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Worried that the current paradigm of political corruption (individual corruption: the misuse of public office for private gain) is too narrow to protect democratic institutions from private interests, the political theorist Dennis Thompson resurrects the premodern notion of institutional corruption, which refers to practices that undermine the purpose of political institutions. From the lenses of institutional corruption, practices such as money in political campaigns, lobbying, or wealth inequality are to be condemned and eradicated to protect democratic institutions. The goal of this paper is to provide reasons against resurrecting the notion of institutional corruption in the realm of policy for three main reasons. First, it is baseless: there is no empirical evidence that the sole presence of money alters democratic results. Second, it is unnecessary: individual corruption can be used to condemn and sanction illegal actions that undermine democratic decision making. And third, it is unclear whether policies against money in politics are beneficial or detrimental to electoral competition. In the light of empirical evidence, I conclude, we should not resurrect the unnecessary and potentially misleading idea of institutional corruption. Empirical studies, in fact, show that liberal electoral democracies, at least in developed countries, are more responsive to the voters’ will than Thompson believes.

Several political philosophers have recently pointed out that current electoral democracies fail to facilitate accurate and reliable feedback on the performance of public officials. Rather than rejecting democracy as a hopeless ideal, we defend an institutional reform called Service Responsibility, which introduces a superior incentive structure that better aligns the interests of citizens and public officials. Service Responsibility requires increasing or decreasing the income of public officials insofar as they succeed or fail to achieve democratically chosen goals. Later, we consider an alternative institutional scheme, recently proposed by Claudio López-Guerra: Piloting Responsibility. According to this alternative proposal, public officials must utilize a public provider whenever they seek out a basic service. We show that Piloting Responsibility fails to realize the democratic ideal because it generates a perverse incentive structure for public officials. We conclude that Service Responsibility outperforms both the status quo and Piloting Responsibility as an institutional scheme for ensuring competent governance and public justification.

This paper studies the lessons of principled anti-corruption experts who dared to fulfill their duty of justice in highly corrupt societies, through the true story of Ngozi Okonjo-Iweala, the former Finance Minister of Nigeria. My thesis is that when principled anti-corruption experts are epistemic trespassers (when they fail to identify the limits of their skills), they show moral incompetence (the tendency of principled agents to bungle moral situations). Okonjo-Iweala shows moral incompetence in two ways: she misread the opposition to her strategies and misled other honest reformers. Both actions bungled her efforts to eradicate corruption inasmuch as they hindered the possibility of finding successful anti-corruption policies. Okonjo-Iweala’s moral incompetence is, I argue, the result of her epistemic trespassing that led her to act like an expert in an environment where she was not. I conclude that, in highly corrupt societies, principled anti-corruption experts should embrace moral humility, stop thinking that they are experts, and act more like students, asking questions and not rushing to think that they understand the answers.

There has always been a tension, in theory, between the public accountability and the professional efficiency of the agencies of the administrative state. How has that tension been handled? What would it be like for it to be well handled?

Traditional views tend to identify the problem of corruption in the dishonesty of public officials. The main purpose of the research is to recover Montesquieu’s view of corruption and show that there are at least two different causes of corrupt behaviors. In The Spirit of Laws, Montesquieu distinguishes “two kinds of corruption: one, when the people do not observe the laws, the other when they are corrupted by the laws; the latter is an incurable ill because it lies in the remedy itself.” Recent studies about Montesquieu’s account of corruption do not pay much attention to this distinction. This paper unpacks the two kinds of corruption. The first kind tracks a problem of individuals who use their public office for private gain. The second track is the deficiency of the laws that contradict social behaviors and, therefore, are obeyed exclusively out of fear and violated whenever possible. The distinction is relevant to the anti-corruption literature because it implies two different ways to eradicate corruption. Corruption as a problem of individuals can be solved with better enforcement of the law: improving monitoring systems, better rewards for honesty, or higher punishments. Personal corruption can be dealt with what Celine Spector calls “a legislative arsenal.” However, improving enforcement mechanisms is unlikely to solve the problem in corrupting laws, given that people violate the law due to the high standards that it imposes on them. The solution for the second kind of corruption is to remove or modify the corrupting law. Montesquieu promoted the separation of powers and the spirit of moderation in the legislators to avoid corrupting laws. The result of this investigation is the importance of distinguishing between the situations in which more coercion can eradicate corruption and those in which more force against corruption leads to despotism. Keywords: Corruption, Legislation, Moderation, Montesquieu, Separation of Powers, Spirit of the Laws.

Currently, the combustion cars of a large number of electronic equipment: the electronic control unit, position sensors, flow sensors, automatic brake system, ABS system, among others. Currently and in broad strokes cars a set of mechanical parts controlled by an electronic system. In the future, cars are fully electronic, but prior to this step, hybrid cars will be developed which have their respective electric motors controlled by a power stage and their internal combustion engine (Cevallos 2016). This paper identifies the disturbances in the automotive systems that are introduced to the micro network of the automobile, its effects to analyze the effects that may have on the LED lighting system. Objetivos: Estudiar los transitorios y permanentes en automóviles para clasificar su comportamiento. Analizar las perturbaciones que pudieran ser perjudiciales para los sistemas electrónicos del automóvil. Cuantificar de perturbaciones a partir de la Transformada Rápida de Fourier (FFT). Estudio y análisis de los efectos a través de la simulación numérica de los transitorios en convertidos de CD-CD empleado para la iluminación.

This paper presents the analysis of the lifetime of a power LED based on its power waveforms. In this work, the luminous degradation of the LED is analyzed, based on the LM-80 and TM-21 Norm, comparing it with a curve fitting of the experimental data. The device under test consists of a 1W white LED, which operates for 6500 hours at a temperature of 85° C. The compared waveforms are the direct current and a rectified half-sine wave. The continuous wave presents minimal deterioration and its useful life corresponds to more than 50,000hrs. While the LED powered with a rectified sinusoidal half-wave presents a strong deterioration reducing its useful life to less than 7000 hrs., and showing a strong deterioration in its elements (silicone mold), in addition to losing its phosphor layer and emitting bluish light. The power waveform reduces the useful life of the LED since it affects its structure and its PN junction as shown in this article.

Common mode voltage is an important issue in motor drive systems since its dynamics could produce leakage ground current reducing the machine lifetime. In order to contribute to reduce the effects of the leakage ground current, three-phase power inverters can be designed using dedicated pulse width modulation strategies. Space vector modulation technique is a commonly used continuous method due to its flexibility to implement different vector sequences. In this paper it is proposed a space vector based modulation technique to reduce common mode voltage in a three-phase ANPC inverter. An analysis and comparison regarding conventional space vector modulation techniques are performed. Numerical results are obtained to prove the feasibility of the proposed method.

The use of the genetic algorithm to obtain the appropriate switching sequence of a multilevel inverter has been increasing during the last years; this algorithm has been implemented through a Matlab solver. However, the choosing of the solver parameters have been by means of trial-and-error or by the user experience. In order to maximize the Matlab genetic algorithm performance, the present work proposes the use of Taguchi design approach to determine the optimal switching sequence of a five-level multilevel inverter to decrease the THD in the output voltage.

In this paper, the identification of the parameters of a battery model is addressed by measuring the current and voltage at the terminals of the battery and by using a moving window least square method in an online application. The battery is considered to supply a DC voltage reference to a dedicated load through a buck converter with an LC filter at the input. The converter output voltage is regulated through a conventional controller that ensures stability, sufficient damping and zero steady-state error at constant voltage references. The results of numerical simulations show that the presented scheme is capable of identifying battery parameters such as internal resistance, battery capacity and the time constant of an RC network when referring to an equivalent electric circuit model that considers the battery relaxation effect.

Grid-connected low-power PV systems are becoming more and more popular inside the energy market. Such a systems, are commonly installed in residential and small commercial buildings, having as a main objective the reduction of the energy bill. Efficiency is a key word in the design of PV systems since this parameter contributes with economic benefits for the investors. Among low power systems, microinverters are designed to inject the generated energy from a single PV panel to the electrical grid. A single photovoltaic panel produces a voltage around 35 V, therefore microinverters are generally designed using two stages. First stage boost and regulate the output DC voltage while the second stage produces the injected AC current. Single-phase H-bridge inverter is the basic topology used in the second stage of the isolated microinverters. In this paper, a modified hybrid high-frequency H-bridge inverter is proposed using a combination between MOSFET’s and IGBT’s according with the low and high frequency pulse width modulated signals. The proposal is evaluated by means of numerical simulations and compared with transformerless topologies considering the total harmonic distortion and efficiency as the comparative parameters.

In this paper, the controller for an extended step-down conversion ratio converter is designed and experimentally validated through a laboratory prototype. The converter that is considered is formed by a conventional buck converter to which an array of capacitors and diodes is added at the input that allows extending the step-down conversion ratio. The objective of the controller is to provide closed-loop stability and assure the regulation of the output voltage. Its design is based on the averaged converter model and consists of two control loops, one voltage and one current. Closed-loop experimental results are presented.

This paper addresses the analysis and experimental validation in steady state of a non-isolated quadratic buck converter to which an LC input filter has been added. This modification ensures that the power source is continually connected and delivering power during each switching period, which yields a reduction of switching components at the input. This may even entail a time-continuous input current. Continuous input current is a desired requirement for sensitive electric power sources and electric storage systems. The space-state model of the converter and the dynamical analysis of the open-loop linearized model are presented. Steady-state analysis is also presented that allows obtaining expressions for switching ripples and average values and conditions for boundary conduction mode operation. Experimental results, performed in a laboratory prototype of the converter, are included to verify the presented analysis.

This paper presents the mitigation of current harmonics in the stator of a Wind Energy Conversion System based in a doubly fed induction generator and a back to back converter. This converter consists in a Rotor Side Converter and a Grid Side Converter, and the current harmonics mitigation occurs through the selection of the PI parameters in the Rotor Side Converter control. The case of study is a test rig based on a 372W doubly fed induction generator, and the considered grid voltage harmonics components are fifth and seventh. Simulations are implemented in PSIM in sub-synchronous speed, testing different frequencies designs in the Rotor Side Converter control in order to evaluate the current harmonics compensation.

Nowadays, there is an increasing interest to use renewable electrical energy sources instead of those based on fossil fuels. Must of the commonly used are the solar and the wind energy which have become very popular in last years. Solar energy uses solar panel arrays to generate electrical energy with a direct current (DC) waveform. Therefore, in order to inject the generated energy to the electrical grid, it is necessary to convert the DC signal into an alternating current (AC) signal. Multilevel inverters allows the grid connection with a good power quality and reducing the output filter size. In particular, direct grid connected inverters, additionally provides low size and low cost to the final system. In this paper, a pulse width modulation (PWM) strategy is designed for a hybrid multilevel inverter based on a T-type inverter combined with an AC-decoupling technique. The PWM method is intended to reduce leakage ground current which is one of the must important issues in transformerless inverters. Simulation results are provided in order to validate the proposed strategy.

Currently LED technology for lighting has a great boom in the automotive industry. In this industry it is required that the main headlights change luminosity instantaneously; this is achieved using LED arrays. In this type of power LED arrays can be controlled independently using a dc-dc converter for each of the arrays, or using a converter that controls the voltage or series depending on the change in brightness. An important factor in determining what type of strategy to implement is the failure rate of the system, as it is known that the greater the number of components or stages, the system will be more likely to fail in a certain time. In this article we analyzed the conditions of the Flyback converter for five power levels, it was established that the element with the highest failure rates is the switching MOSFET, this element was also the one that increased its temperature more in the last power interval. Therefore the study of this case determines that to have a lower failure rate it is recommended to have several converters of less power than a larger one.

The control system block in a photovoltaic (PV) system includes the algorithm which makes possible the PV system operation under adequate conditions to extract the maximum electrical power available from the PV array, this algorithm is commonly called Maximum Power Point Tracker (MPPT). In the literature, different algorithms that researchers have developed, some more efficient, more easily to implement, more robust and faster than others, have been reported. Therefore, in this paper a comparative analysis between frequently used MPPT methods is presented. The methods considered in this analysis correspond to the classical Hill Climbing method, Perturb and Observe (P&O) method and the Incremental Conductance (INC) technique. The analysis has been oriented to measure the efficiency of each method being this parameter one of the most important to determine their performance. The simulated results permit to analyze the MPPT algorithms between them, in such a way the reader can discern the most appropriate method for his own application.

This paper discusses the proposal of a single-phase inverter to deal with the leakage ground current problem in transformerless photovoltaic systems. The high efficiency and low cost allow non-isolated inverters to widespread their applications in the grid connected photovoltaic energy market. The removal of the low or high frequency transformer in a photovoltaic system let a ground path for the circulating leakage current produced by voltage variations in the stray capacitance formed between the photovoltaic panel surface and its grounded frame. To deal with this issue, a single-phase inverter and its modulation strategy is discussed in this paper. The topology is based in the conventional single-phase half-bridge inverter plus a single-phase full-bridge rectifier connected to a single switch. A conventional sinusoidal based pulse with modulation is proposed to improve the topology performance regarding leakage current. Finally, silicon carbide diodes are used in the diode bridge to significantly improve the overall inverter efficiency. Numerical results show that the proposed PV inverter modulated with the proposed modulation strategy complies with the transformerless norms and regulations and operates with high efficiency, being this suitable for applications of grid-connected transformerless PV energy generators.

In this paper presents the study and implementation of a model for an ultraviolet light-emitting diode (UV LED). This model is used to characterize series and parallel UV LED arrangements. The proposed model can be used for different power LED. An exponential expression of a term that describes the electrical characteristics of the V-I curve of a UV LED is used. The principle of implementation of UV LED is described, and in this way they can be used in simulation software. The proposed model this designed for any number of LED in series or parallel. To perform the proposed model radiation is analyzed in terms of temperature and power.

Two model-based controllers for the quadratic boost converter with different number of sensors are presented and compared. The quadratic boost converter model is a bilinear control system whose linearization has complex right-half plane zeros. Common-use controllers consist in current and voltage control loops and rely on the requirement that the current dynamics is faster than the voltage dynamics. Controllers that are reviewed in this paper aim at the output voltage regulation and are obtained by requiring that the derivative of an energylike function be negative semi-definite along the trajectories of the closed-loop system. The considered controllers make use the complete four state variables and a subset of the state variables. The controllers include a load conductance estimation scheme to cope with possibly variations of the converter load. Closed-loop operation is verified via numerical simulation under equal conditions.

In this paper, the analysis and design methodology of a high-frequency self-oscillating (SO) electronic ballast with lamp current control are presented. SO electronic ballasts have two important drawbacks: First, the lamp current varies according to the ac input voltage, causing undesired effects in the lamp brightness, and second, the design method lacks precision at very high frequency operation (greater than 200 kHz) mainly due to the parasitic capacitance. The ballast is modeled by using the descriptive function method and the extended Nyquist criterion; the model of the ballast includes a control circuit and takes into account the high-frequency effect of the MOSFET parasitic capacitance . Finally, experimental results of a 38-W SO electronic ballast prototype with lamp current control for high-intensity discharge lamps are presented to validate the analysis and the proposed methodology. The switching frequency is selected at 2 MHz in order to avoid the acoustic resonance problem.

This paper describes a nonlinear model of high-intensity discharge (HID) lamps based on electrical variables. The proposal, oriented to the engineering area, has a special application for the design of electronic ballast. Parameters are obtained from straightforward measurement of electrical variables as power, current, and voltage in the lamp. The lamp resistance is obtained as a function of electrical power; which is estimated from the Saha equation. This model, which can be simulated using software such as ?Simulink? or ?Pspice,? takes into account some important dynamic behaviors of HID lamps, which are normally omitted in some other models suggested in literature nowadays. Experimental and simulation results are shown.

In this paper, the use of input current shaper converters (ICSCs) working in discontinuous-conduction mode to stabilize the discharge arc in high intensity discharge lamps without close loop control is proposed. The analysis of how the ICSC stabilizes the lamp current, the description of the proposed topology and the design methodology are presented. Experimental results indicated the feasibility to stabilize the lamp with no close loop control and obtaining high efficiency with fewer components that conventional ballasts used for this application. Experimental results when dimming is applied are included too

This paper studies a modified DC-DC boost converter where the input inductance has been replaced by an LCL filter. The voltage conversion ratio of the proposed converter is equivalent to the conversion ratio of a conventional boost converter, and it has only one active switching device. A controller is proposed to regulate the output voltage to a given reference with guaranteed reduced input current ripple, i.e., high-frequency current components are minimized at the input current source. Low current ripple is required when dealing with sensitive electric power sources such as fuel cells, batteries and electrolytic capacitors used at DC-links in power electronics applications. The controller design follows a Lyapunov approach, and provides active damping to the input LCL filter. Numerical simulations are presented to evaluate the closed-loop performance.

This paper presented a comparative study in function reliability between dc-dc converters used in power LED. Between dc-dc converters more used to power LED are the Buck and Flyback converter, because the Buck provides a lower output voltage than the input, and in the case of flyback has galvanic isolation. The study has objetive to determine the reliability obtaining the failure rate of the system and the average time when failures occurs, because the LED driver must have an average life similar to the LED lamp. The reliability analysis is based in the standard MIL-HDBK-217, for this study performed was used a LED load of 54.6 W in both converters. The results have shown that the buck converter has a lower failure rate and a higher mean time between failures, therefore has a longer useful life.

This paper presents a self-oscillating electronic driver for a 36 W LED string. The design consists of a simple control that reduces the component number and cost of the driver. Self-oscillating converters are popular in compact fluorescent lamps; therefore, it is proposed the use of this self-oscillating control technique for the LED lamp. The self-oscillating LED driver represents a very suitable solution in compact LED products. This paper describes the design of a self-oscillating electronic driver at high frequency. The output of the sine wave of the resonant inverter is rectified. This LED driver not require of electrolytic capacitors, because LED is operated with pulsating output current.

Cascaded DC-DC boost power converters are topologies that have as main advantage their high voltage step-up ratio. This feature makes them suitable in applications, for instance, in non-conventional electric energy systems such as in photovoltaic, wind-turbine, battery and fuel cell applications, among others. However, the control of these power converters, commonly requires the computation of the voltage and current references. For some controllers, which are already reported in the literature, the knowledge of the value of the load is essential for operation in load-changing conditions. In this paper is addressed a comparative evaluation of three different load observers for the two stage, or quadratic, boost converter. Numerical simulations of each estimator and discussion about its performance are presented.

Transformerless photovoltaic systems are one of the best options to connect a photovoltaic system to the electrical grid given their high efficiency, low cost, small size and low weight regarding their counterparts based on a transformer. In this paper a multilevel single-phase inverter is aimed to link a photovoltaic generator with the electrical grid with reduced common mode current. A sinusoidal based modulation strategy is also presented which focus not only in the reduction of the common mode current but also in the reduction of the switching and conduction losses. Five voltage levels are obtained at the inverter output, therefore, a good behavior is achieved regarding harmonic distortion. Numerical results show that the proposed inverter and modulation strategy give a reduced common mode current and low harmonic distortion which is suitable for transformerless photovoltaic systems.

This paper presents an improved current mode control for a DC-DC buck converter which works as an electronic drive to feed the lighting system based on power LEDs. The automotive industry requires LED based lighting system with fast lighting changes, besides a constant voltage and a forward current are needed to maintain the required luminous flux despite the load changes. Based on a controller previously reported, here a model based controller is proposed which is aimed to reduce the number of the sensors maintaining the performance of the drive. Numerical results are performed in order to validate the controller.

This paper presents an electronic ballast based high power LEDs for headlights automobile. The ballast is based on a buck converter to feed a load of high power LED. The load is divided into five high power LED (10W), in automobile lighting systems rapid changes of lighting is required (power changes), therefore the buck converter must deliver constant voltage levels to changes in power and further the current necessary to maintain a flow of light required. To solve this problem this paper proposes a control law for buck converter control, which maintains a fixed voltage level for the different power (10.9W, 21.8W, 32.7W, 43.6W, 54.5W) dynamic response to these changes is fast and constant levels of current and luminous flux at each change of load is maintained.

This paper presents a comparison between two different passive filters for power converters tied to the grid with the application of active power injection. It addresses the L (inductive) filter and the LCL (inductive-capacitive-inductive) filter in single-phase power converters for which are presented the parameter design and modeling. These filters provide coupling of the power converter to the electrical grid and mitigation of high frequency harmonics which are inherent to switching power converters. It is obtained the state-space model and the transfer function of both type of filters and some design considerations for active power injection are presented. An evaluation, by means of numerical simulations, is presented for a single-phase H-bridge inverter with unipolar pulse width modulation for active power injection.

This paper presents a self-oscillating electronic ballast for a 36 W LED string. The design consists of a simple control that reduces the component number and cost of the ballast. Self-oscillating converters are popular in compact fluorescent lamps; therefore, it is proposed the use of this self-oscillating control technique for the LED lamp. The self-oscillating LED driver represents a very suitable solution in compact LED products. This paper describes the design of a self-oscillating electronic ballast at high frequency. The output of the sine wave of the resonant inverter is rectified and, then its high frequency yields a reduction in the value of output capacitor.

This paper presents a control law for single-phase power converters, coupled to the grid by means of an L filter, aimed at active power injection. This control law makes use of an estimation scheme which obtains estimations of the filter parameters in order to cope with the compensation of time-periodic signals arising in the error average model and with the possible existence of harmonics in the grid voltage. An evaluation of the proposed control law is performed by means of numerical simulations where a single-phase H-bridge inverter with unipolar pulse width modulation is used.

This paper presents the modeling and control design of a single-phase full bridge neutral point clamped (FB-NPC) multilevel converter used in an active power filter (APF) application. The proposed topology is aimed to compensate reactive power and current harmonic distortion. Based on the system model, a multi-loop controller is proposed, which is aimed to accomplish three control objectives, namely, AC current tracking, and DC voltage regulation and balance. The controller comprises two main loops referred as the inner (current) loop, and the outer (voltage) loop. The outer loop includes both the regulation loop and the balance loop. The inner loop is aimed to compensate both the power factor (PF) displacement and the harmonic distortion of the grid current. The control design considers odd harmonics of the fundamental, as this is the usual distortion present in single-phase nonlinear loads. The proposed solution guarantees a line current proportional to the fundamental component of the grid voltage. Numerical results are presented to assess the performance of the proposed solution. Experimental results are under development and will be presented in the final version of the paper.

Single-phase transformerless photovoltaic (PV) inverters have become more widespread in the solar energy market. This is due to the higher efficiencies they achieve together with the very low ground currents, which are their main advantages. In this paper a multilevel transformerless single-phase topology, based on the H-bridge with an active clamping, is proposed. Multilevel output voltage is achieved by using a split DC link and an active bidirectional switch to clamp the first leg in the H-bridge circuit. Therefore, a good behavior is achieved regarding total harmonic distortion (THD). A sinusoidal based pulse width modulation (PWM) strategy is also proposed to control the power converter. Numerical results show that the proposed PV inverter complies with the transformerless norms and regulations, operating with high efficiency, and being suitable for the transformerless PV inverters market.

This paper presents the design guidelines of electronic ballast for HID lamps. High efficient electronic ballast with high power factor and low THD (total harmonic distortion) is presented. The use of input current shaper converters (ICSC) working in Discontinuous-Conduction Mode (DCM) to stabilize the discharge arc in High Intensity Discharge (HID) lamps is proposed. The analysis of how the ICSC stabilizes the lamp current through the analysis of the output capacitor Co and model lamp is presented. The results indicated the feasibility to stabilize the lamp and obtaining high efficiency, high power factor and low THD in a single stage is presented.

In this paper, it is proposed to treat the square wavelet coefficients as a probability density function in order to be able to measure energy concentration/dispersion in the tiled time-frequency plane. The proposed measure is the average distance to the center of mass of the tiled time frequency plane. This measure not only indicates energy concentration/dispersion in the tiled time-frequency plane but also hints that near symmetric orthogonal wavelets detect better the different electrical disruptions such as: transients, harmonics, interharmonics, voltage disruptions as well as sag and swell. To better illustrate the usefulness of the proposed approach a synthetic signal is generated containing the above mentioned electrical disruptions. The following wavelets are used to see which one concentrates better the energy in the tiled time-frequency domain: Daubechies, Coiflets, Symlets, Haar and the discrete Meyer wavelet.

In this paper a simple method to design and improve the performance of high frequency self-oscillating electronic ballasts is presented. The proposed method is based on the describing function method and allows minimizing the parasitic elements effects presented above 200 kHz by considering the gate-source parasitic capacitance of power Mosfets and the switching delay times. Its main advantage is a better operating frequency approximation and hence a better performance of the ballast. Experimental results of the proposed method are compared against a conventional method in a frequency range of 200 kHz to 2 MHz, showing the feasibility of the proposed method

In this paper a consideration to design and improve the performance of high frequency self-oscillating electronic ballasts is presented. The proposed method is based on the describing function method and allows minimizing the parasitic elements effects presented above 200 kHz by considering the gate-source parasitic capacitance of power Mosfets and the switching delay times. Its main advantage is a better operating frequency approximation and hence a better performance of the ballast. Experimental results of the proposed method are compared against a conventional method in a frequency range of 200 kHz to 2 MHz, showing the feasibility of the proposed method.

In order to determine the stability of electronic ballasts, it is necessary to use a small-signal model. Various techniques has been proposed to obtain a small signal model; these techniques are complex and require multiple measurements. In this paper, a simple methodology to obtain small-signal model using only a simple test is presented. The parameter of the model are obtained through step response and experimental results validate the procedure.

In this paper, a simple and effective method to obtain the small signal model of discharge lamps by means of step response is presented. The lamp parameters measurement is improved by means of a circuit based on passive elements. This study describes the conditions that must fulfill the parameters extraction, as well as the additional information that provides the step response test. The stability analysis, simulation and experimental results of the lamp-ballast set together with a buck-boost converter are presented.

This paper describes the effects of applying square waveforms to the fluorescent lamps. In this work the additional benefits of using square waves and their effects in the luminous efficacy, power factor and crest factor for different power levels are presented. The study was realized by varying switching frequency in a wide range and it showed that the efficacy in the lamp fed with square waveforms remains almost constant and higher than the efficacy obtained with sinusoidal waveforms. On the other side, power factor and crest factor were almost unitary in all the frequency range. The employment of square waveforms in low or high frequency presents an advantage against sinusoidal waveforms. The obtained results suggest the possibility to employ square waveforms in lighting sources where efficacy is critical, like emergency lighting sources.