized. In this paper, a position control system of SRM is suggested to verify the possibility of SRM in servo drive application. A prototype 1-hp SRM is used to prove the validity of this algorithm.

A position sensorless control system of SRM over wide speed range

This paper presents a position sensorless control system of SRM over wide speed range. The rotor position estimation of the SRM is somewhat difficult because of its highly nonlinear characteristics. In this paper, the magnetizing curve of prototype 1-hp SRM is obtained from locked rotor test and complicated data patters are trained using neural network. To estimate more accurate rotor position, current-flux-rotor position lookup table over wide operating rage is generated using trained neural network. Experimental result for a 1-hp SRM over 16:1 speed control range is presented for the verification of the proposed sensorless control algorithm.

An modular-type axial-flux permanent magnet synchronous generator for gearless wind power systems

In this paper, the design and characteristics analysis of dual axial-flux permanent magnet synchronous generator, 60 |Hz|, 10 |kVA|, 300 |rpm| for wind energy system application are presented. The dual axial-flux generator has inherently desirable features such as; (1) by employing two air gaps, the rotor-stator attractive forces are balanced and no net axial or thrust load is applied on the generator bearings; (2) heat produced by the stator windings appears on the outside of the generator, and it is easy to remove the heat. This paper describes characteristics of a dual axial-flux type permanent-magnet generator for a gearless wind energy system, which aims to satisfy the variable operating conditions. Finite-element method (FEM) is applied to analyze generator performance at variable loads. The results of FE analysis show this generator has a promising future for wind turbine applications.

An optimal efficiency control of reluctance synchronous motor using neural network with direct torque control

This paper presents an implementation of efficiency optimization of reluctance synchronous motor (RSM) using a neural network (NN) with an direct torque control (DTC). The equipment circuit in RSM, which consider with iron losses is theoretically analyzed and the optimal current ration between torque current and exiting current analytically derived. For RSM, torque dynamics can be maintained even with controlling the flux level because a torque is directly proportional to the stator current unlike induction motor. In order to drive RSM at maximum efficiency and good dynamics response, the NN is used. The experimental results are presented to validate the applicability of the proposed method. The developed control system show high efficiency and good dynamic response features with 1.0 [kW] RSM having 2.57 ratio of d/q.

A Method for Dynamic Simulation and Detection of Air-gap Eccentricity in Induction Motors by Measuring Flux Density

This paper presents results of the finite-element (FE) analysis and experiment of air-gap flux variation in induction motor when rotor eccentricity conditions occur. An accurate modeling and analysis of rotor vibration in the motor are made using air-gap flux simulation, and search coils are used for measuring the actual magnetic flux. The simulated vibration system with 380 [V], 5 [HP], 1,742 [rpm] induction motor is built, and search coils are designed and inserted under the stator wedge of the motor. FE analysis results are compared with experiment test results

Analysis of a three phase induction motor under eccentricity condition

This paper presents results of the finite-element (FE) analysis of air-gap flux variation in an induction motor when the rotor vibrates due to its eccentricity. An accurate modeling and analysis of rotor vibration in the machine are made using air-gap flux simulation, and search coils are used for measuring the actual air-gap flux. The simulation was done for the induction motor with 380 [V], 5 [HP], 4P, 1,742 [rpm] ratings using the commercial FE analysis tool. The simulation and experiment results can be useful for on-line vibration monitoring of an induction motor.

A High Performance Motion Control System of Switched Reluctance Motor

This paper presents a high performance motion control system of Switched Reluctance Motor (SRM). Recently, the variable-speed and servo drive systems have been developed because of industrial automation. One of the possible electrical machines in modern servo drive system is the SRM. The control of SRM drive system requires several controllers including switching angle and current controller. Generally switching angle controller is used to increase the drive efficiency, while current controller is adapted to control the electromagnetic torque and to prohibit the over-current. Due to the development of high performance micro-controllers, such as TMS320F2812 Digital Signal Processor (DSP), many complicated control algorithms can be realized. In this paper, a motion control system of SRM is suggested to verify the possibility of SRM in servo drive application. A prototype 1-hp SRM is used to prove the validity of this algorithm.

A study on dynamic simulation and detection of air-gap eccentricity in induction machines

This paper presents results of the finite-element (FE) analysis of air-gap flux variation in an induction motor when the rotor vibrates due to its eccentricity. An accurate modeling and analysis of rotor vibration in the machine are made using air-gap flux simulation, and search coils are used for measuring the actual air-gap flux. The simulation was done for the induction motor with 380 [V], 5 [HP], 4P, 1,742 [rpm] ratings using the commercial FE analysis tool. The simulation results can be useful for on-line vibration monitoring of an induction motor.