移相全桥ZVS变换器的分析和设计

移相全桥零电压开关变换器是中大功率直直变换场合的理想拓扑之一,但其次级整流二极管反向恢复时,产生严重的寄生振荡,二极管上存在很高的尖峰电压。而文献1中的变换器通过增加一个谐振电感和两个二极管,不仅可以实现软开关,还可以消除次级整流二极管反向恢复引起的电压振荡。基于此变换器的工作原理,文中设计了一台500W移相控制零电压软开关电源,给出了主电路的设计过程和实验波形。     

一种零电压全桥变换器尖峰抑制器的设计

采用原边加箝位二极管的变换器工作在电流断续模式时,箝位二极管工作在硬关断状态,极易损坏,严重影响系统的可靠性。文章分析了该变换器的工作原理并提出变压器副边整流管串联尖峰抑制器且原边不加箝位二极管的设计方案,该尖峰抑制器在电流连续模式和电流断续模式都能够有效抑制寄生振荡,消除尖峰电压。文中给出新方案主要参数设计方法,并通过实验验证了所给出方案的有效性。     

谈谈彩电中的整流桥堆

在彩色电视机的开关电源中,输入交流市电都要经过二极管整流及电容滤波,得到不稳定的直流电压(约300V)。为了使用方便,往往采用一种叫整流桥堆的组件,即将4只整流二极管按桥式全波整流电路的方式连接,并整体包封,引出4只引脚便成了整流桥堆,简称桥堆或全桥。如金星C4720型彩电开关电源中的D901(RB156),如附图所示。整流桥堆在彩电开关电源电路中,是一个很重要的部件。如果整流桥堆损坏,     

吸收电路在模拟电路设计中的技术研究

针对模拟电路实际设计中,电子器件容易损坏的问题,研究了几种不同的吸收电路,通过在器件两端并联电容、电阻以及二极管等措施来改善其电压和电流尖峰脉冲,最后通过PSPICE仿真软件验证了理论分析的正确性。     

一种全桥ZVZCS DC/DC变换器的研究

提出了一种全桥零电压零电流(FB-ZVZCS)DC/DC变换器拓扑,副边采用电容和二极管构成了两个辅助电路,它们与谐振电感谐振形成的阻断电压源相串联,实现了滞后臂较大范围的ZCS,同时此种结构抑制了副边整流二极管尖峰电压;针对高输出电压设计,输出采用双全桥串联整流电路以降低整流二极管的高电压应力和解决它们的均压问题。变换器控制简单、没有辅助开关和缓冲电路。文中详细分析了工作原理和参数设计,仿真和样机实验验证了方案的正确性。     

高效率雪崩渡越(IMPATT)二极管测试电路

已研究出一种高性能的雪崩渡越二极管测试电路,它对减小寄生振荡非常有效。用此电路,测得一个6000兆赫的锗二极管有12.1％的连续波效率和0.620瓦的输出。     

英飞凌发布面向低电压应用的最新防静电二极管

2012年7月16日,英飞凌科技发布了一系列可用于改善静电防护性能的瞬态电压抑制(TVS)二极管。静电放电(ESD)可能对敏感的消费电子系统造成损害。全新±3.3 V双向二极管系列拥有行业领先的箝位电压和静电吸收率,可以防止电尖峰脉冲对系统的音频输入端口或触屏接口电路等部位造成冲     

光伏并网逆变器输入反接保护设计

设计了一种光伏并网逆变器的输入反接保护电路,辅助电源由光伏电池经整流桥供电,继电器的常开开关串联在光伏电池与电解电容之间,防反二极管与限流电阻串联后与继电器的常开开关并联,通过检测电解电容两端的电压变化判断是否接反。该反接保护电路安全可靠、损耗小,且具有告警功能。     

ESD3V3S1．B：TVS二极管

英飞凌科技推出一系列可用于改善静电防护性能的TVS（瞬态电压抑制）二极管。静电放电（ESD）可能对敏感的消费电子系统造成损害。新±3．3V双向二极管系列拥有行业领先的箝位电压和静电吸收率,可以防止电尖峰脉冲对系统的音频输入端口或触屏接口电路等部位造成冲击。     

LTC4413：双通道二极管

凌特公司日前推出双通道理想二极管LTC4413，针对减少热量、压降与占板面积及延长电池使用时间而设计。LTC4413适用于需要理想二极管“或”功能来实现负载共享或两个输入电源间自动切换的应用。通过配备多个智能电路，LTC4413能够对每个理想二极管的使用加以控制(允许调整切换电压)，并指示所选理想二极管是否导通。LTC4413还具有限流和热保护以及保护器件免受电压尖峰破坏的慢关断功能。     

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.     

Zero-Voltage-Switching PWM Hybrid Full-Bridge Three-Level Converter With Secondary-Voltage Clamping Scheme

A hybrid full-bridge (H-FB) three-level (TL) converter can realize zero-voltage-switching for switches with the use of resonant inductance (including the leakage inductance of the transformer) and intrinsic capacitors of the switches. As it can operate in three-level and two-level (2L) modes, the secondary rectified voltage is always close to the output voltage over the input-voltage range; thus, the output filter requirement is significantly less. Meanwhile, the voltage stress of the rectifier diodes can also be reduced. Therefore, the H-FB TL converter is very attractive for wide input-voltage-range applications. However, there is a serious voltage oscillation across the rectifier diodes caused by reverse recovery like the Buck-derived converters. In this paper, two clamping diodes are introduced to the H-FB TL converter to eliminate the voltage oscillation across the rectifier diodes. The arrangement of the positions of the resonant inductance and the transformer is discussed. The operation principle of the proposed converter is analyzed in details. A 1.2-kW prototype was built and tested in the laboratory to verify the operation of the proposed converter.     

An Alternative Energy Recovery Clamp Circuit for Full-Bridge PWM Converters With Wide Ranges of Input Voltage

A full-bridge dc--dc converter employing a diode rectifier in the output experiences a severe voltage overshoot and oscillation problem across the diode rectifier caused by interaction between junction capacitance of the rectifier diode and leakage inductance of the transformer. The pronounced reverse-recovery current of high-power diodes significantly contributes to these issues by increasing power loss and voltage overshoot. Conventional energy recovery clamping circuits suffer from high voltage overshoot if the converter input voltage is wide. In this paper, a novel energy recovery clamp circuit is proposed to overcome this problem. The proposed circuit requires neither active switches nor lossy components. Therefore, the proposed circuit is very promising in high-voltage and high-power applications. Performance of the proposed circuit is verified both theoretically and experimentally with a 70-kW dc--dc converter.      

Zero-Voltage Switching Two-Transformer Full-Bridge PWM Converter With Lossless Diode-Clamp Rectifier for PDP Sustain Power Module

This paper presents a zero-voltage switching (ZVS) two-transformer full-bridge (TTFB) pulsewidth modulation (PWM) converter with lossless diode-clamp rectifier for a plasma display panel sustaining power module (PSPM). The TTFB converter has series-connected two transformers which act as an output inductor as well as a main transformer. Although the naturally doubled leakage inductor due to the series-connected two transformers contributes to achieve the ZVS of the lagging leg, it creates a serious voltage ringing across the output rectifier diodes. This results in the heavy voltage stresses across the rectifier diodes. Thus the dissipative snubber circuits are required in spite of the severe power dissipation. To overcome these problems, a new lossless diode-clamp rectifier (LDCR) is employed as the output rectifier, which helps the voltage across rectifier diodes to be clamped at one half the output voltage ($V_o/$2) or a full output voltage$(V_o)$. Therefore, no dissipative snubber circuits for the rectifier diodes are needed and a high efficiency as well as a low noise output voltage can be realized. In addition, the clamping capacitors of the LDCR can help considerably to reduce the primary circulating current. The operations, analysis, and design consideration of proposed converter are presented. Also, a 425-W, 385-$V_ dc$input, 170-$V_ dc$output prototype is constructed and experimental results show the validity of the proposed converter.     

A Novel High-Power-Density Three-Level LCC Resonant Converter With Constant-Power-Factor-Control for Charging Applications

This paper proposes a variable-frequency zero-voltage-switching (ZVS) three-level LCC resonant converter that is able to utilize the parasitic components of the high turns-ratio transformer. By applying a three-level structure to the primary side, the voltage stress of the primary switches is half of the input voltage. Low-voltage MOSFETs with better performance can be used in this converter, and zero-current-switching (ZCS) is achieved for rectifier diodes. By applying a magnetic integration technique, only one magnetic component is required in this converter. The power factor concept of resonant converters is proposed and analyzed, and a novel constant power-factor control scheme is proposed. Based on this control strategy, the circulating energy of resonant converters is considerably reduced. High efficiency can be obtained for high-voltage high-power charging applications. The operation principle of the converter is analyzed and verified on a 700-kHz, 3.7-kW prototype, with which a power density of 72 ${hbox {W/inch}}^{3}$ is achieved.      

A zero-voltage and zero-current switching three-level DC/DC converter

This paper presents a novel zero-voltage and zero-current switching (ZVZCS) three-level DC/DC converter. This converter overcomes the drawbacks presented by the conventional zero-voltage switching (ZVS) three-level converter, such as high circulating energy, severe parasitic ringing on the rectifier diodes, and limited ZVS load range for the inner switches. The converter presented in this paper uses a phase-shift control with a flying capacitor in the primary side to achieve ZVS for the outer switches. Additionally, the converter uses an auxiliary circuit to reset the primary current during the freewheeling stage to achieve zero-current switching (ZCS) for the inner switches. The principle of operation and the DC characteristics of the new converter are analyzed and verified on a 6 kW, 100 kHz experimental prototype.     

Analysis and Implementation of an Improved Current-Doubler Rectifier With Coupled Inductors

In this paper, an improved current-doubler rectifier with coupled inductors is proposed. The proposed rectifier can extend duty ratio to reduce the peak current through the isolation transformer winding and lower output current ripple as well as voltage stress of the rectifier diodes. In this study, a 500-W prototype with a full-bridge phase-shift converter, the proposed rectifier, with input voltage of 400 V and output voltage of 12 V was built. Theoretical analysis and experimental results have verified that the proposed rectifier is attractive for high step-down voltage and high-power applications.