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入出力 高調波 低減形 VVVF 시스템으로 制御되는 3相 誘導電動機 高效率 運轉
柳喆魯,李公熙,李星龍 全北大學校 1990 論文集 Vol.32 No.-
Recently, the variable speed control by the VVVF system for controlling induction motor has been applied in the various field. But the harmonic which is generated in rectifier and inverter device give rise to the various obstacles. And also the efficiency improvement of induction motor, which is occupied above 80% in the industrial areas, is important to economize the energy because the induction motor has fault that it is the low efficiency in the low load. Therefore, in this study 1. From the side of reducing harmonics in input-output currents a. The reduction of harmonics by the tap changing method of converter b. The reduction of harmonics by the PWM method of inverter 2. From the side of the variable and the high efficiency of induction motor drive a. The problem of lock by the novel PLL system b. The problem of design of the V/f controller 3. From problem of simplification of the system a. The problem of simplification of the system b. The problem of the main transformer capacity and turn ratio In comparison with optimum value by computer simulation about the above items, we have made this system in accordance with theory, and then proved this validity through experiments. And also we developed the high efficiency drive system of induction motor for reducing harmonics in input-output currents by applying this conclusion.
柳喆魯,趙成翊 全北大學校 1990 論文集 Vol.32 No.-
SCF(Switched Capacitor Filter) can be easily integrated because of consisting of switches, capacitors and OP AMPs(Operational Amplifier). And resently, SCF simulated resistor by the ratio of capacitors and fc(clock frequency) has been widely used for voice frequency baseband filtering. In this paper, therefore, when voice band signal frequency had been selected by SCF, we designed Chebyshev 3rd order high pass SCF by applying SC(Switched Capacitor) method to remove the power-line frequency noise from input signal, and then researched the characteristics of it by SCANP(SCF simulator). Also, we performed the LAYOUT of Chebyshev 3rd order high pass SCF using 3㎛ CMOS N-well process parameters.
柳喆魯 全北大學校 1969 論文集 Vol.11 No.-
The circuit and the operation of frequency multiplier using Semiconductor Controlled Rectifier(S.C.R.) are discussed. The modes of operation are discussed and the circuit begavior is analyzed for output weveform. An approximate equivalent circuit is used to de scribe the load condition. Experimental results are shown for the loaded(only resistive load)frequency multiplier.
姜錤文,柳喆魯,朴正淳 全北大學校 1984 論文集 Vol.26 No.-
The third harmonic current contain much at the poltransformer exciting current of 22.9KV-Y 3-phase 4wire distribution system, therefore, that misoperated groundfault protective relay and overheated main transformer. magnitude of this higher harmonic current keeps under restrict at unbalance, but that presented increase phenomenon due to electro static capacity of cable etc. We install small AC filter on the ground fault relay to prevent this misoperation. In this paper, I deal with higher harmoniㅊs occurrence phenomenon, harmonic analysis method of distribution system circuit and counter-measure of disturbance by harmonic of protection relay.