Characteristics of a low EMI noise inverter using resonant dc link circuit

Recent developments in electronics apparatus design, consisting in the redu ction of operating voltage of their LSI components to lower their energy co nsumption, result, in principle, in a diminished immunity of electronic dev ices to electromagnetic interference (EMI). Therefore, since the suppressio n of EMI generated by such peripheral devices as, for example, uninterrupti ble power sources providing power to such electronic apparatus has become a n important topic of research, we decided to investigate low-noise inverter circuits in which a resonant power converter circuit technology and soft s witching techniques are used. The resonant de link inverters consist of a c onventional PWM inverter with an LC resonant circuit added to its de input, thus making it possible to turn the internal semiconductor switches on and off at the zero voltage state. It is not unreasonable to expect that such arrangements can produce a resonant inverter having the simplest configurat ion. In this paper, we discuss methods of designing the LC resonant circuit s, methods of application of the PWM techniques to the output voltage contr ol, and configuration of the circuit protecting the resonant circuit from o vervoltage at large capacities. In addition, the results of experiments con ducted on a 10-kW-rated prototype unit demonstrated that this inverter is c haracterized by a low level of emitted EMI, and even with its main circuits exposed, it satisfies the class 1 requirements of the VCCI recommendations on permissible EMI levels. (C) 2000 Scripta Technica, Electron Comm Jpn.