Performance evaluation of three control strategies for three-level neutral point clamped PWM rectifier

This paper presents the performance evaluation and comparisons of three typical control strategies for three-level neutral point clamped (NPC) rectifier with pulse width modulation (PWM). These are voltage oriented control (VOC), direct power control (DPC) and direct power control based on space vector modulation (DPC-SVM). The theoretical background is described, and the advantages and disadvantages of each scheme are studied through analyses and a series of experiments. A comprehensive comparison and evaluation are implemented for the three methods from several aspects such as algorithm complexity, steady state and dynamic performances, current THD with unbalanced power source voltage, and startup current which is important for the high power applications. The results show that all the three schemes can provide good abilities; and VOC and DPC-SVM possess better steady state performance while DPC is provided with best dynamic performance.