L. M. F. Morais

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.

Passivity-based control of PFC boost converter with high-level programming

This paper presents a procedure for high-level programming of a microcontroller using passivity-based control implemented in PFC (Power Factor Correction) boost converters. This is a non-conventional approach, where libraries are used to directly interface with the Texass DSP 2812. Initially, the block diagrams that contain the control equations are constructed. Then, the codes are generated automatically. The advantages provided by the proposed method are: economy of development cycle time, easy understanding of the control process and programming, standardization and concurrent simulation. The other contribution of the paper refers to the development of a regulated source with high power factor and low THD using a boost converter controlled via passivity-based method. The approach based on passivity has been studied recently due to clear advantages in view of disturbances in the operation conditions of the system. The purpose of this technique is to improve the converter efficiency in applications of low and medium power, and improve the quality of the energy in the grid. Finally, in a new and satisfactory way, this nonlinear control technique has been validated experimentally for boost converters.

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.

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.

Hardware in the loop simulation of non linear control methods applied for power converters

This paper presents a Hardware in the loop (HIL) simulation of a microcontroller using non-linear control implemented in PFC (Power Factor Correction) boost, buck and SEPIC converters. This is a non-conventional approach, where libraries are used to directly interface with the Texass DSP 2812. Initially, the block diagrams that contain the control equations are constructed. Then, the codes are generated automatically. The advantages provided by the proposed method are: security, economy of development cycle time, easy understanding of the control process and programming, standardization and concurrent simulation. Three nonlinear control techniques - state feedback linearization (SFL), passivity based control (PBC) and interconnection and damping assignment passivity-based control (IDA-PBC) has been validated experimentally using HIL simulation for boost, buck and SEPIC converters.

Comparison of nonlinear control techniques applied to SEPIC and CUK converters with reduced modeling and hybrid solutions

This paper presents a study and comparison of nonlinear control techniques applied to SEPIC and CUK converters with reduced modeling and hybrid solutions based on boost converter. Three nonlinear control techniques — state feedback linearization (SFL), passivity based control (PBC) and interconnection and damping assignment passivity-based control (IDA-PBC) has been validated experimentally using HIL simulation for boost and SEPIC converters. Simulation results are also presented for these converters and control methods.

Integration of solid state transformer with DC microgrid system

This paper investigates a Solid State Transformer (SST) based DC microgrid architecture, addressing the design and control of the multiple SST power conversion stages and the power management strategy required for its integration with other microgrid elements, such as storage devices and local distributed generation. The advantages of a SST in relation to conventional low frequency transformers are commonly listed as a substantial reduction of volume and weight, fault isolation capability, voltage regulation, harmonic filtering, reactive power compensation and power factor correction. The SST also constitutes the required infrastructure that will enable DC power distribution to homes and commercial buildings in the near future and provides a more efficient way to integrate storage devices and distributed generation into the electrical grid. In this sense the SST behaves as an energy router, which represents a key element in an intelligent power system. The behavior of the proposed architecture for different operating conditions and disturbances will be assessed through computational simulations in the software MATLAB/Simulink.

A study of HPS lamp models performance and behavior with third harmonic injection to avoid acoustic resonance

One seeks, in this paper, to develop and compare the performances of four different models for HPS lamps operating with harmonic injection. Simulation results of the models studied are compared with experimental results for the lamp fed with sine waveform voltage due to LC network connected between the inverter and the load. The behavior of incremental impedance is observed in simulation by the variation in the imposed current to the lamp. From this comparison one chooses the model presenting the best performance rates at both low and high frequencies.