Research Of Modulation Strategy Of Restraining The Influence Of Abnormal Input Voltage And Imporving The Voltage Transfer Ratio

There is no energy storage element in matrix converter topology, input side and output side connected directly, and this is one of the matrix converter's advantages. However, it can affect output performance of converter with abnormal input voltage; meanwhile, the voltage transfer ratio of matrix converter is low and it cannot satisfy the need of actual drive system. The problems of the influence on output performance of matrix converter under abnormal working condition and low voltage transfer ratio are researched.Basic principle of matrix converter and double space vector modulation are discoursed and output performance of matrix converter at the condition of abnormal operating mode (unbalanced,non-sinusoidal and abrupt input voltage) is investigated. Feed-forward compensation algorithm is adopted to compensate influence caused by abnormal operating mode, theoretical and simulation analyses are carried out simultaneously, and results show that the algorithm is effective.In order to raise voltage transfer ratio and compensate the influence of abnormal input, the inverter modulation strategy of the virtual uncontrollable rectification matrix converter is modified and feed-forward compensation algorithm is adopted. The modified strategy can not only raise the voltage transfer ratio up to 0.95 in linear range but also restrain low order harmonic component and influence on matrix converter output performance at abnormal input voltage.The paper adopts a method that the high-frequency transformer has been added into the topology of the matrix converter in order to solve the problem of the lower voltages transfer ratio. The space vector modulation strategy (SVPWM) and feed-forward compensation algorithm are adopted to improve the method. It can amend output performance of matrix converter, raise the voltage transfer ratio up to 1 and improve the output wave under the abnormal working condition significantly.Two kinds of simulations models of the matrix converter modified strategies have been built. The simulation results indicate that the two strategies can both restrain the distortion of the output voltage under the abnormal input and improve the voltage transfer.The control strategy is coded on DSP28335, which is the core of control unit of the matrix converter. The improved modulation strategy is proved to be practicable and effective.