15 research outputs found
Co-simulation techniques based on virtual platforms for SoC design and verification in power electronics applications
En las 煤ltimas d茅cadas, la inversi贸n en el 谩mbito energ茅tico ha aumentado considerablemente. Actualmente, existen numerosas empresas que est谩n desarrollando equipos como convertidores de potencia o m谩quinas el茅ctricas con sistemas de control de 煤ltima generaci贸n. La tendencia actual es usar System-on-chips y Field Programmable Gate Arrays para implementar todo el sistema de control. Estos dispositivos facilitan el uso de algoritmos de control m谩s complejos y eficientes, mejorando la eficiencia de los equipos y habilitando la integraci贸n de los sistemas renovables en la red el茅ctrica. Sin embargo, la complejidad de los sistemas de control tambi茅n ha aumentado considerablemente y con ello la dificultad de su verificaci贸n.
Los sistemas Hardware-in-the-loop (HIL) se han presentado como una soluci贸n para la verificaci贸n no destructiva de los equipos energ茅ticos, evitando accidentes y pruebas de alto coste en bancos de ensayo. Los sistemas HIL simulan en tiempo real el comportamiento de la planta de potencia y su interfaz para realizar las pruebas con la placa de control en un entorno seguro.
Esta tesis se centra en mejorar el proceso de verificaci贸n de los sistemas de control en aplicaciones de electr贸nica potencia. La contribuci贸n general es proporcionar una alternativa a al uso de los HIL para la verificaci贸n del hardware/software de la tarjeta de control. La alternativa se basa en la t茅cnica de Software-in-the-loop (SIL) y trata de superar o abordar las limitaciones encontradas hasta la fecha en el SIL.
Para mejorar las cualidades de SIL se ha desarrollado una herramienta software denominada COSIL que permite co-simular la implementaci贸n e integraci贸n final del sistema de control, sea software (CPU), hardware (FPGA) o una mezcla de software y hardware, al mismo tiempo que su interacci贸n con la planta de potencia. Dicha plataforma puede trabajar en m煤ltiples niveles de abstracci贸n e incluye soporte para realizar co-simulaci贸n mixtas en distintos lenguajes como C o VHDL.
A lo largo de la tesis se hace hincapi茅 en mejorar una de las limitaciones de SIL, su baja velocidad de simulaci贸n. Se proponen diferentes soluciones como el uso de emuladores software, distintos niveles de abstracci贸n del software y hardware, o relojes locales en los m贸dulos de la FPGA. En especial se aporta un mecanismo de sincronizaron externa para el emulador software QEMU habilitando su emulaci贸n multi-core. Esta aportaci贸n habilita el uso de QEMU en plataformas virtuales de co-simulacion como COSIL.
Toda la plataforma COSIL, incluido el uso de QEMU, se ha analizado bajo diferentes tipos de aplicaciones y bajo un proyecto industrial real. Su uso ha sido cr铆tico para desarrollar y verificar el software y hardware del sistema de control de un convertidor de 400 kVA
An Investigation into the Implementation and Performance of Spectrally Shaped Orthogonal Frequency Division Multiplex
Orthogonal Frequency Division Multiplex (OFDM) is a flexible, robust multi-carrier
modulation scheme. The orthogonal spectral shaping and spacing of OFDM sub-carriers
ensure that their spectra can be over-lapped without leading to undesirable inter-carrier
interference. Conventional OFDM systems have non-band limited Sinc(x) shaped subcarrier
spectra. An alternative form of OFDM, referred to hereafter as Spectrally Shaped
OFDM, employs band limited Nyquist shaped sub-carrier spectra. The research described
in this thesis investigates the strengths and weaknesses of Spectrally Shaped OFDM as a
potential modulation scheme for future mobile radio applications.
From this research a novel Digital Signal Processing architecture for modulating and
demodulating Spectrally Shaped OFDM sub-carriers has been derived which exploits the
combination of a complex Discrete Fourier Transform (DFT) and PolyPhase Network
(PPN) filter. This architecture is shown to significantly reduce the minimum number of
computations required per symbol compared to previous designs.
Using a custom coded computer simulation, the effects of varying the key parameters of
the novel architecture's PolyPhase Filter (PPN) filter an the overall system complexity,
spectral performance and system signal-to-distortion have been extensively studied. From
these studies it is shown that compared to similar conventional OFDM systems, Spectrally
Shaped OFDM systems possess superior out-of-band spectral qualities but significantly
worse Peak-to-Average-Power-Ratio (PAPR) envelope performance. lt is also shown that
the absolute value of the end PPN filter coefficients (dependent on the roll-off factor of the
sub-carrier spectral shaping) dictate the system signal-to-distortion ratio when no time-domain
windowing of the PPN filter coefficients is applied. Finally the effects of a both time
and frequency selective fast fading channels on the modulation scheme's uncoded Bit
Error Rate (BER) versus Signal-to-Noise (SNR) performance are simulated. The results
obtained indicate that Spectrally Shaped OFDM is more robust (lower BER) to
frequency-selective fading than time-selective fading
Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)
Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression
NASA Tech Briefs, November 1994
Topics: Advanced Manufacturing; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Reports
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Intelligent optimisation of analogue circuits using particle swarm optimisation, genetic programming and genetic folding
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University London.This research presents various intelligent optimisation methods which are: genetic algorithm (GA), particle swarm optimisation (PSO), artificial bee colony algorithm (ABCA), firefly algorithm (FA) and bacterial foraging optimisation (BFO). It attempts to minimise analogue electronic filter and amplifier circuits, taking a cascode amplifier design as a case study, and utilising the above-mentioned intelligent optimisation algorithms with the aim of determining the best among them to be used. Small signal analysis (SSA) conversion of the cascode circuit is performed while mesh analysis is applied to transform the circuit to matrices form. Computer programmes are developed in Matlab using the above mentioned intelligent optimisation algorithms to minimise the cascode amplifier circuit. The objective function is based on input resistance, output resistance, power consumption, gain, upperfrequency band and lower frequency band. The cascode circuit result presented, applied the above-mentioned existing intelligent optimisation algorithms to optimise the same circuit and compared the techniques with the one using Nelder-Mead and the original circuit simulated in PSpice. Four circuit element types (resistors, capacitors, transistors and operational amplifier (op-amp)) are targeted using the optimisation techniques and subsequently compared to the initial circuit. The PSO based optimised result has proven to be best followed by that of GA optimised technique regarding power consumption reduction and frequency response. This work modifies symbolic circuit analysis in Matlab (MSCAM) tool which utilises Netlist from PSpice or from simulation to generate matrices. These matrices are used for optimisation or to compute circuit parameters. The tool is modified to handle both active and passive elements such as inductors, resistors, capacitors, transistors and op-amps. The transistors are transformed into SSA and op-amp use the SSA that is easy to implement in programming. Results are presented to illustrate the potential of the algorithm. Results are compared to PSpice simulation and the approach handled larger matrices dimensions compared to that of existing symbolic circuit analysis in Matlab tool (SCAM). The SCAM formed matrices by adding additional rows and columns due to how the algorithm was developed which takes more computer resources and limit its performance. Next to this, this work attempts to reduce component count in high-pass, low-pass, and all- pass active filters. Also, it uses a lower order filter to realise same results as higher order filter regarding frequency response curve. The optimisers applied are GA, PSO (the best two methods among them) and Nelder-Mead (the worst method) are used subsequently for the filters optimisation. The filters are converted into their SSA while nodal analysis is applied to transform the circuit to matrices form. High-pass, low-pass, and all- pass active filters results are presented to demonstrate the effectiveness of the technique. Results presented have shown that with a computer code, a lower order op-amp filter can be applied to realise the same results as that of a higher order one. Furthermore, PSO can realise the best results regarding frequency response for the three results, followed by GA whereas Nelder-
Mead has the worst results. Furthermore, this research introduced genetic folding (GF), MSCAM, and automatically simulated Netlist into existing genetic programming (GP), which is a new contribution in this work, which enhances the development of independent Matlab toolbox for the evolution of passive and active filter circuits. The active filter circuit evolution especially when operational amplifier is involved as a component is of it first kind in circuit evolution. In the work, only one software package is used instead of combining PSpice and Matlab in electronic circuit simulation. This saves the elapsed time for moving the simulation
between the two platforms and reduces the cost of subscription. The evolving circuit from GP using Matlab simulation is automatically transformed into a symbolic Netlist also by Matlab simulation. The Netlist is fed into MSCAM; where MSCAM uses it to generate matrices for the simulation. The matrices enhance frequency response analysis of low-pass, high-pass, band-pass, band-stop of active and passive filter circuits. After the circuit evolution using the developed GP, PSO is then applied to optimise some of the circuits. The algorithm is tested with twelve different circuits (five examples of the active filter, four examples of passive filter circuits and three examples of transistor amplifier circuits) and the results presented have shown that the algorithm is efficient regarding design.Tertiary Education Trust Fund (TETFUND) through University of Calabar, Nigeria
Proceedings of the 35th WIC Symposium on Information Theory in the Benelux and the 4th joint WIC/IEEE Symposium on Information Theory and Signal Processing in the Benelux, Eindhoven, the Netherlands May 12-13, 2014
Compressive sensing (CS) as an approach for data acquisition has recently received much attention. In CS, the signal recovery problem from the observed data requires the solution of a sparse vector from an underdetermined system of equations. The underlying sparse signal recovery problem is quite general with many applications and is the focus of this talk. The main emphasis will be on Bayesian approaches for sparse signal recovery. We will examine sparse priors such as the super-Gaussian and student-t priors and appropriate MAP estimation methods. In particular, re-weighted l2 and re-weighted l1 methods developed to solve the optimization problem will be discussed. The talk will also examine a hierarchical Bayesian framework and then study in detail an empirical Bayesian method, the Sparse Bayesian Learning (SBL) method. If time permits, we will also discuss Bayesian methods for sparse recovery problems with structure; Intra-vector correlation in the context of the block sparse model and inter-vector correlation in the context of the multiple measurement vector problem