Abstract
Current-fed inverters for off-grid power systems have several advantages, such as no lower-limit of the dc-voltage range, and no electrolytic capacitors. However, the inverter with ordinal PWM (Pulse-Width-Modulation) scheme produces undesirable lower order harmonics in the ac-output voltage and the dc-input current under an inductor with limited inductance. Thus, the PWM scheme requires smoothed dc-inductor currents and so, a bulky and expensive inductor on the dc-side is necessary. To overcome the problem, the authors propose a three-phase current-fed inverter for off-grid power systems with a predictive-instantaneous-voltage-control and PSM (Pulse-Space-Modulation). In this paper, the principle and theoretical operation of the proposed inverter are described in detail and the theory is confirmed through simulation studies.
