An Algebraic Modulation and Controlled-Impedance-Source Method for Vienna Rectifier Under Unbalanced Conditions

Generally, the performance of the Vienna rectifier is severely affected by the dc-side unbalanced capacitance and load, the ac-side unbalanced inductance, and the nonideal grid voltage. To solve these problems, an algebraic modulation and a controlled-impedance-source method are proposed in this article. The algebraic modulation method achieved neutral-point (NP) voltage control in the case of asymmetric parameters on the dc-side. The decoupling of NP potential balance control and vector synthesis can be achieved. In addition, the controlled-impedance-source method shapes the Vienna rectifier into a controlled impedance, and in this way, control objectives under unbalanced ac-side parameters are simply and effectively achieved. Different controlled-impedance-source forms can achieve three basic control objectives including symmetrical input current, constant active power, and constant reactive power. Experiments verify the effectiveness of the proposed methods.