S. I. Seleme

Acoustic Resonance Avoidance in High Pressure Sodium Lamps Via Third Harmonic Injection in a PWM Inverter-Based Electronic Ballast

Third harmonic injection in the high pressure sodium lamp voltage by means of a controlled pulsewidth modulation inverter is studied in this paper. It can be shown that acoustic resonance can be avoided by using this technique with a judicious amount of third harmonic injection. Furthermore, the crest factor in the lamp current can also be reduced

Comparative analysis of power LEDs dimming methods

Light emitting diodes (LEDs) have many features that make them very attractive for use in lighting. The main features that stand out is its small size compared to incandescent and fluorescent lamps. Also, they have high luminous efficiency, long lifetime and are resistant to shocks and vibrations, which contributes to increasing their reliability. This paper presents a current source for Power LEDs. As the luminous intensity of LEDs is directly related to the direct current flowing through them, this source must have characteristics of current source. Two methods of dimming LEDs are analyzed: continuous variation of current and pulse width modulation (PWM). These methods are implemented, tested and compared. A current loop to control the current through the LEDs is designed to keep the current in the LEDs always constant, so that the luminous flux emitted by them does not change.

Comparison of MPPT approaches in autonomous photovoltaic energy supply system using DSP

This paper presents a methodology for choosing the most suitable Maximum Power Point Tracking - MPPT for charging the batteries of an autonomous photovoltaic energy supply system. Experimental results are provided.

PLL-based repetitive control applied to the single-phase power factor correction using boost converter

The low frequency ripple in single-phase power factor correction (PFC) boost converters dramatically limits the bandwidth in standard control strategies, deteriorating the overall system performance. This paper presents the study and the implementation of a Phase-Locked Loop (PLL)-based repetitive controller in order to improve the dynamics and the input current distortion in a PFC boost converter. The repetitive control applied to the PFC presents a straightforward implementation with satisfactory results when compared to other techniques, as described in the paper. Experimental results validate this claim.

Acoustic Resonance Rejection via Voltage Modulation Method for HPS Lamps

A voltage modulation method in order to prevent acoustic resonance (AR) in HPS lamps is presented. Two voltage modulation techniques via PWM inverter are proposed. The first one injects harmonic components in the lamp voltage reference. The second one consist of high frequency voltage modulated by a low frequency waveform. These techniques allow the control of crest factor other than rejecting the AR.

Study of the application of bidirectional dual active bridge converters in dc nanogrid energy storage systems

This paper discusses the application of a dual active bridge converter (DAB) as a bidirectional interface between the energy storage system and the main dc bus in a dc nanogrid. A novel control technique based on control loops competition is proposed to perform the energy management between both systems, which allows the dual active bridge to concomitantly regulate the main dc bus and control the battery bank charging process with a four states method.

Stability in passivity-based boost converter controller for power factor correction☆

Abstract This paper addresses the control of Boost converters applied for Power Factor Correction in universal-line applications with unknown load, using adaptive nonlinear control based on passivity. The closed loop system stability is discussed based on the analysis of the internal dynamics resulting from the use of the proposed control strategy. The performance of the proposed PFC rectifier is tested on an experimental 630-W universal-line PFC prototype.

Interconnection and damping assignment passivity-based control of a PMSG based wind turbine for maximum power tracking

The use permanent magnet synchronous generators (PMSG) in wind turbines has been increase considerably in offshore applications due to its efficiency, low maintenance costs and reliability. PMSGs are connected to the grid by means of frequency converters. Generally a back-to-back full converter structure is preferred. This work presents the application of interconnection and damping assignment passivity-based control (IDA-PBC) in order of a PMSG based wind turbine. This strategy is combined with a mechanical torque estimator in order to track the maximum power point of the system. Simulation results show the operation of the proposed strategy during wind speed variations. Proposed strategy extracts maximum power of wind turbine and injects generated power into the grid.

Regenerative PWM source for power transformer loading tests

Most of power transformers, before being commercialized, must undertake a series of tests with the objective of analyzing their operational behavior under real operating conditions. Such tests sometimes demand a high amount of power increasing significantly their costs. The paper presents a proposed system which allows testing in closed loop, reducing the energy consumption to the natural losses of the equipment, thus constituting a regenerative system. A VSI-based test environment for power transformers where controlled active and reactive power can be supplied is designed, simulated and realized as a 50KVA- prototype. Special care is taken concerning the ac-filters in order to keep the harmonics within the limits set by standards valid for testing of power transformers. The simulation and experimental results show that the prototype fulfills the given requirements.

Minimum motor losses point tracking for a stand-alone photovoltaic pumping system

Solar photovoltaic energy has been, for many years now, a promising alternative in the diversification of global energetic sources. Although photovoltaic energy has many advantages, it has not yet become commercially popular, because it is still an expensive alternative. In fact, studies have already shown that the investment in such systems are paid back, but it is still hard to find people willing to wait five or six years to have their money back. The aim of this work is to reduce the payback time of photovoltaic stand-alone pumping systems, optimizing not only the efficiency of the photovoltaic conversion, using a maximum power point tracking algorithm, but also minimizing the losses in the induction motor. Based on the design procedures described in this paper, a prototype has been developed and experimental results with the optimizing strategy are shown.