Research & Design Of Three-Phase PV Grid-connected Inverter

With the emergence of energy crisis and environmental pollution,more and more attention has been paid to developing clean energy. Solar energy is a kind of clean energy which is of great value of large scale development and has a good prospect of application and extension. Photovoltaic generation is one of the efficient ways to utilize solar energy which has drawn more and more concerns in recent years. Research on photovoltaic grid-connected generation is such a subject that it has great theory value as well as practical significance. The main part--grid-connected inverter-- of PV generation system has been studied in this task.The two main control task of PV grid-connected Inverter is maximum power point tracking(MPPT)control and waveform control of grid-connected current。The operational principal and basic characteristics of solar cell were firstly analyzed,then the equivalent circuit and mathematical model were presented. Several MPPT control strategies were introduced of which the principals,advantages and disadvantages had been compared.The topology and current control strategy of PV grid-connected inverter were emphatically investigated,the mathematical models in static three phase coordinate and synchronous dq coordinate were established,the control strategies under these two coordinates were analyzed and compared. The filtering way of grid-connected inverter output current was also discussed and studied,L type and LCL type filters were compared,the parameter design of L&LCL Filter was presented.Finally,the hardware and software design of three phase PV grid-connected Inverter were presented. Microchip`s digital signal controller(DSC)dsPIC30F4011 was introduced as the main controller,a three-phase bridge was used as the main circuit,an Fuji IGBT module was selected as the Power converting Device;control circuit included perfect protection circuit such as over-current protection circuit,over-voltage protection circuit,over-heat protection circuit and so on;two type filters of L&LCL were designed,the filtering effects were compared through experiment results;the main circuit and control circuit was layout on one PCB board,EMI was analyzed in layout of PCB design. A 15kW experimental prototype was made to illustrated and verified the current control strategy and design. The grid-connected experiment results show that the control strategy and the designed circuit can satisfy the design requests,the prototype works safely and stably。...