Efficient Modulation Technique for a Four-Leg Fault-Tolerant Neutral-Point-Clamped Inverter

Abstract

This paper presents a new low-loss modulation technique for the hybrid three-level four-leg converter. The total losses of the converter are reduced on about 18% in average compared to the standard three-leg neutral-point-clamped converter. Furthermore, the low-frequency voltage oscillation in the neutral-point is completely cancelled, and maximum benefit of the dc-link voltage is obtained. All these facts, together with the fault-tolerant ability due to the fourth leg, make this topology very interesting for applications such as wind generation, in which it is important to maximize efficiency and reliability. Some experimental results confirm good performance of the proposed modulation technique.

A Simplified Space-Vector Modulation Algorithm for Four-Leg NPC Converters

“…Considering all the aforementioned issues, four-leg multilevel converters, such as the four-leg NPC converter shown in Fig. 1, are attractive solutions [14], [16], [17]. To control four-leg NPC converters, different modulation approaches have been proposed in the literature.…”

The Space Vector Modulation PWM Control Methods Applied on Four Leg Inverters

“…But the Space Vector Modulation SVM has been proved to be the most favourable pulse-width modulation schemes, thanks to its major advantages such as more efficient and high DC link voltage utilization, lower output voltage harmonic distortion, less switching and conduction losses, wide linear modulation range, more output voltage magnitude and its simple digital implementation. Several works were done on the SVM PWM firstly for three legs two level inverters, later on three legs multilevel inverters of many topologies [11], [43][44][45][46], [56][57], [65][66][67][68]. For four legs inverters there were till now four families of algorithms, the first is based on the αβγ coordinates, the second is based on the abc coordinates, the third uses only the values and polarities of the natural voltages and the fourth is using a simplification of the two first families.…”

A Comparative Reliability Study of Three Fundamental Multilevel Inverters Using Two Different Approaches

“…It can be said that, in recent years, there has been much attention to redundancy structures in different circuits. For instance, different redundancy structures have been proposed for different converters: Inverters [70,71], the matrix converter [72], multilevel converters There are different researches in the field of power electronics reliability. In References [66,69], numerous redundancy structures and methods for improving the reliability of power electronic circuits have been assessed.…”

“…It can be said that, in recent years, there has been much attention to redundancy structures in different circuits. For instance, different redundancy structures have been proposed for different converters: Inverters [70,71], the matrix converter [72], multilevel converters [73], DC-DC converter [74], and power factor correction rectifiers [75].…”