And Grid-connected Inverter Based On The Quasi-pr Control

Nowadays, on accout of the problem of environment pollution and exhaustion of energy resources becoming worse and worse, exploring and using of new energy become more and more important, Distributed Resource is accepted commonly for its advantages such as economical and cleaness, and the inverter is the most important power converter in the Distributed Generation System, whose performance will directly influence the efficiency of the use of Distributed Resource. This paper focus on single-phase and H-bridge grid-connected inverter, which is widely used now, andanalyzed the topology of the system, control strategy and Digital PLL technology.Firstly, the grid-connected system was particularly introduced, including its topology, ideal model, working state, grid-conneced demand, and the design of output filter.Secondly, the control strategy was analyzed in detail. Quasi-PR controller which is based on the traditional PI control method, can infinite gain at the fundamental frequency and hence can achieve zero steady-state error, also can elimate the effect of grid voltage disturbance. Subsequently, DPLL was introduced. Using the capture function of DSP, not only the frequency but also the phase was corrected. The experiment results testify that the output current of the reference sine wave has the same phase with the grid. This means that the efficiency of the inverter is 1, and this method is available.Next, each part of the hard circuit was introduced, including the main circuit, the control circuit, and the protect circuit. Then the diagram of the program was gived.Finally, TMS320LF2407A of TI incorporated is used as the main digital controller, a 1kW experimental prototype is produced, the experimental waveforms of grid-connected inverter are obtained. It shows that the design circuit and the control strategy can satisfy the design requests, this prototype works safely and stably.