Research On The Three-Phase Current Source Buck-Boost Inverter

As the interface of new energy generation system and grid, inverters are important in the distributed generation system. The traditional new energy power generation system either voltage source or current source can not adapt to condition with the input source strong fluctuations because of the single function of step-up or step-down. Considering the characteristics of high efficiency and wide range of voltage regulation, a new three-phase current Buck-Boost inverter is introduced in this paper.On the basis of reading a large number of journal literatures at home and abroad, a single-stage Buck-Boost inverter topology combinations that a mode of cascade inverter type by sharing device are analyzed and compared in this paper. Finally a single-stage three-phase current Buck- Boost inverter topology is selected as the research object.Compared with traditional bridge, the Buck-Boost inverter is proposed in this paper not only realize the buck converter, but also can realize the boost converter. Because of bridge structure, the topology can be SPWM modulation and SVPWM modulation topology. In addition, an improved one-dimensional modulation strategy is proposed on the basis of in-depth study of modulation topology. And then the mathematical model of three-phase Buck-Boost inverter is established to analysis its ability. According to the mathematical model of topology, the control block diagram is established and the stability of the system and regulator parameter is designed in this paper. Some different kinds of closed loop control method that classic double closed loop, pole assignment strategy closed loop and power decoupling control are used to verify the correctness and feasibility by simulation.Finally, the software and hardware of the main circuit are designed on the experiment platform. Using DSP + FPGA as the main control chips to verify the correctness of the theoretical analysis and simulation.