DC-Side Voltage Harmonic Control of a Three-Phase Current Source Rectifier Under Unbalanced AC Voltage Conditions

This paper proposes a control strategy that can suppress the double-frequency fluctuation of the DC-side voltage for a three-phase current source rectifier under unbalanced ac input conditions. The proposed method obtains the reference value of the grid voltage and current at any time by extracting the positive and negative sequence components of the grid-side voltage, at the same time, starting from the complex power of the three-phase current source rectifier unbalanced system, set the power and reactive power that generate the double frequency fluctuation of the DC voltage to zero, then solve the given value of the grid current. The given value is used to calculate the control quantity at the next moment, so as to remove the second harmonic of the DC-side voltage and ensure that the grid side voltage and current being in the same phase. The proposed control strategy does not need to sample the three-phase input current, it can eliminate the double-frequency fluctuation of the DC-side voltage. A simulation model is built in MATLAB to verify the effectiveness of the proposed method.