• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.774-779
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• 1998

For the speed control of motors, the position or speed sensors are necessary to obtain the position information of the rotor. Specially, SRM(Switched Reluctance Motor) needs an accurate rotor position data because both the rotor and the stator have a salient pole structure. High functional sensors like resolver or encoder are expensive and have complex connecting lines to the controller so the pure signals are apt to be mixed with noised. In the sight of SRM drives, the high temperature, heavy dust, and the EMI surroundings reduce the reliability of speed and position sensors. Therefore, the speed and position sensorless control algorithms using observer have been accepted widely. In this paper An adaptive sliding observer is described to control the SRM without speed or position sensors. The adaptive sliding observer is set on the basis of variable structure control theory. The sliding surface is constructed by current error terms and this surface guarantees the errors converge to "zero". The stability of observer is affirmed by Lyapunov stability analysis and popov's hyper stability theory.ty theory.

• Journal of Power Electronics
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• v.11 no.1
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• pp.37-44
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• 2011

In this paper, a four-phase 8/6-pole 4-kW SR motor drive model is presented. Based on experimental data, the model allows an accurate simulation of a drive in dynamic operation. Simulations are performed and a laboratory type set-up is built based on a TI TMS320F2812 platform to experimentally verify the theoretical results obtained for a SR motor. To reduce acoustic noise and to correct the power factor of this drive, a two-stage power converter is proposed that uses a current source rectifier (CSR) as the input stage for the asymmetrical converter of the studied SRM. Employing the space-vector modulation (SVM) method in matrix converters, the CSR switching allows the dc link's capacitors to be eliminated and the power factor of the SRM drive to be improved. As the electrical motive force (emf) is directly proportional to the rotor speed, the input voltage to the machine can be programmed to be a function of the speed with the modulation index of the CSR, leading to a reduction in the acoustic noise of the SRM drive. Simulation of the whole SRM drive system is performed using MATLAB-Simulink. The results fully comply with the required conditions such as power factor correction with an improvement in the THD.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.55-57
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• 2002

In industry, A pallet truck is drived mainly by d.c motor, because it use to battery for input power. However, d.c motor has a brush, this is the disadvantage of the d.c motor for a pallet truck. Though a brushless d.c motor has a permanent magnet, it is for low torque. Switched reluctance motors(SRM) 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, this paper design the shape of the switched reluctance motor that will replace a d.c motor for A pallet truck. First of all, designed parameter of SRM, outer diameter, diameter of rotor and stock length, from the outputr equation considering electric loading and magnetic loading. Next, design diameter of stator and rotor, depth of slot pole width, air gap as inner size of motor. The design of SRM certify the torque, the efficiency and the output power by a simulation.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.47-50
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• 1997

The FEM(Finite Element Method) can be used to analysis SRM(Switched Reluctance Motor) as it can account for the salient pole geometry of the stator and rotor and the nonlinear properties of the magnetic materials. However, FEM requirers a lot of computer memory and computing time because, the kind of SRM drivers is verity and the switching strategies are various for one SRM driver. In this paper we proposed the method of analysis of a SRM which results are similar to FEM and has very short computing time. The Inductance and torque for each phase current at each rotor position are calculated by using two-dimensional nonlinear FEM analysis. Using the look-up table of inductance and torque and the voltage equations of SRM we obtained the phase current and torque. To verify proposed algorithm, 3 phase 6/4 SRM is analysed and found a good agreement with FEM results. And computing time is about 1/1600 of the FEM analysis.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.3
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• pp.166-176
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• 2007

Radio frequency (RF) microelectromechanical systems (MEMS) have been pursued for more than a decade as a solution of high-performance on-chip fixed, tunable and reconfigurable circuits. This paper reviews our research work on RF MEMS switches and switching circuits in the past five years. The research work first concentrates on the development of lateral DC-contact switches and capacitive shunt switches. Low insertion loss, high isolation and wide frequency band have been achieved for the two types of switches; then the switches have been integrated with transmission lines to achieve different switching circuits, such as single-pole-multi-throw (SPMT) switching circuits, tunable band-pass filter, tunable band-stop filter and reconfigurable filter circuits. Substrate transfer process and surface planarization process are used to fabricate the above mentioned devices and circuits. The advantages of these two fabrication processes provide great flexibility in developing different types of RF MEMS switches and circuits. The ultimate target is to produce more powerful and sophisticated wireless appliances operating in handsets, base stations, and satellites with low power consumption and cost.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.79-84
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• 2015

Transformer is widely used element on power system and industrial area. Especially the transformers installed at power system are exposed to an environment of arbitrary changed. Thus the prediction of degradation and the analysis of response to impulse are important. To conduct those works, the electrical characteristics of system should be analyzed, effectively. But the analysis of electrical characteristic in electric machine level such as pole and pad-mounted transformer is almost no, thus commercial VNA (Vector Network Analyzer) is used to getting the response in wide frequency range. However, the output power of VNA is usually under 10mW, so verification for effectiveness of measuring electrically large component should be conducted, firstly. Next, after getting total S-parameter of transformer, predicting impulse response can be performed in time-domain with circuit simulator. In this paper, it is introduced that verification effectiveness of VNA using transfer function from SFRA (Sweep Frequency Response Analyzer), firstly. Next, total S-parameter, six by six matix form, was built using measured 2 port S-parameter from vector network analyzer. To get the response to impulse which is defined by IEC 60060-1, time-domain simulation is conducted to ADS (Advenced Design System) circuit simulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1930-1935
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• 2009

This paper deals with the torque ripple reduction of permanent magnet synchronous motor using harmonic current injection. Torque ripple of electric motor reduces system stability and performances, therefore efforts to reduce torque ripple are exerted in the design process. Torque ripple can be reduced by appropriate pole/slot combination, skew of rotor or stator, design of magnetic circuit, etc. In addition, torque ripple can be also reduced by input voltage and current, and many researches have been conducted to reduce torque ripple for six-step drive. Torque ripple reduction for current vector controlled permanent magnet synchronous motor also have been conducted and verified by investigating back emf wave form. Torque ripple reduction in this paper started from getting torque profile according to input current and electrical angle calculated by FEA, then instantaneous currents at each electrical angles for constant torque are calculated and applied to experiments. Therefore, 0% of torque ripple can be obtained theoretically with harmonic current injection. In order to maximize the effect of torque ripple reduction, a BLDC motor having high harmonic component of back emf is chosen. With sinusoidal current drive, over 100% of torque ripple is obtained initially, then 0.5 % of torque ripple is obtained by FEA using harmonic current injection. The effect is verified by experiment and the presented method can be effectively applicable to Electric Power Steering(EPS).

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.197-208
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• 2010

Unified power flow controller (UPFC) is the most reliable device in the FACTS concept. It has the ability to adjust all three control parameters effective in power flow and voltage stability. In this paper, a linearized model of a power system installed with a UPFC has been presented. UPFC has four control loops that by adding an extra signal to one of them, increases dynamic stability and load angle oscillations are damped. In this paper, after open loop eigenvalue (electro mechanical mode) calculations, state-space equations have been used to design damping controller and it has been considered to influence active and reactive power flow durations as the input of damping controller, in addition to the common speed duration of synchronous generators as input damper signal. To increase stability, further Lead-Lag and LQR controllers, a novel on-line adaptive controller has been used analytically to identify power system parameters. Closed-loop calculations of the electro mechanical mode verify the improvement of system pole placement after controller designing. Suitable operation of adaptive controller to decrease rotor speed oscillations against input mechanical torque disturbances is confirmed by the simulation results.

• Transactions on Electrical and Electronic Materials
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• v.16 no.6
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• pp.328-333
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• 2015

Squirrel cage induction motors have mostly been used for their small capacity because the starting torque is smaller than the starting current during start-up. However, as more and more mid-to-large capacity motors are developed, the demands for improvements in performance characteristics have also increased. In this study, the starting characteristics of squirrel cage induction motors were analyzed based on the rotor materials and shapes using a finite element method to provide design data suitable for different use purposes and capacities. We further completed analysis by combining electromagnetic equations deduced from Maxwell’s equations and the circuit equations of stators and rotors. A moving coordinator was introduced to rotate the rotor during the analysis, and the torques calculated via the finite element method were combined with the motion equations to calculate the position and angular velocity of the rotors at the next time, thereby analyzing the transient characteristics. The analysis results of the transient characteristics were applied to a 3-phase 4-pole 5-hp induction motor to calculate the starting torque, speed, and rotation angle of the rotors. In the reference model, the materials and shapes of the rotor slot were changed to copper and silicon copper and a deep slot, shallow slot, and long-neck-shaped slot.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.5
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• pp.81-89
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• 2001

Power system stabilizer act efficiently to damp the electromechanical oscillations in interconnected power systems. This paper presents an algorithm for the optimal parameter selection of a power system stabilizer in two-area power systems with a series HVDC link. This method is one of the classical techniques by allocating properly pole-zero positions to fit as closely as desired the ideal phase lead between the voltage reference and the generator electrical power and by changing the gain to produce a necessary damping torque over the matched frequency range. The small signal stability and transient stability studies using the PSS parameters obtained from this method show that a natural oscillation frequency of the study case system is adequately damped. The simulation used in the paper was performed by the Power System Toolbox software program based on MATLAB.