An Easy-Implemented Pulsewidth Modulation Method for Vienna Rectifier With Minimized Current Distortion Including Overmodulation Operation

Vienna rectifier is a unidirectional three-level ac–dc converter, which is widely used in many applications. For Vienna rectifier, the current zero crossing distortion (CZCD) is usually occurred because the reference voltage vector cannot be accurately synthesized although in the linear modulation region. Moreover, in the overmodulation region, the reference voltage vector also cannot be accurately synthesized, which results in current distortion. To alleviate current distortion, a modulation method including overmodulation region is proposed for Vienna rectifier in this article. By redividing space vector diagram according to the characteristic of voltage vector synthesis, the corresponding modulation methods suitable for different regions are derived. The criteria and final modulation voltages of each region are obtained only with simple algebraic operation. Besides, active neutral point voltage (NPV) control method is also considered. Finally, the superiority of the proposed modulation method is verified by theoretical analysis and experiments.