Research On Fractional Repetitive Control Scheme Based On Sampling Separation Principle And Its Application To Inverter

Inverters,as the core of the distributed power generation system,has been studied widely and received widespread attention both from academic and industrial communion.In recent years,researches about inverters have come a long way especially in topology,modulation and control schemes.With the upgrading requirement of inverter output waveform quality,it is of great significance to optimize the traditional inverter control strategy to improve performance.This thesis takes the methods of the voltage harmonic suppression for the single-phase stand-alone inverter,summarizes the previous researches and then proposes a fractional order based on sampling separation principle to improve performance of the phase lead compensator and notch filter.First,this thesis introduces the conventional repetitive control(CRC)and investigate the repetitive control strategy in terms of four aspects: theoretical background,stability,parameter design and performance test.Then it analyzes the existing problems in low sampling rates and proposes a fractional order repetitive control(FORC)strategy.It is found that,compared with the conventional integer order repetitive control,FORC strategy can better the control performance.Next,in order to solve the inaccuracy resulting from fractional order based on Lagrange interpolation algorithm which is only a mathematical approximation,an original method is presented from the physical perspective based on sampling separation principle to realize a real fractional order repetitive control.Lastly,the theoretical analysis and simulation are given to testify the effectiveness of FORC strategy.In order to verify the performance of upgraded FORC,a sinusoidal pulse width modulation(SPWM)inverter experiment platform is established with a digital signal processor(DSP)serves as the control system.Then the design of principle prototype is given,including the hardware and software.Through the experiment of upgraded fractional repetitive control based on principle prototype,the thesis hopes to demonstrate its merits on the waveform control.