Uncoupled direct power control based on improved sector selection algorithm for three-level PWM rectifier

Direct power control (DPC) is a popular control strategy with superior dynamic performances for pulse width modulation (PWM) rectifiers. However, when the conventional DPC is applied to three-level PWM rectifiers, the coupling between controls of active power and reactive power depresses the steady state performances seriously. By improving the switching table of three-level DPC, the effect of power control coupling can be eliminated to some extent. But at the same time, switching frequency of the rectifier will be distinctly increased due to the enlarged optional vector range of the improved switching table, which is unacceptable to high power applications. In this paper, based on the analyses of power control coupling and its effect, an uncoupled three-level DPC with improved sector selection algorithm is proposed in order to eliminate the control coupling without increasing the switching frequency. Experimental results verify the feasibility and the superiority of the proposed strategy.