The 3L-NPC (three-level Neutral-Point-Clamped) is the most popular multilevel converter used in high-power medium-voltage applications. An important disadvantage of this structure is the unequal distribution of losses among the switches. The performances of 3L-NPC structure were improved by developing the 3L-ANPC (Active-NPC) converter which has more degrees of freedom. In this paper the switching states and the loss distribution problem are studied for different PWM strategies. A new PWM strategy is also proposed in the paper. It has numerous advantages: (a) natural doubling of the apparent switching frequency without using the flying-capacitor concept, (b) dead times do not influence the operating mode at 50% of the duty cycle, (c) operating at both high and small switching frequencies without structural modifications and (d) better balancing of loss distribution in switches. The PSIM simulation results are shown in order to validate the proposed PWM strategy and the analysis of the switching states.
The 3L-NPC (three-level Neutral-Point-Clamped) is the most popular multilevel converter used in high-power mediumvoltage applications. An important disadvantage of this structure is the unequal distribution of losses among the switches. The performances of 3L-NPC structure were improved by developing the 3L-ANPC (Active-NPC) converter which have more degrees of freedom. In this paper the switching states are studied for different PWM strategies. A numeric calculus method for the total losses in switches was also presented in order to compare the efficiency for the 3L-NPC and 3L-ANPC converters. The PSIM simulation results are shown in order to validate the analysis of the switching states.
The unequal distribution of losses among the semiconductors represents one major disadvantage for 3L-SC (Stacked Cells) and 3L-NPC (Neutral Point Clamped) commutation cells. The paper studies the loss distribution problem for 3L-SC and 3L-NPC topologies and proposes the 3L-SNPC (Stacked NPC) commutation cell to overcome this drawback. A new PWM strategy for 3L-SNPC commutation cell is also presented. It has numerous advantages: (a) natural doubling of the apparent switching frequency without using the flying-capacitor concept, (b) dead times do not influence the operating mode at 50% of the duty cycle, (c) operating at both high and small switching frequencies without structural modifications and (d) better balancing of loss distribution in switches. The PSIM simulation and experimental results are shown in order to validate the proposed PWM strategy and the analysis of the switching states.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.