The purpose of this study is to compare and analyze the conventional constant-speed compressor driven by an induction motor and the BLDC-applied capacity variable compressor in order to improve the energy efficiency of the refrigeration system. Through this study, it was found that, when a reciprocating hermetic compressor is operated, more power is consumed than a BLDC compressor due to the consumption of current through the instantaneous starting capacitor when operating at a constant voltage than a BLDC compressor.

본 논문은 Z-형 컨버터와 수정된 공간벡터 PWM인버터로 구성된 분산전원시스템의 회로모델과 제어 알고리즘을 보여주고 있다. Z-형 컨버터는 수동소자인 L과 C로 간단히 구성되어 있으며 인버터의 상하 양 소자가가 동시에 도통되도록 하는 구간을 이용해 승압을 함으로써 기존의 DC/DC 변환기와는 다른 형태를 취하고 있다. 점근 관측기를 이용한 이산시간 슬라이딩모드제어를 통해 전류제어를 함으로써 센서수를 줄이고 제어성능을 개선하였다. 대체에너지로 관심이 많은 태양광이나, 연료전지 그리고 소형 풍력발전으로부터 생산된 직류 에너지를 상용으로 사용할 수 있도록 하는 전력변환기로써 유용하게 사용될 수 있을 것이다.

A fish pump makes very important roles in an automation system of an aquaculture farm, thus it has been used widely in order to transfer fishes from one place to the other place automatically. In spite of its significant roles, the efforts for developing performance and promoting efficiency of the fish pump are not sufficient yet. In this paper, a method which makes the fish pump automation system is suggested. Automation of the fish pump can be accomplished by using variable voltage and variable frequency inverter system including induction motors. Especially, very simple logic to generate Pulse width Modulation(PWM) wave to control induction motor efficiently and three steps speed control method to regulate liquid quantity of the fish pump simply are suggested. Owing to the simplifies speed control and PWM wave generation technique, a cheaper microprocessor, 80C196KC, than a digital signal Processor(DSP) can be used to operate control algorithm in induction motor systems for real time control Also, a new idea of remote control for the simplifies novel inverter system by Programmable logic Controller(PLC) without special output unit, digital to analog converter(D/A), is suggested in this paper. Consequently the function of reliability, availability and serviceability of the fish pump system are developed. It will be expected to contribute expanding of application of the fish pump in aquaculture farms because the system can reduce energy consumption and some difficulties according to manual operation prominently.

Among various Power converters, a variable voltage variable frequency (VVVF) three-phase PWM inverter is regarded as most promising power converter due to its capabilities, which permits the control of voltage, frequency and harmonic contents in a single power stage employing only on DC source. As a modulating technique of the PWM inverter, the regular sampling technique has rendered possible the on-line computation and generation of PWM control waveforms with a reasonably high switching frequencies. In this paper, microprocessor based three-phase regular samping PWM inverter with real-time control algorithm and control circuits for driving three phase AC motor has been developed. Harmocic components of PWM waveform were analized theoretically in terms of Bessel function series and then calculated by digital computer and observed with spectrum analyzer