准谐振软开关反激变换器的研究

介绍了一种准谐振软开关反激变换器。它的主要优点是利用开头两端的电容与变压器原边电感产生的谐振，通过适当控制实现了零电压开通，减小了开关损耗，提高了变换器的效率。整个电路结构简单，满载效率高，空载损耗小。     

交错式反激变换器在光伏MIC系统中的应用

分析了微型逆变器(MIC)系统的硬件结构和控制策略;介绍了交错式反激MIC的整个工作原理及设计要点,并分析了有源箝位电路的工作过程;介绍了电流控制器的前馈控制策略及最大功率点跟踪(MPPT)算法,然后采用状态空间平均法建立了并网式反激变换器的小信号模型,并在此模型基础上完成了电流环和均流环设计;制作了200W样机进行实验,验证了整个设计的合理性。     

基于LM5025的有源箝位反激变换器的设计

详细分析了有源箝位反激变换器的拓扑结构和工作原理,给出了电路主要元器件参数的设计方法,并基于LM5025设计了一款功率为6 W、开关频率为640 kHz的小功率开关电源。实验结果表明,主开关管两端的电压被箝位在一定数值,在输入电压允许的范围内基本实现了主开关管的零电压开通,有效降低了主开关管的损耗,提高了开关电源效率。     

反激变换器开关应力控制技术研究

对反激变换器的各种开关应力抑制技术进行了分析研究，指出了它们各自的优缺点和应用场合。     

零电流开关PWM反激变换器

针对反激变换器的变压器漏感中的储能损失以及开关管存在较大的开关损耗和电压尖峰等问题,提出基于新型ZCS-PWM辅助电路的反激变换器.详细分析了工作原理和稳态特性,给出参数设计的原则,并通过一台150 W、50 kHz的原理样机实验验证了该零电流开关技术的可行性.实验结果表明,该变换器在整个负载范围内实现了所有开关管的零...     

直流微网中多输入软开关反激变换器设计

多输入反激DC/DC变换器以电路结构简单,成本少,开关应力低等优点在直流微网中分布式电源联合供电小功率应用场合中具有很好的应用前景。但随着输入源的增加,控制自由度更加灵活,相应的开关损耗和开关应力也增大。将有源箝位软开关技术应用到多输入反激变换器中,实现了各个开关管的零电压开通和关断,减小了开关应力和损耗,输入源既可单独也可同时向负载供电。以双输入为例详细分析了软开关工作过程,并推导了谐振电路主要参数,实验结果验证了理论分析的正确性。     

电流控制型反激变换器分析与研究

对反激变换器的不同工作模式进行了分析和比较,指出了其采用电流控制的优点及存在问题,针对存在问题提出了解决方法。     

双管反激变换器研究分析

本文研究了基丁峰值电流模式的双管反激变换器．分析了它的工作原理，并说明它在高压输入场合的优点。     

双管反激变换器研究分析

研究了基于峰值电流模式的双管反激变换器，分析了它的工作原理，说明了它在高压输入场合的优点。     

断续模式反激变换器设计中的关键问题

反激断续模式电路的优点是功率电路简单,成本低廉,可以适应宽输入电压范围,在小功率充电器、适配器获得广泛应用。变压器设计,参数确定与具体电路结构,器件定额等有关,是关键。本文从反激断续模式工作原理,实际器件限制出发,给出了反激变压器设计的基本关系,指出设计参数确定的原则,为设计和调试反激变换器提供参考。     

Novel interleaved ZVS converter with ripple current cancellation

This paper presents a zero voltage switching (ZVS) converter with interleaved pulse‐width modulation scheme. An active clamp circuit is adopted in the proposed converter to recycle the energy stored in the leakage inductor of the transformer and reduce the voltage stress of the main power switch in the converter. The ZVS feature of switches can be achieved due to the resonance during the transition interval of two power switches. Two full‐wave rectifiers with ripple current cancellation are connected in parallel at the output side to reduce the current stress of the secondary winding of transformers. Instead of the conventional interleaved forward converter, power switches in the proposed converter can perform the functions of both forward converter and active clamp at the same time. Therefore, the circuit components in the power circuit are less than that of in the conventional interleaved forward converter. The operation principle and system analysis of the proposed converter are provided. Some experimental results for a 240 W (12 V/20 A) prototype are provided to demonstrate the effectiveness of the proposed converter. Copyright © 2008 John Wiley & Sons, Ltd.     

Analysis and design of a dual‐mode control flyback converter

This letter presents a dual‐mode control scheme to improve the efficiency of a flyback converter in a wide load range. The proposed flyback converter features a novel dual‐mode operation. The valley‐switching technique is adopted to reduce the switching loss at light load. On the other hand, the fixed off‐time (FOT) controls with continuous conduction mode operations decrease the conduction losses at heavy load. The principles and design procedures of the proposed dual‐mode controller are discussed and analyzed. Finally, a 140‐W dual‐mode flyback converter with an output voltage of 19 V is implemented. Experimental results agree with the theoretical analysis. Copyright © 2012 John Wiley & Sons, Ltd.     

Design and implementation of an interleaved soft‐switching converter with output voltage doubler

An interleaved pulse‐width modulation (PWM) converter with less power switches is presented in this paper. The buck type of active clamp circuit is used to recycle the energy stored in the leakage inductor of a transformer. The zero voltage switching (ZVS) turn‐on of power switches is realized by the resonance during the transition interval of power switches. At the secondary side of transformers, two full‐wave rectifiers with dual‐output configuration are connected in parallel to reduce the current stresses of the secondary windings of transformers. In the proposed converter, power switches can accomplish two functions of the interleaved PWM modulation and active clamp feature at the same time. Therefore, the circuit components in the proposed converter are less than that of the conventional interleaved ZVS forward converter. The operation principle and system analysis of the proposed converter are provided in detail. Experimental results for a 280 W prototype operated at 100 kHz are provided to demonstrate the effectiveness of the proposed converter. Copyright © 2008 John Wiley & Sons, Ltd.     

一种新型交错并联ZVS电流型推挽变换器

电流型推挽变换器适用于低压输入高压输出场合,但传统拓扑结构功率管工作在硬开关状态,开关损耗大、电压应力高,所需变压器匝比大。文中提出了一种新型的交错并联零电压开关(ZVS)电流型推挽变换器。所提出结构在传统拓扑基础上只需增加一个简单的箝位支路即可实现所有功率管的ZVS开通,箝位电路可有效吸收变压器漏感能量,输入并联输出串联结构可以减小原边功率管的电流应力、副边二极管的电压应力、滤波器的大小及变压器匝比。文中详细讨论了所提出变换器的工作原理、关键设计,搭建了一台800 W原理样机验证了所提拓扑的有效性。     

LLC谐振变换器交错并联技术研究

LLC串联谐振变换器(LLC-Series Resonant Converter)因具有高效率、低EMI、便于磁集成等特有的优点而被广泛应用在现代电力电子设备中,但其本身固有的副边电流纹波系数大的缺点使得LLC-SRC难以被应用于低压大功率的场合。然而,两相或多相LLC-SRC交错并联技术能有效减小输出电流的纹波,提高电源的功率等级,但是并联又带来了负载不均流的问题。采用一种简单的并联结构,解决了两相LLC交错并联中负载不均流问题,300 W实验样机验证了理论分析的正确性和方案的可行性。     

Analysis and implementation of a new zero current switching flyback inverter

In this paper, a novel zero current switching (ZCS) flyback inverter in discontinuous conduction mode (DCM) is proposed. In the proposed flyback inverter, the ZCS for the primary switch is achieved by adding a simple auxiliary circuit to the conventional flyback inverter. Also, the auxiliary switch is turned on and turned off at ZCS condition. Therefore, the switching losses of the switches are negligible, which increases the efficiency and allows higher switching frequency and more compact design. The resonant auxiliary cell is activated only in short transition times that makes its conduction losses negligible. Furthermore, the voltage overshoot of the main switch is limited during the turn-off process, which allows utilization of lower voltage metal-oxide semiconductor field-effect transistors (MOSFETs) with low conduction losses and low cost. The detailed operation of the flyback inverter with auxiliary circuit and design considerations are presented. Simulation and experimental results are presented to verify the performance of the proposed inverter.     

Analysis and improvement of cross‐regulation effect in the primary side‐regulated multi‐output flyback converter

In the multi‐output primary side‐regulated (PSR) flyback converters, cross‐regulation effect denotes the phenomenon that change of load current in either one of the outputs would lead to the output voltage variations in other output terminals. Because the PSR flyback converters are frequently used to provide power supplies in a power system, the steady operation of the power system may be affected. Based on an improved Cantilever model, this paper proposes a thorough analysis on the cross‐regulation effect in the PSR flyback converter. It has been found that the coupling between the output windings and the topology of the output terminal would have significant influence on the cross‐regulation effect. Moreover, a mathematical expression has been derived to calculate the relationship, in the time domain, between the voltages of the output windings in the PSR flyback converter. In the mathematical expression, the leakage inductances in the improved cantilever model are lumped into a matrix R ′. Hence, the winding method and the geometry of the transformer can be optimized to improve the precision of the multi‐output voltages in the PSR flyback converter. A 10‐W PSR flyback prototype with three output terminals is built. Experimental results are given to validate the theoretical analysis. Copyright © 2017 John Wiley & Sons, Ltd.     

反激PFC变换器输出电压纹波分析

详细分析了断续导电模式(DCM)反激功率因数校正(PFC)变换器和临界连续导电模式(CRM)反激PFC变换器实现功率因数校正的工作原理.通过推导DCM和CRM反激PFC变换器的输入电流的表达式,证明2种变换器都可以实现PFC功能.进一步推导DCM和CRM反激PFC变换器的输出电压纹波峰峰值的表达式,揭示了工作模式对PFC变换器的输出电压纹波的影响,发现CRM反激PFC变换器的输出电压纹波峰峰值比DCM反激PFC变换器的输出电压纹波峰峰值小.最后通过仿真和实验验证了理论推导的正确性.     

一种改进型两相交错并联Boost变换器

提出一种改进型两相交错并联Boost变换器.与传统的两相交错并联Boost变换器相比,该电路比传统的两相交错并联Boost变换器多了一个开关电容,保持了传统两相交错并联Boost变换器结构简单的优点.由于开关电容的存在,改进型拓扑不仅提高了电压增益,同时还降低了开关器件的电压应力,有利于电路选择低耐压、高性能的开关器件,从而降低电路的损耗.开关电容的充放电平衡,使得电路工作在占空比0.5≤D＜1时无需采取任何均流措施就可以自动均衡各相的电感电流.分析占空比0＜D＜0.5与0.5≤D＜1两种工作状态下的工作原理,研制了一台输出功率为72 W的小功率改进型两相交错并联Boost变换器原理样机,通过实验验证了理论分析的正确性和可行性.