共查询到18条相似文献,搜索用时 156 毫秒
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为提高转换效率并降低电源开关的电流应力,提出一种基于新型有源缓冲电路的PWM DC-DC升压变换器。该有源缓冲电路使用ZVT—ZCT软开关技术,分别提供了总开关ZVT开启及ZCT闭合、辅助开关ZCS开启及ZCT闭合。消除了总开关额外的电流及电压应力,消除了辅助开关电压应力,且有源缓冲电路的耦合电感降低了电流应力。另外,通过连续将二极管添加到辅助开关电路,防止来自共振电路的输入电流应力进入总开关。实验结果表明,相比传统的PWM变换器,新的DC-DC PWM升压变换器在满负荷时电流应力降低且总体效率能达到98.7%。 相似文献
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具有无损耗缓冲电路的软开关双管正激式变换器 总被引:2,自引:0,他引:2
介绍了一种具有无损耗缓冲电路的软开关双管正激式变换器。它采用无损耗缓冲技术,使开关管工作在软开关状态,抑制了dv/dt,使开关管的开关损耗下降一半左右。同时缓冲电路本身并不消耗能量,而是将能量返回到系统中,提高了整机效率。文中对其工作原理,缓冲电路的能量转换过程进行了分析,并给出了实验结果及波形。 相似文献
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无源软开关电路拓扑的研究 总被引:1,自引:0,他引:1
提出一个研究无源软开关电路的新技术方法;其特征是对基本的单管隔离型PWM DC/DC变换器进行类比分析,由此直接导出可行的缓冲能量再生复位电路.该新方法能使DC/DC PWM硬开关变换器转变为软开关变换器.以新型Boost无源软开关变换器为例,进行了电路理论分析与中功率样机的实验测试;结果表明此新变换器具有较宽的软开关工作范围、较低的电应力、较小的缓冲元件量值等特点.由此认为,这种研究方法推导简单、物理意义清晰,还能深入地研究无源软开关的新电路拓扑. 相似文献
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近年来零电压开关PWM变频技术受到人们的普遍关注。其基本思想是,通过零电压开关电路使逆变器主电路在各载波周期起始时刻产生谐振,确保各功率开关器件在主电路P、N极间电压为零期间进行动作切换。为了使谐振电路正常工作,通常采用正负斜率交替的锯齿波作为载波,这使得该PWM模式的零电压矢量的作用时间较传统硬开磁SPWM模式发生了很大变化。本文利用空间电压矢量概念,深入分析了软开关PWM模式下磁链的运动轨迹。指出在硬开关PWM模式下,磁链的运动速度靠零空间电压矢量调节;而在软开关PWM模式下,空间电压矢量的作用时间发生了很大变化,有时甚至没有零空间电压矢量。但该模式依靠非零空间电压矢量进行调节,使得磁链的运动速度仍然保持与硬开关时完全相等。文章还分析了软开关PWM逆变器电流波形畸变的原因,并从磁链轨迹圆出发,提出相应的补偿方法。实验证明了该方法能有效地改善逆变器的输出电流波形。 相似文献
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以CRT为像源的平视显示系统对高压电源的性能、效率、体积、重量等有很高的要求,PWM型高压开关电源因为具有体积小、重量轻、效率高等优点而获得了广泛的应用。对PWM型高压电源的原理、单元电路等进行详细的介绍。电路采用逆变方式,从27 V直流电压,经过功率变换、升压变压、倍压整流等环节产生所需要的高电压。电压的稳定调节通过安置在负反馈通道中的脉宽调制器SG1525A实现,其基本原理是,采样电路对输出电压进行采样,与基准电压进行比较后,引起PWM产生的方波宽度改变,控制功率变换器中开关管的通断时间,使得输出电压向相反方向改变,从而使输出电压保持稳定。 相似文献
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This paper proposes the analysis and design methodology of lossless, passive soft switching methods for PWM converters. The emphasis of the design and analysis is for PWM converters that use nonminimum voltage stress (non-MVS) circuit cells to provide soft switching. PWM converters with non-MVS circuit cells have several distinct advantages over converters that use minimum voltage stress (MVS) cells. With the same relative size of the inductor and capacitor added for soft switching, the non-MVS cells have a substantially larger duty ratio range where soft switching is guaranteed. In addition, the overcurrent stress of the main switch, under most conditions, will be lower and an optimum value of inductor and capacitor added for soft switching can be used. Therefore, with proper design, the non-MVS cells provide higher efficiency. These advantages are obtained with the price of higher switching voltage stress and one additional inductor. The loss model for a MOSFET and optimum capacitor and inductor values are utilized in the design procedure. Examples of the design procedure are given for PFC and DC-DC applications. Experimental results backup the claim of higher efficiency. 相似文献
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Jong-Woo Choi Seung-Ki Sul 《Power Electronics, IEEE Transactions on》1995,10(4):479-484
This paper proposes a novel resonant circuit capable of PWM operation with zero switching losses. The resonant circuit is aimed at providing zero voltage intervals in the DC link of the PWM converter during the required converter device switching periods, and it gives minimum DC bus voltage stresses and minimum peak resonant current. It requires only two additional switches compared to a conventional PWM converter. It is observed that the resonant circuit guarantees the soft switching of all the switching power devices of converters including the switches for resonant operation. Simulation results and experimental results are presented to verify the operating principles 相似文献
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Chien-Ming Wang 《Industrial Electronics, IEEE Transactions on》2005,52(3):689-700
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. 相似文献
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Moschopoulos G. Jain P.K. Yan-Fei Liu Joos G. 《Power Electronics, IEEE Transactions on》1999,14(4):653-662
A zero-voltage-switched (ZVS) pulsewidth-modulated (PWM) boost converter with an energy feedforward auxiliary circuit is proposed in this paper. The auxiliary circuit, which is a resonant circuit consisting of a switch and passive components, ensures that the converter's main switch and boost diode operate with soft switching. This converter can function with PWM control because the auxiliary resonant circuit operates for a small fraction of the switching cycle. Since the auxiliary circuit is a resonant circuit, the auxiliary switch itself has both a soft turn on and turn off, resulting in reduced switching losses and electromagnetic interference (EMI). This is unlike other proposed ZVS boost converters with auxiliary circuits where the auxiliary switch has a hard turn off. Peak switch stresses are only slightly higher than those found in a conventional PWM boost converter because part of the energy that would otherwise circulate in the auxiliary circuit and drastically increase peak switch stresses is fed to the load. In this paper, the operation of the converter is explained and analyzed, design guidelines are given, and experimental results obtained from a prototype are presented. The proposed converter is found to be about 2%-3% more efficient than the conventional PWM boost converter 相似文献
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This paper presents the analysis and design methodology of lossless passive soft switching converters from an engineering perspective. The circuit operation and soft switching loss analysis are detailed and an intuitive procedure is derived that enables quick and accurate design. Analysis is given for a set of soft switching circuit cells with minimum switch voltage stress used to synthesize a family of soft switching converters. The design is based on minimizing switching losses while maintaining soft switching over the desired operating range. A new simple loss model is derived to optimize the values of the resonant components for a particular design. As an example of the design procedure, a PFC boost converter is designed and tested 相似文献
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A new ZVT-PWM DC-DC converter 总被引:7,自引:0,他引:7
In this paper, a new active snubber cell that overcomes most of the drawbacks of the normal "zero voltage transition-pulse width modulation" (ZVT-PWM) converter is proposed to contrive a new family of ZVT-PWM converters. A converter with the proposed snubber cell can also operate at light load conditions. All of the semiconductor devices in this converter are turned on and off under exact or near zero voltage switching (ZVS) and/or zero current switching (ZCS). No additional voltage and current stresses on the main switch and main diode occur. Also, the auxiliary switch and auxiliary diodes are subjected to voltage and current values at allowable levels. Moreover, the converter has a simple structure, low cost, and ease of control. A ZVT-PWM boost converter equipped with the proposed snubber cell is analyzed in detail. The predicted operation principles and theoretical analysis of the presented converter are verified with a prototype of a 2 kW and 50 kHz PWM boost converter with insulated gate bipolar transistor (IGBT). In this study, a design procedure of the proposed active snubber cell is also presented. Additionally, at full output power in the proposed soft switching converter, the main switch loss is about 27% and the total circuit loss is about 36% of that in its counterpart hard switching converter, and so the overall efficiency, which is about 91% in the hard switching case, increases to about 97% 相似文献
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A novel zero-Voltage-switching PWM boost rectifier with high power factor and low conduction losses 总被引:1,自引:0,他引:1
Chien-Ming Wang 《Industrial Electronics, IEEE Transactions on》2005,52(2):427-435
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-voltage-switching PWM (ZVS-PWM) auxiliary circuit is configured in the presented ZVS-PWM rectifier to perform ZVS in the main switches and the passive switches, and zero-current switching in the auxiliary switch. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZVS-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 ZVS-PWM rectifier in one switching period are described. A prototype rated at 1 kW, operating 80 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage of 400 V/sub dc/ has been implemented in the laboratory. An efficiency of 96.7% and power factor over 0.99 has been measured. Analysis, design, and the control circuitry are also presented in this paper. 相似文献