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For on-line partial discharge (PD) monitoring of rotating machines, a novel sensor is proposed, which can be installed on the power lead inside the terminal box of the machine. The sensor has been designed to have high capacitance, and minimal reflection of measured pulses. As a sensitivity of the sensor, transfer impedance Zt has been measured and compared to conventional coupler-type sensors. A simple method is presented for measuring Zt of coupler sensors, using a vector network analyzer and a practical lead-cable of rotating machine. Through this method, it became possible to measure the Zt of coupler sensors including the installation environment of them. The Zt of the proposed sensor is higher than that of same sized other conventional couplers at frequencies between 30 and 92 MHz. Another sensitivity test has been performed using a PD calibrator as a test pulse source. The proposed sensor has higher measured peak voltage than the conventional coupler type sensors when the same charges were input.

A novel haze technique for analyzing point-defect distribution in Czochralski Si (CZ-Si) wafers without intentional contamination by transition metals was proposed. Based on the background haze in high-temperature oxidation, a three-step oxidation process including two-step low-temperature precipitation and a single-step high-temperature wet oxidation process was designed. After the newly designed heat processing and preferential etching, surface haze was formed selectively on the interstitial-dominant region of the wafer. Through electron microscopy analysis, surface defects decorated with Ni were observed, which suggested that the surface accumulation of non-gettered Ni adsorbed from the furnace causes surface haze on the interstitial-dominated region. The widths of the hazes could be optimized by adjusting the processing times of the first two steps, which affected the Ni gettering ability in the vacancy-dominated regions of the wafers. Additionally, the second stage at 1000 °C was associated with precipitate growth, as well as with haze formation.

Herein, the effect of pre-annealing on oxygen precipitation in a silicon P/P-epitaxial wafer was investigated using an experimental approach. Czochralski-grown silicon wafers were annealed at 800–900 °C to enhance their bulk micro defects (BMDs), before the epitaxial growth process. The effect of the pre-annealing temperature on oxygen precipitation was greater than that of the pre-annealing time, and the effect of pre-annealing temperature varied between polished and epitaxial wafers. Regarding pre-annealed epitaxial wafers that were annealed at low temperatures, the pre-annealing time also had as large an effect on BMD formation as the pre-annealing temperature. These experimental results were used to determine the optimal pre-annealing temperature for enhancing oxygen precipitation in epitaxial wafers. The experimental results regarding the optimal conditions were consistent with prior hypotheses. Crystal originated particles (COPs) and COP-free crystals exhibited their highest BMD density values at similar pre-annealing temperatures.

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.

Brushless Direct Current(BLDC) Motor is essential to measure a rotor position because of that this motor type needs to synchronize the rotor`s position and changeover phase current instead of a brush and commutator used on the existing dc motor. Recently, many researches have studied on sensorless control drive for BLDC motor. The conventional control methods are a compensation value dq, Kalman filter, Fuzzy logic, Neurons neural network, and the like. These methods has difficulties of detecting BEMF accurately at low speed because of low BEMF voltage and switching noise. And also, the operation is long and complex. So, it is required a high-performance microprocessor. Therefore, it is not suitable for a small BLDC motor sensorless drive. This paper presents control methods suitable for economic small BLDC motor sensorless drive which are an improved design of the BEMF detection circuit, simplifying a complex algorithm and computation time reduction. The improved motor sensorless drive is verified stability and validity through being designed, manufactured and analyzed.

This paper proposes a new diagnosis algorithm to detect broken rotor bars (BRBs) faults in induction motors. The proposed algorithm is composed of a frequency signal dimension order (FSDO) estimator and a fault decision module. The FSDO estimator finds a number of fault-related frequencies in the stator current signature. In the fault decision module, the fault diagnostic index from the FSDO estimator is used depending on the load conditions of the induction motors. Experimental results obtained in a 75 kW three-phase squirrel-cage induction motor show that the proposed diagnosis algorithm is capable of detecting BRB faults with an accuracy that is superior to a zoom multiple signal classification (ZMUSIC) and a zoom estimation of signal parameters via rotational invariance techniques (ZESPRIT).

Partial discharge (PD) has been identified as one the main root causes of stator winding failures in low voltage (LV) random wound AC motors fed by PWM inverters. To ensure that PWM inverter-fed motors (type I) are PD-free under impulse excitation, the test procedure for acceptance testing of the stator insulation system was developed (IEC TS 60034-18-41). Although many successful cases of applying the TS have been reported, some concerns regarding the test procedure have been raised, and the TS is currently under revision. It is implied in the TS that the rotor has no impact on the surge PD test result, and testing is often performed without the rotor; however, it was observed that the surge PD test results can change with rotor insertion for some types of machines. The off-line surge PD test must be performed under conditions representative of actual operation (with the motor assembled) to guarantee absence of PD. Therefore, it is important to investigate the influence of the rotor, and to incorporate the findings in the test procedure, if necessary. In this paper, the influence of the rotor on the off-line surge PD test is investigated for AC machines, and it is shown that the PD inception voltage (PDIV) can change significantly depending on the rotor design. A detailed analysis is given along with experimental test results on a number of induction and permanent magnet (PM) synchronous motor samples with different rotor designs. Based on the observations made in this work, suggestions on the TS that can provide surge PDIV measurements under conditions closer to that of the actual operation with the rotor are given to help reduce the likelihood of false indications with off-line surge PD testing.

The diagnosis of motor failures using an on-line method has been the aim of many researchers and studies. Several spectral analysis techniques have been developed and are used to facilitate on-line diagnosis methods in industry. This paper discusses the first application of a motor flux spectral analysis to the identification of broken rotor bar (BRB) faults in induction motors using a multiple signal classification (MUSIC) technique as an on-line diagnosis method. The proposed method measures the leakage flux in the radial direction using a radial flux sensor which is designed as a search coil and is installed between stator slots. The MUSIC technique, which requires fewer number of data samples and has a higher detection accuracy than the traditional fast Fourier transform (FFT) method, then calculates the motor load condition and extracts any abnormal signals related to motor failures in order to identify BRB faults. Experimental results clearly demonstrate that the proposed method is a promising candidate for an on-line diagnosis method to detect motor failures.

Internal pressure of vacuum interrupter (VI) is one of the most important parameters in VI operation and may increase due to the outgassing from the materials inside VI or gas permeation through metal flange or ceramic vessel. The increase of the pressure above a certain level leads to the failures of switching or insulation. Therefore, an effective pressure check of VI is essential and an analysis of partial discharge (PD) characteristics is an effective monitoring method to identify the degree of the internal pressure of VI. This paper introduces a research work on monitoring the internal pressure of VI by analyzing PDs which were measured using a capacitive PD coupler. The authors have developed cost effective capacitive coupler based on the ceramic material that has an excellent insulation properties and the main component of the capacitive coupler is made by SrTiO3. Detectable internal pressure range and distinguishability of the internal pressure of VI were investigated. From the PD tests results, the internal pressure range, from 10 -2 torr to 500 torr, can be monitored by PD measurements using the capacitive coupler and PD inception voltage (PDIV) follows the Paschen's law. In addition, rise time of PD pulse at 13.2kV decreases with the increase of the internal pressure of VI.

In this study, we developed a method for evaluating the gettering efficiencies between the gettering sites in p well region and the internal gettering sites in the wafer after p-well formation using implantation and evaluated the efficiencies of copper and nickel gettering. The bulk microdefects (BMDs) introduced by heat treatment caused gettering of copper and nickel, which were introduced by intentional spiking of the device with 65 Cu and 60 Ni solutions. For evaluating the gettering efficiencies, we performed trace analyses using 65 Cu and 60 Ni stable isotopes. This study demonstrates the phenomenon of competitive gettering between the p-well region and the internal gettering sites in the wafer. Moreover, the fact that silicon-integrated circuit devices act as efficient metal traps should be taken into account when evaluating the actual gettering ability of silicon wafers. The gettering efficiencies evaluated for the wafers in the no-implantation and boron-implantation groups. The gettering efficiencies of the wafers in the no-implantation and boron-implantation groups are in the range 99.78–100% and 68–100%, respectively. This implies that the gettering efficiency of the wafers is sufficiently high when the competitive gettering between the device and the internal gettering sites is not considered. However, in the competitive-gettering model, 100% gettering is observed only in the p − /p + epitaxial wafer. The results of the present study indicate that p − /p + epitaxial wafers have better competitive gettering efficiency than normal polished wafer or rapid thermal annealing (RTA) wafer designed with proximity gettering ability.

The present study describes the considerations on the long-term reliability of the on-line partial discharge (PD) ceramic sensor for thermal power generators. Voltage acceleration aging tests were carried out under continuous and impulsive thermal aging at more than 100℃, considering the practical service environment. Experimental results show that the sensors have a life that could last for more than 100 years, excellent dielectric characteristics, and insulation strength. In addition, the ceramic on-line PD sensors were installed in a thermal power generator in Korea for demonstration. The results of the PD calibration and test voltage application prove that the on-line ceramic sensors have satisfactory performances for on-line PD measurement.

In this paper, a method for detecting broken rotor bar and stator winding fault in a low voltage squirrel-case induction motor using an air-gap flux variation analysis is proposed to develop a simple and low cost diagnosis technique. To measure the leakage flux in radial direction, a radial flux sensor is designed as a search coil and installed between stator slots. The proposed method is able to identify two kinds of motor faults by calculating load condition of motors and monitoring abnormal signals those are related with motor faults. Experimental results obtained on 7.5kW three-phase squirrel-cage induction motors are discussed to verify the performance of the proposed method. Induction motors are widely used electrical machines, for their simplicity of construction and reliability. However, they are subject to failures those may be due to production processes or operating conditions. These unexpected failures cause severe damages in industrial processes. Motor reliability working group have announced that percentage failure in induction motors is typically: stator related (38%), rotor related (10%), bearing related (40%), and others (12%) (1). Recently, many researchers have studied diagnosis techniques to predict motor failures at their incipient stage and decide proper replacement time of induction motors. Most of them are focused on the failure prediction method using abnormal signals of failure patterns of motors from current and vibration signals (2)- (4). Although vibration and current analysis are the most powerful methods for diagnosing motor faults, their sensors are occasionally difficult to install where the environment of industrial field is in poor condition. In addition to this installation problem, there are many low priced low voltage induction motors in the field. Therefore, the diagnosis technique should be easy to install their sensors and low cost comparing to the price of motors. This paper proposes a method for detecting broken rotor bar and stator winding fault in a low voltage squirrel-cage induction motor using a radial flux sensor to develop a simple and low cost diagnosis technique. The sensor is designed as a search coil and installed between stator slots during motor production to measure the leakage flux in radial direction at the air-gap. The proposed method consists of a calculating load condition, finding abnormal signals and monitoring those signals related with motor faults to indentify two kinds of motor failures. To demonstrate the performance of the method, experimental results obtained on 7.5kW three-phase squirrel-cage induction motors are discussed.

The new metrology, Advanced Poly-silicon Ultra-Trace Profiling (APUTP), was developed for measuring bulk Cu and Ni in heavily boron-doped silicon wafers. A Ni recovery yield of 98.8% and a Cu recovery yield of 96.0% were achieved by optimizing the vapor phase etching and the wafer surface scanning conditions, following capture of Cu and Ni by the poly-silicon layer. A lower limit of detection (LOD) than previous techniques could be achieved using the mixture vapor etching method. This method can be used to indicate the amount of Cu and Ni resulting from bulk contamination in heavily boron-doped silicon wafers during wafer manufacturing. It was found that a higher degree of bulk Ni contamination arose during alkaline etching of heavily boron-doped silicon wafers compared with lightly boron-doped silicon wafers. In addition, it was proven that bulk Cu contamination was easily introduced in the heavily boron-doped silicon wafer by polishing the wafer with a slurry containing Cu in the presence of amine additives.

The control and evaluations of alkali metal such as Na have been important issues in device process. LTO layer was deposited on backside of wafer as backseal of epitaxial substrate. The backseal wafer with LTO was evaluated to study effect of Na contamination which was observed after NaOH mixture dip. We found Na out diffusion from LTO layer inducing surface oxidation rate increase in oxidation process. These phenomena considered to Na property of low boiling temperature point. However, Na from LTO layer did not affect epitaxial process because of hydrogen pre-baking in epitaxy process.

In this study, we propose a diagnosis method for the rotor eccentricity in induction machines fed by a PWM converter by considering the harmonics in a transient magnetic phenomenon. The influences of the asymmetrical whirling motions are studied using the back EMF of a search coil, which enables the detection of motor faults. The analysis results of the rotor eccentricity could be obtained by comparing the characteristics of motors fabricated with normal and irregular air gaps, and the validity is verified from the experimental results. The simulation and experimental results can be useful for the online faults detection monitoring system of induction machines.

Asymmetric electromagnetic force caused by the frictional worn bearing, rotor misalignment, and unbalanced rotor, etc., leads to an asymmetrical operation, vibration, and electromagnetic noise. The need for the detection of these rotor eccentricities has lead to the development of monitoring methods by increasing sensitivity and noise immunity. This paper proposes a diagnosis method for an induction motor driven by a PWM-controlled inverter considering the harmonics in a transient magnetic phenomenon. The effects of asymmetrical whirling motion are studied using the current, vibration spectrum, and back EMF of a search coil. The analysis results of rotor eccentricity could be obtained by comparing the characteristics of motors that have normal and irregular air gaps and verified reliability. Simulation and experimental results can be useful for online fault detection monitoring systems for induction motors.

The control and evaluation of surface defects are important issues in SOI production. We introduce new a technique which is mixing of the HF dipping and Cu decoration method (HCM). HCM has high sensitivity to detect potential defects, such as small holes, imperfect top Si, imperfect buried oxide (BOX) and isolated BOX layer. Furthermore, the defects can be observed visually, so we can easily find the position and distribution of defects.

We investigated the correlation between the junction leakagecurrent and bulk micro-defect (BMD) density for p-n+ junctions fabricated on Czochralski (CZ) Si wafers. In order to measure BMD, the wafers were annealed at 800oC for 4hr, followed by 1000oC for 8, 16, and 24 hr in a N2 ambient. After that, they were polished by 15 μm to remove the denuded zone (DZ) to disclose the BMD for detection using p-n+ junctions. We confirm the junction depth and dopant concentration of the p-n+ junctions by using secondary ion mass spectrometry (SIMS). After the electrical measurements we confirmed that the junction leakage current increases with increasing BMD density. The correlation factor between the junction leakage current and BMD density was about 99%.

Gate oxide integrity (GOI) is very important Si wafers, but it is very difficult to explain the origin of the oxide breakdown because the gate oxide is destroyed by the strong electric field. In this study, we detect the origin of the breakdown without destroying the gate oxide using copper reduction by the potential sweep method, followed by SEM/EDS and TEM analysis. These results show that the crystal defects near the gate oxide induce the growth of copper agglomerates without destroying the gate oxide. Hence, it can supply information on the origin of GOI fails by a simple electrochemical study.

Fault detection and diagnosis is the most important technology in condition-based maintenance (CBM) systems, which typically starts from collecting signatures of running machines by multiple sensors for subsequent accurate analysis. Recently, there has been an increasing requirement of selecting special sensors, which are cheap, robust, easily installed, and good classifiers that have accurate classification, stable performance, and short calculating time. This article carries out a comparative study of various classification algorithms for fault diagnosis of electric motors using different types of signals. The authors evaluate experimentally the relative performances of five classifiers using five types of steady-state signals based on three kinds of performance evaluation strategies: training-test, cross-validation, and similar measure. First, the raw signals are collected and features are extracted from the collected signals. Then, the extracted features are classified using the five classification algorithms. Next, an overall comparison of the five classifiers is described, and experiment results are discussed. Finally, conclusions are summarized and suggestions are offered.

The online partial discharge (PD) diagnosis has been recently accepted as an effective technique for the evaluation of the insulation condition of stator windings in high-voltage rotating machines. There are several types of sensors used for detecting PD in rotating machines. The so-called capacitive coupler, which is connected to the conductor, has been used most widely. Another sensor, the so-called stator slot coupler (SSC), is used by inserting it between the wedge and the top stator coil. However, these are not economically efficient for small-size rotating machines due to their high installation costs. Also, it takes a long time for insertion to take place and it a difficult process, if the SSC is inserted into small-size rotating machines. In this paper, a novel sensor called the partial discharge locating coupler (PDLC) was developed, which is easily mounted into the small-size rotating machines for the PD measurement, and tested to characterize its detectable frequency band and sensitivity. As a result, it was found that the PDLC has a detection frequency band up to several tens of megahertz, and it detects the induced signals with reasonable sensitivity. The PDLC combined with the digital filtering technique enables us to locate the PD activities. Also, it was found that the radiation or end-winding coupling of the PD signals is initiated >13 MHz.

Recently, researchers have an interest on the electric vehicle because it is more eco-friendly and efficient than gas vehicle. Instead of a gas engine, the electric vehicle has a motor for propulsion. The permanent magnet synchronous motor which has permanent magnet instead of field winding in the rotor has especially higher efficiency and torque per weight than other types of motor. When the irreversible demagnetization is occurred, users can be expose to high risk of accident by the fault operation of motor. Because of this, the irreversible demagnetization of permanent magnet should be detected by using any kinds of method to reduce the risk of accident. In this study, the demagnetization diagnosis method based on the result of locked rotor test is proposed. Base on short measurement time, the proposed diagnosis method aims to detect the demagnetization fault when the electric vehicle is at a complete standstill. The proposed method is verified by using the finite element analysis.

In this paper, measurement of hydrogen gas using three kinds of gas sensors were studied for improving selectivity and quantification on hydrogen gas. Output characteristics for each sensors were analyzed to some concentrations of hydrogen gas. It was illustrated that the wide range of hydrogen gas concentrations upto 10,000[ppm] can be reliably measured from investigation of concentration ranges with high amplitudes and good resolutions. Also, the combinations of outputs from three kinds sensors were able to improve the selectivity of hydrogen gas.

In this paper, we dealt with a partial discharge(PD) measurement method that has been accepted as an effective and non-destructive technique to estimate insulation performance of low-voltage electric and electronic devices. The PD measurement system Is composed of a coupling network, a low noise amplifier, and associated electronics. h shielded box Is adopted to make a better measurement environment against around noise. A low cut-off frequency of the coupling network estimated by a sinusoidal wave input was 125 kHz (-3 dB). Calibration tests on laboratory set-up have shown that the PD measurement system has a stable sensitivity of 10 mV/pC. In an application test oil a low-voltage three phase Induction motor (5 HP), we could detect 0.53 pC level of partial discharge at the applied voltage of AC 650 .

This paper deals with the loss distribution in a three-phase induction motor fed by a pulsewidth-modulated (PWM) inverter. The copper losses in the stator winding and rotor conductor bar, and iron loss except for mechanical and stray load losses, are computed by the variable time-stepping finite-element method (FEM) considering the switching action of the PWM inverter. The iron loss is evaluated by the frequency analysis of the magnetic flux density distribution using discrete Fourier transforms (DFT) and iron loss curves, which are provided by the manufacturer. Simulation results by the presented method are verified by the experiment results. Finally, the loss distribution of the PWM inverter type three-phase induction motor is compared with that of the conventional three-phase induction motor that is directly fed by the sinusoidal three-phase voltage source without any control devices.

The effect of heat treatment conditions and point defects on oxygen precipitation was investigated with various grown-in defect region wafers. The behavior of oxygen precipitation depends on the nucleation temperature and the type and the concentration of point defects. The peak temperature of nucleation for oxygen precipitation is 687–734°C in vacancy-rich, oxidation-induced stacking fault ring, interstitial Si-rich and interstitial pure regions. In vacancy-pure region, the peak temperature of nucleation is about 870°C. The vacancy plays an important role in increasing the peak temperature of nucleation for oxygen precipitation.

The behavior of oxygen precipitation was investigated in radial direction using Si wafers with different generation area of vacancy-related defects. Oxygen precipitation is more enhanced in vacancy-rich region than in interstitial-rich region. The behavior of oxygen precipitation in the radial direction is strongly dependent on the size of vacancy-rich region which is related to crystal growth condition. Anomalous oxygen precipitation occurred in the marginal vacancy-rich region and the inner edge of interstitial rich region. In the marginal interstitial-rich region, however, oxygen precipitation is suppressed to nearly zero.

The radial distribution of the delta [Oi] for the heavily doped silicon wafers was investigated using X-ray diffraction technique. In order to obtain the correlation between delta [Oi] and X-ray intensity ratio for the lightly doped wafers with different initial [Oi] concentrations, the oxygen concentration using FTIR and X-ray intensity were measured before and after two-step annealing. The relation between delta [Oi] and X-ray intensity ratio showed that it was close to the parabolic correlation rather than the linear correlation. The deviation of this measurement was about ±0.4 ppma. This correlation equation could be applied to the heavily doped wafers. It is shown that the radial distribution of the delta [Oi] is not uniform in the radial direction but has the symmetric relation at the wafer center. The bulk micro defect (BMD) density using etching method was measured to confirm these results.

The development of the diagnosis algorithm is carried out for identifying health and faulted conditions in three-phase induction motors. The algorithm consists of feature calculation, feature extraction, and feature classification procedures in sequence. For that, the non-linear feature extraction method with kernel function is used and the classifier of k-nearest neighbors is introduced to decide motor conditions among normal motor, broken rotor bar, short-turn stator windings, and bearing faults. Signal for this algorithm is acquired flux sensor. It is to measure the change of magnetic flux at the air-gap. To get the effective features related with faults, the peak ratio of some frequencies related with line frequency is introduced. This work proposes the efficient diagnosis method for induction motors by developing the powerful algorithm. The calculated features show a good linearity according to faults severities. Moreover, the final results show a good classification rate on motor conditions.

In this paper, we introduce two position control scheme; the lead-lag control and the sliding mode control for a stage system, which is levitated and driven by electric magnetic actuators. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal forces. Dynamic equations of the stage system are derived simply. The sliding mode control algorithm is more effective than the lead-lag control algorithm to reduce effects from movements and disturbances of other axis.

We introduce two position control scheme; the lead-lag control and the sliding mode control for a stage system, which is levitated and driven by electric magnetic actuators. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal forces. Dynamic equations of the stage system are derived simply. The sliding mode control algorithm is more effective than the lead-lag control algorithm to reduce effects from movements and disturbances of other axis.

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.

This paper presents results of the finite-element (FE) analysis and experiment of air-gap flux variation in induction motor when rotor eccentricity phenomenon occurs. 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 4-poles, 380 [V], 7.5 [kW], 1,768 [rpm] induction motor is built, and search coils are designed and inserted under the stator wedge of the motor. The FE analysis results are compared with experiment test results, and it shows that it is an effective method for developing on-line monitoring system on rotor vibration of an induction motor.

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

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.

In this paper, we address a position control scheme for a stage system, which is levitated and driven by electric magnetic actuators. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by using the vertical and horizontal forces. Dynamic equations of the stage system are derived based on Newton-Euler method and its special Jacobian matrix describing a relation between the Joint velocity and platen velocity is done. There are proposed two control schemes for positioning, which are Cartesian space controller and Joint space controller. The control performance of the Cartesian space controller is better than the Joint space controller in task space trajectory', while the Joint space controller is simpler than the Cartesian space controller in controller realization.

This paper presents the control principles and algorithms for the antilock brake system (ABS) with pneumatic brake. Also a new simulation method, the hardware in-the-loop simulation (HILS), which includes hardware in the control and simulation loop, is presented. It includes pneumatic brake hardware between the controller input and simulated vehicle dynamics output. How to construct the HILS for antilock brake system of a vehicle is described. Also how to evaluate the antilock brake algorithms and electronic control unit (ECU) in laboratory is explained. If the HILS is used, functional tests of the newly developed antilock brake controller can be made in a short time using repeated experiments. As a result, times and costs needed for developing the new antilock brake controller can be reduced. Also the developed controller was equipped in a real vehicles and tested in the real test road for comparison. It can be said that the HILS is a good method for developing a new system especially in automotive applications, in which many trial and errors are required for practical implementation.

In this paper, it Is a study to valid a compatibility of digital control unit (DCU) for an aircraft brake system through a dynamometer test as well as HILS test It is very important because results of this test are satisfied before installing on an aircraft. The dynamometer system is composed of dynamo, HILS (hardware-in-the-loop-simulation) and velocity sensors installed on wheel and dynamo. The DCU was tested under various friction conditions in HILS and dynamometer test. The DCU with ABS control algorithm protected very well a wheel skid on high friction condition as well as low friction 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 results can be useful for on-line vibration monitoring of an induction motor.

Today, most fixed-wing aircrafts are equipped with an antiskid brake system (ABS). The ABS can modulate braking moments in the wheels optimally whenever an aircraft lands. So it can reduce landing distance and increase safeties. The ABS for an aircraft is mainly composed of braking moment modulators (hydraulic servo valves) and brake control unit in addition to the conventional hydraulic brake system. In this paper, a Mark IV type-fully digital-brake controller is studied. For the development of its control algorithms, a 5 degree of freedom (DOF) aircraft landing model is composed in the form of the Matlab/Simulink model at first. Then antiskid control algorithms using wheel decelerations and slips are made. The developed algorithms are tested in software simulations using state-flow toolboxes in the Matlab/Simulink model. Also, the hardware in-the-loop simulation (HILS) systems are made using real-time simulators, where hydraulic brake systems of a real aircraft, braking moment modulator and its controller are included as hardware components. Algorithms tested in software simulations are coded and downloaded into a newly developed digital signal processing (DSP) controller and the dynamics models are downloaded to real-time simulators and the simulations have been done in the same road conditions as software simulations. Both the software and HIL simulation results are presented.

In this paper, improved rotor position estimation for position sensorless control system of the switched reluctance motor (SRM) is presented. For more accurate rotor position estimation, the phase locked loop (PLL) based position interpolation is adapted. In the current-flux-rotor position lookup table based rotor position estimation, the inherent current and flux-linkage ripple can cause the position estimation error. Instead of the conventional low-pass filter, the PLL based position interpolation technique is used for the better dynamic performance. The developed rotor position estimation scheme is realized using TMS320 F2812 digital signal processor and prototype 1-hp SRM.

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.

Nowadays, emerging technologies such as IT (information technologies) under ubiquitous environment has become an important issue for asset management and condition assessment of power apparatus. And it has been said that management of electrical network and power apparatus is in fact asset management. The paper explains the potential technologies and the cost benefit in installation, operation and maintenance of electric power system under ubiquitous environment.

In this paper, we address two position control scheme; the lead-lag control and the sliding mode control for a stage system, which is levitated and driven by electric magnetic actuators. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal forces. Dynamic equations of the stage system are derived simply. The sliding mode control algorithm is more effective than the lead-lag control algorithm to reduce effects from movements and disturbances of other axis.