Single-stage line-coupled half-bridge ballast with unity power factor and ripple-free input current using a coupled inductor

A single-stage line-coupled half-bridge ballast with unity power factor and ripple-free input current using a coupled inductor is proposed. The proposed power-factor-correction circuit can achieve unity power factor and ripple-free input current using a coupled inductor. A saturable transformer constituting the self-oscillating drive limits the lamp current and dominates the switching frequency of the ballast. The proposed ballast has high energy efficiency, low cost, and high reliability compared to the conventional high-power-factor electronic ballasts. Experimental results obtained on a 30-W fluorescent lamp is discussed.     

Small-signal analysis of a low-cost power control for LCC series-parallel inverters with resonant current mode control for HID lamps

In this paper, a low-cost power control for LCC series-parallel inverters with resonant current mode control for high intensity discharge (HID) lamps is presented. These resonant inverters require controlling the power supplied to the lamp in order to avoid exceeding the maximum lamp power recommended by the lamp manufacturer. The classical control method measures the lamp voltage and current and they are multiplied analogically, obtaining the lamp power consumption measure. This control circuitry results very complex due to the lamp voltage and current wide variations range during ignition and discharge processes. Assuming a regulated input dc voltage (bus voltage) provided by the power factor correction (PFC) pre-regulator and an inverter constant efficiency along the lamp aging, the lamp power consumption may be estimated and regulated properly measuring the inverter average input current. Also, the small-signal analysis performed allows obtaining the small-signal resonant inverter input impedance and studying the connection stability between PFC pre-regulator and inverter. The inverter small-signal analysis has been performed and an electronic ballast prototype for 250-W HPS lamps has been implemented and tested verifying the low-cost lamp power control method proposed.     

Analysis and design of a high power factor, single-stage electronic ballast for high-intensity discharge lamps

This paper proposes a single-stage electronic ballast for high-intensity discharge lamps. The ballast consists of the integration of a boost converter in discontinuous conduction mode (DCM) and a full-bridge LCC resonant inverter. The boost semi-stage working in DCM functions as a power factor corrector and the inverter semi-stage operated above resonance is employed to drive the lamp. The sine-wave approximation is used to design the inverter at steady-state. The proposed electronic ballast can save a controller, reduce size and possibly increase system reliability compared to conventional two-stage system. The proposed ballast is analyzed, simulated and experimentally verified with a 125 W HPS lamp.     

The Influence of the Startup Process of Small Metal-Halide (MH) Lamps on Electronic Ballast Design

In this paper, the authors present the results of an investigation into the starting process of a small wattage metal halide lamp and address the influence of the starting process, at extra- high frequency (>350 kHz), upon the performance of two most commonly used electronic ballast circuit topologies, namely the LCC resonant inverter and LCL resonant inverter. The starting transient processes driven by both ballast systems are captured, analyzed and explained. It has been found that the starting process could affect the operating performance of an LCL ballast and may destroy its power switches in the worst case while a LCC ballast gets the advantage over the LCL ballast for the stability during the transient starting process.     

A novel single-stage constant-wattage high-power-factor electronicballast

A novel single-stage high-power-factor electronic ballast is presented in this paper. The ballast is obtained from the integration of a buck-boost converter and a half-bridge LC resonant inverter. The ballast features lamp power regulation against line voltage fluctuations together with high power factor and dimming capability. The steady-state analysis of the ballast is performed and a low-frequency model of the input stage is derived. A design example, including closed-loop circuitry, is also presented. Finally, some experimental results from a laboratory prototype are shown     

一种E类驱动单级式电子镇流器的仿真研究

提出了一种E类驱动结构的谐振式电子镇流器,将E类结构和buck-boost功率因数校正结构整合成一种单级式电子镇流器。由于E类驱动式的谐振电路只需一个开关管,经过整合后的电路也只需一个控制电路和一个开关管,进一步降低了镇流器的成本提高了效率。文章分析了E类镇流器电路工作在最佳情况下的工作状态,仿真采用脉宽调制控制电路工作。     

A single-stage high-power-factor electronic ballast withduty-ratio-controlled series resonant inverter

A single-stage high-power-factor electronic ballast is developed by making an integration of an active filter and a series resonant inverter. The function of power-factor correction is performed by adjusting the duty ratio of the inverter power switches with a simple control circuit. A prototype unit designed for a 36-W compact fluorescent lamp is built and tested to verify the predicted results     

Digital Control of a Low-Frequency Square-Wave Electronic Ballast With Resonant Ignition

This paper proposes a two-stage low-frequency square-wave (LFSW) electronic ballast with digital control. The first stage of the ballast is a power factor correction (PFC) stage, and the second is a full-bridge (FB) converter used for both lamp ignition and LFSW drive. As a novelty for LFSW ballasts, ignition is achieved without an additional igniter circuit by operating the FB during start-up as a high-frequency resonant inverter. After ignition, the converter operates as an LFSW inverter to avoid exciting acoustic resonances by controlling the FB as a buck converter and regulating alternately positive or negative current to the lamp. Lamp power is regulated by adjusting the average current supplied by the PFC stage. Another contribution of this paper is to utilize digital control as a simple solution to achieve multimode control, including resonant lamp ignition, LFSW transitions, and lamp current and power regulation.      

TRIAC dimmable ballast with power equalization

A two-stage, two-wire TRIAC dimmable electronic ballast for fluorescent lamps is presented in this paper. It is constructed by using a flyback converter as the input power factor corrector to supply a half-bridge series-resonant parallel-loaded inverter to ballast the lamp. The flyback converter is operated in discontinuous conduction mode so that the filtered input current profile is the same as the TRIAC-controlled voltage waveform. The switches in the inverter are switched at a constant frequency slightly higher than the resonant frequency of the resonant tank. Based on the constant average input current characteristics of the inverter, the dimming operation is simply achieved by pulsewidth modulation control of the magnitude of the flyback converter output voltage. No synchronization network is required between the input and output stages. In addition, a linear power equalization scheme is developed so that the dc-link voltage (and hence the lamp power) is in a linear relationship with the firing angle of the TRIAC. The average output voltage of the dimmer controls the equalized flyback converter output voltage. Modeling, analysis, and design of the ballast will be described. A prototype was implemented to verify the experimental measurements with the theoretical predictions.     

Design of fluorescent lamp ballast with PFC using a power piezoelectric transformer

An investigation of a high-power piezoelectric transformer (PT) as a potential component for a fluorescent lamp (FL) ballast with power factor correction (PFC) is discussed. The attractiveness of the PT is primarily the simplicity of the resulting circuit, and it is easy to be produced in mass with a low cost. A single-stage charge-pump PFC ballast using a PT is proposed. The proposed ballast circuit improved the drawbacks of the conventional voltage-source charge-pump PFC (VS-CPPFC) scheme. Empirical PT modeling based on power level excitation is performed to design the proposed circuit, and the experimental and simulation results are provided to verify theoretical analysis.     

Power-mode-controlled power-factor corrector for electronic ballast

Medium- to high-power electronic ballasts are designed with two power conversion stages. The power-factor corrector (PFC) stabilizes the voltage supplied to the second stage and forces the utility current to meet the required standard. The inverter section stabilizes the arc in the lamp, and keeps the lamp power under the specified values. This paper proposes that the PFC section is to provide the power stability of the system while the inverter section operates in open loop. Consequences of this solution are: the power variation in the lamp caused by its aging is prevented, the complex dynamic of the lamp has no influence in the design, some extra voltage is available to achieve the lamp ignition, warmup time is reduced, and dimming control is easily implemented by modifying either the power reference or the bias value in the PFC control circuit. The inverter section is a half-bridge LC/sub p/C/sub s/ resonant inverter designed to require minimum variation of the input voltage to supply constant power to the lamp. In this way the operation point suffers little changes and no overdimensioning of the PFC and inverter components is necessary to meet the power source condition.     

Improving crest factor of electronic ballast-fed fluorescent lampcurrent using pulse frequency modulation

In case where electronic ballast employing a valley-fill passive power-factor correction (PFC) circuit is used for feeding fluorescent tamps, a new method to reduce crest factor of the lamp current is studied in this paper. It is known that a 50% valley-fill passive PFC provided for high input power factor results in undesirable value of crest factor of the fluorescent lamp current, In order to reduce crest factor to a lower value, a pulse frequency modulation technique based on the waveform of the DC-link voltage which is predetermined by the passive PFC circuit is taken into the switching control action of the electronic ballast. An equation-based analysis between the crest factor of lamp current and the effect of varying the inverter switching frequency is comprehensively performed. Several simulation and experiment results illustrate the Effectiveness of the proposed control scheme     

Single-stage electronic ballast with dimming feature and unitypower factor

Analysis, design, and practical consideration of a single-stage electronic ballast with dimming feature and unity power factor are presented in this paper. The proposed single-stage ballast is the combination of a boost converter and a half-bridge series-resonant parallel-loaded inverter. The boost semistage working in the discontinuous conduction mode functions as a power factor corrector and the inverter semistage operated above resonance are employed to ballast the lamp. Replacing the lamp with the plasma model, analysis of the ballast is fulfilled. The dimming feature is carried out by pulse-width modulation (PWM) and variable-frequency controls simultaneously. The proposed single-stage ballast is suitable for applications with moderate power level and low-line voltage while requiring a high-output voltage. It can save a controller, an active switch and its driver, reduce size, and possibly increase system reliability while requiring two additional diodes over a conventional two-stage system. A prototype was implemented to verify the theoretical discussion. The hardware measurements have shown that the desired performance can be achieved feasibly     

Low-cost single-stage electronic ballast based on aself-oscillating resonant inverter integrated with a buck-boost PFCcircuit

In this paper, a new solution to implement and control a single-stage electronic ballast based on the integration of a buck-boost power-factor-correction stage and a half-bridge resonant inverter is presented. The control signals are obtained from the inverter resonant current by means of a saturable transformer. Core saturation is used to control the required dead time between the control pulses of both switches. Since no special integrated circuits are required to control the ballast, the total number of components is minimized and the final cost of the ballast is reduced compared to a typical two-stage configuration. Analysis and basic design guidelines are presented in the paper, together with experimental results obtained from a laboratory prototype     

High-efficiency low-stress electronic dimming ballast for multiplefluorescent lamps

An electronic dimming ballast with a lead-lag tank operation (LLTO) having the properties of high efficiency and low stress is introduced in this paper. The ballast is configured with a voltage-fed half-bridge series-resonant parallel-loaded inverter (SRPLI) acting as a lamp driver. It is loaded with resonant tanks which are designed and operated to be capacitive and inductive to theoretically achieve both zero-voltage switching (ZVS) and zero current switching (ZCS) and to eliminate the reactive current circulating through the switches, resulting in low switching and conduction losses. Moreover, the merit of a successive lamp ignition can be attained with the proposed operation scheme so that current stress imposed on the switches can be reduced. With the plasma model of fluorescent lamps, the analysis, operating principle, and dimming control strategy of the electronic ballast are described in detail. On the other hand, the limitations of the proposed scheme are pointed out. Computer simulation results and experimental measurements are used to verify the theoretical prediction and analytical discussion     

A Novel Single-Switch Single-Stage Electronic Ballast

A single-stage single-switch high- frequency electronic ballast topology is presented. The circuit topology is the integration of a buck power- factor-correction （PFC） converter and a class E resonant inverter with only one active power switch. The buck converter is operated in discontinuous conduction mode and at a fixed switching frequency, and constant duty cycle to achieve high power factor and it can be controlled easily. Detailed analysis of the operation and characteristics of the circuit is provided. Simulation results satisfy present standard requirements.     

A Novel Constant Power Control Circuit for HID Electronic Ballast

This paper presents a constant power control circuit for a three-stage high-intensity discharge (HID) electronic ballast. The three-stage electronic ballast is composed of a boost pre-regulator to achieve a high power factor, a DC/DC buck converter to regulate lamp current with constant lamp power, and a full-bridge inverter to drive the HID lamp with a low-frequency ac squarewave current. The buck converter operating in current mode utilizes current sense level-shift technique to achieve constant power output. The proposed constant power control circuit is easily designed and implemented for the three-stage HID electronic ballast. Finally, a laboratory prototype of a 70 W HID electronic ballast is implemented. The measured results show that the proposed ballast can be applied for various HID lamps with low lamp power variation (less than 0.6%).     

基于半桥双Buck功率变换器的电子镇流器

低频方波驱动模式是目前小功率金属卤化物灯电子镇流器抑制声谐振最有效的方法。本文提出了半桥双降压(Buck)型准方波谐振功率变换器,使所有的半导体开关器件都可以在零电压的条件下开通。并将其应用到70W金属卤化物灯电子镇流器中,达到了金属卤化物灯正常工作的要求。     

A novel single-stage high-power-factor electronic ballast with symmetrical topology

This paper proposes a novel single-stage high-power-factor high-efficiency electronic ballast with symmetrical topology for fluorescent lamps. The circuit topology originates from the integration of two half-wave rectifiers with buck-boost power-factor-correction converters and a half-bridge series-resonant parallel-loaded inverter. A high power factor at the input line is assured by operating the buck-boost converters in discontinuous conduction mode. With symmetrical operation and carefully designed circuit parameters, zero-voltage switching on the active power switches of the inverter can be retained to achieve high circuit efficiency. The design equations are derived from the analyzed results based on fundamental approximation, and then an easy-to-use design tool is provided accordingly under considerations of filament heating and ignition. A prototype circuit designed for two T9-40W rapid-start fluorescent lamps is built and tested to verify the analytical predictions. Satisfactory performance is obtained from the experimental results.     

Design and analysis of an IC-less self-oscillating series resonant inverter for dimmable electronic ballasts

This paper presents a low-cost solution of converting the popularly adopted nondimmable electronic ballast circuit for fluorescent lamps with self-oscillating series resonant inverter into a dimmable one. The dimming function is achieved by increasing the switching frequency of the inverter from the natural frequency of the resonant tank, so that less energy is coupled to the lamp. Control of the switching frequency is based on deriving an adjustable dc current source from the resonant inductor in the resonant tank to control the operating point of the saturable transformers for driving the switches in the inverter. The overall implementation does not require any integrated circuit. A 17-W prototype has been built and studied. Theoretical predictions have been verified with experimental results. The lamp can be dimmed down to 10% of the full power.