Means of Reducing Number of Sensors in Single-Phase Power Converters with an Active Power Buffer

Abstract

Recently, there is a big need in the industry to develop high power density, high efficiency and high reliability (H3) single-phase power conversion technology. One key approach towards achieving H3 is the adoption of active power buffer technology, a technology that can replace the bulky and less reliable dc-link capacitors in conventional single-phase power converters (mainly for buffering the twice-line-frequency ripple power) with an active auxiliary circuit that can be built much more compact and reliable. The introduction of an extra power circuit, however, generally implies that more sensors are mandated in the overall system to accomplish the closed-loop control than those in conventional single-phase systems. The need for more sensors could adversely offset the gains in power density and reliability with the active buffer technology. In this paper, a simple and reliable algebraic observer is proposed to reduce the number of sensors needed in the system, thereby offering advantages such as low cost, high compactness and improved reliability. Moreover, by leveraging the simple form of the state- space equation, the proposed observer is shown to exhibit high accuracy and fast responses. The feasibility of the proposed observer is testified in both simulation and experimental setup.