Modified Unipolar Carrier-Based PWM Strategy for Three-Level Neutral-Point-Clamped Voltage Source Inverters

Abstract

-This paper presents a simple modified unipolar carrier-based pulsewidth modulation (CB-PWM) strategy for the three-level neutral-point-clamped (NPC) voltage source inverter (VSI). Analytical expressions for the relationship between modulation reference signals and output voltages are derived. The proposed modulation technique for the three-level NPC VSI includes the maximum and minimum of the three-phase sinusoidal reference voltages with zero-sequence voltage injection concept. The proposed modified CB-PWM strategy incorporates a novel method that requires only of one triangular carrier wave for generate the gating pulses in three-level NPC VSI. It has the advantages of being simplifying the algorithm with no need of complex two/multi-carrier pulsewidth modulation or space vector modulation (SVM) and it's also simple to implement. The possibility of the proposed CB-PWM technique has been verified though computer simulation and experimental results.

Harmonic Domain Modelling of Space Vector Based STATCOM

“…Previous work conducted in harmonic domain has been primarily focus on modeling PWM, multi-module, selective harmonic elimination based STATCOM [11]. The complete equivalent circuit, represented as a harmonic Norton equivalent, is incorporated in the external system according to the transformer electrical connections [5] [12]- [15].…”

FCS-MPC Control Strategy for a New Fault Tolerant Three-level Inverter

“…However, the inverter still exist some problems, firstly, the unbalance of neutral point across the dc-link will generate order harmonic in output [3], a modulation strategy was proposed in [4] which ensures that the average neutral-point current within a switching period is equal to zero,. However, the nonidealities of the components, transients, etc., may cause the neutral-point voltage variation.…”