To overcome this, the OPCA is applied hierarchically in two stages. The input of the first stage are single feature vectors of one time instance. The input of the second stage are the combined output of several time instances of the first stage

单级半带滤波器设计，简单，很容易懂，适合初学者理解-Single-stage half-band filter design, simple and easy to understand for beginners to understand

对一种由Boost和带LCL滤波器的逆变电路组成的两级式单相光伏并网逆变器进行了研究。-A two-stage single-phase photovoltaic grid-connected inverter has been studied,which consists of a boost DC/DC converter and a DC/AC inverter with LCL filter