Research On The Control Method Of Non-linear Load Inverter Power Supply

With the development of various industrial control technologies and new energy technologies,equipment in many fields has higher and higher requirements for operational performance.The AC power provided by the universal AC grid cannot meet the requirements of equipment,but must be powered according to the requirements of electricity consumption.Electronic technology transforms electrical energy to obtain the required electrical energy.As an energy conversion device,the inverter power supply plays an important role in the power supply system.Due to the increasing number of power electronic devices,the types,quantities and proportions of nonlinear loads on the output of inverter power supply are increasing rapidly,and a series of problems such as harmonic increase and waveform distortion caused by nonlinear loads will be serious impact on the normal operation of power electronic equipment,thus having a serious impact on the power supply system.This thesis firstly establishes the mathematical model of the main circuit of the inverter power supply,expounds the SPWM modulation method and the digital implementation method,and analyzes the output characteristics of the inverter power supply under the condition of nonlinear load with the typical rectifying load as the representative of the nonlinear load.Secondly,for the problem caused by the nonlinear load inverter power supply,a repetitive control method is introduced to solve the problem.By superimposing the"past control deviation",the controlled object is controlled to eliminate the harmonics existing in the output voltage waveform,thereby suppressing periodic interference and improving the control quality of the system.However,the inherent delay of the repetitive control,the control will have a cycle delay,and need to join another control method.Therefore,based on the traditional integer-order PID control,fractional-order PID control is adopted,and the improved Oustaloup approximation method is used to replace the fractional-order function,which makes the control dimension of the whole system increase,the dynamic performance is better,and the anti-interference ability is enhanced.The simulation model of control system is built by MATLAB/Simulink,and the composite control method combining repetitive control and fractional-order PID control is verified.It can track the given signal well,reduce the distortion rate of the output waveform of the inverter and improve the adaptability of the load.Finally,based on the theory and simulation,the software and hardware design of the nonl:inear load inverter power supply control system with high-performance digital signal processor TMS320F28335 as the control core is carried out.The hardware includes DSP minimum system,drive circuit and sampling circuit,etc.Including the control system main program and the generation of SPWM signals.The experimental waveform results show that the composite control system meets the design requirements and can effectively improve the quality of the output waveform of the nonlinear load inverter power supply.