Design And Control Of Unidirectional High-Frequency Isolated Matrix Converter

As a core equipment of energy conversion and power control,power electronic converter plays an important role in new energy generation and utilization.High frequency isolated matrix converter is composed of high-frequency transformer and matrix converter,which is regarded as a kind of power electronic converter with great potential.It has the advantages of unit power factor operation,high-frequency electrical isolation,small volume and light weight,and is widely used in more and more fields such as wind power generation,electric vehicles,battery energy storage system,etc.In this paper,a unidirectional high-frequency isolated matrix converter topology is proposed,in which LC filter and matrix converter are used in the front stage,uncontrolled rectifier and resistive load are used in the back stage,and magnetic coupling and power transmission are carried out through high-frequency isolation transformer in the middle stage,so as to realize ac high-frequency AC-DC power conversion.The main research contents are as follows:1.On the basis of introducing the research background and significance of high-frequency isolated matrix converter,the development and characteristics of high-frequency isolated matrix converter are summarized,and the existing design ideas and optimization methods of high-frequency isolated matrix converter system are introduced from the perspectives of topology,modulation strategy and control technology.2.The operation principle and commutation technology of the unidirectional highfrequency isolated matrix converter are analyzed.According to the circuit topology,the operation mode of unidirectional high-frequency isolated matrix converter in one switching cycle is analyzed in detail.Aiming at the technical difficulties of safe commutation of bidirectional switch,this paper studies the four-step commutation method,realizes the safe commutation of bi-directional switch of high-frequency isolated matrix converter,and eliminates the voltage spike.3.The space vector modulation strategy of unidirectional high-frequency isolated matrix converter is studied and designed.The input current of high-frequency isolated matrix converter is analyzed in different sectors.According to the reference vector of input current,the current vector is used to synthesize the reference vector,and the dwelling time of current vector is calculated.The modulation strategy can realize soft switching of switching devices at the same time,the safe commutation of unidirectional high frequency isolated matrix converter is realized.Based on MATLAB / Simulink,a numerical simulation model of the converter is built to verify the performance of the modulation strategy.4.The mathematical models of the unidirectional high-frequency isolated matrix converter system in different coordinate systems are established,and the DC load current closed-loop controller is designed.This paper studies the suppression method of LC resonance in the grid side of high-frequency isolated matrix converter based on virtual impedance method,designs the corresponding control parameters,and verifies the effectiveness of the control strategy through numerical simulation.5.An experimental platform of a unidirectional high-frequency isolated matrix converter is developed based on MOSFET power devices.The experimental platform is built and verified by experiments.The experimental results verify the effectiveness and feasibility of the operation principle,modulation strategy and control strategy of the unidirectional highfrequency isolated matrix converter.The research results of this paper can be used in the field of electric vehicle charging and wind power generation.