Natural doubling of the apparent switching frequency using three-level ANPC converter

Abstract

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.

Reliability-Driven Assessment of GaN HEMTs and Si IGBTs in 3L-ANPC PV Inverters

“…Different modulation strategies can be implemented for the 3L-ANPC inverter in order to achieve a balanced switching loss distribution or doubling of the effective switching frequency at the output [34]. Solutions proposed in [31]- [33] and [35] are limited to the use of Si devices and were optimized for IGBTs as well as for MOSFETs.…”

Multilevel Inverters Power Topologies and Voltage Quality: A Literature Review

“…For instance, it is possible to choose the modulation type for balancing losses. An active NPC topology (ANPC) was proposed in [13]. By adopting a modified PWM strategy, this topology is able to double the apparent switching frequency and enhances the loss distribution balance in semi-conductors.…”

“…As a consequence, cascaded H-bridge, NPC and FLC are the basic and most used multilevel inverters. After that, multitude of derived and hybrid multilevel topologies were introduced [6][7][8][9][10][11][12][13][14][15][16]. However, they still on the shadow of the major multilevel configurations previously stated.…”

Transformerless topologies for grid-connected single-phase photovoltaic inverters

“…This topology is called active NPC (ANPC) and its main feature lies in the control of the current path during the free-wheeling periods [63,64], which lets the distribution of losses to be improved [65][66][67], thus loading uniformly the power transistors, and increasing the maximum output power of the converter [49,51]. However, sometimes it could be cheaper to select a higher maximum current NPC topology [68], especially in low-power applications.…”