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

Abstract

Recent developments in electronics apparatus design, consisting in the reduction of operating voltage of their LSI components to lower their energy consumption, result, in principle, in a diminished immunity of electronic devices to electromagnetic interference (EMI). Therefore, since the suppression of EMI generated by such peripheral devices as, for example, uninterruptible power sources providing power to such electronic apparatus has become an important topic of research, we decided to investigate low-noise inverter circuits in which a resonant power converter circuit technology and soft switching techniques are used. The resonant dc link inverters consist of a conventional PWM inverter with an LC resonant circuit added to its dc 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 configuration. In this paper, we discuss methods of designing the LC resonant circuits, methods of application of the PWM techniques to the output voltage control, and configuration of the circuit protecting the resonant circuit from overvoltage at large capacities. In addition, the results of experiments conducted on a 10-kW-rated prototype unit demonstrated that this inverter is characterized 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. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(10): 29–39, 2000