Parallel Time-sharing Power Supply Voltage Type Single-stage Multi-input Grid-connected Inverte

In the context of the"Carbon Dioxide Peaking and Carbon Neutrality"era,China also advances to speed up the transition of energy consumption patterns and vigorously develop renewable new energy in the 13th Five Year Plan.Solar energy,wind energy,hydrogen energy,geothermal energy and other new energy sources have the advantages of low-carbon,clean,affordable,and abundant,which have received widespread attention from governments around the world.Among them,photovoltaic power generation is the most fully utilized and promising new energy source.A single new energy source is subject to location,climate,and other factors,resulting in discontinuous and unstable power supply,which is no longer able to meet the needs of the power grid.In order to overcome the shortcomings of a single new energy supply as well as improve the stability and flexibility of the power supply system,it is urgent to explore and seek multi-input grid-connected inverters that use a single-stage topology structure.Therefore,it is of significant theoretical value and engineering application value to conduct research on parallel time-sharing supply voltage type single-stage multi-input grid-connected inverter.On the basis of discussing the development and research status of traditional single input DC converter type and multi-input DC converter type two-stage multi-input inverters,this dissertation proposes a parallel time-sharing supply voltage type single-stage multi-input grid-connected inverter by simplifying the circuit structure and reducing the power conversion stage.And in-depth theoretical analysis,simulation,and experimental research were conducted on the circuit topology,energy management control strategy,the steady-state principle characteristics,modeling analysis,and main circuit parameter design of this grid-connected inverter,and important conclusions were drawn.The circuit topology of the proposed parallel time-sharing supply voltage type single-stage multi-input grid-connected inverter is cascaded of the input filtering capacitors,the parallel time-sharing selection switches,a full bridge high-frequency inverter circuit,an industrial frequency transformer with primary leakage inductance L_f1,and a CL output filtering circuit.The inverter adopts a maximum power output energy management SPWM control strategy with output filtering inductance current feedback of photovoltaic MPPT,achieving maximum power output from multiple input sources and stable output grid connected current.The steady-state principle characteristics of the parallel time-sharing supply voltage type single-stage multi-input grid-connected inverter are deeply analyzed and studied,including high-frequency switching process analysis,derivation of multi-input sources duty cycle expression,external characteristics derivation,suppression of turn off voltage spike of parallel time-sharing selection switches and other key technologies.The small-signal modeling of the single-stage multi-input grid-connected inverter is established,and the design criteria for control loop,input filters,industrial frequency transformer and LCL output filter is provided.Using the proposed circuit topology and energy management control strategy,a 1k W parallel time-sharing power supply voltage type single-stage multi-input grid-connected inverter experimental device was designed and constructed.The theoretical analysis,simulation,and experimental results of a 1k W single-stage multi-input grid-connected inverter indicate that the proposed inverter has excellent performance such as simple topology structure,electrical isolation between the output grid and the multi-input sources side,high conversion efficiency,small size and weight（compared with similar industrial frequency transformer structures）,high integration,and high-quality grid connected current waveform.It has broad application prospects in the field of joint power supply with multiple new energy sources such as photovoltaic and wind power.