Research On Single-phase Frequency-variable Inverter Control Method Based On Variable Parameter Quasi-pR Control

Variable frequency inverter power supply has been widely used in every field of daily production and life.The single-phase variable-frequency inverter power supply studied in this paper is mainly used in the field of intelligent watt-hour meter calibration.Its output voltage amplitude and frequency can be adjusted wide range,with good quality of output waveform and smaller output steady-state error.The performance of the power supply will directly affect the intelligent watt-hour meter calibration's precision.The traditional inverter controlled by PI controller is not easy to adjust the output parameter and its steady-state error is large.Based on this background,this paper mainly studies the control method of single-phase inverter power supply,in order to reduce its output steady-state error and improve the calibration accuracy of intelligent electricity meters.Aiming at the requirements of adjustable output voltage amplitude and frequency,this paper deduces the PWM calculation formula based on asymmetric regular sampling method and gives the realization method of frequency modulation and amplitude modulation based on digital control.For the phenomenon of voltage mutation in the process of changing frequency,a detailed analysis is given and the method of solution is proposed.To meet the requirement of better waveform quality,this paper analyzes the relationship between filter parameters and output volta ge frequency and selects filter parameters.To meet the requirement of small steady-state error of the output voltage,this paper analyzes the influence of traditional PI control method on output voltage steady-state error in detail.It is found that the steady state error of the inverter system controlled by PI is large at high frequency and heavy load.On the basis of PI double loop control,the limitations of load current feed forward method to suppress output steady state error of inverter inverter system are also analyzed.In view of the large steady-state error of the inverter when using the traditional PI control,a variable parameters quasi-PR control method is proposed based on the double-loop control.This paper elaborates how the control parameters affect the performance of the controller in detail and gives a parameters setting method of variable parameter quasi-PR controller.The stability of the proposed control method in full load range and full frequency range is analyzed,and the effectiveness of the proposed method to suppress output voltage steady-state error is verified in this paper.On the basis of theoretical analysis,PLECS simulation software was used to build a simulation platform for single-phase inverter.The traditional PI control method,load current feed forward method and variable parameter quasi-PR control method were simulated and analyzed respectively.The steady-state error of output voltage under three control methods is compared through the simulation results.Finally,a power supply test prototype is built,and the proposed control method is verified by simulation and experiment.