The Research On Dual Mode Control And Seamless Switching Of Household PV Inverter With Battery

The design goal of household PV inverter with battery systems is a multifunctional solar energy generation equipment that can be widely promoted.Common PV grid-connected inverter can only be running when connecting to the grid.Off-grid PV inverter with battery systems can not put the excess energy delivered to the grid that the user can achieve economic.The single function and poor flexibility of these equipments has greatly restricted the utility.The researches in photovoltaic inverter with battery systems that can be running with off-grid and grid-connected are able to work to strengthen the practicality of solar power.On this basis,if we can realize seamless switching between the dual modes,we will provide users with uninterrupted power supply to ensure the reliability of power supply to critical loads,this will greatly expand the household photovoltaic inverter range of applications.Based on the analysis of household load situation that household photovoltaic inverter with battery will face,the inverter topology is selected.First,based on this topology and power requirements,the appropriate IGBT type is selected,IGBT drive circuit is designed,and the hardware of inverter part is designed and producted.Secondly,the modulation strategy matching inverter topology is proposed,and based on the harmonic characteristics of the inverter,LCL filter is designed.In order to meet the demand of phase locking and system protection requirements,the three-phase phase-locked loop integrating fault protection function is designed.Combined with the typical off-grid and grid-connected strategy,the dual mode strategy which is developed to realize seamless switching is proposed.In order to realize the seamless switching,household PV Inverter with battery system's off-grid and grid-connected strategy adopts the same current loop,the process of switching adopt to the voltage vector Angle keeping strategy and current loop given reference value compensation strategy,and limiting the parameters change rate in the process of mode switch to prevent the volatility of the control loop.MATLAB simulation software is used to build simulation model to prove that the control mode can completely reach the expected function requirements.On the prototype confirmed the inverter and driving circuit board can realize the dual mode operation,asymmetric load power supply,load tracking and seamless switching function.