Research On Inverter Based On Repetitive And Fuzzy Control

Since the beginning of the new century,with the rapid development of science and technology,the power grid and various electrical equipment for ac power quality requirements are more and more strict,and electrical equipment in the non-linear load especially rectifying load proportion is also more and more large.Nonlinear load will bring a lot of harmonics to the circuit,resulting in serious distortion of the output voltage waveform,which will affect the electrical safety of the equipment and bring harm to the whole circuit.Traditional inverters and inverter devices can no longer meet the industrial needs,so PWM(Pulse Width Modulation)inverter system needs to be more digital,modular and intelligent.Aiming at the characteristic of rectifying load,this paper adopts intelligent compound control method to provide theoretical basis and experimental analysis for the design of the system.In this paper,the single-phase full-bridge SPWM(Sinusoidal pulse width modulation)inverter model is established based on the basic inverter model.As a typical nonlinear load,the voltage and current output characteristics of the inverter with rectifying load are analyzed.Secondly,according to the periodic characteristic of rectifying load harmonic,the repetitive control is introduced to eliminate it.Repetitive control adopts internal model principle,which can control periodic harmonics well.However,due to the inherent delay in the repetitive control method,there will be a one-period delay problem in the control of external disturbances and harmonics,so it is necessary to add a control method that can respond quickly to make up for the deficiency of repetitive control.This paper chooses fuzzy control in intelligent control method.Fuzzy PI control has the characteristic of parameter adaptive,which can adjust the PI parameters according to the fuzzy rules quickly when the disturbance or distortion occurs.However,because of the fuzzy principle and fuzzy rule base,the waveform adjustment can not be very accurate.Considering the advantages and disadvantages of repetitive control and fuzzy PI control,this paper adopts a compound control method combining the two,which can not only obtain good dynamic characteristics but also give consideration to the steady-state performance of the system.Using MATLAB/Simulink software to simulate the split ring system,separate repetitive control,separate fuzzy control and compound control respectively,verify the composite of duplication and fuzzy PI control can better track the given signal,reduce output voltage inverter system's THD(Total Harmonic Distortion and Total Harmonic Distortion),improve the output voltage waveform and the power quality.Finally,on the basis of the existing theoretical research and simulation experiments,the prototype is built by using the TMS320F28335 chip developed by TI company.The hardware system of inverter with nonlinear load and corresponding software control program are designed.The experimental results show that the repetitive-fuzzy PI control system meets the design requirements and achieves the goal of optimizing the output voltage quality.