Optimization Control Method Of Backflow Power Of Isolated AC-DC Matrix Converter

Bidirectional isolated AC-DC Matrix Converter（IAMC）has the advantages of bidirectional energy flow,controllable input power factor,high transmission efficiency,no DC side energy storage link and strong reliability.It has been widely used in new energy power generation system,communication power supply and battery energy storage system.The above applications have a high demand for energy transmission efficiency.However,in the actual operation of the system,when the output voltage of the three-phase to single-phase matrix converter is opposite to the transmission inductance current,it will lead to the problem of return power and seriously reduce the transmission efficiency of IAMC.Therefore,it is necessary to propose corresponding control algorithm to solve the problem of reflux power in IAMC.Firstly,this paper briefly introduces the research background and significance of matrix converter.The research status of reflux power control method is described.Then,the working principle of IAMC under two-stage coordinated modulation strategy is described in detail,It includes the bipolar current space vector modulation（B-C-SVM）modulation strategy adopted at the side of three-phase to single-phase matrix converter（3-1MC）and the single-phase-shift（SPS）coordinated control strategy adopted at the side of H（full）bridge converter.The working modes of IAMC under SPS control are analyzed in detail,The generation mechanism of reflux power in IAMC is explained,and the power model under SPS control is constructed.The working principle of IAMC under dual-phase-shift（DPS）control is analyzed,and the working mode under this control mode is analyzed.On this basis,the corresponding power model is deduced.Then a DPS control method based on IAMC is proposed.The control method can achieve:given different DC voltage U₀,the optimal internal and external shift comparison combination when the return power is zero can be obtained by using the proposed control method.When the system meets the optimal internal and external shift phase ratio,the return power in IAMC can be basically eliminated;When different external phase shift ratios are given,the unique internal phase shift ratio can be obtained by using this algorithm.When the system meets the internal and external phase shift ratio,the return power is basically eliminated.The simulation model of the system is built in Matlab.Through the comparative analysis of the simulation experiment results,the feasibility of the proposed method is verified.Next,the return power of IAMC under triple-phase-shift（TPS）control is studied,the working principle of IAMC under TPS control is analyzed,the working mode under this control mode is analyzed,the backflow power model is deduced,and the theoretical phase-shift ratio combination when the backflow power is zero is obtained.Finally,the simulation experiment platform of the control system is built,simulation results verify the advantages of this control method.