新颖的含PFC的PWM ZVX AC—DC变换器

提出了一种新的具有功率因数补偿（ＰＦＣ）功能的零电压开关（ＺＶＳ）ＡＣ－ＤＣ变换器基于不连续导电模式（ＤＣＭ）下的Ｂｏｏｓｔ环节实现ＰＦＣ功能,但其具有ＺＶＳ机制从而解决了ＤＣＭ下因开关关断大的峰值电流引起的关断同、ＥＭＩ严重的问题,同时还消除了由于开关的寄生电容引起的开通损耗,该变换器可以采用通用控制芯片并工作在ＰＷＭ模式,文中分析了提出变换器的工作原理,并给出了基本设计原则,模拟和实验结果证明     

LED电源设计优化的功率器件考虑事项

LED照明应用中的开关电源在输入级越来越多地采用有源功率因数校正(PFC)设计,以期满足国际谐波规范要求。非连续导通模式(DCM)中的升压拓扑是功率额定值小于300W转换器的最适合PFC方法。在这种拓扑中,升压开关的开通功率损耗可以忽略,而主要的功率损耗是关断损耗和导通损耗。在引入了超级结器件之后,超级结器件通常被看作一种针对有源PFC而优化的开关,因为它们具有极低的导通阻抗和     

软开关隔离型升压DC-DC变换器设计与实现

为了满足升压型变换器低成本和大功率密度的需求,本文提出了一种软开关单极隔离型DC-DC变换器。该变换器电路包含一个无损耗缓冲器,通过漏电感固定住开关的电压峰值,从而实现开关的ZVS关断。在失谐状态下,使用Lr-Cr串联谐振电路来实现二极管的ZCS关断。由于磁化电流低,相较于传统的基于反激的变换器,变压器的容量更少。在输出功率250W和开关频率100kHz的条件下进行了实际测试,提出的变换器的最大测量效率为97.0%。     

新型容性整流ZVZCS三电平直流变换器

提出一种新型零电压零电流(ZVZCS)飞跨电容型不对称PWM半桥三电平变换器,该变换器原边开关器件的电压应力为输入电压的一半;所有开关器件在较宽负载范围内实现软开关,其中超前管实现ZVS开通,ZCS关断;滞后管实现ZCS开通,ZVS关断,从而降低开关损耗;副边采用容性整流,在续流阶段将原边电流降至0,使得开关器件的电流分布更加均衡并减小飞跨电容的电流应力;与此同时,消除二极管反向恢复损耗。文中讨论了电路的结构、工作原理和基础特性,为证明理论正确性,搭建一台500W实验样机来验证。     

开关电容boost—buck功率因数校正组合开关变换器

文章提出了一种基于开关电容网络的boost-buck组合开关变换器,当其输入环节工作在不连续导电模式（DCM）时,具有功率因数校正（PFC）功能,详细分析了这类变换器的工作原理、临界条件、输入输出电压变比以及各器件的应力。实验结果与理论分析相符。     

一种Boost型PFC电路在DCM下的恒频控制方案

通过对Boost型变换器在不连续导电模式DCM(Discontinued Conduction Mode)下平均电感电流的分析,得到了在恒 频状态下实现功率因数校正 PFC ( Power Factor Correction)时,功率开关管所需的开启时间与输入、输出电压之间的数学关系,并结合实际电路设计,提出了一种PF...     

具有自驱动有源缓冲器的GaN基高效准谐振反激式功率变换器

提出了一种具有自驱动有源缓冲器的GaN基高效准谐振(QR)反激式功率变换器,以解决准谐振反激式功率变换器中开关管关断时电压过高的问题。电路以GaN高电子迁移率晶体管(HEMT)器件为主开关管和同步整流器开关管,自驱动有源缓冲器由钳位电容和有源开关管组成。该变换器在主开关管关断期间将开关管的电压浪涌钳位为恒定电压,由于有源开关管驱动信号由变压器的次级侧电流控制,因此不需要单独的控制电路。为验证所提出的变换器和控制电路的有效性,搭建了一个60 W的AC-DC功率变换器,测试结果表明,主开关管的最大电压浪涌约为450 V,具有高达91.6%的能量转换效率。     

MPPT控制Boost变换器的一种软开关实现策略

提出了最大功率点跟踪MPPT(Maximum Power Point Tracking)控制Boost变换器的一种软开关实现策略:将MPPT控制Boost变换器设计在断续导通模式DCM(Discontinuous Conduction Mode)下。首先推导了MPPT控制Boost变换器的等效负载,然后借助工作模式分析推导得到输入电感的临界值。设计输入电感为临界值就可以使得变换器在全输入电压范围内工作在DCM模式下,开关器件实现自然的软开关。最后,在PSIM软件中完成了仿真验证。     

一种最小电压应力的软开关无桥PFC技术研究

针对传统桥式整流升压功率因数校正(PFC)电路效率较低的缺点,提出了一种最小电压应力的软开关无桥PFC电路拓扑.在理论分析和仿真验证的基础上,研制了一台300 W的实验样机.结果表明,改进的无桥PFC电路拓扑具有通态损耗低、电流采样简单,能实现开关管零电压关断和零电流开通,同时实现整流二极管零电压导通和接近零电流软关断...     

新型空间矢量调制软开关PWM变换器的分析

在空间矢量调制三相全桥移相ZVS-PWM变换器的基础上,提出一种软开关范围较宽的新型空间矢量调制变换器。该变换器既具有单位功率因数和低的输入电流谐波失真,而且电路的所有功率开关均可实现软开关(ZVS、ZCS)。文中分析了这种电路的工作过程和工作波形,给出了工程设计的一些规则,并给出了仿真结果。     

Design considerations and performance evaluations of synchronousrectification in flyback converters

Design tradeoffs and performance comparisons of various implementations of the flyback converter with a synchronous rectifier (SR) are presented. Specifically, the merits and limitations of the constant-frequency (CF) continuous-conduction mode (CCM), CF discontinuous-conduction mode (DCM), variable-frequency (VF) DCM, and zero-voltage-switched (ZVS) DCM flyback converters with SRs are discussed. The theoretical efficiency improvements of the discussed synchronous rectification approaches relative to Schottky diode implementations are derived. Finally, theoretical results are verified on an experimental universal-input off-line 15 V/36 W flyback prototype     

一种提高单电感双输出升/降压型转换器轻载效率的设计策略

为了提高单电感双输出升/降压型直流-直流转换器在轻载下的效率,设计实现了适用于不同转换条件的非连续导通模式(DCM)功能和脉冲频率调制(PFM)控制。前者降低了电感电流的均方根值,减少了导通损耗;后者降低了开关频率,减少了开关损耗。详细分析了在PFM控制下转换器的驱动能力、电感电流纹波和输出电压纹波之间相互制约的关系,并采取了一种可以由两路任意升/降压输出灵活复用的自适应导通时间控制方法。经0.25μm 2P4M CMOS混合信号工艺流片验证,测试结果显示DCM和PFM时序与设计方案吻合,各种转换条件下输出电压纹波在40~70 mV。通过比较发现,对轻载效率的提升可以达到30%以上。     

Performance characteristics of the full-bridge zero voltageswitching PWM resonant converter

The authors present the exact analysis of the full-bridge zero voltage switching (ZVS) pulse width modulated (PWM) converter by using the state-plane technique. Based on the analysis, they derive the necessary conditions for ZVS operation and the performance characteristics of the converter in terms of characteristic curves from which the converter design procedure can be formulated. The performances of the converter operating outside the limits of ZVS operation, including the switching loss and the attainable efficiency under different load conditions, are also given. The analytical work is confirmed by experimental results     

储能电感前置软开关移相全桥变流器研究

本文提出了一种适用于低压大电流输出场合的软开关移相全桥变流器。该变流器原边带有储能电感,副边采用同步整流技术,通过合理的设计能够使之工作于断续模式(DCM)。其中原边储能电感可以简单方便地实现超前臂开关管的零电压开通。这种工作模式不但能够实现滞后臂的零电流关断,还能实现副边整流器件的零电流关断,有效地降低其开关损耗、体二极管的反向恢复损耗以及抑制寄生结电容电压震荡尖刺等。又因为副边同步整流管的电压应力受到输出电压箝位,所以可以选用较低耐压的同步整流管降低副边的导通损耗。最后根据理论分析设计研制了一台工作频率100kHz,额定功率300Watts的实验样机验证了它的基本工作原理,而其较高的变换效率也体现了该移相全桥变流器的优点。     

The Power Loss Optimization of a Current Fed ZVS Two-Inductor Boost Converter With a Resonant Transition Gate Drive

This paper develops a power loss optimization method in a current fed zero-voltage switching (ZVS) two-inductor boost converter, which is suitable for the module integrated converter applications in grid interactive photovoltaic systems. The paper conducts the numerical analysis of the variable power loss components and establishes a set of the circuit parameters for an optimized operating point with a minimized average power loss. The ZVS two-inductor boost cell is fed from a sinusoidally modulated two-phase synchronous buck converter with an interphase transformer and produces a rectified sinusoidal voltage, which can be applied to an unfolding stage to generate the grid compatible voltage. The boost cell is also equipped with a resonant transition gate drive circuit to reduce the power loss in the drive circuit under high frequency operations. The experimental results for a prototype 1-MHz 100-W ZVS two-inductor boost converter are presented at the end of the paper.     

Zero-voltage and zero-current-switching full bridge PWM converterfor high-power applications

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) pulse-width modulated (PWM) converter is proposed. The new converter overcomes the limitations of the zero-voltage-switching (ZVS)-FB-PWM converter, such as high circulating energy, loss of duty cycle, and limited ZVS load range for the lagging-leg switches. By using the DC blocking capacitor and adding a saturable inductor, the primary current during the freewheeling period is reduced to zero, allowing the lagging-leg switches to be operated with zero-current-switching (ZCS). Meanwhile, the leading-leg switches are still operated with ZVS. The new converter is attractive for high-voltage (400-800 V), high-power (2-10 kW) applications where IGBTs are predominantly used as the power switches. The principle of operation, features, and design considerations of the new converter are described and verified on a 2-kW, 100-kHz, IGBT-based experimental circuit     

Zero-Voltage-Switching Control for a PWM Buck Converter Under DCM/CCM Boundary

A new zero-voltage-switching (ZVS) control approach is presented for pulsewidth modulation (PWM) buck converters under discontinuous conduction mode (DCM)/continuous conduction mode (CCM) boundary. This proposed technique compensates for control circuit delay, and hence, turns on power MOS at the instant exactly when drain-to-source voltage becomes zero. No complicated timing calculation circuits or additional external components are required. This proposed integrated ZVS control can be applied to other dc–dc converters as well. The corresponding circuit analysis, implementation, and die photograph are presented in this paper. Simulation and experimental results for an example circuit with $V_{{rm IN}}$ of 5 V and $V_{{rm OUT}}$ of 3.3 V reveal that buck converters with the presented ZVS technique have higher efficiency than conventional ones, especially at higher frequencies. At about 3.6 MHz operation, the measured conversion efficiency of the PWM buck converter under DCM/CCM boundary mode with the proposed ZVS approach is 11$%,$ higher.      

带辅助网络的ZVS PWM全桥三电平直流变换器

提出了一种带辅助网络的ZVS PWM全桥三电平直流变换器,很好地解决了ZVS PWM移相全桥三电平变换器中滞后桥臂不容易实现软开关的问题,同时具有开关管电压应力小的特点。加入辅助网络后可以减小谐振电感,达到降低占空比丢失目的。文章分析了变换器的原理,最后通过对一个输出400V,10A的变换器的仿真进行了验证。     

Transformer secondary leakage inductance based ZVS dual bridge DC/DC converter

A novel zero voltage switching (ZVS) dual bridge dc/dc converter is presented. The proposed converter is composed of two dual-transistor-forward converter, coupled with a single high frequency transformer. ZVS is realized by introducing a proper leakage inductance to the secondary of the high frequency isolation transformer with a corporation of a designed pulse-width modulation control. Operation principle and ZVS condition of the proposed converter are analyzed. Experimental results obtained from a 3.2-kW prototype are given. Extensions of the proposed converter topologies and experimental results of one extension converter are presented.     

Zero-voltage-switching PWM three-level converter with two clamping diodes

A zero-voltage-switching pulsewidth-modulation three-level (ZVS PWM TL) converter realizes ZVS for the switches with the use of the leakage inductance (or external resonant inductance) and the output capacitors of the switches, however, the rectifier diodes suffer from reverse recovery which results in oscillation and voltage spike. In order to solve this problem, this paper proposes a novel ZVS PWM TL converter, which introduces two clamping diodes to the basic TL converter to eliminate the oscillation and clamp the rectified voltage to the reflected input voltage; in the meanwhile, all the switches keep to realize ZVS. Furthermore, the proposed ZVS PWM TL converter can be simplified by removing the two freewheeling diodes. The operation principle of the novel converter and the simplified converter are analyzed and are verified by a prototype converter. The experimental results are also included in this paper.