Research On Double Closed-loop Control Strategy Of Single-phase Inverter Based On Sliding Mode Variable Structure Control

With the popularization of new energy in this century,how to fully develop and utilize new energy so as to solve the problems of energy shortage and rapid increase in electricity demand has become a hot spot for scholars from all over the world.At the same time,people’s demand for power quality is getting higher and higher,so inverter technology as a core technology has naturally become the focus of scientists.This paper mainly takes voltage-type single-phase inverter as the research object,analyzes and models its working principle,proposes a linear sliding mode control algorithm,and on this basis,proposes a sliding mode controller based on an improved power reaching law.As a result,the output performance of the single-phase inverter is improved.Since the inverter control system will be interfered by external factors and the uncertainty of parameters in actual operation,it is necessary to establish a mathematical model containing interference items according to the working principle of the inverter.The system adopts a double closed-loop control structure,in which the main voltage outer loop is mainly used,and its rationality is verified by combining with the stability of Lyapunov.In order to further reduce the total harmonic distortion rate and chattering delay of the output waveform,the neural network and sliding mode control are combined to approximate and compensate the interference terms in real time with its high-precision fitting ability of nonlinear functions.Using the combination of Extreme Learning Machine(ELM)and disturbance observer,a new type of arrival control input-fence function is introduced at the same time,and an integral terminal sliding mode controller based on ELM is designed.The interference observer is essentially a strategy for estimating system interference,which makes equivalent compensation for the interference term without the need to establish an accurate model for the interference.In order to verify the feasibility of the controller designed in this paper,five control strategy models were built on the PSIM simulation platform,and The DSP core chip TMS32F28335 is used to build a hardware experiment platform for actual measurement and analysis.The experimental results show that the two optimized sliding mode controllers have improved the robustness of the output waveform of the system,while the Total Harmonic Distortion(THD)of the output waveform of the system based on the ELM integral sliding mode controller is only 1.95% and 3.92%,indicating that the controller makes the system load switching response faster and the output voltage waveform dynamic performance and robustness better.