The Research Of Repetitive-control About Single-phase Bridge Voltage Inverter

Inverter is an indispensable part in off-grid power generation system. It is responsible for converting direct current(DC) to alternating current(AC), for the use of AC load. So the performance of the inverter is very important.Its performance metrics of output waveform include fast dynamic response and low total harmonic distortion. However, dead zone and the diversification of load type makes the inverter output voltage containing a lot of harmonic.In order to solve this situation, taking the single phase full bridge inverter as control object, two kinds control scheme of inverter system based on repetitive-control is prosented.With simulated method,We take continuous system model as object to design controller.Then,We take the controller into the discrete form to realize digital control of inverter system. The main research results and innovative points are as follows:(1) The model of inverter control system based on repetitive control is established.By means of analysis single phase full bridge inverter circuit and the process of SPWM,the mathmatical model of single phase inverter in established.In view of the characteristics of inverter ’s output waveform containing a lot of harmonic,repetitive controller is introduced to eliminate harmonic.(2) The control method of inverter system based on H∞ robust repetitive-control is proposed. The method combines the state feedback control, H∞ control and repetitive control.On the basis of state back control increasing damping ratio and improving the dynamic performance, the modified repetitive controller is embeded to improve the steady state performance.Firstly,wih the concept of damping resistance in actual output filter,virtual resistance is used to determine the state feedback control gain.Then,using the output characteristic of modified repetitive controller,the design of compensator is converted into the problem of H∞ output feedback. It avoid several parameter needing to adjust repeatedly in Traditional inverter control system based on repetitive control.(3) The repetitive-control strategy of inverter system based on the continu ous and discrete two-dimensional model is proposed.And two-dimensional feed back control law is proposed. Firstly,for the mathematical model of inverter s ystem,using the 2D feature in the process of repetitive-control and the method of continuous-lifting, the two-dimensional model is established.Then,with sele cting Lyapunov functionals,the stability condition in the form form of linear matrix inequality is deduced.Lastly,the controller parameters are obtained by L MI.It overcomes the defects that can’t independently adjust the continuous con trol actions and discrete learning actions in traditional linear feedback control law.simulation results show that these two kinds of control strategy can gua rantee the inverter system to have good steady performance and dynamic char-acteristics.During suddenly adding loads or belt type rectifier load,system can still guarantee high quality waveform of output voltage.