一种新型ZVT—PWM软开关BOOST变换器

介绍一种带缓冲电路的新型零电压过渡PWM（ZVT－PWM）软件开关BOOST变换器,缓冲电路的加入,使主,辅助开关都能实现软化,减小了开关管的电压和电流应力,提高了整机效率,对电路的工作原理进行了详细分析,推导出了工作过程中各阶段的状态具体表达式,最后进行了仿真分析,并在此基础上进行实验验证,给出实验结果,实验证明,该电路结构简单,效率较高,具有一定的实用价值。     

新型软开关Boost ZCT-PWM变换器

针对传统Boost ZCT—PWM变换器存在主开关管电流应力大和辅助管硬关断的问题，提出了一种新型Boost ZCT—PWM电路，对其工作原理做了详细的分析并给出了谐振参数的计算。仿真结果表明该电路不仅实现了主开关和辅助开关管的软开关，同时主开关管不增加额外的电流应力，而且电路中所有二极管也都实现了软通断。     

一种新型正激零电压零电流转换PWM DC/DC变换器

提出一种新型的零电压零电流转换(ZCZVT)的正激拓扑。拓扑工作频率为300kHz,能实现主开关管的零电压开通(ZVS)和零电流关断(ZCS),同时辅助开关管也能实现零电流关断(ZCS),且变压器的磁通复位不需要辅助绕组。文章进行了拓扑的稳态分析,并且讨论了谐振电路的参数设计。最后,在研制一台48V输入、12V/100W输出样机的基础上,实验验证这种新型正激ZCZVT PWM DC-DC变换器的软开关特性。     

双有源桥双向DC-DC变换器的多模式控制

双有源桥(Dual Active Bridge,DAB)双向DC-DC变换器能够双向传输功率,实现零电压开关(ZVS),且功率密度高,能够很好地应用到电力自动化设备中。文中详细介绍了DAB变换器的三种常见的控制方式,分别是移相控制、单PWM和双PWM控制。针对变换器存在低载运行时环路电流大、零电压开关范围受限制的缺点,提出一种多模式控制,拓宽了零电压开关的范围,降低了电流的有效值和峰值,使变换器效率提高。最后用MATLAB软件进行仿真,验证了方案的可行性。     

一种新型零电压切换双向DC/DC变换器的设计与仿真

由于电动汽车电源变换器在行驶过程中,电机的调速范围很宽,加减速频繁,因此对电源变换器的动态响应速度,续航能力提出了更高的要求。但汽车电源存在低电压大电流、di/dt和du/dt较大、转换效率低和电磁干扰严重等问题。为此,设计一种新型的具有升压-降压功能的零电压转换双向DC-DC变换器。在传统的升降压变换器的基础上,通过增加两个辅助开关器件和一个LC谐振电路,构成一个H-软开关控制转换电路,产生的有源钳位电压加载到主开关两端,实现电路零电压转换。在Matlab环境下,对所提出的电路进行仿真,结果表明,所设计的电路能降低开关器件的导通损耗,提高电源的效率,并在6 kW双向升降压变换器样机上进行实验。     

零电压转换PWM直流变换器的研究

介绍了典型的零电压转换ZVT(Zero Voltage Transition)PWM直流变换器的基本工作原理,并指出其存在的缺点。文章提出了一种改进型的ZVT-PWM DC/DC变换器电路,全面分析这种变换器的工作原理,利用PSPICE软件对其进行了仿真。     

一种高电压增益低开关应力的DC-DC变换器

为改善传统Y源DC-DC变换器开关管电压应力高、占空比范围小等缺点,本文提出了一种改进型开关电感Y源变换器(ISLY)。该变换器升压能力明显提高,并且存在连续输入电流,与Y源、改进型Y源拓扑相比,增大了占空比的可调节范围,使电路具有更好的控制灵活性,同时减小了功率开关管的电压应力,从而提升工作效率、节约成本。本文对ISLY进行了详细的理论分析,提供了MATLAB/Simulink仿真结果与实验数据及波形,验证了该 DC-DC 变换器的合理性。     

一种新型软开关Boost变换器

针对典型的ZCT-PWM boost电路只能实现主开关零电流关断,不能实现软开启,而辅助开关只能实现零电流开启,不能实现软关断的问题。文章提出了一种新型ZCT-PWM Boost变换器的拓扑结构和控制方法,实现了主开关零电流开启及零电压关断,辅助开关零电流开启和零电压且零电流关断,从而大大降低了开关损耗,提高了变换器的效率。利用计算机仿真证明了电路的可行性及优越性。     

基于高频感应加热电源的新型软斩波器研研究

介绍一种用于逆变电源功率调节的新型零电压零电流转换（ZVZCT）直流斩波器,克服了传统ZCT斩波器或ZVT斩波器不能零电流开通和负载续流二极管不能软关断的缺点,适合用于以MOSFET为开关器件的高频电源场合。对该变换器的稳定运行情况进行了详细的分析,并进行了仿真验证,仿真结果表明,该ZVZCT软斩波器能可靠地运行在高频场合,能实现较大范围内的电压和功率调节。     

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。     

A new ZVT–ZCT quasi-resonant DC link for soft switching inverters

In this article, the new ZVT–ZCT Quasi-Resonant DC Link, which ensures zero crossings at any time required for soft switching (SS) and provides zero voltage transition (ZVT) turn-on and zero current transition (ZCT) turn-off together for the main switch of active snubber cell in pulse width modulated or space vector modulated operation of inverter is presented. The new circuit combines the most desirable features of the circuits presented previously and overcomes most drawbacks of these circuits by using only one auxiliary switch with fewer other components. Consequently, new ZVT–ZCT Quasi-Resonant DC Link, which is verified by a prototype of a 1.2 kW and 50 kHz circuit, is analysed in detail. All semiconductor devices operate under SS, the main switch is subjected to no additional voltage and current stresses, and the stress on the auxiliary switch is very low in the proposed new inverter.     

改进软开关Buck ZCT-PWM开关电路设计及其Pspice仿真

介绍了典型的零电流转换ZCT（Zero Current Transition）PWM直流变换器的基本工作原理,分析了其存在的主开关电流应力大和辅开关硬关断的问题,提出了一种改进型开关电路。对其拓扑结构和工作原理进行了详细分析,设计了电路参数,并对其进行了Pspice仿真。结果证明此改进能够使辅助开关近似零电流关断,提高了变换器的性能。     

一种新颖有源箝位ZVS正激变换器的研究

介绍了一种中心抽头全波整流有源箝位ZVS正激变换器的工作原理及主要参数计算。有源箝位电路由一个箝位开关管和箝位电容组成。变压器磁芯实现无损复位,励磁能量和漏感能量全部传递到负栽.磁芯利用率高,功率开关管承受电压应力降低。通过变压器漏感与开关管输出电容的谐振,主开关管与箝位开关管都可以实现ZVS开通,提高了变换器工作效率。文章首先分析了变换器工作原理,然后给出了主要参数的计算方法,最后通过样机(48V输入5V/20A输出)实验验证了该拓扑的高效性能。     

A new ZVT-ZCT-PWM DC-DC converter

In this paper, a new active snubber cell is proposed to contrive a new family of pulse width modulated (PWM) converters. This snubber cell provides zero voltage transition (ZVT) turn on and zero current transition (ZCT) turn off together for the main switch of a converter. Also, the snubber cell is implemented by using only one quasi resonant circuit without an important increase in the cost and complexity of the converter. New ZVT-ZCT-PWM converter equipped with the proposed snubber cell provides most the desirable features of both ZVT and ZCT converters presented previously, and overcomes most the drawbacks of these converters. Subsequently, the new converter can operate with soft switching successfully at very wide line and load ranges and at considerably high frequencies. Moreover, all semiconductor devices operate under soft switching, the main devices do not have any additional voltage and current stresses, and the stresses on the auxiliary devices are at low levels. Also, the new converter has a simple structure, low cost and ease of control. In this study, a detailed steady state analysis of the new converter is presented, and this theoretical analysis is verified exactly by a prototype of a 1-kW and 100-kHz boost converter.     

采用分段式自适应PWM/PFM调制的Buck型DC-DC转换器设计北大核心

为了在轻重负载条件下获得更高的转换效率，采用分段式结构和导通电阻更小的NMOS作为输入级，并采用PWM/PFM双调制方式，设计了一种Buck型DC-DC转换器。为解决PWM/PFM调制信号切换问题，采用零电流检测方式进行切换。利用断续导通模式(DCM)和连续导通模式(CCM)下端NMOS管导通时电感电压的不同，检测下端NMOS在导通时电感电压大于零的周期。当电感电压大于零的周期大于2时，则处于DCM模式并自动采用PFM调制模式，关闭一部分功率管以减小开关频率和功率管寄生电容，优化轻载效率；反之则处于CCM模式并采用PWM调制。仿真结果表明，在负载电流10～1 000 mA范围内，该电路可以在两种调制模式平稳切换，在800 mA时峰值效率可提升到96%以上。     

A novel ZCS-PWM power-factor preregulator with reduced conduction losses

This paper proposes a new single-phase high-power-factor rectifier, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the active switches and zero-voltage switching in the passive switches. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Nine transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 50 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage 400 V/sub dc/ has been implemented in laboratory. An efficiency of 97.3% and power factor over 0.99 has been measured. Analysis, design, and the control circuitry are also presented in this paper.     

一种改进的ZCT无桥功率因数校正电路设计

为了降低开关损耗,提高变换器的效率,提出了一种改进的零电流转化软开关无桥功率因数校正电路,实现了变换器主开关管和辅助开关管的零电流导通和零电流关断,有效地减小了导通损耗,提高了电路的效率。详细分析了电路的工作模态、工作条件和主开关管的导通损耗。仿真和实验结果表明,该功率因数校正电路实现了输入电流对输入电压的良好跟踪,功率因数高,谐波含量少,效率较传统的全桥功率因数校正电路有明显的提高。 关键词：全桥;零电流转换;无桥;功率因数校正     

Adding active clamping and soft switching to boost-flybacksingle-stage isolated power-factor-corrected power supplies

Single-stage isolated power-factor-corrected power supplies (SSIPP) have the attractive features of fast regulation and a single control loop. However, SSIPP circuits also have higher voltage stress and heavier loss (when compared with a normal DC-DC power converter), which severely limit their practical applications. In this paper, the authors propose to add active clamping to SSIPP to recycle the energy trapped in the leakage inductance of their transformer (to keep the switch voltage stress low) and to achieve soft switching of their electronic devices (to further reduce the loss). This arrangement significantly improves the viability of SSIPP for practical applications. The auxiliary active-clamping transistor in the proposed circuit uses the same control/driver circuit as the main switching transistor. Simulations and experimental works verifying the operation of the converter are reported     

一种ZCT PWM全软开关变换器的仿真研究

在零电流过渡（ZCT）功率变换电路中,主开关管的开通和辅助开关管的关断是工作在硬开关条件下的,其开关损耗大。文中通过对传统主电路拓扑结构及控制方法改进后,详细分析该变换器的工作原理并进行仿真验证。结果表明主开关管和辅助开关管不仅实现了软开关通断的工作方式,同时还能消除升压二极管的反向恢复问题。