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%).     

Acoustic-resonance-free electronic ballast for automotive HID lamps

A novel cost-effective and acoustic-resonance-free electronic ballast used to drive automotive high intensity discharging (HID) lamps that utilise a constant lamp power control scheme is proposed. The presented ballast is comprised of a buck-boost flyback converter to provide negative DC voltages and a half-bridge-type inverter to supply the lamp with low-frequency, square-wave AC voltage/ current. Owing to its low-frequency operation, no acoustic resonance occurs on the automotive HID lamps. Design guidelines and experimental results are demonstrated for a 35 Wautomotive HID lamp prototype ballast operating at 400 Hz switching frequency with battery input DC voltage of 12 V.     

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.     

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.      

Analysis and experimental results of a single-stagehigh-power-factor electronic ballast based on flyback converter

A new single-stage high-power-factor electronic ballast based on a flyback converter is presented in this paper. The ballast is able to supply a fluorescent lamp assuring a high-input power factor for the utility line. Other features are lamp power regulation against line voltage variations and low lamp current crest factor, both assuring long lamp life. The ballast is analyzed at steady-state operation, and design equations and characteristics are obtained. Also, a procedure for the ballast design is presented. Finally, simulation and experimental results from a laboratory prototype are shown     

一种直流供电的陶瓷金卤灯电子镇流器

设计了一款低压直流供电的陶瓷金卤灯电子镇流器.前级采用具有RCD吸收电路的反激变换器.提高镇流器的效率.后级采用低频方波全桥逆变电路.有效克服陶瓷金卤灯的声共振现象.利用单片机实现陶瓷金卤灯的平滑启动、精密恒功率控制、重启动以及各种异常状态保护.测试表明,该电子镇流器性能稳定,效率较高.     

A high-power-factor electronic ballast using a flyback push-pullintegrated converter

This paper describes a high-power-factor electronic ballast for fluorescent lamps. The converter offers a high power factor and a high-frequency supply to the lamp using a single switch. In spite of its simplicity, an excellent performance concerning load and supply is achieved, ensuring a sinusoidal and in-phase supply current. High power factor is achieved by using a flyback converter operating in discontinuous conduction mode. Operating principle, design equations, component stress, and efficiency are presented. Experimental results have been obtained for one 40-W fluorescent lamp operating at 50-kHz switching frequency and 220-V line voltage     

HID Lamp Electronic Ballast With Reduced Component Number

A reduced-component-number single-stage power-processing electronic ballast to drive high-intensity discharge lamps is presented in this paper. A dc–dc buck converter, which controls the current and the power of the lamp, a power factor preregulator based on a discontinuous conduction mode boost converter, and the inverter are combined in a boost integrated with buck rectifier/energy storage/dc–dc converter. It operates with a line-frequency square-wave current driving the lamp. The signals of the power stages are provided by a dedicated microcontroller. Ballast for sodium vapor lamps of 70 W without acoustic resonance was implemented, resulting in a $pf = 0.97$ with 22% total harmonic distortion and $eta = 84%$.      

Family of Zero-Current Transition PWM Converters

In this paper, a new auxiliary circuit is introduced for applying to buck, buck-boost, zeta, forward, and flyback converters. This auxiliary circuit provides a zero-current switching condition for all switching elements. The proposed zero-current transition (ZCT) pulsewidth-modulated buck converter is briefly described. Also, a ZCT flyback converter is analyzed, and its different operating modes are presented. Design considerations are explained, and a design example along with the experimental results of the ZCT flyback converter is presented.     

Current programmed control of a single-phase two-switch buck-boost power factor correction circuit

This paper presents a new current programmed control (CPC) technique for a cascaded two-switch buck-boost converter suitable as a low-cost power factor correction (PFC) rectifier in a variable speed motor drive. This new CPC technique, which is an extension of the conventional CPC method, enables the variable output dc voltage, and is therefore suitable in a pulse amplitude modulated (PAM) motor drive or as a universal input-power supply. The CPC method is very simple and requires only a constant-current reference without any changes in the transition between boost and buck operating mode, and the line current is practically unaffected by the topology-mode shift. Simulations and experimental results verify the presented control technique. Compliance with IEC-61000-3-2 class A is achieved. The experimental setup is based on a commercial CPC integrated circuit (IC) for dc-dc converters. This new control technique enables a simple low-cost control circuit for the two-switch buck-boost converter, which complies with IEC-61000-3-2, and the PFC circuit has inherent in-rush and overcurrent protection.     

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.     

Single-inductor multiple-output switching converters with time-multiplexing control in discontinuous conduction mode

An integrated single-inductor dual-output boost converter is presented. This converter adopts time-multiplexing control in providing two independent supply voltages (3.0 and 3.6 V) using only one 1-/spl mu/H off-chip inductor and a single control loop. This converter is analyzed and compared with existing counterparts in the aspects of integration, architecture, control scheme, and system stability. Implementation of the power stage, the controller, and the peripheral functional blocks is discussed. The design was fabricated with a standard 0.5-/spl mu/m CMOS n-well process. At an oscillator frequency of 1 MHz, the power conversion efficiency reaches 88.4% at a total output power of 350 mW. This topology can be extended to have multiple outputs and can be applied to buck, flyback, and other kinds of converters.     

Actively clamped bidirectional flyback converter

An actively clamped bidirectional flyback converter is proposed. The converter's operation is examined in detail. All switches in the converter have zero-voltage-switching characteristics. A low-frequency behavior model and small-signal transfer functions are derived. It is found that the flow of current is directly under the control of the duty cycle, and that the transformer's leakage inductance has a significant effect on the control characteristic of the converter. It is expected that such bidirectional converters will find wide applications in the interconnection of multiple sources of DC power to a common bus (e.g., in a DC uninterruptible power supply). Simulation and experiment results are also presented     

Integrated Buck-Flyback Converter as a High-Power-Factor Off-Line Power Supply

This paper investigates the integrated buck-flyback converter (IBFC) as a good solution for implementing low-cost high-power-factor ac-dc converters with fast output regulation. It will be shown that, when both buck and flyback semistages are operated in discontinuous conduction mode, the voltage across the bulk capacitor, which is used to store energy at low frequency, is independent of the output power. This makes it possible to maintain the bulk capacitor voltage at a low value within the whole line voltage range. The off-line operating modes of the IBFC are also investigated to demonstrate that the control switch of the proposed converter handles lower root-mean-square currents than those in similar integrated converters. The off-line operation of the IBFC is analyzed to obtain the design characteristics of the bulk capacitor voltage. Finally, the design and experimental results of a universal input 48 V-output 100 W ac-dc converter operating at 100 kHz is presented. Experiments show that the IEC-61000-3-2 input current harmonic limits are well satisfied and efficiency can be as high as 82%.     

A parallel-connected single phase power factor correction approach with improved efficiency

In this paper, a new parallel-connected single phase power factor correction (PFC) topology using two flyback converters is proposed to improve the output voltage regulation with simultaneous input power factor correction and control. This approach offers lower cost and higher efficiency by parallel processing of the total power. Flyback converter-I primarily regulates output voltage with fast dynamic response and processes 55% of the power. Flyback converter-II with ac/dc PFC stage regulates input current shaping and PFC, and processes the remaining 45% of the power. This paper presents a design example and circuit analysis for 200 W power supply. A parallel-connected interleaved structure offers smaller passive components, less losses even in continuous conduction inductor current mode, and reduced volt-ampere rating of dc/dc stage converter. TI-DSP, TMS320LF2407, is used for implementation. Simulation and experimental results show the performance improvement.     

Integrated high-quality rectifier-regulators

A new family of AC-DC converters is derived which integrate the functions of low-harmonic rectification, low-frequency energy storage, and wide-bandwidth output voltage control into a single converter containing one, two, or four active switches. These converters utilize a discontinuous conduction mode input inductor, an internal energy storage capacitor, and transformer secondary circuits which resemble the bridge, forward, flyback, or Cuk DC-DC converters. A large-signal equivalent circuit model for this family is presented, which uses the “loss-free resistor” concept. Design strategies and experimental results are given. High-performance regulation with satisfactory line-current harmonics is demonstrated with conventional duty-ratio control. Further improvements in line current are possible by simultaneous duty-ratio and switching-frequency control     

Digital power-factor correction for a capacitor-charging power supply

The design and construction of a low-power low-cost power supply capable of charging an energy storage capacitor from a 120-V AC source and capable of power-factor correction (PFC) is presented. The load that is generally connected to a capacitor-charging power supply (CCPS) is a pulsed power load (i.e., laser, cardiac defibrillator, or flash lamp). A flyback converter was incorporated into the CCPS because it is capable of charging a capacitor while maintaining a high power factor. The control system of the CCPS uses peak current control to achieve PFC and is implemented using standard "off-the-shelf" digital logic components. A 300-V prototype has been constructed and tested. The experimental results show that a high power factor is obtained by the CCPS utilizing a flyback converter and the digital logic control system.     

A general technique for derivation of average current mode controllaws for single-phase power-factor-correction circuits without inputvoltage sensing

This paper presents a general technique to derive average current mode control (CMC) laws without input voltage sensing to achieve high power factor for single-phase topologies operating in continuous conduction mode (CCM). The control laws are derived based on the steady-state input-output voltage relationships and the CCM large-signal averaged pulsewidth modulation (PWM)-switch model. Using this methodology, average CMC laws with linear PWM waveforms are discovered for commonly used single-phase power stage topologies such as boost, flyback, SEPIC, and buck/boost. Conventional three-loop-controlled average CMC converters can now be controlled with a two-loop architecture. Hardware results for a boost power factor correction (PFC) and simulation results for flyback, SEPIC, and buck/boost topologies verify operation. The small-signal models of the current loop and voltage loop are derived for the boost topology and are used for control loop design. Input current harmonic distortion measurements demonstrate improved performance compared to the conventional three-loop control technique     

Reduction of power converter EMI emission using soft-switchingtechnique

Measurements of conducted and radiated electromagnetic interference (EMI) emission from hard-switched and soft-switched buck, boost, and flyback converters of similar power ratings are presented. Results indicate that EMI emission can be substantially reduced by using a soft-switching technique in power converters. Thus, the soft-switching technique provides a practical and useful solution to reduce EMI emission from switched-mode power circuits. A comparison of EMI emission on the three classes of converters is also included. The flyback converter is found to be the least EMC friendly among the converters tested     

电流模式反激变换器中功率限制电路的设计

讨论电流模式反激变换器的工作原理与优点,重点分析反激变换器中的过功率保护模块的功能与实现方式。提出在过功率保护电路中利用斜坡电压取代传统的固定电压,以达到不同输入电压下的恒定功率限制。基于CMOS工艺设计了相应的斜坡电压产生电路,该电路结构简单,可广泛适用于各类反激开关电源控制电路。最后并对电路进行了仿真。