Henrique Braga - Academia.edu (original) (raw)
Papers by Henrique Braga
O objetivo deste artigo é apresentar considerações sobre a análise e projeto de reatores eletrôni... more O objetivo deste artigo é apresentar considerações sobre a análise e projeto de reatores eletrônicos ressonantes operando em alta freqüência, destinados ao acionamento de lâmpadas de descarga em alta pressão ou HID – (High Intensity Discharge). O trabalho tem como motivação principal a substituição de reatores convencionais (eletromagnéticos), que constituem uma bancada de testes de componentes usados na iluminação pública. Por necessitar de oito reatores comuns para a avaliação funcional básica de lâmpadas, o peso e o volume da bancada dificultam sua mobilidade. Outras desvantagens se referem ao custo de produção e transporte do equipamento. Num aspecto geral, empregando informações divulgadas na literatura técnica, apresenta-se a concepção de projeto de unidades de reatores eletrônicos “universais”, operando em alta freqüência e numa fração da potência nominal das lâmpadas, o que resulta na redução do volume e peso do equipamento de teste. Além disso, a bancada passa a consumir me...
2018 13th IEEE International Conference on Industry Applications (INDUSCON)
This paper describes step-by-step guidelines concerning the design of a flyback-based offline LED... more This paper describes step-by-step guidelines concerning the design of a flyback-based offline LED driver intended to constitute a visible light communication system. The focus is on efficiency and simplicity. Some details are presented, in regard to definition of the converter parameters, the main switch snubber design, transformer calculation and implementation, EMI filter definition, dimming technique, flicker levels and modeling. The methodology applied define the main parameters with routines and graphical analysis. A design example is presented leading to a laboratory prototype whose efficiency was around 90% with 0.997 power factor when providing power to an LED module with nominal parameters of 180 V, 63 W. The main applications are in large commercial areas and industrial, for lighting and communication services.
Resumo – Este trabalho fornece uma compilacao e uma revisao bibliografica cuidadosa sobre os conv... more Resumo – Este trabalho fornece uma compilacao e uma revisao bibliografica cuidadosa sobre os conversores estaticos multiniveis em tensao e corrente. As referencias mais significativas, bem como as estruturas basicas, sao apresentadas e comentadas sob o ponto de vista da divisao equilibrada das grandezas eletricas (tensao ou corrente) entre as celulas individuais e quanto a possibilidade de aproveitamento dos niveis intermediarios destas grandezas. Alguns resultados de simulacao computacional sao apresentados e uma discussao inedita sobre estruturas multiniveis simultaneamente em tensao e corrente e apresentada ao final do texto.
2018 13th IEEE International Conference on Industry Applications (INDUSCON)
This work presents the state-space average modeling of the low frequency off-line LED driver base... more This work presents the state-space average modeling of the low frequency off-line LED driver based on the boost pre-regulator converter with an LC filter output. The small signal modeling of the converter was derived. A control strategy of the current through the LED arrangement is also proposed. The converter was designed to supply power to a street lighting LED luminaire. The LED driver prototype was able to present a high power factor (PF) and a low total harmonic distortion (THD). The output power of the LED driver was 186 W with 93 % efficiency, when fed by 220 V, 60 Hz mains. The modeling presented in this paper aimed to seek a more precise derivation of the control to output transfer function, i. e., the transfer function concerning the output current and the duty cycle switch parameter. The paper also provides details of the frequency domain design of the current compensator by employing the improved transfer function. The compensator must perform two main tasks, which are the output luminous control (dimming feature) and the rejection of input voltage disturbances. In addition, the compensator transfer function was discretized for future implementation in a microcontroller. Simulation results of the digital compensator in open-loop and closed-loop are presented to validate the small signal modeling and to observe the dynamic response of the proposed compensator.
2018 13th IEEE International Conference on Industry Applications (INDUSCON), 2018
This paper describes step-by-step guidelines concerning the design of a flyback-based offline LED... more This paper describes step-by-step guidelines concerning the design of a flyback-based offline LED driver intended to constitute a visible light communication system. The focus is on efficiency and simplicity. Some details are presented, in regard to definition of the converter parameters, the main switch snubber design, transformer calculation and implementation, EMI filter definition, dimming technique, flicker levels and modeling. The methodology applied define the main parameters with routines and graphical analysis. A design example is presented leading to a laboratory prototype whose efficiency was around 90% with 0.997 power factor when providing power to an LED module with nominal parameters of 180 V, 63 W. The main applications are in large commercial areas and industrial, for lighting and communication services.
2017 Brazilian Power Electronics Conference (COBEP), 2017
This paper proposes an initial study on Visible Light Communication (VLC) system consisting of a ... more This paper proposes an initial study on Visible Light Communication (VLC) system consisting of a 20 W flyback converter operating in Continuous Conduction Mode (CCM) with dimmable capability over the range of 20–80%. The paper uses the VPPM (Variable Pulse Position Modulation) technique for VLC data transmission. This modulation allows the transmission of the bits without modification of the converter duty cycle, ensuring a data transmission that does not affect the current dimming condition. The implemented laboratory prototype features a system efficiency between 85% and 89% over the whole dimming range and a transmission rate of 2.2 kb/s.
2017 Brazilian Power Electronics Conference (COBEP), 2017
This work presents a novel method to perform high-luminous flux LED (light emitting diode) lighti... more This work presents a novel method to perform high-luminous flux LED (light emitting diode) lighting. The technique comprises high current COB (chip-on-board) LEDs while their features and main parameters are properly studied in this paper. Furthermore, a PET (photo-electro-thermal) modeling is presented and evaluated considering experimental validations. In order to drive this high power COB LED, a two-stage topology has been chosen aiming minimum capacitance associated with high dc voltage bus. The first stage comprises a front-end PFC (power factor correction) boost pre-regulator operating in CCM (continuous conduction mode) whereas the second stage concerns an interleaved CCM buck structure in order to minimize current stresses in switches by sharing the rated current properly. Besides, simulation results are carried out and analyzed in order to obtain high power factor, low THDi (total input current harmonic distortion) and proper COB driving. Moreover, power quality results are...
2017 Brazilian Power Electronics Conference (COBEP)
This paper presents a discussion about the use of a low frequency Ćuk-based pre-regulator as an o... more This paper presents a discussion about the use of a low frequency Ćuk-based pre-regulator as an offline LED driver and its application to a street lighting LED luminaire. This AC-DC converter may provide high power factor, low input current distortion and compliance with IEC 61.000-3-2 Class C standard, which limits the emission of harmonic currents of lighting equipment. The analysis of the Ćuk pre-regulator is revised and a simplified method of microcontrolled control is proposed. Experimental results are shown to an LED luminaire which delivers around 80 W to the lighting devices. For the presented prototype, no electrolytic capacitors are required, which define an extended lifetime for this driver. Moreover, the proposed LED driver can make use of conventional choke inductors employed in nowadays HID-ballasts.
2017 Brazilian Power Electronics Conference (COBEP)
This work presents an innovative method to achieve extra-high luminous flux (higher than 20 klm) ... more This work presents an innovative method to achieve extra-high luminous flux (higher than 20 klm) in solid-state outdoor floodlighting. This technique makes use of high-current COB (chip-on-board) LEDs (light emitting diodes) instead of high-voltage modules, which are normally built using series connection of discrete elements. For this purpose, a current multilevel PFC (power factor correction) buck rectifier is proposed and properly studied as a COB LED driver. This driver presents important features when dealing with outdoor lighting, namely high power factor, low input current distortion, and good overall efficiency. Simulation analysis is performed considering intrinsic and parasitic elements aiming more a realistic study. A discussion is provided with focus on converter feasibility for high-current applications. Finally, the compliance with power-quality-related standards is also investigated.
2017 Brazilian Power Electronics Conference (COBEP)
This paper presents an offline LED driver based a low-frequency boost converter and its applicati... more This paper presents an offline LED driver based a low-frequency boost converter and its application to street lighting luminaires. The analysis of the boost pre-regulator is revised and two simplified methods of microcontrolled control are proposed. Experimental results are shown to an LED luminaire operating in 165W.
Journal of Control, Automation and Electrical Systems
Eletrônica de Potência
This paper describes the analysis and design of an electronic ballast devised to drive both, high... more This paper describes the analysis and design of an electronic ballast devised to drive both, high pressure sodium vapor (HPS) and high pressure mercury vapor (HPMV) lamps, in dimmed operation with no need of parameter modification. The main objective is to achieve weight and volume reduction of a public lighting components bench test equipment, used to perform basic operational tests in a Brazilian electric utility company. Specifically, the analysis, design and implementation of an electronic ballast, based on a series-parallel loaded resonant inverter, for 70 W HPS and 125 W HPMV lamps testing is presented. Experimental results from a lab prototype, performing high intensity discharge (HID) lamp tests in dimmed operation and no discharge arc instability, evidences the feasibility of the proposed ballast concerning the intended application.
Eletrônica de Potência, Aug 1, 2012
This paper describes the analysis and design of an electronic ballast devised to drive both, high... more This paper describes the analysis and design of an electronic ballast devised to drive both, high pressure sodium vapor (HPS) and high pressure mercury vapor (HPMV) lamps, in dimmed operation with no need of parameter modification. The main objective is to achieve weight and volume reduction of a public lighting components bench test equipment, used to perform basic operational tests in a Brazilian electric utility company. Specifically, the analysis, design and implementation of an electronic ballast, based on a series-parallel loaded resonant inverter, for 70 W HPS and 125 W HPMV lamps testing is presented. Experimental results from a lab prototype, performing high intensity discharge (HID) lamp tests in dimmed operation and no discharge arc instability, evidences the feasibility of the proposed ballast concerning the intended application.
Eletrônica de Potência
This work presents some results of modeling and control design of a 30 kWp photovoltaic system co... more This work presents some results of modeling and control design of a 30 kWp photovoltaic system connected to the grid in the Campus of Federal University of Juiz de Fora. The interface converter is connected to the grid using only the leakage inductance of a single-phase transformer bank as passive filter. The control algorithm is carried out in the synchronous reference frame (dq0). Two identical proportionalintegral controllers (PI-SRF) are designed to regulate the currents in each coordinate. It will be shown that the PI-SRF controller may have its effectiveness compromised due to distorted currents drained by the connection transformer. To overcome the aforementioned problem a repetitive controller (RC) is designed and connected in parallel with the PI-SRF. The performance of the hybrid controller (PI-SRF + RC) is tested under steady-state and transient conditions for variations in the power generated by the photovoltaic (PV) panels. Experimental results are presented to validate the design and performance of the proposed hybrid controller.
IEEE Journal of Emerging and Selected Topics in Power Electronics
This paper presents an optimization strategy for designing an offline light-emitting diode (LED) ... more This paper presents an optimization strategy for designing an offline light-emitting diode (LED) driver with a wide-bandwidth controller aimed at reducing the converter storage capacitance. The approach is based on the modeling of all the designing process as a nonlinear constrained optimization problem so that the power circuit elements and also the controller are designed, simultaneously in order to optimize a given parameter, such as the filtering capacitance or the total harmonic distortion. Although the low-frequency ripple compensation can insert a distortion in the input current of the converter, the proposed technique ensures that all the design requirements are fulfilled, including the IEC 61000-3-2 compliance, and also the maximum low-frequency ripple constraints. In order to verify the feasibility of the design procedure, the strategy was employed to an offline LED driver based on the integrated double buck-boost converter. Experimental results taken from a 75-W laboratory prototype, fed from a 220-V grid voltage, attested the proposed methodology.
IEEE Transactions on Power Electronics
This paper presents the study of an offline flyback-based light-emitting diode (LED) driver with ... more This paper presents the study of an offline flyback-based light-emitting diode (LED) driver with reduced storage capacitance. An approach called active ripple compensation was used for minimizing the converter bulk capacitance. This technique is oriented to voltage-controlled pulse width modulation converters and is based on the modulation of the duty cycle, which allows for the reduction of the filtering capacitance by increasing the harmonic content of the input current up to the limits established by the standards. By means of the design procedure presented in this paper, the amount of capacitance reduction and input current distortion can be fully controlled and theoretically predicted. In addition, no extra sensors are required to implement the proposed technique, apart from the LED current sensor already available in most LED drivers. Experimental results from a 50-W laboratory prototype supplied from a 220-V 60-Hz grid were carried out. The results were compared with the conventional approach, attesting the superior performance of the proposed methodology.
Journal of Control, Automation and Electrical Systems
This paper proposes a smart LED lighting system for street lighting applications. Besides the opt... more This paper proposes a smart LED lighting system for street lighting applications. Besides the optical LED arrangement, the luminaire is composed by a Ćuk-based power converter operating in discontinuous conduction mode, with dimming capability, a set of sensors, and a digital processor. The system has the capability of executing several functions simultaneously. Among the main features are the capability of controlling the current flowing through the LEDs, the control of the light level with a PWM dimming technique, and the protection of the driver against some common failures, such as output overvoltage (load disconnection). Furthermore, the smart luminaire is also capable of estimating its power consumption and even monitoring specific power quality parameters related to the grid voltage, such as sags and swells. All of the aforementioned functions were developed with a minimalist set of sensors, which reduces the hardware requirements of the system. In order to perform an experimental evaluation of the proposed system, a software intended to manage the luminaire functionalities and a 70-W prototype were built. The experimental results demonstrated a good performance of the LED driver as well as the functionalities of the proposed luminaire.
IEEE Transactions on Power Electronics, 2017
This study proposes a novel approach for low-frequency output current ripple minimization in offl... more This study proposes a novel approach for low-frequency output current ripple minimization in offline light-emitting diode (LED) drivers. This strategy is based on the large-signal modulation of the LED converter duty-cycle so that the output ripple can be reduced and, consequently, the required filtering capacitances of the converter can be somehow decreased. This technique is devised to be used on converters in which a single control loop is employed, such as offline integrated converters, where a single control loop is responsible to control the output current while maintaining the high power factor at the input (mains). The duty-cycle modulation is used to change the shape of the main waveforms of the converter, especially input and output currents. This allows for a reduction of the output current peak-to-peak ripple while the harmonic content of the input current is increased but kept within the limits imposed by the IEC standard. An application example for an integrated two-stage converter based on the cascade connection of two buck–boost converters is shown. Experimental results from a 70-W laboratory prototype supplied from a 115-V grid were carried out and compared with conventional approaches in order to verify the feasibility of the proposed technique.
2015 IEEE 13th Brazilian Power Electronics Conference and 1st Southern Power Electronics Conference (COBEP/SPEC), 2015
This work describes and compares two compensation strategies for shunt active filters in circuits... more This work describes and compares two compensation strategies for shunt active filters in circuits comprised by two phases and neutral derived from three-phase grids. In the “double single-phase strategy”, the active filter is controlled as a superposition of two single-phase filters. In the other approach, called “zero neutral current strategy”, the active filter is controlled to mitigate neutral currents. Both strategies are described and experimental results are presented to show the characteristics of each compensation strategy.
O objetivo deste artigo é apresentar considerações sobre a análise e projeto de reatores eletrôni... more O objetivo deste artigo é apresentar considerações sobre a análise e projeto de reatores eletrônicos ressonantes operando em alta freqüência, destinados ao acionamento de lâmpadas de descarga em alta pressão ou HID – (High Intensity Discharge). O trabalho tem como motivação principal a substituição de reatores convencionais (eletromagnéticos), que constituem uma bancada de testes de componentes usados na iluminação pública. Por necessitar de oito reatores comuns para a avaliação funcional básica de lâmpadas, o peso e o volume da bancada dificultam sua mobilidade. Outras desvantagens se referem ao custo de produção e transporte do equipamento. Num aspecto geral, empregando informações divulgadas na literatura técnica, apresenta-se a concepção de projeto de unidades de reatores eletrônicos “universais”, operando em alta freqüência e numa fração da potência nominal das lâmpadas, o que resulta na redução do volume e peso do equipamento de teste. Além disso, a bancada passa a consumir me...
2018 13th IEEE International Conference on Industry Applications (INDUSCON)
This paper describes step-by-step guidelines concerning the design of a flyback-based offline LED... more This paper describes step-by-step guidelines concerning the design of a flyback-based offline LED driver intended to constitute a visible light communication system. The focus is on efficiency and simplicity. Some details are presented, in regard to definition of the converter parameters, the main switch snubber design, transformer calculation and implementation, EMI filter definition, dimming technique, flicker levels and modeling. The methodology applied define the main parameters with routines and graphical analysis. A design example is presented leading to a laboratory prototype whose efficiency was around 90% with 0.997 power factor when providing power to an LED module with nominal parameters of 180 V, 63 W. The main applications are in large commercial areas and industrial, for lighting and communication services.
Resumo – Este trabalho fornece uma compilacao e uma revisao bibliografica cuidadosa sobre os conv... more Resumo – Este trabalho fornece uma compilacao e uma revisao bibliografica cuidadosa sobre os conversores estaticos multiniveis em tensao e corrente. As referencias mais significativas, bem como as estruturas basicas, sao apresentadas e comentadas sob o ponto de vista da divisao equilibrada das grandezas eletricas (tensao ou corrente) entre as celulas individuais e quanto a possibilidade de aproveitamento dos niveis intermediarios destas grandezas. Alguns resultados de simulacao computacional sao apresentados e uma discussao inedita sobre estruturas multiniveis simultaneamente em tensao e corrente e apresentada ao final do texto.
2018 13th IEEE International Conference on Industry Applications (INDUSCON)
This work presents the state-space average modeling of the low frequency off-line LED driver base... more This work presents the state-space average modeling of the low frequency off-line LED driver based on the boost pre-regulator converter with an LC filter output. The small signal modeling of the converter was derived. A control strategy of the current through the LED arrangement is also proposed. The converter was designed to supply power to a street lighting LED luminaire. The LED driver prototype was able to present a high power factor (PF) and a low total harmonic distortion (THD). The output power of the LED driver was 186 W with 93 % efficiency, when fed by 220 V, 60 Hz mains. The modeling presented in this paper aimed to seek a more precise derivation of the control to output transfer function, i. e., the transfer function concerning the output current and the duty cycle switch parameter. The paper also provides details of the frequency domain design of the current compensator by employing the improved transfer function. The compensator must perform two main tasks, which are the output luminous control (dimming feature) and the rejection of input voltage disturbances. In addition, the compensator transfer function was discretized for future implementation in a microcontroller. Simulation results of the digital compensator in open-loop and closed-loop are presented to validate the small signal modeling and to observe the dynamic response of the proposed compensator.
2018 13th IEEE International Conference on Industry Applications (INDUSCON), 2018
This paper describes step-by-step guidelines concerning the design of a flyback-based offline LED... more This paper describes step-by-step guidelines concerning the design of a flyback-based offline LED driver intended to constitute a visible light communication system. The focus is on efficiency and simplicity. Some details are presented, in regard to definition of the converter parameters, the main switch snubber design, transformer calculation and implementation, EMI filter definition, dimming technique, flicker levels and modeling. The methodology applied define the main parameters with routines and graphical analysis. A design example is presented leading to a laboratory prototype whose efficiency was around 90% with 0.997 power factor when providing power to an LED module with nominal parameters of 180 V, 63 W. The main applications are in large commercial areas and industrial, for lighting and communication services.
2017 Brazilian Power Electronics Conference (COBEP), 2017
This paper proposes an initial study on Visible Light Communication (VLC) system consisting of a ... more This paper proposes an initial study on Visible Light Communication (VLC) system consisting of a 20 W flyback converter operating in Continuous Conduction Mode (CCM) with dimmable capability over the range of 20–80%. The paper uses the VPPM (Variable Pulse Position Modulation) technique for VLC data transmission. This modulation allows the transmission of the bits without modification of the converter duty cycle, ensuring a data transmission that does not affect the current dimming condition. The implemented laboratory prototype features a system efficiency between 85% and 89% over the whole dimming range and a transmission rate of 2.2 kb/s.
2017 Brazilian Power Electronics Conference (COBEP), 2017
This work presents a novel method to perform high-luminous flux LED (light emitting diode) lighti... more This work presents a novel method to perform high-luminous flux LED (light emitting diode) lighting. The technique comprises high current COB (chip-on-board) LEDs while their features and main parameters are properly studied in this paper. Furthermore, a PET (photo-electro-thermal) modeling is presented and evaluated considering experimental validations. In order to drive this high power COB LED, a two-stage topology has been chosen aiming minimum capacitance associated with high dc voltage bus. The first stage comprises a front-end PFC (power factor correction) boost pre-regulator operating in CCM (continuous conduction mode) whereas the second stage concerns an interleaved CCM buck structure in order to minimize current stresses in switches by sharing the rated current properly. Besides, simulation results are carried out and analyzed in order to obtain high power factor, low THDi (total input current harmonic distortion) and proper COB driving. Moreover, power quality results are...
2017 Brazilian Power Electronics Conference (COBEP)
This paper presents a discussion about the use of a low frequency Ćuk-based pre-regulator as an o... more This paper presents a discussion about the use of a low frequency Ćuk-based pre-regulator as an offline LED driver and its application to a street lighting LED luminaire. This AC-DC converter may provide high power factor, low input current distortion and compliance with IEC 61.000-3-2 Class C standard, which limits the emission of harmonic currents of lighting equipment. The analysis of the Ćuk pre-regulator is revised and a simplified method of microcontrolled control is proposed. Experimental results are shown to an LED luminaire which delivers around 80 W to the lighting devices. For the presented prototype, no electrolytic capacitors are required, which define an extended lifetime for this driver. Moreover, the proposed LED driver can make use of conventional choke inductors employed in nowadays HID-ballasts.
2017 Brazilian Power Electronics Conference (COBEP)
This work presents an innovative method to achieve extra-high luminous flux (higher than 20 klm) ... more This work presents an innovative method to achieve extra-high luminous flux (higher than 20 klm) in solid-state outdoor floodlighting. This technique makes use of high-current COB (chip-on-board) LEDs (light emitting diodes) instead of high-voltage modules, which are normally built using series connection of discrete elements. For this purpose, a current multilevel PFC (power factor correction) buck rectifier is proposed and properly studied as a COB LED driver. This driver presents important features when dealing with outdoor lighting, namely high power factor, low input current distortion, and good overall efficiency. Simulation analysis is performed considering intrinsic and parasitic elements aiming more a realistic study. A discussion is provided with focus on converter feasibility for high-current applications. Finally, the compliance with power-quality-related standards is also investigated.
2017 Brazilian Power Electronics Conference (COBEP)
This paper presents an offline LED driver based a low-frequency boost converter and its applicati... more This paper presents an offline LED driver based a low-frequency boost converter and its application to street lighting luminaires. The analysis of the boost pre-regulator is revised and two simplified methods of microcontrolled control are proposed. Experimental results are shown to an LED luminaire operating in 165W.
Journal of Control, Automation and Electrical Systems
Eletrônica de Potência
This paper describes the analysis and design of an electronic ballast devised to drive both, high... more This paper describes the analysis and design of an electronic ballast devised to drive both, high pressure sodium vapor (HPS) and high pressure mercury vapor (HPMV) lamps, in dimmed operation with no need of parameter modification. The main objective is to achieve weight and volume reduction of a public lighting components bench test equipment, used to perform basic operational tests in a Brazilian electric utility company. Specifically, the analysis, design and implementation of an electronic ballast, based on a series-parallel loaded resonant inverter, for 70 W HPS and 125 W HPMV lamps testing is presented. Experimental results from a lab prototype, performing high intensity discharge (HID) lamp tests in dimmed operation and no discharge arc instability, evidences the feasibility of the proposed ballast concerning the intended application.
Eletrônica de Potência, Aug 1, 2012
This paper describes the analysis and design of an electronic ballast devised to drive both, high... more This paper describes the analysis and design of an electronic ballast devised to drive both, high pressure sodium vapor (HPS) and high pressure mercury vapor (HPMV) lamps, in dimmed operation with no need of parameter modification. The main objective is to achieve weight and volume reduction of a public lighting components bench test equipment, used to perform basic operational tests in a Brazilian electric utility company. Specifically, the analysis, design and implementation of an electronic ballast, based on a series-parallel loaded resonant inverter, for 70 W HPS and 125 W HPMV lamps testing is presented. Experimental results from a lab prototype, performing high intensity discharge (HID) lamp tests in dimmed operation and no discharge arc instability, evidences the feasibility of the proposed ballast concerning the intended application.
Eletrônica de Potência
This work presents some results of modeling and control design of a 30 kWp photovoltaic system co... more This work presents some results of modeling and control design of a 30 kWp photovoltaic system connected to the grid in the Campus of Federal University of Juiz de Fora. The interface converter is connected to the grid using only the leakage inductance of a single-phase transformer bank as passive filter. The control algorithm is carried out in the synchronous reference frame (dq0). Two identical proportionalintegral controllers (PI-SRF) are designed to regulate the currents in each coordinate. It will be shown that the PI-SRF controller may have its effectiveness compromised due to distorted currents drained by the connection transformer. To overcome the aforementioned problem a repetitive controller (RC) is designed and connected in parallel with the PI-SRF. The performance of the hybrid controller (PI-SRF + RC) is tested under steady-state and transient conditions for variations in the power generated by the photovoltaic (PV) panels. Experimental results are presented to validate the design and performance of the proposed hybrid controller.
IEEE Journal of Emerging and Selected Topics in Power Electronics
This paper presents an optimization strategy for designing an offline light-emitting diode (LED) ... more This paper presents an optimization strategy for designing an offline light-emitting diode (LED) driver with a wide-bandwidth controller aimed at reducing the converter storage capacitance. The approach is based on the modeling of all the designing process as a nonlinear constrained optimization problem so that the power circuit elements and also the controller are designed, simultaneously in order to optimize a given parameter, such as the filtering capacitance or the total harmonic distortion. Although the low-frequency ripple compensation can insert a distortion in the input current of the converter, the proposed technique ensures that all the design requirements are fulfilled, including the IEC 61000-3-2 compliance, and also the maximum low-frequency ripple constraints. In order to verify the feasibility of the design procedure, the strategy was employed to an offline LED driver based on the integrated double buck-boost converter. Experimental results taken from a 75-W laboratory prototype, fed from a 220-V grid voltage, attested the proposed methodology.
IEEE Transactions on Power Electronics
This paper presents the study of an offline flyback-based light-emitting diode (LED) driver with ... more This paper presents the study of an offline flyback-based light-emitting diode (LED) driver with reduced storage capacitance. An approach called active ripple compensation was used for minimizing the converter bulk capacitance. This technique is oriented to voltage-controlled pulse width modulation converters and is based on the modulation of the duty cycle, which allows for the reduction of the filtering capacitance by increasing the harmonic content of the input current up to the limits established by the standards. By means of the design procedure presented in this paper, the amount of capacitance reduction and input current distortion can be fully controlled and theoretically predicted. In addition, no extra sensors are required to implement the proposed technique, apart from the LED current sensor already available in most LED drivers. Experimental results from a 50-W laboratory prototype supplied from a 220-V 60-Hz grid were carried out. The results were compared with the conventional approach, attesting the superior performance of the proposed methodology.
Journal of Control, Automation and Electrical Systems
This paper proposes a smart LED lighting system for street lighting applications. Besides the opt... more This paper proposes a smart LED lighting system for street lighting applications. Besides the optical LED arrangement, the luminaire is composed by a Ćuk-based power converter operating in discontinuous conduction mode, with dimming capability, a set of sensors, and a digital processor. The system has the capability of executing several functions simultaneously. Among the main features are the capability of controlling the current flowing through the LEDs, the control of the light level with a PWM dimming technique, and the protection of the driver against some common failures, such as output overvoltage (load disconnection). Furthermore, the smart luminaire is also capable of estimating its power consumption and even monitoring specific power quality parameters related to the grid voltage, such as sags and swells. All of the aforementioned functions were developed with a minimalist set of sensors, which reduces the hardware requirements of the system. In order to perform an experimental evaluation of the proposed system, a software intended to manage the luminaire functionalities and a 70-W prototype were built. The experimental results demonstrated a good performance of the LED driver as well as the functionalities of the proposed luminaire.
IEEE Transactions on Power Electronics, 2017
This study proposes a novel approach for low-frequency output current ripple minimization in offl... more This study proposes a novel approach for low-frequency output current ripple minimization in offline light-emitting diode (LED) drivers. This strategy is based on the large-signal modulation of the LED converter duty-cycle so that the output ripple can be reduced and, consequently, the required filtering capacitances of the converter can be somehow decreased. This technique is devised to be used on converters in which a single control loop is employed, such as offline integrated converters, where a single control loop is responsible to control the output current while maintaining the high power factor at the input (mains). The duty-cycle modulation is used to change the shape of the main waveforms of the converter, especially input and output currents. This allows for a reduction of the output current peak-to-peak ripple while the harmonic content of the input current is increased but kept within the limits imposed by the IEC standard. An application example for an integrated two-stage converter based on the cascade connection of two buck–boost converters is shown. Experimental results from a 70-W laboratory prototype supplied from a 115-V grid were carried out and compared with conventional approaches in order to verify the feasibility of the proposed technique.
2015 IEEE 13th Brazilian Power Electronics Conference and 1st Southern Power Electronics Conference (COBEP/SPEC), 2015
This work describes and compares two compensation strategies for shunt active filters in circuits... more This work describes and compares two compensation strategies for shunt active filters in circuits comprised by two phases and neutral derived from three-phase grids. In the “double single-phase strategy”, the active filter is controlled as a superposition of two single-phase filters. In the other approach, called “zero neutral current strategy”, the active filter is controlled to mitigate neutral currents. Both strategies are described and experimental results are presented to show the characteristics of each compensation strategy.