一种新颖的交错并联正激三电平变换器

本文提出的一种交错并联正激三电平直流变换器(ITLFC)，可以使输出滤波电感大大减小。如果将它应用于负载动态变化很快的变换器场合(比如电压调节模块VRM)，不仅可以提高变换器的动态响应速度，还可以减小输出滤波电容，从而使得输出滤波器体积明显减小，利于提高变换器的功率密度。本文首先分析该变换器工作原理，然后和传统的Buck型变换器进行比较，最后试制一台0.8V/100A输出的VRM样机对该变换器性能进行试验验证。     

一种新颖的零电压开关PWM组合式三电平变换器

该文提出一种新颖的零电压开关组合式直流三电平变换器,它实质上是由半桥三电平变换器和全桥变换器组合而成.该变换器所有开关管的电压应力均为输入电压的一半,特别适用于高压输入场合;其输出整流电压交流分量很小,可以大大减小输出滤波器的体积,提高变换器的动态性能;其输入电流脉动很小,可以减小输入滤波器;此外,该变换器可以在三电平和两电平两种模式下工作,输入整流二极管电压应力小,适合于宽范围输入电压场合.该文介绍了该变换器的工作原理及其特性,并给出实验结果.     

零电压开关PWM全桥三电平变换器

该文针对全桥三电平变换器提出了一种新的控制一一斩波加移相控制，引入了飞跨电容和钳位二极管，使全桥三电平变换器可以工作在三电平模式和两电平模式，同时实现所有开关管的零电压开关，从而使变换器适应宽范围输入电压的要求，并保持较高的变换效率。由于开关管的电压应力只有输入电压的一半，使该变换器非常适合高压输入的场合。此外，全桥三电平变换器输出滤波电感比传统全桥变换器大大减小，副边整流一极管的电压应力得到了降低。由于变换器的输入电流纹波很小，输入滤波器也得到了减小。该文详细分析全桥三电平变换器在该控制策略下的工作原理，讨论参数设计，并且给出实验结果。     

输入输出共地的三电平变换器

三电平直流变换器不仅可以降低开关管的电压应力，同时还可以大大减小储能电感和电容。但是6种不隔离的三电平变换器的输入输出不共地，其应用范围受到限制。该文引入隔直电容的概念，对这6种不隔离的三电平变换器进行改进，使其输入与输出共地，同时保留其所有优点：①开关管电压应力只有其原型电路的一半：②储能电感和电容可以大大减小。该文以Buck三电平变换器为例进行分析和实验验证。     

零电压零电流开关PWM组合式三电平变换器

提出一种零电压零电流开关PWM组合式三电平变换器，它由半桥三电平变换器与全桥变换器组合而成。该变换器所有开关管的电压应力均为输入电压的一半；可以在很宽的负载范围内实现MOSFET的ZVS，在很宽的负载范围内实现IGBT的ZCS；输出滤波器上高频分量小，可以大大减小输出滤波器的体积；可以在三电平和两电平两种工作模式下切换工作，输出整流二极管的电压应力小。该文分析该变换器的工作原理，介绍了其特点，并给出实验结果。     

全桥三电平变换器的一种新型控制策略

对全桥三电平变换器提出了一种新的脉宽调制控制策略一双移相（Double phase—shift,DPS）控制。对比斩波加移相（Chopping plus phase—shift,CPS）控制,该控制策略大大减小开关管体二极管的损耗,使全桥三电平变换器可以工作在三电平模式和两电平模式,从而提高了变换器的效率。同时保持开关管的电压应力只有输入电压的一半,使该变换器非常适合高压输入的场合,并实现所有开关管的零电压开关。此外,全桥三电平变换器输出滤波电感比传统全桥变换器也大为减小。副边整流二极管的电压应力得到了降低。由于变换器的输入电流纹波很小,输入滤波器也得到了减小。本文详细分析全桥三电平变换器在双移相控制策略下的工作原理,讨论参数设计,并且给出实验结果。     

可全负载范围实现ZVS的复合式全桥三电平变换器

提出一种倍流整流方式ZVSPWM复合式全桥三电平变换器,它可以在整个输入电压和很宽的负载范围内实现所有开关管的零电压开关和输出整流管的自然换流,从而有效地消除输出整流管上的电压尖峰和振荡。该变换器还有利于减小输出滤波电感纹波电流和输出纹波电流,适用于宽输入电压范围场合。该文阐述该变换器的工作原理,对参数进行选择,并通过一台540W的原理样机验证该变换器的工作原理,最后给出实验结果。     

一种交错并联反激式三电平DC-DC变换器

本文在传统反激变换器基础上,引入三电平技术,并针对传统反激三电平DC-DC变换器电源两端并联的分压电容不均压的问题,提出了一种交错并联反激式三电平DC-DC变换器。该变换器具有电路拓扑简洁,输出只需电容滤波,减小输出滤波器,提高了变换器功率密度等优点。深入分析了该变换器的工作原理及工作过程,推导了其输入输出关系,和传统的反激两电平变换器相比,可以得出该并联交错三电平反激变换器能减小输出电容,降低功率开关管电压应力等结论。最后设计了闭环控制策略,并基于saber对电路进行仿真,验证了该拓扑的正确性和输出电容小、功率开关管电压应力低等特点。     

Buck三电平变换器

提出一种Buck三电平变换器 ,该变换器中开关管的电压应力为输入电压的一半 ,采用交错控制方式 ,可以大大减小输出滤波器的大小 ,详细分析Buck三电平变换器的工作原理 ,分析该变换器的输入输出特性 ,讨论主要参数的设计 ,提出一种使输入分压电容电压均衡的方法 ,并进行实验验证。     

一类新型三电平软开关DC-DC变换器的研究

该文针对一类新型的三电平DC—DC变换器进行详细的研究，该电路使用一个双向开关构造中间电平，大大简化原有多电平电路的复杂程度，使多电平电路有可能被用于中低功率场合。通过将该电路与传统的全桥电路相比较研究可以发现，该电路具有输出谐波含量小的特点，可以非常有效减小输出无源滤波元件的体积和重量。该文详细探讨了这类新型三电平DC—DC：变换电路的电路结构和工作原理，并进行了实验研究。实验结果证明该电路原理正确，可以正常工作。     

一种新型快速瞬态响应VRM拓扑

微处理器的迅速发展,使其对功率管理的要求越来越高。作为CPU电源的电压调节模块(VRM),其瞬态响应已成为目前研究的热点问题。提出了一种新型快速瞬态响应VRM拓扑,分析了该拓扑的结构、工作原理和控制策略。通过一台1.8 V/15 A的样机实验,证明了该拓扑在提高瞬态响应方面的有效性。     

复合式全桥三电平LLC谐振变换器

该文提出了一种适合于燃料电池供电系统新颖的复合式全桥三电平LLC谐振变换器。它是在复合式全桥三电平变换器的基础上加入了LLC谐振网路以实现开关管ZVS和整流二极管ZCS。该变换器集合了复合式全桥三电平变换器和LLC谐振变换器的优点：适合于在宽输入电压范围的应用场合；三点平桥臂的开关管电压应力只有输入电压的一半；整流二极管实现ZCS，其电压应力仅为输出电压；可以在全负载范围内实现ZVS。该文通过一个200－400V输入，360V/4A输出的原理样机验证了它的工作原理，并给出实验结果。     

具有低频电流纹波抑制功能的电流型桥式光伏微逆变器

合理的低频电流纹波水平能有效增加微逆变器的寿命,提高光伏电池的输出功率。文中提出一种器件复用的电流型桥式变换器,作为两级式光伏微逆变器的前级,针对该变换器提出了一种双占空比调制策略,分析了在该策略下变换器的工作原理,在此基础上提出了一种可实现光伏电池侧低频电流纹波抑制的策略。分析了变换器的小信号模型,分别设计了升压电感电流内环、光伏电池电压外环以及低压侧电压环的调节器参数,并通过根轨迹验证了在整个光伏电池运行范围内变换器均能稳定运行。实验样机运行结果验证了分析与设计参数的正确性。     

A single-phase p-type ac–ac converter with reduced components count and high boost factor

This paper proposes a new single-phase direct step-up ac–ac converter by modifying the p-type impedance source. It provides a high boost factor as well as high efficiency, while only six parts are required to design it, involving just two bidirectional power switches. A safe commutation method has been applied to power switches to make the converter snubber-free and high efficient. Input and output harmonic filters are no longer required since input and output currents variate continuously with small ripple and low total harmonic distortion (THD). The proposed topology only modulates the output voltage amplitude, not the phase and frequency, so the output frequency is identical to the input frequency and constant. Thus, it can be utilized in step-up conversion applications, like inductive power transmission from low ac voltage sources. Input and output have the same ground, which is a good protective feature. In this paper, the operating principle of the converter is demonstrated. Experimental results have been represented to evaluate the performance of the converter. For this purpose, an experimental prototype has been fabricated. Results are investigated and compared with other previous step-up ac–ac converters. Results confirm the theory, operating principle, and performance of the converter.     

Novel interleaved ZVS converter with ripple current cancellation

This paper presents a zero voltage switching (ZVS) converter with interleaved pulse‐width modulation scheme. An active clamp circuit is adopted in the proposed converter to recycle the energy stored in the leakage inductor of the transformer and reduce the voltage stress of the main power switch in the converter. The ZVS feature of switches can be achieved due to the resonance during the transition interval of two power switches. Two full‐wave rectifiers with ripple current cancellation are connected in parallel at the output side to reduce the current stress of the secondary winding of transformers. Instead of the conventional interleaved forward converter, power switches in the proposed converter can perform the functions of both forward converter and active clamp at the same time. Therefore, the circuit components in the power circuit are less than that of in the conventional interleaved forward converter. The operation principle and system analysis of the proposed converter are provided. Some experimental results for a 240 W (12 V/20 A) prototype are provided to demonstrate the effectiveness of the proposed converter. Copyright © 2008 John Wiley & Sons, Ltd.     

Experimental evaluation of a variable-speed, doubly-fed wind-powergeneration system

The paper evaluates the potential of a brushless doubly-fed generation system for wind power applications. A 1.5 kW proof-of-concept laboratory prototype is used to investigate the feasibility of the proposed variable-speed generation principle. Experimental results show that the prototype system can achieve high efficiency over a range of speeds. The system efficiencies achieved at the power levels considered compare favorably with conventional squirrel cage induction machines. It is experimentally demonstrated that the brushless doubly-fed system achieves variable-speed operation with a power converter of reduced rating. For the prototype under consideration, a 2:1 speed range can be covered with a power converter rated at approximately 25% of system capacity. While reactive power control can be realized with the proposed system, the magnitude is limited by the desired low power converter rating. The prototype system also is also shown to exhibit excellent output current waveforms     

Multi-input DC/DC converter based on the multiwinding transformer for renewable energy applications

A multi-input DC/DC power converter based on the flux additivity is proposed in this paper. Instead of combining input DC sources in the electric form, the proposed converter combines input DC sources in magnetic form by adding up the produced magnetic flux together in the magnetic core of the coupled transformer. With the phase-shifted pulsewidth-modulation (PWM) control, the proposed converter can draw power from two different DC sources and deliver it to the load individually and simultaneously. The operation principle of the proposed converter has been analyzed in detail. The output voltage regulation and power flow control can be achieved by the phase-shifted PWM control. A prototype converter with two different DC voltage sources has been successfully implemented. Computer simulations and hardware experimental results are presented to verify the performance of the proposed multi-input DC/DC power converter.     

一种具有自动均压均流特性的组合式LLC谐振变换器

提出一种具有自动均压和均流特性的组合式LLC谐振变换器。该变换器拓扑基于多个LLC模块的ISOP结构,通过在变换器前级开关电容网络中加入飞跨电容实现各串联模块输入端电压的均衡,在不同模块的谐振槽中串联耦合电感实现各模块电流的均衡。该拓扑保持了传统LLC谐振变换器的高效率、软开关和低电磁干扰(EMI)等优良特性,且具有控制简单、系统可靠性高等优点,非常适用于高降压比、大功率输出场合。以两个LLC模块的组合式变换器为例,对该拓扑的均压和均流原理进行详细分析。最后,通过一台输入400~550V、输出48V/24A的实验室样机,对该拓扑的均压和均流效果进行实验验证。