Seung-Kwon Na

A study on MRAS(Model Reference Adaptive System) Method Instantaneous Speed Observer for Very Low Speed Drive of Induction Motors

This study configuration Vector Control System which is stable and has outstanding Dynamic Characteristics in Very Low Speed Region and Low Speed Region, and proposes Instantaneous Speed Observer and Very Low Speed Control method and vector control system of the speed estimation a using Reduced-Dimensional State Observer. The Observer proposed in this system, by appling Reduced-Dimensional State Observer to Load-Torque estimation and using for speed estimation, implements system composition simply and is capable of accurate Instantaneous Speed estimation in Very Low Speed Region. Also, this study reduces influence by System Noise and suggests an induction motor speed control system which is effective in Load Disturbance, modeling error, estimation noise and so on without changing pole of an Observer.

A Study on Speed Control by means of voltage·current model complex flux estimator

Abstract This study uses the algorithm which estimates the magnetic flux using different models in the low speed driving area and the high speed driving area by the voltage-current model synthesis magnetic flux Estimator and, from this result, estimates the magnetic flux angle to achieve the stable speed control through all the areas from the low speed to the high speed drive.In particular, the current change and the magnetic flux change under variable load were estimated in real time in the low speed area and this made the control characteristic improved in the low speed area. According to this, even under variable load, the more stable simulation and experiment could have been completed using PI current controller and PI flux controller in all the areas. As a result, the outstanding speed control characteristic has been achieved. Key Words : flux estimator, flux angle, PI current controller, PI flux controller, voltage-current model synthesis * Corresponding Author : Lark-Hoon HwangTel: +82-10-5487-5525 email: lhhwang@semyung.ac.kr 접수일 12년 08월 10일 수정일 12년 09월 06일 게재확정일 12년 11월 08일

A Study on Power LED driving constant Current-type DC-DC converter Driven using microcontroller

Abstract In this paper, Power LED(Light Emitting Diodes) is studied to driver as a new lighting system in the spotlight, replacing a large existing lighting system with fluorescent and incandescent lighting. To take advantage a variety of DC power as the boost DC-DC converter design specifications through the inductor L and capacitor C through PSPICE to calculate the best estimate of the value. Converters switching frequency is 50[kHz], the first Duty Rate was made to increase gradually depending on the value of the detection were, 10[%] in the output voltage. As a result, the simulated Boost Power LED driver characteristics is in comparison with the design specifications, 5[%] or less as the error was approximated. So, when input 15[V] were offered, a stable output 24[V] were obtained, and Dimming Control through the adjustment of brightness and current consumption were obtained to possible result. Key Words : LED(Light Emitting Diodes), Reverse Recovery Time, Constant Current Controller, Dimming Control PSPICE

A Study on the Flux Estimation Simulator Application for the Induction Motor Speed Control

Abstract In this paper, flux estimation method at the Induction motor is applied to stability flux estimate of possibility in overall speed domain. angle operation has voltage and current and speed information using the Induction motor direct control method. Induction motor direct control is material to flux information. Exact flux estimation method to using current model flux estimator of low-speed domain and voltage model flux estimator of high-speed domain. Speed and current and flux controller using PI controller. And error of integral requital for add to Anti-Windup PI controller. Verified to performance of Current model Flux controller and voltage model flux controller using Matlab / Simulink. Analysis has parameter influence of direct vector control and indirect vector control at the Induction motor vector control. So, verified to minute control. Analyzed to simulation result and proof to validity of presented algorithm.Key Words : Flux estimation method, PI controller, Matlab / Simulink, Anti-Windup

A study on High Frequency DC-DC Converter Drive using a Piezoelectric Transformer

Recently, as the piezoelectric transformer technology develops, piezoelectric transformer may become a variable alternative to magnetic transformers in various applications. Because it was have to favorable characteristics such as electromagnetic-noise free, compact size, higher efficiency, and superior power density, linkage flux, noiseless, etc. its resonance frequency was used to output waveform of a sine wave. In this paper, the switching mode power supply of about 87.2[KHz] is driven by the multilayer thickness vibration mode piezoelectric transformer and the DC to DC converter drive circuit using an electrical equivalent circuit is proposed. Also, it was possible to drive power source device of the high-luminance LED by propose circuits.

A study on Control toad Torque of Induction Motor using a Disturbance Cancellation Observer

In this paper, vector control to applied disturbance offset feedforward loop control for changing disturbances with various mechanical parameter is suggested. The proposed system estimate load torque based on induction motor torque using minimum diemension state observer. Because speed controller using state observer is used on condition of feedforward loop fur a torque, the robust speed control system realized. In this study, the proposed paper does to heighten reliability of system by presuming and use the speed by voltage and current that is detected without speed sensor. To prove the propriety of this paper, the various simulation carried out adequacy using a Matlab Simulink, and at the same time real system is made, using a ADMC300 digital signal processor, so it is proved. As the experimental result of embodying the system, the robust system is realized.