Hung-Liang Cheng

A digitally wireless dimmable lighting system for two-area fluorescent lamps

The digitally dimming control method is suitable for lighting application in buildings, offices, conference rooms and classrooms, and it features remote control capability. The conventional RS-232-based digitally dimmable lighting system for two-area fluorescent lamps consists of two power factor correctors and two half-bridge resonant inverters as the main circuit, and a microcontroller-based driver and two drivers/dimmers for two inverters. The drawbacks of the conventional lighting system are limited transmission length and transmission speed, and each lighting area needs its own driver and dimmer, which results in a large number of circuit components and low cost-effectiveness for application of multi-area lighting control for fluorescent lamps. Therefore, this paper presents a digitally wireless dimmable lighting system for fluorescent lamps. The main purpose of this paper is to utilize USB-based protocol instead of the RS-232-based one and increase dimming controlled nodes (devices) with the use of ZigBee transmission interface, which is a new wireless communication technology. In addition, a micro-controller is adopted to fulfill remote wireless dimming controlled electronic lighting system for two area fluorescent lamps. A prototypical electronic lighting system has been developed to drive a 32W-rated (T8-type) fluorescent lamp for each area with the use of a LabVIEW man-machine interface software to carry out the remote dimming control. The experimental results demonstrate the functionality of the presented electronic lighting system.

Analysis and implementation of a novel single-stage low-frequency electronic ballast for HID lamps

The paper presents a single-stage high-power-factor electronic ballast for metal halide lamps. The proposed ballast integrates a buck-boost converter, a buck converter and a full-bridge inverter into a single power conversion circuit. The buck-boost converter served as a power-factor corrector (PFC) is designed to operate at discontinuous conduction mode (DCM) to achieve nearly a unity power factor at the input line. By adjusting the duty-ratio of the active switches of the PFC, the lamp power is remained at rated value for universal input voltage ranged from 90 Vrms to 264 Vrms. The four active switches of the full-bridge inverter, an inductor and a capacitor form a bidirectional buck converter which supplies a low frequency square-wave current for the lamp at to avoid the lamp from happing acoustic resonance. The circuit operation is analyzed in detail to derive the design equations. A prototype electronic ballast for a 70 W metal halide lamp is built and tested. Experimental measurements are provided to verify that the proposed ballast has the merits of a nearly unity input power factor, high circuit efficiency and the metal halide lamp is free of acoustic resonance.

Implementation of a digitally dimming controlled lighting system for two-area fluorescent lamps

The digitally dimming control interface is a new kind of dimming control for a variety of lighting applications, including building, office, and conference room; it also features remote control, real-time dimming control and lamp condition recognition. The conventional RS-232-based digitally dimming lighting system for fluorescent lamps consists of a power-factor corrector and a half-bridge resonant inverter as the main circuit, and a microcontroller-based driver and dimmer as a controller. The drawbacks of this conventional lighting system are its short transmission length and low transmission speed, and that each lighting area needs its own driver and dimmer circuit, which results in large numbers of circuit components and non-cost-effectiveness for multi-area lighting control of fluorescent lamps. Therefore, this paper presents a new digitally dimming control lighting system for fluorescent lamps. The main goal of the paper is to boost the transmission length and speed with use of a new transmission interface. A compact universal-serial-bus (USB)-based lighting system for two lighting areas are developed and measured using the function of remote dimming control in order to improve the transmission speed and to reduce circuit components as compared with the conventional version.

A constant power controller of DC-AC electronic ballast inverter for HID lamps

This paper presents a constant power controller for use in the DC-AC inverter of an electronic ballast for high-intensity-discharging (HID) lamps. The proposed DC-AC inversing stage is a high-frequency combined with low-frequency square-wave-driven half-bridge-type inverter with a constant lamp power control scheme; it supplies the HID lamp with low-frequency square-wave sources to avoid acoustic resonance and to sense the lamp feedback voltage and current in order to keep the lamp power constant throughout aging. The features of the proposed inverter for driving HID lamps are cost-effectiveness, constant lamp power, and lack of acoustic resonance. This paper describes the operational principles and experimental results of the proposed constant-power-controlled inverter of an electronic ballast, for one 70W HID lamp operating with an input DC-linked bus voltage of 400 V.

A novel low-frequency square-wave-driven electronic ballast for automotive HID lamps

This paper proposes a novel two-stage electronic ballast used to supply automotive high-intensity-discharge (HID) lamps with low-frequency square-wave sources. The ballast is composed of a flyback converter with two output windings plus cascaded voltage doublers to boost the 12 V input voltage up to a high DC voltage level of 400 V, and a high-frequency combined with low-frequency square-wave-driven half-bridge inverter for supplying low-frequency square-wave sources to the lamp without incurring acoustic resonance. Analysis and design guidelines are included for the presented ballast, as are experimental results of a prototype ballast that features limited-output lamp-power control for providing one 35 W automotive HID lamp with a 12 V input DC voltage.

A compact, high-power-factor HID lamp ballast

This paper presents a two-stage, high-power-factor electronic ballast for high-intensity-discharging (HID) lamps. The presented ballast is composed of a boundary-conduction-mode (BCM)-operated buck-boost-flyback converter to achieve input current shaping, and a high-frequency (20kHz) combined with low-frequency (200Hz) square-wave-driven half-bridge-type inverter to supply the lamp with low-frequency square-wave sources. The features of the proposed ballast are high power factor (>0.99), low total harmonic distortion (THD) (<13%) of input utility-line current, cost-effectiveness and lack of acoustic resonance. This paper presents the operational principles and experimental results of the proposed ballast for one 70W MH-type HID lamp operating with 110V-rms input AC voltage.

A Color LED Driver Implemented by the Active Clamp Forward Converter

Because light emitting diodes (LEDs) have the advantages of dc working voltage, high luminescent efficiency, shortignition time, high reliability and pollution free, they have substituted for incandescent bulbs and fluorescent lampsgradually. In order to simplify circuit complexity, an active clamp forward converter with the sequential color display(SCD) control is proposed to drive red, green and blue (RGB) LED arrays. The proposed converter has zero-voltageswitching (ZVS) operations of both the main switch and the auxiliary switch, resulting in high system efficiency. DrivingRGB LED arrays sequentially by one converter can save components and reduce cost significantly. Additionally, thepulse-width modulation (PWM) control is applied to achieve a large chromaticity variation. The circuit operations areanalyzed in detail and the circuit parameters are designed based on the practical considerations. Finally, an illustrativeexample is implemented to demonstrate the feasibility and validity of the proposed LED driver.

Modeling and design of the LLC resonant converter used in solar array simulator

An LLC resonant converter has been used to provide the electrical characteristics of solar arrays. In this paper, its small signal model is derived based on the extended describing function concept. The corresponding frequency response can be easily obtained from IsSpice simulation of the equivalent circuit model. Furthermore, a closed-loop compensation controller is designed according to the derived small-signal model. The experimental measurements have really proved that the stable and fast transient response can be achieved in the system. The system output voltage and current can be adjusted simultaneously to match the electrical characteristics of photovoltaic output.

Low-frequency square-wave-driven automotive HID lamp ballast without acoustic resonance

This paper proposes a novel two-stage electronic ballast used to supply automotive high-intensity-discharge (HID) lamps with low-frequency square-wave sources. The ballast is composed of a boost-flyback converter with two output windings plus cascaded voltage doublers to boost up the 12 V input voltage to a high DC voltage level of 400 V, and a high-frequency combined with low-frequency square-wave-driven half-bridge inverter for supplying low-frequency square-wave sources to the lamp without incurring acoustic resonance. Analysis of operational modes for the presented ballast and experimental results of a prototype ballast for providing one 35 W automotive HID lamp with a 12 V input DC voltage are demonstrated.

A single-stage HID lamp electronic ballast with high PF

This paper presents a single-stage electronic ballast for the high-intensity-discharge (HID) lamp with high power factor (PF). The presented ballast consists of a discontinuous-conduction-mode (DCM) operated dual-boost converter to achieve input-current shaping, and a high-frequency combined with low-frequency square-wave-driven half-bridge-type inverter for supplying the HID lamp with low-frequency square-wave sources. The features of the proposed ballast are high PF, low total harmonic distortion (THD) of input utility-line current, cost-effectiveness and freedom from acoustic resonance. This paper presents the operational principles, design guidelines and experimental results of the proposed ballast for one 70W MH-type HID lamp operating with 110V-rms input utility-line voltage.