| At present, more and more attention was paid to photovoltaic technology, but their efficiency is generally low. This paper mainly centers around the key technologies of a novel inverter topology, which was called single-phase time-sharing inverter, which aims at improving the efficiency of inverter which was connected to the grid.Firstly, this paper described the operating principle of the novel topology, then the modulations in different working mode was introduced, especially the modulation when the inverter worked coordinately. Then we established the unified mathematical model in different working mode. And then we finished the experiment at the open loop condition, the experiment proved the feasibility of the new topology. Then we test the efficiency of the topology, at the same time the efficiency evaluation was made.And then we projected the closed-loop controller, which consisted of two PI current loops. Then we done the closed-loop experiment. Then we introduced a single-phase PLL which is based on a SOGI and finished the experiment when the inverter was jointed to the grid at low power level. Then we analysis the condition the PV inverter connected to the high impedance grid. And then the active damping and the passive damping method was introduced. This paper used the virtual resistor method of the active damping to restrain the resonance, when the new topology was connected to the high impedance grid. The experiment was done to verify the feasibility of the method.Finally, this paper discussed the common current of the single-phase time-sharing inverter. We first introduced the causes and hazards of common-mode currents. Then we analyzed the generating mechanism of the common mode current in detail. And then some method was recommended to suppress the common current. Lastly, we used the method above to repress the common current in the single-phase time-sharing grid-connected inverter, and the simulation verification was completed. |
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