A New Modulation Strategy to Improve the Performance of Bidirectional Isolated AC-DC Matrix Converter

For the bidirectional isolated AC-DC matrix converter(BIMC), a cooperative modulation strategy of the front-stage matrix circuit and the back-stage full-bridge circuit is proposed. The modulation of the front-stage matrix circuit is based on the idea of two-wire voltage modulation. The back-stage’s full-bridge circuit cooperates with the front-stage’s two-line voltage, and it is coordinated and controlled by alternately adjusting the phase shift angle and pulse width. The simulation results show that the modulation method can meet the requirements of grid-side current THD in both rectifier and inverter modes, the power factor is close to 1, the dynamic response of load shedding is fast, and the high-frequency flux linkage transformer has no DC bias. And compared with the traditional phase-shift modulation, the high-frequency flux linkage inductor current ripple is reduced by 39.2%. This proves that the proposed modulation strategy can well realize bidirectional power transmission and can reduce the high frequency flux linkage inductor current ripple.