Douglas Pappis

A semiconductor lighting system controlled through a LIN network to automotive application

This paper proposes an intelligent lighting system for bus interior environment using LEDs (light emitting diodes) controlled through an automotive communication network. The system consists on a master central control and slaves lighting modules, using a LIN (local interconnect network) network to perform communication. This network is a low cost alternative to the proposed system requirements, due to its low bit rate and physical needs. The slaves are independent lighting modules that supply a group of LEDs and measure the environment lighting level. The master sets LEDs module parameters (slaves), such as the state (on/off), and desired lighting level The master makes the user interface, sets the lighting parameters, as timer and lighting level and, more over, it establishes communication with other bus systems through a CAN (controller area network) gateway. This paper presents a complete logical description, including block and state diagrams, a physical description and some relevant experimental results.

Simple valley-fill self-oscillating electronic ballast with low crest factor using pulse-frequency modulation

This paper presents an alternative to achieve fluorescent lamp current low crest factor, using the valley-fill filter as a passive power-factor-correction method. Pulse frequency modulation is used to reduce lamp current high crest factor. Self-oscillating electronic ballast is employed in order to avoid complex circuitry. The partial smoothing valley-fill DC-link bus voltage is used to control the switching frequency. Crest factor correction is achieved through a low power bipolar transistor, which connects a low power passive circuit parallel within the self-oscillating gate-driver circuit. The switching frequency changes in order to keep the lamp current crest factor lower than 1.7 and a modified valley-fill filter is used to meet IEC61000-3-2 requirements. Simulations and experimental results are presented to demonstrate the simplicity, and feasibility of the proposed system.

Generalized state-space model for the interleaved buck converter

This paper presents a complete AC small-signal general model for the interleaved buck converter (IBC) operating in continuous conduction mode. Average state-space technique is used and the most important parasitic elements are included. A ready-to-use generalized model for n-cells structure is developed by obtaining its DC model and AC small-signal model for a certain operation point. Besides, it is presented an n-cells inductor value analysis against duty-cycle and a second-order model is derived from that, which can replace the complete model with accuracy, simplifying the dynamics analysis. Models have been successfully verified experimentally, and compared via simulation in Matlab/Simulink.

An electronic ballast to supply automotive HID lamps in a low frequency square waveform

This paper presents an electronic ballast to supply a 35 W high intensity discharge (HID) xenon lamp for automotive applications. The ballast consists on a bidirectional flyback operating in discontinuous conduction mode (DCM) and an igniter circuit. The converter supplies the lamp in a 400 Hz square waveform and the igniter is responsible for providing the necessary voltage for lamp start up. The purpose of this work is to supply the xenon lamp from a 12 V battery with a reduced number of components, decreasing the system final costs without penalty the reliability. Some experimental results are presented to validate the proposed ballast behavior.

Interleaved buck converter applied to high power HID lamps supplying: Design, modeling and control

As the output current levels of power converters increases, interleaved topologies become widely used. A well-known topology is the interleaved buck converter (IBC), which presents as main characteristic a low ripple output current source behavior. Due to HID lamp voltage source characteristics and their acoustic resonance issue, it is necessary to drive them with nearly constant current with a square-wave shape. Therefore, a buck-interleaved converter can be advantageous for supplying high power HID lamps. The goal of this paper is a proposal of an electronic ballast based on a two-cell buck-interleaved converter for high power HID lamps, with current control loop, voltage sensing and constant power. A DC model based on averaged state-space technique is derived for the ballast, as well as an AC model based on small-signal disturbances. The results are verified experimentally and through simulation in Matlab/Simulink and PSIM softwares.

Modified flyback for HID supply: Design, modeling and control

This paper presents a ballast for driving high intensity discharge (HID) lamps with low frequency square waveform from a dc supply, with expansion for integrated PFC (buck-boost converter). From the dc source (battery or PFC rail), a flyback arrangement is inserted into a switching structure whose output provides low frequency voltage yet avoiding instability issues. Proposals main advantage is the need for reduced chokes count and two active switches only. Converter design for DCM is presented in this work, besides an equivalent circuit from a control point of view. Small signal ac model is obtained and feedback control loop designed based upon frequency response. HID dynamics is inserted into converter model, with feedback directly implemented. For design conformity, experimental and simulation results from Matlab and PSIM are presented, as well as discussions about its feasibility.

Automatic luminous control for self-oscillating electronic ballast

This paper presents a simple alternative of automatic luminous control for electronic ballasts operating in self-sustained oscillating mode feeding fluorescent lamps for energy saving. The luminous flux level control is based on a signal from a lighting dependent resistor, which measures the luminous flux level. The dimming feature is obtained using switching frequency variation. Thus, the circuit interprets the measurement from the sensor to control the switching frequency in the self-oscillating gate-driver circuit automatically. Experimental results from one 40 W fluorescent lamp are presented to demonstrate the feasibility of the proposed system.

Modified Flyback for HID Lamp Supply: Design, Modeling, and Control

This paper presents an electronic ballast for driving high intensity discharge (HID) lamps with low frequency square waveform from a dc supply. From the dc source (e.g., PFC rail), a flyback arrangement is inserted into a switching structure whose output provides low frequency voltage yet avoiding instability issues. Proposals main advantage is the use of one single choke of simple assembly and only two active switches for current control and inversion. Converter design for DCM is presented in this work, besides an equivalent circuit from a control point of view. Small signal ac model is obtained and a feedback control loop is designed, based upon frequency response stability and performance analysis. HID dynamics is inserted into converter model, with feedback directly implemented. A prototype is presented and described in detail, consisting of a complete power and sensing circuit fully referenced to the switches common ground proposal. For design conformity, experimental and simulation results from Matlab and PSIM are presented, as well as discussions about the converter feasibility.

High power HID lamps electronic ballast based on the interleaved buck converter

This paper presents an electronic ballast to supply high power (> 400 W) high intensity discharge (HID) lamps based on interleaved converters. Due to HID lamps voltage source characteristics and their acoustic resonance issue, it is necessary to drive them with nearly constant current (reduced ripple) with a square-wave shape. Interleaved topologies become widely used as the output current levels of power converters increases. A well-known topology is the interleaved buck converter (IBC), which presents as main characteristic a low ripple output current source behavior. Therefore, an IBC can be advantageous for supplying high power HID lamps. The main goal of this paper is to introduce an IBC operating in continuous conduction mode (CCM) applied to electronic ballasts, in order to supply high power HID lamps. The IBC inductor design is the target point, since the number of cells, losses and inductor value strongly influence the overall performance in terms of size and efficiency. Inductances, magnetic core and semiconductors are analyzed and compared across the number of cells. Results are verified through simulation in PSIM software and experimentally.

Modified flyback for HID lamp supply: Concept and design

This paper presents a ballast for driving high intensity discharge (HID) lamps with low frequency square waveform from a dc supply, with expansion for integrated PFC (buck-boost converter). From the dc source (battery or PFC rail), a flyback arrangement is inserted into a switching structure whose output provides low frequency voltage yet avoiding instability issues. Proposals main advantage is the need for reduced chokes count and two active switches only. Converter design for discontinuous conduction mode (DCM) is presented in this work, highlighting its principle and design. For proposal validation, experimental results from a built prototype are presented, as well as discussions about its feasibility and general aspects.