Research On Space Vector Modulation Technology Of Three-phase Current Source Converter

In order to assume the responsibility of a great power in solving the climate change problem and to promote the construction of ecological civilization and high-quality development in China,President Xi Jinping,in his speech at the general debate of the 75 th session of the United Nations General Assembly,pointed out the "double carbon" goal to be achieved by China in the face of climate change.The development of clean energy and the use of large amounts of electric energy are conducive to the realization of the "double carbon" goal,so the development and utilization of electric energy has become a hot spot for research in industry and academia.As the core equipment for the development and utilization of electric energy,electric energy converters can be divided into voltage source converters and current source converters.Current-source converters are gaining more and more attention in many fields,such as high-voltage DC transmission systems and electric vehicles,wind/solar power generation systems,etc.due to their inherent advantages of current limiting and short-circuit protection,low switching dv/dt and high reliability.As an important technical method for performance optimization in the field of power electronics,modulation strategies have the advantages of no change in hardware equipment and low cost.Therefore,this paper mainly discusses how to improve some performance indexes of the three-phase current source converter by optimizing the space vector modulation strategy.The main contents are as follows:Firstly,the working principle of three-phase current source converter and the working principle and mechanism of space vector modulation are introduced in detail in this paper,which lays a theoretical foundation and solution idea for solving some problems existing in three-phase current source converter and introduce the problem of large DC-link current ripple and the problem of overlap time effect that current source converter suffers in the practical application.Second,Chapter 2 of this paper reveals the problem of continuous increase of DClink current ripple in the existing inductor current ripple suppression scheme,which leads to large DC-link current ripple,and proposes a new ripple suppression strategy.The results show that without increasing the switching frequency and other hardware,the DC-link inductor current ripple amplitude of the proposed ripple suppression scheme is reduced by about 30% compared with the comparison scheme,and the current ripple suppression effect of the proposed scheme is better than that of the comparison scheme in the whole regulation range.Moreover,since the current studies on the stacking time of current-source converters are all based on the premise of the conventional vector synthesis approach and the effective suppression effect.Therefore,this paper reveals the impact of the overlap-time in the new vector synthesis method in Chapter 2,and proposes a method to replace the overlap-time by constructing a continuity channel.The research results show that this scheme can effectively replace the overlap-time as well as eliminate the 5th and 7th current harmonics introduced by the overlap time.After completing the theoretical analysis,this paper firstly builds a simulation model in MATLAB/Simulink software so as to initially verify the effectiveness of the proposed modulation optimization scheme and the correctness of the theoretical analysis.On this basis,a three-phase current source converter experimental platform is designed and built,including hardware platform design,device selection and experimental program design.Finally,the validity of the proposed scheme and the correctness of the theoretical analysis are further verified by comparing different types of experimental results obtained on the experimental platform with the theoretical analysis and simulation results.