A HPF AC-AC converter for Permanent Magnet Generator applications

This paper describes the design and development of a high input power-factor (HPF) AC to AC converter for naval applications using Permanent Magnet Generator (PMG). The proposed converter comprises an isolated three-phase uncontrolled multipulse rectification stage directly connected to a single-phase inverter stage, without the use of DC to DC intermediary stage, resulting in more simplicity for the overall circuitry, assuring robustness, reliability and reduced costs. Furthermore, the multipulse rectifier stage is capable to provide high power factor and input currents with low total harmonic distortion (THD). The output voltage of the PMG varies from 260V rms (220 Hz) to 380V rms (360 Hz), depending on load conditions. The output single-phase inverter stage was designed to operate with wide range of DC bus voltage, maintaining 120V rms, 60 Hz output. Measured total harmonic distortion for the AC output voltage represents less than 2%, at 3.6kW nominal linear load. © 2010 IEEE.

Proposal of a dedicated telemetry device for real-time and remote measurements

This work aims to demonstrate an application of telemetry for monitoring process variables. The authors developed the prototype of a dedicated device capable of multiplexing, encoding and transmitting real-time data signals via amplitude-shift keying modulation to remotely located device(s). The prototype development is described in details, enabling the reproduction of the proposed telemetry system for a three-phase motor as well as for other devices. Furthermore, the proposed device has an easy implementation by using of accessible components and low cost, also presenting a tutorial and educational purpose. © 2011 IEEE.

Comparative analysis of current and voltage-controlled photovoltaic Maximum Power Point tracking

Maximum Power Point tracking (MPPT) in photovoltaic (PV) systems may be achieved by controlling either the voltage or current of the PV device. There is no consensus in the technical literature about how is the best choice. This paper provides a comparative analysis performance among current and voltage control using two different MPPT strategies: the perturb and observe (P&O) and the incremental conductance techniques. © 2011 IEEE.

Main maximum power point tracking strategies intended for photovoltaics

This paper presents evaluations among the most usual MPPT techniques, doing meaningful comparisons with respect to the amount of energy extracted from the photovoltaic panel (PV) (Tracking Factor - TF) in relation to the available power, PV voltage ripple, dynamic response and use of sensors. Using MatLab/Simulink® and DSpace platforms, a digitally controlled boost DC-DC converter was implemented and connected to an Agilent Solar Array E4350B simulator in order to verify the analytical procedures. The main experimental results are presented and a contribution in the implementation of the IC algorithm is performed and called IC based on PI. Moreover, the dynamic response and the tracking factor are also evaluated using a Friendly User Interface, which is capable of online program power curves and compute the TF. Finally, a typical daily insulation is used in order to verify the experimental results for the main PV MPPT methods. © 2011 IEEE.

Bridgeless interleaved boost PFC converter with variable duty cycle control

This paper proposes a bridgeless boost interleaved PFC (power factor correction) converter with variable duty cycle control. The application of bridgeless technique causes reduction of conduction losses, while the interleaving technique of converters cells allows division of efforts in semiconductor devices and reduction of weight and volume of the input EMI filter. The use of variable duty cycle control has the functions of regulating the output voltage and eliminating the low order harmonic components that appears in the input current of the common interleaved power factor converters working in Discontinuous Conduction Mode (DCM). The simulation results of the proposed converter presented high power factor and a good transient response in relation to the output voltage regulation in presence of high load variations and supply voltage variations. © 2011 IEEE.

AC-DC three-phase multipulse converter with boost DC-DC stage and constant hysteresis control

This work proposes a new three-phase multipulse rectifier based on the delta autotransformer connection with DC-DC Boost stages and constant hysteresis control which has the objective of providing a reliable DC bus for on-board applications, electric motor drives and similars, always considering power quality issues. Thus, the proposal presents 0.99 power factor, 6% harmonic distortions in the currents from the mains and enhanced magnetic core utilization, which results in low weight and volume for the overall converter. The proposed control technique uses the simple constant hysteresis concept, thus leading to a low-cost but effective and reliable strategy. © 2011 IEEE.

Resonant (P+RES) controller applied to voltage source inverter with minimum DC link capacitor

Voltage source inverters use large electrolytic capacitors in order to decouple the energy between the utility and the load, keeping the DC link voltage constant. Decreasing the capacitance reduces the distortion in the inverter input current but this also affects the load with low-order harmonics and generate disturbances at the input voltage. This paper applies the P+RES controller to solve the challenge of regulating the output current by means of controlling the magnitude of the current space vector, keeping it constant thus rejecting harmonic disturbances that would otherwise propagate to the load. This work presents a discussion of the switching and control strategy. © 2011 IEEE.

Power flow optimization for grid connected inverter using evolutionary algorithm and additional control loop

In this work it is proposed to validate an evolutionary tuning algorithm in plants composed by a grid connected inverter. The optimization aims the tuning of the slopes of P-Ω and Q-V curves so that the system is stable, damped and minimum settling time. Simulation and experimental results are presented to prove the feasibility of the proposed approach. However, experimental results demonstrate a compromising effect of grid frequency oscillations in the active power transferring. In addition, it was proposed an additional loop to compensate this effect ensuring a constant active power flow. © 2011 IEEE.

Reference generator for voltage controlled power conditioners

Voltage reference generation is an important issue on electronic power conditioners or voltage compensators connected to the electric grid. Several equipments, such as Dynamic Voltage Restorers (DVR), Uninterruptable Power Supplies (UPS) and Unified Power Quality Conditioners (UPQC) need a proper voltage reference to be able to compensate electric network disturbances. This work presents a new reference generator's algorithm, based on vector algebra and digital filtering techniques. It is particularly suited for the development of voltage compensators with energy storage, which would be able to mitigate steady state disturbances, such as waveform distortions and unbalances, and also transient disturbances, like voltage sags and swells. Simulation and experimental results are presented for the validation of the proposed algorithm. © 2011 IEEE.

Shunt active compensation based on the Conservative Power Theory current's decomposition

Considering the operation of shunt active compensators, such as active power filters, this paper proposes possible compensation strategies by means of the recent formulation of the Conservative Power Theory (CPT). The CPT current's decomposition results in several current components, which are associated with specific load characteristics (power transfer, energy storage, unbalances and/or non linearities). These current components are used for the definition of different compensation strategies, which can be selective in terms of minimizing particular disturbing effects. In order to validate the applicability of these new compensation strategies, simulation and experimental results for three-phase four-wire systems are presented. © 2011 IEEE.

Properties of individual YBCO layers in a two-layered design for energy-efficient digital data cables

We are developing two-layered Yttrium Barium Copper Oxide (YBCO) thin film structures for energy efficient data links for superconducting electronics and present the results of their property measurements. High temperature superconductors (HTS) are advantageous for the implementation of energy-efficient cables interconnecting low temperature superconductor-based circuits and other cryogenic electronics circuits at higher temperature stages. The advantages of the HTS cables come from their low loss and low dispersion properties, allowing ballistic transfer of low power signals with very high bandwidth, low heat conduction and negligible inter-line crosstalk. The microstrip line cable geometry for typical materials is a two-layered film, in which the two superconducting layers are separated by an insulation layer with a minimized permittivity. We have made a proof of concept design of two YBCO films grown by pulsed laser deposition and then assembled into a sandwich with uniform insulating interlayer of tens of micrometers thick. We report on results obtained from such systems assembled in different ways. Structural and electromagnetic properties have been examined on individual films and on the corresponding sandwich composite. © 2013 IEEE.

Sistema de extração de potência (power harvesting) usando transdutores piezelétricos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Uma nova metodologia de projeto e controle para o inversor Boost (CSI) monofásico, para o aproveitamento de fontes alternativas e renováveis de energia elétrica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Supressor eletromagnético de componentes harmônicas de sequência zero

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise e aplicação de compensação reativa em redes secundária de distribuição com cargas não lineares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)