Fault‐tolerant multilevel cascaded H‐bridge inverter using impedance‐sourced network

Abstract

This study proposes a fault-tolerant scheme for an impedance-sourced cascaded H-bridge (CHB) converter that can fully restore the converter operation to the pre-fault conditions without any hardware intervention. The proposed faulttolerant scheme has three key elements: a new quasi-z-source CHB converter, a modified modulation method for the introduced z-source CHB, and a modified implementation of the fundamental phase shift compensation (FPSC) method. In case of a fault on one of the inverter switches, the proposed fault-tolerant scheme enables the z-source CHB to generate balanced line-to-line voltages with the same amplitude as the pre-fault voltages, while evenly distributing an inevitable voltage stress increase over all converter switches. In this study, first a brief review of CHB converters and the FPSC method is provided. Then the proposed fault-tolerant scheme is introduced. Finally, several experimental results from a prototype converter are provided to validate the operation of the proposed strategy.

Investigation on pulse‐width amplitude modulation‐based single‐phase quasi‐Z‐source photovoltaic inverter

“…Further, there is no requirement of phase-leg dead time, which improves reliability and lowers ac output harmonics. The single-phase qZSI has broad applications, because it works not only as an independent single-phase power system [1,[5][6][7][8][9][10][11][12][13][14][15], but also as a power module within a cascaded multilevel inverter (CMI), so-called quasi-Z-source (qZS)-CMI [1][2][3][4][16][17][18][19][20][21][22]. For the single-phase qZSI and the formed qZS-CMI, modulation methods have a significant effect on the size of passive components, due to the second harmonic (2ω) power flowing from the ac side to dc side.…”

Computationally Efficient Distributed Predictive Controller for Cascaded Multilevel Impedance Source Inverter With LVRT Capability

“…The analysis of qZS-CMI topologies is investigated in [20]- [23]. In [24], MPC for a grid-tied qZS multilevel inverter is proposed; however non-linearities and fluctuations of PV sources are not considered in the control scheme.…”

Contribución al desarrollo de convertidores multinivel de alta tensión tolerantes a fallos

“…Las ventajas de usar varios tipos de Impedance-Source Networks con Convertidores Multinivel, han sido documentadas en la literatura. De esta forma se es capaz de aprovechar las características de las dos topologías: alta eficiencia, bajo estrés de conmutación y baja distorsión armónica, [26]. Las "Z source networks" (ZSIs), son fácilmente adaptables a los Convertidores de Potencia de la topología Cascaded Hbridge.…”

“…Esta ganancia la conseguiremos aumentando la tensión (figura 2.16), aprovechando las características del qZSI. Los resultados obtenidos en [26], se pueden ver en la figura 2.17, donde se representan las tensiones compuestas y simples de las 3 fases y la tensión de una celda ante un fallo en la fase 'b' y otro fallo en la fase 'c'. En estas condiciones, los ángulos de las tensiones simples son ajustados a = = = 101,5°.…”

“…En caso de que ocurra una falta, el ZSI-CHB ofrece una flexibilidad al poder implementar el FPS y poder restaurar las mismas condiciones post-falta previas al fallo sin necesidad de actuar sobre la configuración del hardware. En[26], integra cuasi-ZSIs junto al tradicional Cascaded H-bridge, tal y como se puede ver en la figura 2.16.…”