Setting the preheating and steady-state operation of electronic ballasts, considering electrodes of hot-cathode fluorescent lamps

This paper presents a new methodology for the adjustment of the preheating process and steady-state operation of electronic ballasts intended for hot-cathode fluorescent lamps. The classical series-resonant parallel-loaded half-bridge inverter is the power stage analyzed in this paper. In addition, the preheating process is based on the imposition of a constant rms current through the electrodes, in order to provide a proper value of the R-h/R-c ratio before the lamp start. According to the proposed methodology, it is possible to set suitable operating points for, the electronic ballast, considering optimal conditions for the lamps electrodes. Therefore, the proposed methodology for setting the preheating and steady-state operation is a complete platform to the design of electronic ballasts for hot-cathode fluorescent lamps.

Automatic dimming multi-lamp fluorescent management system with active input power factor corrector stage

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dependence on composition of electronic properties and stability of Pt-Fe/C catalysts for oxygen reduction

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Surface structure and electronic properties of Pt-Fe/C nanocatalysts and their relation with catalytic activity for oxygen reduction

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Electronic ballast for multiple fluorescent lamp systems

An electronic ballast for multiple tubular fluorescent lamp systems is presented. The proposed structure has a high value for the power factor, a dimming capability, and soft switching of the semiconductor devices operated at high frequencies. A zero-current switching pulse width modulated SEPIC converter is used as the rectifying stage and it is controlled using the instantaneous average input current technique. The inverting stage consists of classical resonant half-bridge converter with series-resonant parallel-loaded filters. The dimming control technique is based on varying the switching frequency and monitoring the phase shift of the current drained by the filters and lamps in order to establish a closed loop control. Experimental results are presented that validate the theoretical analysis.

A high efficiency HPF-ZCS-PWM Sepic for electronic ballast with multiple tubular fluorescent lamps

This paper presents a high efficiency Sepic rectifier for an electronic ballast application with multiple fluorescent lamps. The proposed Sepic rectifier is based on a Zero-Current-Switching (ZCS) Pulse-Width-Modulated (PWM) soft-commutation cell. The high power-factor of this structure is obtained using the instantaneous average-current control technique, in order to attend properly IEC61000-3-2 standards. The inverting stage of this new electronic ballast is a classical Zero-Voltage-Switching (ZVS) Half-Bridge inverter. A proper design methodology is developed for this new electronic ballast, and a design example is presented for an application with five fluorescent lamps 40W-T12 (200W output power), 220Vrms input voltage, 130Vdc dc link voltage, with rectifier and inverter stages operating at 50kHz. Experimental results are also presented. The THD at input current is equal to 6.41%, for an input voltage THD equal to 2.14%, and the measured overall efficiency is about 92.8%, at rated load.

Comparison of algorithms for loss allocation in transmission networks considering power redispatch

An analysis of the performances of three important methods for generators and loads loss allocation is presented. The discussed methods are: based on pro-rata technique; based on the incremental technique; and based on matrices of circuit. The algorithms are tested considering different generation conditions, using a known electric power system: IEEE 14 bus. Presented and discussed results verify: the location and the magnitude of generators and loads; the possibility to have agents well or poorly located in each network configuration; the discriminatory behavior considering variations in the power flow in the transmission lines. © 2004 IEEE.

An improved design procedure for LCC resonant filter of dimmable electronic ballasts for fluorescent lamps, based on lamp model

This paper presents an improved design methodology for the determination of the parameters used in the classical series-resonant parallel-loaded (SRPL) filter employed in the switching frequency controlled dimmable electronic ballasts. According to the analysis developed in this paper, it is possible to evaluate some important characteristics of the resonant filter during the dimming operation, such as: range of switching frequency, phase shift, and rms value of the current drained by the resonant filter + fluorescent lamp set. Experimental results are presented in order to validate the analyses developed in this paper. © 2005 IEEE.

Installation of a getter vacuum pump in cathode-anode region of a high-power klystron amplifier - Propose and feasible

The possibility to install a getter vacuum pump and its feasible in the anode of a high-power klystron amplifier is investigated in order to decrease of the pressure in the gun and consequently increasing its lifetime. The study is conducted using a 1.3 GHz, 100 A and 240 kV high-power klystron with five reentrant coaxial cavities, assembled in a cylindrical drift tube 1.2 m long. This work takes into account the specific conductance of components of gun and all important gas sources, like the degassing of the drift tube, the cavity walls, the cathode, the anode, and the collector, as well the position and pumping speed of the getter vacuum pump in anode region. © 2006 IEEE.

Technology assessment for power quality mitigation devices - Micro-DVR case study

This work presents a case study on technology assessment for power quality devices. A system compatibility test protocol for power quality mitigation devices was developed in order to evaluate the functionality of three-phase voltage restoration devices. In order to case test this test protocol, a development platform with reduced power for DVR (Dynamic Voltage Restorer), the Micro-DVR, was tested, and results were discussed based on voltage disturbances standards. ©2008 IEEE.

A neural approach to evaluate the effect of lightning in power transformers

This paper proposes the application of computational intelligence techniques to assist complex problems concerning lightning in transformers. In order to estimate the currents related to lightning in a transformer, a neural tool is presented. ATP has generated the training vectors. The input variables used in Artificial Neural Networks (ANN) were the wave front time, the wave tail time, the voltage variation rate and the output variable is the maximum current in the secondary of the transformer. These parameters can define the behavior and severity of lightning. Based on these concepts and from the results obtained, it can be verified that the overvoltages at the secondary of transformer are also affected by the discharge waveform in a similar way to the primary side. By using the tool developed, the high voltage process in the distribution transformers can be mapped and estimated with more precision aiding the transformer project process, minimizing empirics and evaluation errors, and contributing to minimize the failure rate of transformers. © 2009 The Berkeley Electronic Press. All rights reserved.

Trolleybus power system for operation with AC or DC distribution networks

This paper presents the development and experimental analysis of a special input stage converter for a Trolleybus type vehicle allowing its operation in AC (two wires, single-phase) or DC distribution networks. The architecture of proposed input stage converter is composed by five interleaved boost rectifiers operating in discontinuous conduction mode. Furthermore, due to the power lines characteristics, the proposed input power structure can act as AC to DC or as DC to DC converter providing a proper DC output voltage range required to the DC bus. When operation is AC to DC, the converter is capable to provide high power factor with reduced harmonic distortion for the input current, complying with the restrictions imposed by IEC 61000-3-4 standard. Finally, the main experimental results are presented in order to verify the feasibility of the proposed converter, demonstrating the benefits and the possibility for AC feeding system for trolleybus type vehicle. © 2010 IEEE.

Methodology analysis of a computational tool used in electronic circuit design

This paper considers the importance of using a top-down methodology and suitable CAD tools in the development of electronic circuits. The paper presents an evaluation of the methodology used in a computational tool created to support the synthesis of digital to analog converter models by translating between different tools used in a wide variety of applications. This tool is named MS 2SV and works directly with the following two commercial tools: MATLAB/Simulink and SystemVision. Model translation of an electronic circuit is achieved by translating a mixed-signal block diagram developed in Simulink into a lower level of abstraction in VHDL-AMS and the simulation project support structure in SystemVision. The method validation was performed by analyzing the power spectral of the signal obtained by the discrete Fourier transform of a digital to analog converter simulation model. © 2011 IEEE.

Single stage converters for low power stand-alone and grid-connected PV systems

This work presents the evaluation of different power electronic integrated converters suitable for photovoltaic applications, in order to reduce complexity and improve reliability. The rated voltages available in Photovoltaic (PV) modules have usually low values for applications such as regulated output voltages in stand-alone or grid-connected configurations. In these cases, a boost stage or a transformer will be necessary. Transformers have low efficiencies, heavy weights and have been used only when galvanic isolation is mandatory. Furthermore, high-frequency transformers increase the converter complexity. Therefore, the most usual topologies use a boost stage and one inverter stage cascaded. However, the complexity, size, weight, cost and lifetime might be improved considering the integration of both stages. In this context, some integrated converters are analyzed and compared in this paper in order to support future evaluations and trends for low power single-phase inverters for PV systems. Power decoupling, MPPT and Tri-State modulations are also considered. Finally, simulation and experimental results are presented and compared for the analyzed topologies. © 2011 IEEE.

Factors affecting the adoption of supply chain management practices: Evidence from the Brazilian electro-electronic sector

This study on the factors affecting the adoption of supply chain management (SCM) practices develops four hypotheses based on a literature review, and tests them using survey data of Brazilian electro-electronic firms. The results reveal the big picture of the SCM practices in the sector and suggest that contextual factors such as size, position and bargaining power affect the adoption of SCM practices, which are also more customer oriented. Sector characteristics are very important in analysing SCM practices. Contrary to the findings of literature, the relationship between competitive priorities and SCM practices was not supported statistically. © 2011.