Research On 1kW Soft-switch Grid-connected PV Inverter

The PV inverter is an important part of the PV system. In order to improve the efficiency of the PV inverter, Soft-switch technology is used in the grid-connected inverter. TMS320LF2407A is used as the control chip in the PV inverter. A 1kW soft-switch grid-connected inverter is designed at the end.The history and the current condition of the soft-switch technology are introduced at the beginning of the paper. And then the paper introduces a new soft-switch topology which is fit for the grid-connected inverter. The control method of the topology is described in detail. Several current control methods are discussed in the paper. Each method has its virtue and defect. Then the paper presents an improved current control method. From analysis of the mathematical model of the inverter, the formula to calculate the PI parameters is achieved. And the char flow of the main program is also presented in the paper. Hardware design is studied in detail in the fourth chapter. Three MPPT control methods are discussed in this paper. Two methods are combined in order to get better result that is proved by experiment. Island phenomena is introduced and the harm to the grid is discussed. A few methods that can detect the Island phenomena are discussed. And a method that has been proved effectively by experiment is given in the end. At the end of the paper experiment results are discussed and the conclusion is given.