LC필터를 이용한 3상유도전동기의 전류파형 개선에 관한 연구

A Study on the improvement of current waveforms of a three-phase induction motor with LC filter

An AC induction motor of constant speed characteristics has been widely used as power source because of simple structure and low maintenance cost in industrial field. Recently, the variable speed 3Φ induction motor driven by the inverter is utilized as a servo-motor of automatic control device and as a power source of elevator and electric locomotive, etc. The variable frequency AC source made by a conventional inverter which is composed of power semi-conductors and drive systems includes much noises in sine wave current due to high speed switching of direct current. In this paper, the low pass LC Filter for a variable speed induction motor driven by a full bridge inverter is introduced to solve EMI problem originated by much noise current. The modified LC filter based on the 3rd order Butterworth LC filter is used for the computer simulations and real experiments. The characteristics of proposed LC filter are investigated through FFT analysis. From experimental results, it is confirmed that noiseless AC current of sine wave fer a variable speed 30 induction motor can be obtained by the designed LC filter.