Search

Cascaded H-Bridges Multilevel Inverters are an innovative and promising solution in different application fields. This topology allows obtaining an improvement in the performance (e.g. reduced harmonic content, the low voltage stress on power components, and high efficiency) in respect to the traditional two-level inverters. In this context, the Multicarrier-PWM strategies play an important role thanks to their features. This paper presents an experimental investigation on the performance of a three-phase five-level Cascaded H-Bridge inverter by using different PWM modulation strategies. In particular, the paper is focused on the experimental validation of the main features of Multicarrier PWM taken into account by varying the modulation index and the switching frequency.

The underlying concept of the Internet of Things (IoT) is simply to connect all devices and systems together via the Internet so that more suitable services can be provided to users. Many infrastructures, systems, and devices of the IoT have matured while some are still being developed. This is why several recent studies have claimed that IoT will dramatically change our lives. Today, we can find research topics driven by IoT technologies and can imagine that the era of smart homes and cities will be coming in the foreseeable future. The development of the IoT has reached a crossroad. One of the current research trends is to make this kind of system smarter, by using intelligent technologies to provide a much more convenient environment for humans. Among the intelligent technologies, how to handle the massive amount of data generated by the systems and devices of the IoT has been widely considered. Many other technologies, such as data mining, big data analytics, statistical and other analysis technologies, have also been used for analyzing data generated from the IoT. In addition to the analysis technologies, intelligent system technologies also provide many possibilities for the IoT because they can be used to enhance not only the performance of a system and its devices, but they can also be aware of events that have occurred.

The power quality requirements are increasingly stringent, due to the continuous growth of devices connected to the grid that introduce harmonics. These devices include DC to AC energy conversion systems, i.e. grid connected inverters. The design, control and operation of these systems must take into account the rules of interconnection to the electricity grid. To improve the quality of the output waveform of the grid-connected inverter, Multilevel Converters (MC) with selective harmonic elimination modulation technique can be used. This paper presents a single-phase nine level grid-connected inverter with DC/DC input stages. The obtained switching angles for THD minimization are independent of the modulation index. The proposed control technique is able to regulate both the active and the reactive power, acting respectively on the control of the DC/DC and the inverter stages.

This paper presents an overview and experimental analysis of the MC SPWM techniques for single-phase cascaded H-bridge inverter. The multilevel power converters are an alternative to traditional converters known as “three-level converters”. The voltage waveforms and the related frequency spectra, which have been obtained by simulation analysis in Matlab-Simulink environment, are here reported for all the proposed modulation techniques. The simulation results have been experimentally validated through means of a DC/AC, five-level, single-phase converter prototype with an appropriate test bench.