Internal-model-principle-based Fractional Order Phase Compensation Repetitive Control Technology For Single Phase PWM Inverter

The conventional repetitive control provides a precise waveform control scheme that enables zero-steady-state error tracking of any known integer period signal to compensate for harmonic distortion caused by parametric changes,especially for non-linear loads.The repetitive control system requires that the external control signal period must be an integer multiple of the sampling period.However,it cannot always be satisfied in practical applications.When the delay index term has a fractional order,the conventional repetitive control can not accurately track the control cycle signal,resulting in a significant decline in the performance of power e lectronic devices.To this end,this paper proposes a fractiona l phase compensation repetitive control technology based on the internal model principle,which uses the low pass filter of Lagrangian interpolation algorithm to approximate non-integer term delay.The fractional phase compensation repetitive control provides a solution for the lag non-integer terms at the fixed sampling frequency.In this paper,the single phase full bridge constant voltage constant frequency PWM inverter is used as the main circuit model.Firstly,the state space equation of the inverter is established and analyzed,and the parameters of the filter circuit are given.Then,the control principle of linear feedback control is expounded,the principle of conventional repetitive contro ller is discussed,and its system characteristics are analyzed.Based on this,a fractional phase compensation repetitive controller is introduced,and then the design principle and system characteristics of the fractional phase compensation repetitive control system are analyzed in detail.In order to verify the accuracy and superiority of the proposed fractional order phase compensation repetitive controller,a linear feedback control system,a conventional repetitive control system and a comparative simulation experiment of the proposed control system are carried out in the simulation environment.Besides,a single-phase PWM inverter circuit with DSP as the control system is built.The hardware circuit of the sampling circuit and the driving circuit is selected and analyzed,the software design including the main program,ADC sampling,SPWM generation and controller program is analyzed.Finally,the experimental waveform and data verify the accuracy and superiority of the fractional order phase compensation repeatitive controller.