Modulation Strategy for Multiphase Neutral-Point-Clamped Converters
Date
2016-02Keywords
carrier-based modulation
multilevel multiphase converter
neutral-point-clamped (NPC) converter
pulse width modulated inverters
three-level converter
voltage balance
Abstract
This paper presents a novel modulation strategy for n-phase neutral-point-clamped (NPC) converters. The proposed modulation strategy is able to control and completely remove the low-frequency neutral-point (NP) voltage oscillations for any operation point and load types. Even when unbalanced and/or nonlinear loads are considered, the NP voltage remains under total control. Consequently, the strategy is very attractive for n-phase active filters. In addition, it enables the use of low-capacity film capacitors in NPC converters. The proposed modulation takes the carrier-based modulation strategy as a basis. It is formulated following a generalized approach that makes it expandable to n-phase NPC converters. In addition, the NP voltage is controlled directly using a closed-loop algorithm that does not rely on the use of the linear control regulators or the additional compensators used in other modulation algorithms. Therefore, no tuning of parameters is required and it performs optimally ...
Type
journal article