The Research And Realization On Grid Connected Inverter Based On LCL Filter

With the constantly increase of the pressure of the environment and energy,the development of new energy power generation technology Represented by wind energy,solar energy has become an important way to solve the global environmental and energy issues.Grid connected inverter as the new energy power generation equipment connected with the public power grid interface has a great research value.Firstly,a series of grid connected converter are introduced in this paper ? based on research results at home and abroad,introduces the LCL filter design principles and methods,several kinds of current control strategy,the active damping and passive damping control method.Through The establishment and analysis of the mathematical model of grid connected converter,use the automatic control engineering design method of control system to design the voltage loop and current loop of the converter control system.According to the mathematical model of LCL filter,analysis the impact of various parameters on the filter performance,puts forward the design method of LCL filter.Then,analysis the stability of the control system when the position of the feedback current is defferent through the zero pole distribution diagram.aimed at that the system is unstable when the Amount of feedback is arm side current,puts forward the active damping scheme that take the current of the capacitor as feedback,and feedback function is configured proportional component.by Bode diagram how to select the best proportional coefficient when the Harmonic is suppressed and the performance is not reduced.Although this method can suppress the resonance,and can be realizied simply,but increase the number of sensors.Then put forward to feedback the leg side current,and slect high pass filter as the feedback configuration function for active damping scheme.In addition,in order to achieve unity power factor grid,this paper proposes a method to modified the current of q axis.when the grid connected converter is running,calculate the current of q axis by the sample frequency,voltage,the d axis current value.The simulation verifies the proposed method is feasible.Finally,introduces the design of hardware circuit of grid connected converter including the power circuit,drive circuit and protection circuit.An experimental platform is built with TI TMS320F28335 as main control chip.Complete the experiments at the Guangzhou Institute of Energy Conversion.CAS.and verify the proposed active damping scheme is feasible,and has good practical value.