• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.30-32
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• 2001

Switched reluctance motors have the advantage a high torque/weight ratio, as the large reluctance torque is made by salient poles of both start and rotor, and a high reliability. On the other hand, the switched reluctance motors have the disadvantage of a large ripple torque which is made by salient poles. So the application for the industrial fields have been limited to special cases. Geometric significant parameters are ${\beta}_r$ and ${\beta}_s$ respectively the rotor and stator pole arc while the significant electric parameters are the angles where the drive switches are turned on and off. It can be simulated that ${\beta}_r$ and ${\beta}_s$ must be chosen in a particular region of the plane (${\beta}_r,\;{\beta}_s$) called the feasible triangle. The aim of this paper is to simulate the minimum of the torque ripple by using finite element method and to determine the best choice of the rotor and stator pole arc.

• Journal of the Korea Society of Computer and Information
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• v.23 no.10
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• pp.65-72
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• 2018

In this paper, we used LSTM as a method to detect abnormal behavior of motors. We fixed the high layout size to 1 and changed the range of the input values and the neural network structure to see what change in power consumption prediction. Now, as the fourth industrial revolution era, smart factories are attracting attention. All the physical actions of smart factories are done using motors. Continuous monitoring of motor malfunctions helps to detect malfunctions and efficient operation. However, it is difficult to acquire the power consumption constantly due to the influence of the noise. We have experimented with a simple experimental environment, a method of predicting similarity to input data by adjusting the range of the input data or by changing the neural network structure.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.159-164
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• 2013

Difficulty of torque measurements in high-speed permanent magnet (HSPM) motors has necessitated the development of improved torque calculations. Hence, this paper presents an analytical torque calculation of a high speed permanent magnet (HSPM) motor based on the power factor angle. On the basis of analytical magnetic field solutions, the equations for circuit parameters such as back-emf and synchronous inductance are derived analytically. All analytical results are validated extensively by non-linear finite element (FE) calculations and measurements. The internal angle (${\delta}$) between the back-emf and the phase current is calculated according to the rotor speed by using analytical circuit parameters and the measured power factor because this angle is not measured but estimated in case of sensorless drive of the HSPM motor, significantly affecting torque calculation. Finally, the validity of the torque analysis method proposed in this paper is confirmed, by showing that the torque calculated on the basis of the internal angle is in better agreement with the measurements.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.540-544
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• 2011

Novel phosphrous flame retardant tetramethylene bis(orthophosphorylurea) (TBPU) was synthesized by the reaction of diphosphoric acid with 1,4-butanediol and urea, and charaterized by Fourier transform infrared spectroscopy (FT-IR). As the amount of TBPU added in polyurethane foam (PUF) was increased, the flame retardancy of PUF was increased and the mechanical properties were not decreased. Also, in the flame resistance test after the reduced pressure storage, the flame retardancy of TBPU added PUF was retained. We could find out that the thermal resistance of TBPU added PUF increased compared to that of pure PUF.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.4
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• pp.256-262
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• 2021

Six-phase motors can be used in industrial applications, such as an electric vehicle, due to their high reliability and low current magnitude per phase. An asymmetrical PMSM with two sets of three-phase windings is a commonly used structure for six-phase motors, with each winding set demonstrating a phase difference of 30°. Although the asymmetrical PMSM presents low torque ripples, its dynamic torque response deteriorates due to coupled components in the two three-phase windings. The decoupled VSD control is applied to eliminate the coupling effect. Load ratio control of two inverters for the six-phase PMSM is proposed in this study. DQ currents are controlled on the basis of two synchronous reference frames, and the six-phase drive system can be changed to a three-phase drive system when one inverter presents fault conditions. The operation and effectiveness of the proposed algorithm is verified through simulation and experiments. The six-phase drive system is transferred to a three-phase drive system by changing the current reference of the second DQ reference frame. Moreover, control of both torque and speed exhibits satisfactory performance before and after the mode change.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.473-479
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• 2016

This paper describes an accurate and stable current control method of switched reluctance motors(SRMs), which have recently attracted considerable wide attention owing to their favorable features, such as high performance, high durability, structural simplicity, low cost, etc. In most cases, the PI controllers(PICC) have been used mostly for the current control of electric motors because their algorithm and selection of controller gain are relatively simpler compared to other controllers. On the other hand, the PI controller requires an adjustment of the controller gains for each operating point when nonlinear system parameters change rapidly. This paper presents a stable current control method of an SRM using self-tuning fuzzy current controller(STFCC) under nonlinear parameter variation. The performance of the considered method is validated via a dynamic simulation of the current controlled SRM drive using Matlab/Simulink program.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.289-294
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• 2014

Industrial manipulators are usually heavy given the payloads they carry. Therefore, they require high-capacity servomotors and speed reducers, which leads to high costs. However, if manipulator weight could be compensated for using a counterbalance mechanism, the motors' and speed reducers' capacities could be minimized substantially. However, it is usually difficult to assure durability and reliability with the conventional wire-based counterbalance mechanism. Therefore, a more robust gear- and roller-based counterbalance mechanism is proposed in this study. A manipulator was developed using this mechanism; this manipulator maintains its performance even when using motors and reducers of lower capacities. The results of various simulations and experiments verified that the proposed mechanism provides the torque required to compensate for gravitational torque in any configuration and minimizes the torque required for supporting a large payload.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.84-92
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• 2020

This paper describes the estimation method of cable fault location in rocket motors using M-sequence (Maximal Length Sequence). In order to estimate the location of a cable fault, three methods have been usually used: TDR (Time Domain Reflectometry), FDR (Frequency Domain Reflectometry), and TFDR (Time-Frequency Domain Reflectometry). However, these methods suffer the disadvantage of requiring users to be close to a test field, which is dangerous. The estimation method of cable fault location using M-sequence is proposed to solve this problem. The proposed method can make use of DAS (Data Acquisition System). The experiments were three cases: damaged, open, and short. The RG-58 coaxial cable was used in the experiments. As a result, the proposed method has better performance than that of conventional methods such as TDR and TFDR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6446-6451
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• 2014

Pneumatic motors are quite attractive for many applications because of their competitive price, light-weight, easy assembly, safety in hazardous areas as well as other features, such as a good force/weight ratio and operation in exceptionally harsh environments. In contrast to these advantages, pneumatic motors have limited use in applications, particularly those requiring a fast and precise response. These undesirable characteristics are due to the high compressibility of air and from the nonlinearities in pneumatic systems. This paper presents the sliding mode controller based on 3-loop(SMCB3L), which increases the load stiffness to control the rotation angle of a pneumatic motor. The characteristics for the step responses and load disturbances of the proposed controller were compared with the conventional PID controller. The experimental results showed that a properly designed SMCB3L is capable of high positioning accuracy within ${\pm}0.05mm$. Furthermore, the load stiffness of the SMCB3L can be improved 3.5 fold compared to that of PID controllers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.492-498
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• 2016

It is well known that since abrupt faults in induction motors tend to lead to subsequent faults and deterioration of the drive apparatus, motor faults may lead to several operating restrictions, such as security problems and economic loss. A lot of research has been done in the area of diagnosis to detect machine faults and to prevent catastrophic hazards in the motor drive system. This paper presents a new method of motor current signature analysis in which the DC-link current of the inverter-driven induction motor system, where a single current sensor is employed instead of three AC current sensors, is measured, and fast Fourier transform analysis is performed. This proposed method makes it possible to easily discern and clearly separate the motor fault current signature from the normal operation current flowing through the stator and rotor windings.