Direct Power Control of PWM rectifier with elimination of dc voltage oscillations and current harmonics under unbalanced network

© 2017 IEEE. Direct power control (DPC) is an attractive control method for three-phase pulse-width modulation (PWM) rectifiers, due to the merits of simple structure, quick dynamic response and little tuning work. However, conventional switching table based DPC presents relatively high power ripples and current harmonics, which is especially serious when the grid voltages are unbalanced. Introducing space vector modulation (SVM) into DPC can obtain improved steady state performance with fixed switching frequency. However, it still presents highly distorted grid current and oscillations in dc voltage with unbalanced network. This paper proposes a novel DPC-SVM method which is not only able to eliminate the harmonics in the grid current but also obtain a constant dc voltage in the output side. Compared to conventional DPC-SVM, the proposed method only needs to add a power compensation block to the original power references. Thus, the advantages of conventional DPC-SVM, such as simple structure, fast dynamic performance and good steadystate performance, are fully reserved. Experimental tests are carried out to verify the effectiveness of the proposed method