Fabiano Salvadori

A Carrier-Based PWM Technique for Capacitor Voltage Balancing of Single-Phase Three-Level Neutral-Point-Clamped Converters

In this paper is presented a PWM technique for single-phase neutral-point-clamped converters for capacitors voltage balancing. The technique is based on the injection of a common mode voltage signal into the sinusoidal modulating signals of the conventional carrier-based pulse width modulation. Although several strategies have been reported for such a problem by using the voltage signal injection, the proposed method is very simple with easy implementation. It is presented a set of equations to demonstrate how the injected voltage signal introduces a dc component on the neutral-point current, which can be controlled in order to allow the capacitors voltages balancing. Selected results have been used demonstrate the effectiveness of the proposed strategy.

Impacto de métodos de sincronismo no desmpenho de geradores de indução auto-excitados

This paper analyzes digital sensorless control systems used to regulate the output voltages of a self-excited squirrel-cage induction generator. Different mechanical sensorless synchronization methods are evaluated and their performances are compared under several load conditions, including unbalanced and nonlinear loads. Simulation and experimental results are included to demonstrate the impact of distinct digital control systems on the output voltages distortion and the unbalance factor.

An integration algorithm for induction motor stator flux estimation with DC offset compensation

This paper presents an integration algorithm for induction motor stator flux estimation. The proposed algorithm is able to solve the problems associated with pure integrators and operates over a wide speed range. The estimated and the actual stator flux are indirectly compared by using the estimated electromagnetic torque and the measured load torque.

Low-power energy generation systems for two-phase PM machine with reduced-switch-count controlled switches

This paper presents two power generation systems with a two-phase permanent magnet (PM) synchronous machine associated to a rectifier with small number of controlled switches. The topologies have as main purpose converting wind energy into electrical energy for low power applications, providing a great potential to be used in urban areas. They can be used in applications connected to the grid or in the stand-alone mode or feeding a micro grid. Compared with two three-phase generation systems that use reduced number of controlled switches, the proposed topologies permit obtaining sinusoidal machine currents, with low harmonic distortion, using a smaller number of controlled switches. Simulation and experimental results also are presented.

Sistema de acionamento com motor de indução orientado indiretamente pelo campo com adaptação MRAC da velocidade

This paper investigates the use of the model reference control strategy for induction motor drive systems based on indirect field oriented control principles. The proposed control scheme does not require the use of any electromechanical sensor and is fairly independent of the rotor time constant. For example, this scheme is well suited for applications where there is no speed control but it is required to keep the indirect field oriented controller permanently tuned to obtain a high performance torque control. The parameter sensitivity of the control scheme to changes in rs and sls is also investigated in this paper. Experimental results are presented and demonstrate the correctness and feasibility of the proposed methodology.

Design of an intelligent electronic device based on TivaC platform for smart grid applications

Smart Grid (SG) can be defined as a modern electric power grid infrastructure for improved efficiency, reliability and safety, with smooth integration of renewable and alternative energy sources, through automated control and modern communications technologies. The increased need for more effective control on electrical power systems has led to the development and the increased research interest on SG. The construction of SG involves the positive transformation of traditional electricity networks, with one-way power flow, to a system with a new technology, by adding intelligent sensors, distributed generation and storage system, back-end information systems, smart meters and communications networks, to permit two-way power flow with communication and control. All this information should be obtained from the network. So, the development and implementation of Intelligent Electronic Device (IED) improves the efficiency, reliability and security of the electric power system. This paper presents the development of an IED, based on TivaC platform for Smart Grid applications, with high capacity processing, communication features, portability/versatility, low cost, easy integration (interoperability) and maintenance. For the communication the proposed IED uses the Hybrid Network Architecture (HNA) concept and open source programming.

Applied control strategy in a micro system interconnected between a renewable energy source and a single-phase electric power

In this paper is presented a synchronous reference frame control strategy applied to a single-phase microgrid system connected to a renewable energy power source. The control strategy aims to regulate active power flow and to optimize the power factor at the point of common coupling (PCC). The whole control system is carried out on the synchronous reference frame of the PCC voltage. On this frame the direct current is responsible for active power regulation while the quadrature one regulates power factor. The direct current is used to regulate the dc-link voltage of the single-phase converter, consequently keeping the active power balance on the system. Experimental results are presented to demonstrate the system feasibility and effectiveness.

Fault tolerant high performance drive system using six-phase induction machine

In this paper is presented a fault tolerant drive system based on Six-Phase Induction Machine (SPIM) with both Direct Torque Control - DTC and Indirect Field Oriented Control-IFOC strategies. The system is mainly comprised by a six phase Voltage Source Inverter (VSI) and a Six-phase Induction Machine (SPIM). Simulation and experimental results are addressed to support the conclusions.

Design and implementation of a flexible intelligent electronic device for smart grid applications

According to the International Energy Agency/USA (lEA): “a smart grid (SG) is an electricity grid that uses digital technology to monitor and manage the transportation of electricity from all sources of generation, finding a variety of demands and users. These networks will be able to coordinate the needs and capabilities of all generators, operators, end-users and stake holders of the electricity market in order, to optimize the use and operation of the assets in the process, minimizing environmental costs and impacts while maintaining reliability, resilience and stability of the system”. The increasing need for more effective power electrical systems (generation, transmission and distribution) control has made the development of SG the main object of study for many researchers. In this context and looking for the integration and convergence of different systems to incorporate an infrastructure of a SG, this work designs and implements an flexible intelligent electronic device (lED). The proposed lED differs from the existing lEDs presenting a flexible capacity, as it can perform the acquisition of different variables (voltage, current, temperature, pressure, etc.) with different conditioning values, furthermore, the conditioning is carried out by software. The IED can operate as a smart meter, as a dynamic controller (local) and/or as a supervisory controller, thus improving the efficiency, reliabihty and security of the system. Other advantages of the proposed lED are: low cost, versatility (changes can be made by software), high processing capacity (ARM processor), communication features (hybrid network architecture (HNA)), easy integration (interoperability), easy maintenance (modularity) and scalability.

Low-Power Energy Generation Systems for Two-Phase PM Machine With Reduced-Switch-Count Controlled Switches

This paper investigates two power generation systems that utilize a rectifier with small number of controlled switches associated to a two-phase permanent magnet synchronous machine. The proposed topologies have as a main purpose converting wind energy into electrical energy for low-power applications, giving them large potential to be employed in urban and rural areas. Each configuration is commanded by only two controlled switches and has natural protection against short circuit on the dc link. Compared with two three-phase generation systems that use a reduced number of controlled switches, the proposed topologies permit obtaining sinusoidal machine currents, with low harmonic distortion, using a smaller number of controlled switches. At last, to investigate the proposed system and control strategy, simulation and experimental results are presented.