Analysis And Research On Realizing Three-phase Rectification Output By Backstepping And Sliding Mode Variable Structure

With the continuous progress of power electronics and power supply technology,the performance and efficiency of power supply devices have more special requirements for the needs of specific occasions.In aerospace,shipbuilding and other fields,the integration of high-frequency switching power supplies into motor equipment constitutes an integrated synchronous power generation system,which is also receiving more and more attention.However,the classic Proportional-Integral control method currently used does not have the ability to accurately and stably output,and it is not suitable for low-voltage and high-current applications.Robustness,reliability,power density and other issues have always been the reasons that restrict the development of the power supply field.This article analyzes and studies the control method of the integrated synchronous power generation system to improve the comprehensive performance of the low-voltage high-current power supply.First of all,this paper analyzes and studies the traditional voltage-type pulse width modulation rectification system,deduces its main topology,and obtains the mathematical model of the rectification system in the rotating coordinate system through coordinate transformation.On this basis,the space vector pulse width modulation technology is analyzed in detail,and its space vector synthesis process and the generation of the modulation signal are described.From the on-off states of the six switching tubes alternately,eight different space vectors can be obtained,of which six non-zero vectors divide the space into six sectors.The working sector is determined by the synthesis of the space vector,and then the control duration,switching time and overmodulation processing method of each synthesized vector are determined,and finally six pulse width modulation signals are obtained to complete the control of the switching tube.Secondly,as the core of the rectification system,control technology has problems such as slow dynamic response and uncertain perturbation leading to poor control effect.This paper uses the backstepping method of nonlinear control to reconstruct the double closed-loop control structure.The double closed-loop control structure is divided into an active component control structure and a reactive component control structure.The theory and applicable conditions of backstepping method are described and judged,and the backstepping method is used to design the global double closed-loop control structure.In the non-linear system model,the intermediate virtual control variable is set and the system tracking and global adjustment are achieved by reducing the tracking error.Lyapunov’s second stability theorem is analyzed and used to judge the obtained control function,so as to obtain a stable and reliable control function.Thirdly,the backstepping method is a recursive control method,but due to the simple structure of the reactive component control structure,there is no need to build a subsystem,and it does not give play to the advantages of the backstepping method.Therefore,based on the in-depth study of the principle of backstepping,this paper proposes the sliding mode variable structure to optimize it,so that the overall double closed-loop control structure has faster response and stronger robustness.Finally,in order to verify the effectiveness of the proposed rectification control method combining the backstepping method and sliding mode variable structure,the global double closed-loop control using the backstepping method is compared with the optimized control method in this paper,and simulations and experiments are carried out.The results show that the combination of the backstepping method and the sliding mode variable structure control method makes the rectification system have better dynamic performance.Not only the system power factor can reach about98.5%,but also it can ensure that the current quickly tracks the voltage while maintaining a good sinusoidal waveform.When the load mutates suddenly,the stable direct current output can be reached again within 0.02 seconds,and the system fluctuation rate does not exceed 2%.