并网独立双模式控制高性能逆变器设计与实现

Design and Implementation of a High Performance Utility-Interactive Inverter

设计并实现了一种小型的用于分布式发电系统的功率调节系统。主电路采用推挽正激变换器和双降压式逆变器。传统的并网逆变器输出端采用工频变压器,体积重量大,成本高。该文采用高频隔离的逆变器,消除了输出端的工频变压器。传统的桥式逆变电路存在桥臂直通问题,该文将双降压式逆变器用于并网发电场合,提高了可靠性及效率。半周期调制方式减小了器件的开关损耗,以及功率场效应管的导通损耗。以往的文献对并网逆变器的分析侧重于单独工作模式或者并网模式,较少涉及到独立工作和并网工作切换过程的分析。该文分析了双模式运行的逆变器的切换过程。采用TMS320F240DSP芯片实现数字锁相同步,实现并网和独立控制的逻辑和基准切换。一个500VA的实验样机证明了方案的可行性。

This paper proposes a novel small two-stage power conditioning system（PCS） suitable for distributed generation. It comprises of a push-pull forward converter and a dual buck inverter. Traditional grid-connected inverter employs low frequency output isolation transformer. It increases weight and cost. This PCS adopts high frequency transformer, thus reducing the weight and cost. This PCS can work in standalone mode to provide power for local loads or in grid-connected mode to supply current .to grid in unity power factor. This paper also analyze the transition between grid-connected and standalone mode which is rarely analyzed in other literatures. Dual buck inverter eliminates the shoot-through problem of conventional inverter and greatly improves the reliability of the system. Also by adopting half cycle modulation ,the loss of switching and conduction losses of MOSFET are reduced. TMS320F240 DSP is used to realize the digital PLL（phase locked loop） and control the operating mode of standalone or grid-connected. A 500VA prototype was built to verify the feasibility of this scheme.