Model predictive control based selective harmonic mitigation technique for multilevel cascaded H-bridge converters

The selective harmonic elimination (SHE) strategy is specially well suited for high-power applications where the power losses must be kept below strict limits. The SHE technique is based on offline calculations and the generation of a pre-programmed voltage waveforms eliminating some low order harmonics. An evolution of SHE is the selective harmonic mitigation (SHM) technique which is based on pre-programmed waveforms non eliminating the low order harmonics but reducing the distortion below the limits imposed by a grid code. However, the main drawback of these pre-programmed SHE and SHM techniques is a low dynamic performance. In a recent paper, an online SHE technique based on the model predictive control (MPC) has been presented improving the dynamic performance of the conventional SHE method. In this paper, the online version of the SHM technique is introduced. It is based also in the MPC strategy and has been tested in a cascaded multilevel converter obtaining a high performance with very low switching frequency

Ultra-Wideband Joint Spatial Coding for Secure Communication and High-Resolution Imaging

This paper introduces new techniques for ultra-wideband (UWB) joint spatial coding in order to establish a secure line-of-sight wireless communication link, performing precision localization of point objects, and generating high-resolution images from complex scenes. For the proposed technique, symbol generation and coding are jointly performed by multiple widely spaced transmitters. This method enables the transmission of directionally modulated signals that can only be decoded at a desired angle, resulting in a secure communication link. It is also shown that joint spatial coding by multiple transmitters that are synchronized with each other enables the precise localization of multiple point objects and allows high-resolution 3-D imaging of distributed objects. The technique is demonstrated experimentally in the frequency range 3-10 GHz by generating and detecting UWB pulses.ISSN:0018-9480ISSN:1557-967