Research On Methods And Experiment Of Suppressing Common-mode Voltage With Photovoltaic Grid-connected Inverter

PV Grid technology is an accompanying human new energy exploration, development and effective use of the process gave birth to a new technology, especially with the miniaturization of high-power photovoltaic grid-connected inverter, modular, modularmulti-functional and high-performance, and control the way digital high reliability, good robustness, the advantages of centralized control, to promote photovoltaic grid-connected inverter applied to the working conditionscontinuously enhance the flexibility and adaptability. To this end, the academia and the engineering of photovoltaic grid connected inverter system launched a multi-dimensional theory and practice. Through a lot of reading literature, the common-mode voltage of the photovoltaic grid-connected inverter, to carry out a certain depth the theory and practice. The main contents of this article can be summarized as follows:(1)Existing three-level grid inverter topology based on the research background, comb on the hazards of the common-mode voltage, combined with the research status, select from the perspective of control strategy and Invertercommon mode voltage suppression or elimination.(2)Focusing on the NPC three level grid-connected inverter topology, analysis of a single NPC three-level inverter works and describes the commutation process. Space right amount of principle, and control system for the overall design.(3)SPWM modulation strategy, for example, the common mode voltage of the Fourier analysis, and the same phase, reversed phase carrier modulation strategy, compared the inhibitory effect of common-mode voltage. SVPWM modulation strategy in the unified modulation algorithm, and the common-mode voltage of the modulation strategy.(4)Analyzed the relationship between the two power companies the peace of three-level switching state, proposed to eliminate the NPC three-level grid-connected inverter modulation strategy, and theory and simulation analysis.(5)Build a the6.5KW prototype experimental platform, and verified by experiments on this platform in-phase carrier of SPWM, RP carrier of SPWM, SVPWM, to eliminate common-mode voltage the SPWM four modulation strategy, a comparative analysis of common-modevoltage. Experimental results show that different modulation strategy for common-mode voltage suppression or elimination of differences and commonalities. A certain reference value for engineering application.Finally, sum up the lack of research, maka a plan for the future research.