가변속 냉동시스템의 On-line FDD를 위한 압축기 전류정보의 활용

This paper describes on-line fault detection and diagnosis(FDD) for a variable speed refrigeration system(VSRS) based on current information analysis of a compressor. We note especially that the inverter driven compressor motors can be unavoidably exposed to hostile environment such as ripple in electrical torque or frequent speed change comparing to the motors under conventional control schemes. Moreover some faults based on only temperature and pressure will not be detected because of its inherent long time constant of the system and compensation of the control variables by control loop. Hence it is shown that the current information can play an important role in the more precise and quick FDD of the refrigeration system. Therefore a novel on-line FDD scheme using not only temperatures and pressures but also analysis of the harmonics and amplitude of the current from compressors is suggested at first. Then we set up the experimental variable speed system for FDD. Finally, the method is applied to the refrigeration system to confirm the validity of the proposed scheme.