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.     

反激变换器RCD箝位电路设计的教学探析

本文针对现有"电力电子技术"课程中普遍存在的对于反激变换器箝位电路的作用、影响及其分析设计不完整的问题,详细分析了反激变换器工作过程,指出了箝位电路的作用及其对反激变压器能量传输过程和传输效率的影响,据此给出了RCD箝位电路设计的原则和步骤。本文有助于学生更加全面深入地理解反激变换器的工作原理和特性,更好地掌握其箝位电路设计的方法,具有一定的教学指导意义。     

Primary side detection and peak current mode control in flyback converter

A new cycle-by-cycle control flyback converter with primary side detection and peak current mode control is proposed and its dynamic characteristics are analyzed.The flyback converter is verified by the OrCAD simulator.The main advantages of this converter over the conventional one are simplicity,small size,rapid regulating and no sensing control signals over the isolation barrier.The circuit is suitable for digital control implementations.     

Single-switch soft-switching flyback converter

A novel control method is proposed to achieve soft-switching in the single-switch flyback converter. Using the proposed scheme, circuit efficiency is increased while the simplicity of the circuit is maintained. A 200 W converter is built to verify the proposed scheme     

基于LM5025的有源箝位反激变换器的前馈控制

在有源箝位反激变换器负载基本恒定的情况下采用前馈控制既可以减小变换器体积,又可降低变换器的成本。文中在分析有源箝位反激变换器工作原理的基础上,结合LM5025器件的前馈控制特性,深入研究了基于LM5025的有源箝位反激变换器前馈控制的实现方案,设计了前馈控制电路的参数,完成了有源前馈反激变换器电路设计。在此基础上进行了实验研究,实验结果证明了有源箝位反激变换器前馈控制的有效性和实用性。     

基于电荷控制反激变换器的设计与研究

对比传统的峰值电流控制反激变换器,提出一种新的电荷控制方式。利用PSIM仿真软件分别设计了两种控制方式连续工作模式下的时域电路模型;利用状态空间平均法建立其统一的交流小信号模型,并通过仿真软件SIMPLIS、MathCAD验证频域分析和数学模型的准确性。最后,设计了两台实验样机进行对比。实验表明,电荷控制方式下反激变换器具有更快的瞬态响应、更高的稳流精度、更小的输出电压纹波以及更宽的稳定范围,验证了理论分析的正确性。     

Adaptive off-time control for variable-frequency, soft-switchedflyback converter at light loads

The soft switching of a flyback converter can be achieved by operating the circuit in the critical conduction mode. However, the critical-mode operation at light loads cannot be maintained due to a very high switching frequency and the loss of the output voltage regulation. A control which regulates the output down to the zero load and maintains soft switching at light loads is proposed. The proposed control scheme was implemented in the 380 V/19 V, 65 W flyback DC/DC converter     

单开关控制的软开关反激变换器

介绍了一种新型的控制方案，可以在反激变换器上实现软开关。在电路简化的同时，有效地减少了开关损耗，提高了变换器效率。详细分析了其工作原理及电路设计，并在一台功率200W的样机上验证了该电路的可行性。     

A Single-Stage High-Power-Factor Electronic Ballast Based on Integrated Buck Flyback Converter to Supply Metal Halide Lamps

In this paper, a novel single-stage electronic ballast with a high power factor is presented. The ballast circuit is based on the integration of a buck converter to provide the power factor correction, and a flyback converter to control the lamp power and to supply the lamp with a low-frequency square-waveform current. Both converters work in discontinuous conduction mode, which simplifies the control. In spite of being an integrated topology, the circuit does not present additional stress of voltage or current in the main switch, which handles only the flyback or buck current, depending on the operation mode. To supply the lamp with a low-frequency square-wave current to avoid acoustic resonances, the flyback has two secondary windings that operate complementarily at a low frequency. The design procedure of the converters is also detailed. Experimental results from a 35-W metal halide lamp are presented, where the proposed ballast reached a power factor of 0.95, a total harmonic distortion of 30% (complying with IEC 61000-3-2), and an efficiency of 90%.     

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。     

An integrated flyback converter for DC uninterruptible power supply

An integrated flyback power converter performing the combined functions of uninterruptible power supply (UPS) and switch-mode power supply (SMPS) is presented. This power converter has a high voltage main power input and a low voltage backup battery input. DC output is obtained from the main input via a flyback power converter during normal operation and from the backup battery via another flyback power converter when input power fails. High conversion efficiency is achieved in normal, backup, and charging modes as there is only a single DC-DC conversion in each mode. The power converter circuit is very simple, with two switching transistors, a relay for mode switching, and a single magnetic structure only. This new design offers substantial improvement in efficiency, size, and cost over the conventional cascade of UPS and SMPS due to single voltage conversion, high frequency switching, and removal of design redundancy. The operation, design, analysis, and experimental results of the power converter are presented     

一种新型原边反馈反激变换器数字采样算法设计

为了实现原边反馈反激变换器的高精度采样,提出了一种新型的数字采样控制算法。该算法根据变压器辅助绕组两端电压信息调整误差信号大小,并输入到内部控制环路实现对输出电压的稳定调节,相比于传统的采样电路,该方法省去了ADC或DAC电路,节省了控制电路的面积和功率的开销。本算法通过matlab仿真,且在一款5V/1A的AC-DC电源样机上验证了其有效性,其中恒压精度达到0.5%,表明该算法有很好的采样实时性、精确性和实用性。     

反激变换器箝位电路的设计

反激式变换器原边漏感引起的电压尖峰对功率器件和电路性能影响很大,本文基于抑制漏感尖峰影响的目的,考虑到次级反射电压也为箝位电路提供能量,同时箝位电容电压并非不变量,采用了一种改进的箝位电路的设计方法,推导出的表达式,结合反激变换器应力、效率和传导干扰实验,得出了随着箝位电阻值的增大,变换器的效率会提高、传导干扰会变差的结论.根据反激变换器对效率和EMI的侧重点不同,选取箝位电路参数可以满足反激变换器不同的设计要求.     

一种含负压输出的多路PDP电源设计

本论文研究了一种含负压的多路输出电源,用于PDP显示器Y电极驱动电路中.该电源按照Y电极驱动的不同条件要求,利用反激式结构,采用主从形式,通过耦合在变压器中的不同匝比,实现三路不同输出.同时论文中还对单端反激式电源的工作原理及负压产生电路进行详细分析,研究了主输出回路对从输出回路的影响,并且通过相关测试进行验证.     

一种等离子显示系统专用电源

设计了一个用于多屏拼接等离子显示系统的专用电源。该电源采用两级变换,前级AC/DC变换采用Boost型有源功率因数校正电路,后级变换器对于不同的回路根据功率的大小分别采用全桥变换器和单端反激变换器。对传统Boost型功率因数校正电路提出了一点改进,有效抑制了传统Boost型功率因数校正电路中大功率时开关管开通时二极管上瞬时大电流。后级变换器中主回路采用一种次级无源箝位ZVZCS全桥变换器,适宜大功率的输出且有效降低了开关损耗。     

A new soft-switched PFC boost rectifier with integrated flyback converter for stand-by power

This paper presents a magnetic integration approach that reduces the number of magnetic components in a power supply by integrating magnetic components in two conversion stages. Specifically, in the proposed approach, a single transformer is used to implement the continuous-conduction-mode boost power-factor-corrected (PFC) converter and the dc/dc flyback converter. The integrated boost and flyback converters offer soft switching of all semiconductor switches including a controlled di/dt turn-off rate of the boost rectifier. The performance of the proposed approach was evaluated on a 150-kHz, 450-W, universal-line range boost PFC converter with 12-V/2.2-A integrated stand-by flyback converter.     

Synthesis and analysis for a novel single-stage isolated high power factor correction converter

A novel single-stage isolated high power factor correction (HPFC) converter operating in the discontinuous conduction mode is proposed in this paper. It is an integration of a buck-boost converter with a flyback converter by means of components placement and synchronous switching technology. It can achieve HPFC, tight output voltage regulation and lower voltage stress of the bulk capacitor, which is independent of the loads. The small-signal mathematical model for the proposed converter is derived separately by the averaging method and the current injected equivalent circuit approach. The IsSpice simulations and experimental results successfully verify the dynamics and performances of the proposed converter.     

可集成于AC-DC转换器的带修调高性能振荡器

提出了一种适用于反激式AC-DC芯片的高效、可修调振荡器电路。相对于传统的振荡器,增加了一块模式控制电路,通过检测负载反馈端电压,可灵活选择两种不同的工作模式,产生不同频率,从而实现芯片在所有负载下都可以保持较高的工作效率。修调电路可以对主电容充放电电流进行调节,实现频率抖动,从而减小EMI的影响。利用华润上华0.8μm 40V高压BCD工艺,对提出的电路进行仿真验证。结果表明,所有负载下变换器转换效率均可达到85%,负载变化时,频率可变范围为22～66kHz,修调电路实现4%的频率抖动。     

An Interleaved AC–DC Converter Based on Current Tracking

In this paper, an interleaved AC-DC converter based on current tracking without any current sharing required is presented and applied to a two-phase flyback converter. This is realized using two critical-conduction-mode (CRM) pulsewidth-modulated chips, together with a field-programmable gate array technique. By doing so, not only are the total harmonic distortion and the power factor improved but the output power is also upgraded. In this paper, the circuit operation is described in detail, with some experimental results given to verify the proposed control scheme.     

基于MATLAB的单端反激式DC/DC变换器的仿真研究

阐述了单端反激式DC/DC变换器的工作原理,在此基础上研究了其在电流连续和断续工作情况下的电路运行模式,最后在MATLAB/Simulink中对理论分析进行了建模与仿真。仿真结果表明,电路在占空比和输出电阻发生改变时,单端反激式DC/DC变换器有可能从连续工作模式下变为断续工作模式。为实际电路的设计提供了方便。