Research And Design Of Charge/Inverter Bi-directional Converter For Household Photovoltaics

With the country began to develop new energy and increase policy support for that,Home PV program is also gradually advancing,charge/inverter bi-directional converter can be a good match with this plan.This paper is based on the application of a charge/inverter bi-directional converter in a small home photovoltaic power generation system,which aims to realize the energy flow between solar energy,battery and power grid.Using a two-stage power topology by an isolated bidirectional DC/DC converter and AC/DC converter,research and design of a high power factor,high efficiency of charge/inverter bi-directional converter.The main contents are as follows:Firstly,the present development status of PV power generation are analysed,on the basis of PV inverter,combined with the charging function are proposed,to realize the two-way flow of energy.Using a two-stage power topology,the former uses current-voltage type bi-directional full-bridge DC/DC converter and the latter adopts single-phase reversible PWM rectifier,the working principles are described in detail.The parameters of the main circuit components and the control circuit are designed,including sampling,driving,communication circuit.Sampling circuit realizes the real-time acquisition of voltage and current,with protection circuit;Driving circuit makes sure that the switch tube can work properly;Communication circuit helps DSP communicate with external equipment.Set up the model of small signal circuit of the converter,export system transfer function,with the help of MATLAB SISOTOOL,design the suitable controller,which makes the system have good dynamic and static performance,Through the simulation has proved the validity of the circuit design and control.Based on the introduction of the direct current control method of single-phase reversible PWM rectifier,this paper adopts a double closed loop control strategy to realize the stability of bus voltage and two-way flow under unit power factor,with simulation analysis.The system control strategy adopts constant current control to realize the two-way flow of energy between the low-voltage DC side and the AC grid.Finally,the feasibility of the control policy is verified by the simulation and the test platform are Completed.The main working waveforms of the system in the process of grid rectifier and inverter mode are tested and analyzed respectively.The rationality of the two-stage power topology and the control strategy of the constant current control are put forward,which can realize the two-way flow of energy between the low-voltage DC side and the AC grid.