Research On Single-phase Time-sharing Grid-connected Inverter

With the rapid development and application of distributed generation,On account ofthat the overall conversion efficiency of grid inverter is not high,this paper proposes a newtopology grid-connectedinverter, the topology has a simple structure, less switchcomponents, a series of advantages as high reliability and high efficiency, this paper mainlyrevolves around it.This paper first analyzes the new topology structure and basic working principle, andthen four-paragraph SPWM modulation calculationand simulation verification was done inthe working mode of low voltage input; And then separate mathematical model of thesingle-phase time-sharing grid-connected inverter was established under different operatingmode, and finally we got the complete mathematical model. Then, the bias problem of theDC/DC push-pull circuit in the new topology were studied, and put forward biassuppression method in the hardware and software aspects; The fundamental cause of thecommon-mode interference problems on the non-isolated grid-connected inverter wereanalyzed, and put forward suppression measures on the hardware of the new topology, andthe simulation verification was finished; Then according to the requirements of thegrid-connected current control, and combined the characteristics of the grid-connectedcurrent of this paper, a double closed-loop PI current controller was designed; A2kwexperiment platform was set up, and the open/closed loop experiments had been done, andwe also made the efficiency evaluation of the new topology in open loop within the scopeof normalvoltages. Then a digital phase-locked loop had been researched and designed, andwe completed interconnection experiment of the new topology under low power; In theend,the dead zone effects of the bridge type power supply was researched and analyzed,this paper proposes a repetitive control way that was adopted to improve the dead zonecompensation, and experimentalverification was done later.Finally, this paper studied grid-connected problems of the new topology under high impedance. The oretical analysis and research was done andput forward correspondingsuppression and compensation scheme on different problems,finally the simulationverification was completed.