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This manuscript describes harmonic generation in semiconductor superlattices, starting from a\ud Nonequilibrium Green's functions input to relaxation rate-type analytical approximations for the\ud Boltzmann Equation in which imperfections in the structure lead to asymmetric current flow and\ud scattering processes under forward and reverse bias. The resulting current-voltage curves and the\ud predicted consequences on harmonic generation, notably the development of even harmonics are in\ud good agreement with experiments. Significant output for frequencies close to 1 THz (7th harmonic)\ud at room temperature, after excitation by a 141 GHz input signal, demonstrate the potential of\ud superlattice devices for GHz-THz applications.

Harmonic distortion is often a challenge in marine vessel power systems due to the presence of large motor drives containing diode or thyristor rectifiers. Governing standards impose requirements on bus voltage Total Harmonic Distortion (THD) which can be demanding to fulfil. An attractive measure to reduce THD is to use 12-pulse rectifiers, as they are known to cancel the 5th and the 7th harmonic. However, the added cost and space of this solution compared with standard 6-pulse rectifiers is significant. This paper proposes to base propulsion motor drives on 6-pulse rectifiers, and mitigate harmonic problems by means of power electronic based active filters. A detailed numeric simulation model is developed for evaluating the performance of the topology. A case study system is defined consisting of two propulsion motor drives and two synchronous generators. The active filter greatly improves the bus voltage THD in all defined simulation cases. The performance is also better than a corresponding system using 12-pulse rectifiers and no active filter © 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

Summary form only given. Partial discharge (PD) monitoring is a key method of tracking fault progression and degradation of insulation systems. Recent research discovered that the harmonic regime experienced by the plant also affects the partial discharge pattern, questioning the conclusions about equipment health drawn from PD data. This paper presents the design and creation of an on-line system for harmonic circumstance monitoring of distribution cables, using only PD data. Based on machine learning techniques, the system can assess the prevalence of the 5th and 7th harmonic orders over the monitoring period. This information is key for asset managers to draw correct conclusions about the remaining life of polymeric cable insulation, and prevent overestimation of the degradation trend.

A discrete-time predictive current controller, for the application of active power filtering, is designed and analyzed in this paper. A modified algorithm of reference current prediction in the conditions of step change in amplitude and/or frequency is proposed. The theoretical analysis and the validity of the proposed method are verified by simulations. Comparison for the 5th and the 7th harmonic current control is made with the results achieved using synchronous PI plus lead compensator.

International audience; This paper presents a vector control of a 5-phase drive composed of a 5-leg Pulse Width Modulation (PWM) Voltage Source Inverter (VSI) supplying a permanent-magnet Brushless DC (BLDC) machine with trapezoidal waveform of the back-electromotive force (EMF). To achieve this control a Multi-machine Multi-converter model is used: the 5-phase machine is transformed into a set of two 2-phase fictitious machines which are each one controlled in a (d,q) frame as 3-phase machines with sine waveform back-EMF. In comparison with the 3-phase BLDC drives, the 5-phase ones present one particularity: a high sensitivity to the 7th harmonic of back-EMF. Experimental results show that the 7th harmonic of back-EMF, which represents only 5% of RMS back-EMF, induces high amplitude parasitic currents (29 % percent of RMS current). The model allows to explain the origin of this sensitivity and how to modify simply the control algorithm. Experimental improvements of the drive are presented.