Parallel Time-sharing Power Supply Forward DC Chopper Type Single-stage Multi-input High-frequency Link Inverter

New energy sources,such as solar energy,wind energy,hydrogen energy,tidal energy and geothermal energy,are clean,pollution-free,cheap,reliable and abundant.Their development and utilization have attracted more and more attention from all over the world.In order to improve the stability and flexibility of the power supply system and realize the priority and full utilization of energy resources,it is necessary to adopt a distributed power generation system with combined supply of multiple new energy sources.In this paper,three types of multi-input two-stage multi-input inverters,i.e.singleinput DC converter-type two-stage multi-input inverters,parallel time-sharing power supply,series simultaneous power supply and multi-winding time/simultaneous power supply,and quasi-single-stage multi-input DC converter-type quasi-single-stage multiinput inverters,are discussed.On the basis of this,a parallel time-sharing forward DC chopper-type single-stage multi-input system is proposed.The circuit topology and energy management control strategy of high frequency link inverters are deeply analyzed and simulated.The key technologies of the inverters,such as circuit topology,energy management control strategy,steady-state principle characteristics,design criteria of main circuit parameters,are studied.And important conclusions are obtained.The proposed parallel time-division power supply forward-excited DC chopper type single-stage multi-input high-frequency link inverter circuit topology is composed of a multi-input parallel time division selection switch,a single input single output combined isolation bidirectional forward DC chopper,the output filters are constructed in cascade.The inverter adopts the maximum power output energy management control strategy when it is connected to the grid.It consists of input source MPPT control and gridconnected current decoupling control.The steady-state operation principle of this kind of inverters is deeply analyzed.A small signal model is established by using the state space averaging method,and the instantaneous current control design is carried out.The suppression of leakage inductance spikes in transformers is analyzed.Based on the input-output relationship,the design criteria of the key circuit parameters of the grid-connected inverter are derived.A 3kW 240~360VDC/220V50 HzAC parallel time-division power supply forward DC chopper type single-stage multi-input high-frequency link inverter system is designed.The steady-state,dynamic and MPPT simulation analysis of the inverter system was carried out by PSIM software,and the experimental prototype is developed.The simulation and experimental results confirm the feasibility and correctness of the proposed circuit topology and energy management control strategy,and provide an effective new method for distributed generation system with multiple new energy sources.