一种次级LC谐振变换器的建模与参数设计

提出一种LC谐振型推挽直流变换器拓扑。初级采用桥型推挽结构,次级采用倍压结构,主要利用变压器漏感和倍压电容构成的LC谐振来传递能量。该变换器能实现初级开关管和次级二极管的零电流开关,有效抑制开关管的最高承受电压。针对电路输入输出特性,采用基波分析法建立相应的电压增益模型,反映谐振品质因数、漏感系数及频率比对电压增益的影响。根据电压增益模型设计了一款22~28 V输入/360 V输出/额定负载650 W的样机的电路参数,实验验证了电路的可行性和电压增益模型的有效性。     

一种双变压器串联谐振软开关推挽电路

针对输出电压与输入电压之比较高的推挽变换器,提出一种双变压器串联谐振软开关推挽电路,以提高其效率。两个推挽变换器的变压器次级串联,并且实现串联谐振软开关。给出了其电路构成及工作原理,推导分析了该电路的工作过程。在此基础上,对该电路与单变压器串联谐振软开关推挽电路作了比较研究。最后研制了12V输入、360V输出、200W功率的DC/DC变换器。通过实验证明,该电路具有较高的效率。     

定频调节的半桥式变压器复用型谐振变换器

提出了一种定频调节的半桥式变压器复用型谐振变换器。该变换器使变压器交替工作于谐振模式与正激模式,提高了磁芯利用率。采用定频脉宽调制(PWM)控制方式,通过改变正激电路的占空比来实现输出电压调节。与传统调频控制方式相比,定频PWM控制更为简单可靠,有利于磁性元器件和滤波电路的设计。此外,该变换器的谐振电路部分具有开关管零电压开关(ZVS)开通和零电流开关(ZCS)关断,以及次级二极管ZCS关断等优点,且谐振电路与正激电路交替工作即可实现变压器复位,无需额外的复位电路,结构简单。详细分析了所提变换器的电路拓扑结构与工作原理,并搭建62～82 V输入,24 V/2.5 A输出的实验样机,最后与传统半桥LLC谐振变换器进行性能比较,实验结果验证了理论分析的正确性。     

正激推挽电路的ZCS方案

提出了正激推挽电路的ZCS方案。在次级整流桥后增加辅助谐振网络，实现了电路主开关管的零电流开关(ZCS)。通过理论推导、仿真分析和28．5V输入75V输出DC／DC ZCS变换器的研制证明了该方案的优点。本电路的零电流方案具有通用性，可以应用到其他有变压器隔离的变换器拓扑中。     

基于MC33067的LLC谐振全桥变换器的应用设计

LLC变换器以其卓越的性能迅速成为DC/DC变换器的首选拓扑,而目前该拓扑大多应用在小功率半桥变换器,而在大功率全桥变换器中的应用还较少。在此提出了一种基于高性能谐振控制器MC33067的LLC谐振全桥变换器设计方案,该拓扑采用了固定死区的互补调频控制方式,巧妙利用了变压器的励磁电感和外置谐振电感与谐振电容发生谐振,实现了初级零电压(ZVS)开通以及次级零电流(ZCS)关断,并给出了输出直流电压48 V,满载功率2 kW的试验结果。试验结果表明,LLC谐振全桥变换器具有高频、高效率等优点,符合电源高功率密度、高效的发展要求。     

光伏发电系统辅助电源设计

为光伏发电系统辅助电源设计了一种采用UC3863控制芯片的多路输出LLC谐振变换器.通过采用高频交流母线和分布式电源供电技术,解决了多路隔离输出的难题.主开关管和输出整流二极管均实现了ZVS和ZCS,提高了能量传输效率.结合200～380 V输入20W输出的样机试验结果,分析了电路的工作特点、励磁电感的设计要求,以及针对不同次级电流所需的次级电路结构设计.该变换器具有效率高、体积小、价格低等优点.     

适合大电流输入高压输出的软开关直流变换器

首先,提出了一种LLC谐振的软开关直流变换器,其中原边包含4个开关管、2个变压器绕组和1个耦合电容,并利用耦合电容构造了2个变压器绕组同时工作的回路,实现了两者的均流;副边包含2个二极管和2个谐振电容,构成了一个谐振式倍压电路;然后,利用变压器漏感、励磁电感和谐振电容产生LLC谐振来传递能量,各开关管能实现零电流开通,二极管零电流关断,且承受的反向电压为输出电压,关断损耗也很小;最后,分析了电路各阶段的工作原理,推导了电压增益特性,并设计了一款22~28 V输入、360 V输出、额定负载800 W的样机。实验测试结果证明,电路最高效率达到93.5%,同时也证明了电路的有效性。     

双谐振腔LLC谐振变换器分析

在大功率开关电源领域中,通常采用多路并联输出的拓扑结构以提高变换器的输出功率.但是由于元器件的生产工艺误差,各路的谐振元件参数不可能完全一致,而LLC谐振变换器的增益特性对谐振元件的参数十分敏感,因此,各路的电流及输出功率不均衡问题较为突出.针对此问题,提出一种双谐振腔LLC谐振变换器,通过将两路变压器的次级用均衡电路连接在一起,实现了较好的均流及功率均衡的特性.分析了变换器的工作原理,建立了变换器的稳态模型,分析了均衡电路的工作原理,并且通过仿真和实验进行了验证.     

基于Saber的电动车LLC电源仿真

动车控制器的辅助电源可采用半桥LLC谐振变换器，为此基于Saber设计了一款DC/DC降压半桥串联谐振变换器。半桥LLC电路采用UC3863作为控制芯片，计算出变压器匝数比、谐振电感、谐振电容等参数后，通过反馈回路采样输出电压和电流，通过隔离脉冲变压器驱动MOSFET管；DC/DC电路采用半桥串联谐振电路，将蓄电池提供的48 V降压到15 V、5 V两路电压。对电源用Saber进行仿真，最终实现了48 V到15 V、5 V的降压输出。     

带箝位辅助谐振支路的改进型变换器研究

移相控制零电压全桥变换器利用变压器漏感和开关管的寄身电容可实现开关管的零电压开关,为了抑制整流输出寄生振荡,可以在初级加入一个谐振电感和两个箝位二极管构成辅助谐振支路,本文将辅助谐振支路与变压器交换位置,使辅助支路与超前臂相连,不仅抑制了次级寄生振荡和电压过冲,使整流管和箝位二极管工作在软开关条件下,而且减小了箝位二极管上电流有效值,减小了次级占空比丢失和初级通态损耗。分析了改进后变换器的工作原理,并对改进前后的变换器进行了比较。实验结果验证了电路的正确性。     

Soft‐switching converter with low circulating current and wide range of ZVS turn‐on

In this paper, a new hybrid dc–dc converter with low circulating current within the freewheeling interval, wide range of zero‐voltage switching and reduced output current ripple is presented. The proposed hybrid circuit includes two three‐level pulse‐width modulation converters and a series resonant converter with the shard lagging‐leg switches. Series resonant converter is operated at fixed switching frequency (close to series resonant frequency) to extend the zero‐voltage switching range of lagging‐leg switches. The output of series resonant converter is connected to the secondary sides of three‐level converters to produce a positive rectified voltage instead of zero voltage. Hence, the output inductances can be reduced. The reflected positive voltage is used to decrease the circulating current to zero during the freewheeling interval. Therefore, the circulating current losses in three‐level converters are improved. Finally, experiments are presented for a 1.44 kW prototype circuit converting 800 V input to an output voltage 24 V/60A. Copyright © 2015 John Wiley & Sons, Ltd.     

Hybrid DC–DC converter with high efficiency,wide ZVS range,and less output inductance

In this paper, a new soft switching direct current (DC)–DC converter with low circulating current, wide zero voltage switching range, and reduced output inductor is presented for electric vehicle or plug‐in hybrid electric vehicle battery charger application. The proposed high‐frequency link DC–DC converter includes two resonant circuits and one full‐bridge phase‐shift pulse‐width modulation circuit with shared power switches in leading and lagging legs. Series resonant converters are operated at fixed switching frequency to extend the zero voltage switching range of power switches. Passive snubber circuit using one clamp capacitor and two rectifier diodes at the secondary side is adopted to reduce the primary current of full‐bridge converter to zero during the freewheeling interval. Hence, the circulating current on the primary side is eliminated in the proposed converter. In the same time, the voltage across the output inductor is also decreased so that the output inductance can be reduced compared with the output inductance in conventional full‐bridge converter. Finally, experiments are presented for a 1.33‐kW prototype circuit converting 380 V input to an output voltage of 300–420 V/3.5 A for battery charger applications. Copyright © 2015 John Wiley & Sons, Ltd.     

一种多模式复合调制的L-R型LCC谐振变换器

提出一种多模式复合调制的线性-谐振(L-R)型LCC谐振变换器.该变换器根据Boost调制的思路,结合传统LCC谐振变换器,实现了电感电流线性-谐振型变化的转换,具有全负载范围的软开关特性.在复合调制方式下,变换器能实现3种工作模式的互相转换以适应宽输出电压和负载变化范围的应用场合,解决了传统LCC谐振变换器在轻载条件下难以实现软开关的问题.与已有的Boost调制型谐振变换器相比,所提变换器通过后置并联谐振电容,在构成LCC谐振腔的同时,配合后级LC滤波结构,解决了Boost调制模式下谐振电流断续导致输出纹波大的问题.详细描述了各模式工作原理,推导了各变量的时域表达式,得到了比较精确的电压增益关系式.最后基于恒流-恒压充电模式设计了一台输入电压为110 V、输出电压为80～150 V、输出电流为0～3.33 A、最大输出功率为500 W的实验样机,给出了各参数以及模式转换的设计方法,实验结果证明了理论分析的正确性.     

Analysis and design of a two‐transformer active‐clamping forward converter with parallel‐connected current doubler rectifiers

A new two‐transformer active‐clamping forward converter with parallel‐connected current doubler rectifiers (CDRs) is proposed in this paper. The presented DC–DC converter is mainly composed of two active‐clamping forward converters with secondary CDRs. Only two switches are required and each one is the auxiliary switch for the other. The circuit complexity and cost are thus reduced. The leakage inductance of the transformer or an additional resonant inductance is employed to achieve zero‐voltage‐switching (ZVS) during the dead times. Two CDRs at the secondary side are connected in parallel to reduce the current stresses of the secondary windings and the ripple current at the output side. Accordingly, the smaller output chokes and capacitors decrease the converter volume and increase the power density. Detailed analysis and design of the presented two‐transformer active‐clamping forward converter are described. Experimental results are recorded for a prototype converter with a DC input voltage of 130??180V, an output voltage of 5 V and an output current of 40 A, operating at a switching frequency of 100 kHz. Copyright © 2010 John Wiley & Sons, Ltd.     

Series resonant high‐voltage DC–DC converter with reduced component count

This paper proposes a novel zero‐current‐switching series resonant high‐voltage DC–DC converter with reduced component count. The series resonant inverter in the proposed topology has two power switches (insulated‐gate bipolar transistors, IGBTs), two resonant capacitors, and only one high‐voltage transformer (HVT) with center‐tapped primary windings. The power switches are connected in the form of a half‐bridge network. The leakage inductances of the transformer's primary windings together with the resonant capacitors form two series resonant circuits. The series resonant circuits are fed alternately by operating the power switches with interleaved half switching cycle. The secondary winding of the HVT is connected to a bridge rectifier circuit to rectify the secondary voltage. The converter operates in the discontinuous conduction mode (DCM) and its output voltage is regulated by pulse frequency modulation. Therefore, all the power switches turn on and off at the zero‐current switching condition. The main features of the proposed converter are its lower core loss, lower cost, and smaller size compared to previously proposed double series resonant high voltage DC–DC converters. The experimental results of a 130‐W prototype of the proposed converter are presented. The results confirm the excellent operation and performance of the converter. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

开环控制的宽范围恒流LCC谐振变换器研究

为了简化LED驱动电路设计,满足开环控制下LED驱动电路宽电压输出恒流的要求,提出了以开环控制的LCC谐振变换器为主电路的LED驱动设计方法。分析了LCC谐振变换器的恒流特性及影响恒流精度的因素,并由软开关条件得到了电路的参数设计方法。以该方法设计的160 W恒流LCC谐振变换器,能在20～80 V的输出电压范围内恒流,最大恒流误差为4.45%,满载效率为94.7%。     

一种L-R复合型桥式DC/DC变换器

提出了一种L-R复合型桥式DC/DC变换器。该变换器在传统半桥LLC谐振变换器的基础上,仅增加一组L桥臂,有高、低2种电压增益模式。在高电压增益模式,采用脉冲宽度调制,通过L桥臂对电感线性储能,获得了比传统LLC谐振变换器更高的电压增益,具有更宽的输出电压范围,且电压增益受励磁电感影响小,电路工作无回馈电流。在低电压增益模式,采用脉冲频率调制,电压增益特性与传统LLC谐振变换器接近,但有更小的回馈电流和循环电流。详细分析了所提拓扑2种电压增益模式的工作原理,推导出增益公式,并与传统拓扑进行对比。最后搭建了一台输入电压为220 V、输出电压为100~160 V的实验样机,实验结果验证了理论分析的正确性。     

基于LCC谐振变换器的脉冲等离子体推力器优化充电技术

针对脉冲等离子体推力器(pulsed plasma thruster,PPT)高压储能电容充电技术,研究了LCC谐振变换器的输出特性。为了满足充电电源需要足够大恒流输出能力的需求,分析了LCC谐振变换器在电流断续模式下的工作原理,并着重解析了双脉冲输出的工作模式,将电流输出能力最大化。为了优化充电电源的效率,研究了变换器的软开关实现条件,特别是在谐振槽能量回馈阶段采用同步整流技术,显著降低了功率管损耗。为了使充电电源具有较高的电压精度,在恒压工作阶段采用了软开关滞环Burst控制策略。最后,搭建了一台输入电压28 V、输出电压2 kV、最大输出功率400 W的实验样机,通过实验证明了所提方案的有效性和可行性。     

Analysis and Implementation of an Interleaved ZVS Converter with High Input Voltage

An interleaved half‐bridge converter is presented for high input voltage application. The features of the proposed converter are zero voltage switching (ZVS) turn‐on for all active switches, ripple current reduction at output side, load current sharing and load voltage regulation. Two half‐bridge converters connected in series and two split capacitors are used to limit the voltage stress of each power switch at one‐half of input DC bus voltage. Thus, active switches with low voltage stress can be used at high input voltage application. On the other hand, the output sides of two half‐bridge converters are connected in parallel to share the load current and reduce the current stresses of the secondary windings and the rectifier diodes. Since two half‐bridge converters are operated with interleaved pulse‐width modulation (PWM), the output ripple current can partially cancel each other such that the resultant ripple current at output side is reduced and the size of output inductors can be reduced. In each half‐bridge converter, asymmetrical PWM scheme is used to regulate the output voltage. Based on the resonant behavior by the output capacitance of MOSFETs and the leakage inductance (or external inductance) of transformers, active switches can be turned on at ZVS during the transition interval. Thus, the switching losses of power MOSFETs are reduced. The proposed converter can be applied for high input voltage applications such as three‐phase 380‐V utility system. Finally, experiments based on a laboratory prototype with 960‐W rated power are provided to demonstrate the performance of proposed converter. Copyright © 2012 John Wiley & Sons, Ltd.