Analysis and Experimental Validation of an Interleaved LLC Resonant Converter with Reduced Component Count

This paper presents an interleaved LLC resonant half-bridge DC-DC converter with lesser component count. Unlike most of the conventional interleaved LLC resonant converters, the proposed converter uses only one power transformer having two primary windings and one secondary winding. The primary windings of the transformer are fed in parallel via dual resonant tanks by operating the power switches of half-bridge network with interleaved half-switching cycle. Due to parallel feeding, core magnetization current divides equally between primary windings. Consequently, the effective value of magnetization inductance seen at each primary winding becomes twofold of the measured value. An equivalent circuit of converter is derived to validate this phenomenon. The gain characteristics of the equivalent circuit indicate that the maximum gain of converter occurs at relatively lower switching frequency than the conventional two power transformers-based interleaved LLC converters. Consequently, the proposed converter will have same operational characteristics at half magnetizing inductance. The validity of developed equivalent circuit and operational principle and performance of converter are confirmed by both simulation and experimental results of a 1000-W prototype. The experimental results show that for an input voltage of 400 V, converter has maximum efficiency of 96.24% at output power of 1000 W.     

Pulse current regenerative resonant snubber‐assisted two‐switch flyback‐type ZVS PWM DC‐DC converter

In this paper, a two‐switch high‐frequency flyback transformer‐type zero voltage soft‐switching PWM DC‐DC converter using IGBTs is proposed. Effective applications for this power converter can be found in auxiliary power supplies of rolling stock transportation and electric vehicles. This power converter is basically composed of two active power switches and a flyback high‐frequency transformer. In addition to these, two passive lossless snubbers with power regeneration loops for energy recovery, consisting of a three‐winding auxiliary high‐frequency transformer, auxiliary capacitors and diodes are introduced to achieve zero voltage soft switching from light to full load conditions. Furthermore, this power converter has some advantages such as low cost circuit configuration, simple control scheme, and high efficiency. Its operating principle is described and to determine circuit parameters, some practical design considerations are discussed. The effectiveness of the proposed power converter is evaluated and compared with the hard switching PWM DC‐DC converter from an experimental point of view, and the comparative electromagnetic conduction and radiation noise characteristics of both DC‐DC power converter circuits are also depicted. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 74–81, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20081     

LLC resonant DC–DC converter with series‐connected primary windings of transformer

This paper proposes a zero‐voltage switching (ZVS) LLC resonant step up DC–DC converter with series‐connected primary windings of the transformer. The series resonant inverter in the proposed topology has two power switches (MOSFETs), two resonant capacitors, two resonant inductors, and only one transformer with center‐tapped primary windings. The power switches are connected in the form of a half‐bridge network. Resonant capacitors and inductors along with the primary windings of the transformer form two series resonant circuits. The series resonant circuits are fed alternately by operating the power switches with an interleaved half switching cycle. The secondary winding of transformer is connected to a bridge rectifier circuit to rectify the output voltage. The converter operates within a narrow frequency range below the resonance frequency to achieve ZVS, and its output power is regulated by pulse frequency modulation. The converter has lower conduction and switching losses and therefore higher efficiency. The experimental results of a 500‐W prototype of proposed converter are presented. The results confirm the good operation and performance of the converter. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Series resonant high‐voltage DC–DC converter with reduced component count

This paper proposes a novel zero‐current‐switching series resonant high‐voltage DC–DC converter with reduced component count. The series resonant inverter in the proposed topology has two power switches (insulated‐gate bipolar transistors, IGBTs), two resonant capacitors, and only one high‐voltage transformer (HVT) with center‐tapped primary windings. The power switches are connected in the form of a half‐bridge network. The leakage inductances of the transformer's primary windings together with the resonant capacitors form two series resonant circuits. The series resonant circuits are fed alternately by operating the power switches with interleaved half switching cycle. The secondary winding of the HVT is connected to a bridge rectifier circuit to rectify the secondary voltage. The converter operates in the discontinuous conduction mode (DCM) and its output voltage is regulated by pulse frequency modulation. Therefore, all the power switches turn on and off at the zero‐current switching condition. The main features of the proposed converter are its lower core loss, lower cost, and smaller size compared to previously proposed double series resonant high voltage DC–DC converters. The experimental results of a 130‐W prototype of the proposed converter are presented. The results confirm the excellent operation and performance of the converter. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

可升压自然软开关变流器

该文提出一种能应用于DC-AC、AC-DC-AC、AC-DC、和DC-DC电能变换的新型电能变化策略。采用该策略的变流器与对应的传统硬开关变流器相比，在直流储能环节的回路中增加一个辅助开关，通过适当的控制可实现：DC电压提升；辅助开关零电压零电流工作；传统变流器更多开关工作在零电压零电流状态。该文通过对一个新型两电平DC-AC三相逆变器的分析来详细阐述此类变流器的基本工作机理，并通过实验加以验证。     

Hybrid DC–DC converter with high efficiency,wide ZVS range,and less output inductance

In this paper, a new soft switching direct current (DC)–DC converter with low circulating current, wide zero voltage switching range, and reduced output inductor is presented for electric vehicle or plug‐in hybrid electric vehicle battery charger application. The proposed high‐frequency link DC–DC converter includes two resonant circuits and one full‐bridge phase‐shift pulse‐width modulation circuit with shared power switches in leading and lagging legs. Series resonant converters are operated at fixed switching frequency to extend the zero voltage switching range of power switches. Passive snubber circuit using one clamp capacitor and two rectifier diodes at the secondary side is adopted to reduce the primary current of full‐bridge converter to zero during the freewheeling interval. Hence, the circulating current on the primary side is eliminated in the proposed converter. In the same time, the voltage across the output inductor is also decreased so that the output inductance can be reduced compared with the output inductance in conventional full‐bridge converter. Finally, experiments are presented for a 1.33‐kW prototype circuit converting 380 V input to an output voltage of 300–420 V/3.5 A for battery charger applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Design and implementation of an interleaved soft‐switching converter with output voltage doubler

An interleaved pulse‐width modulation (PWM) converter with less power switches is presented in this paper. The buck type of active clamp circuit is used to recycle the energy stored in the leakage inductor of a transformer. The zero voltage switching (ZVS) turn‐on of power switches is realized by the resonance during the transition interval of power switches. At the secondary side of transformers, two full‐wave rectifiers with dual‐output configuration are connected in parallel to reduce the current stresses of the secondary windings of transformers. In the proposed converter, power switches can accomplish two functions of the interleaved PWM modulation and active clamp feature at the same time. Therefore, the circuit components in the proposed converter are less than that of the conventional interleaved ZVS forward converter. The operation principle and system analysis of the proposed converter are provided in detail. Experimental results for a 280 W prototype operated at 100 kHz are provided to demonstrate the effectiveness of the proposed converter. Copyright © 2008 John Wiley & Sons, Ltd.     

一种抽能型高抗的抽能绕组匝间短路保护方案研究

抽能型高压并联电抗器,简称抽能高抗,实质是一台由网侧绕组和抽能绕组构成的空心型变压器,属于一种既能吸收系统多余无功也能提供站用电源的新型电抗器。目前,工程上通常采用抽能绕组过电流或零序过电流保护反映抽能绕组的匝间短路故障,存在着选择性差、动作时间长等不足。因此,提出一种新型的抽能绕组匝间短路保护方案以解决这一问题,即综合采用抽能高抗网侧绕组的电压和电流以及抽能绕组环内电流等电气量,由区外异常判据、铁芯饱和判据和自产零序过流判据以逻辑相与的方式共同构成。RTDS仿真实验表明,该保护方案,既能保证在各种非区内故障工况下可靠不动作,又能灵敏反映抽能绕组4%匝以上的匝间短路故障,并将保护动作时间缩短至50 ms左右,解决了以往抽能绕组匝间短路保护方案选择性差、动作时间长等问题。     

A three-phase high-frequency AC/DC converter with power-factor correction

A circuit design of an ac/dc three-phase converter with an isolated output is proposed. The converter consists of identical phase modules with forward pulse transformers, the primary windings of which are fed with phase voltage through power switches. The secondary windings of the transformers are connected to rectifiers, the outputs of which are connected in series. The energy of magnetizing inductance is also transferred to the load through an auxiliary low-power converter. The presented circuit design provides control of the converter currents that makes it possible to perform an active power-factor correction. The design is characterized by a small number of semiconductor switches in the power circuit due to the use of a direct-conversion principle. In addition, the proposed circuit design makes it possible to use power switches with a reduced permissible voltage. High-frequency energy conversion makes it possible to reduce the mass and dimensions of the device. The converter can be used as a power supply for an electric arc for welding and plasma processes. It is possible to generate output characteristics of any type, from direct-voltage to direct-current regulation. If necessary, it is possible to provide increased open-circuit voltage to simplify electric-arc ignition.     

带隔离变压器的DC/DC变换器零电流转换方案

提出了隔离型DC／DC变换器的ZCT实现方案。在变压器副边构造了和主功率回路并联的辅助谐振网络，在主开关管关断以前开通主开关管，通过谐振电容的高电压封锁副边整流桥的输出，使变压器原边电流降到零，在全负载范围内实现了主管和辅管的零电流开关。该文以推挽正激变换器为例，进行了详细的理论分析和关键参数的设计，通过原理样机的研制证明了这种方案的优点。最后给出了应用此种思想实现ZCT的一族变换器拓扑。     

加箝位网络的移相全桥变换器的研究

针对传统移相全桥ZVS PWM DC/DC变换器的缺点,提出了一种次级加箝位网络的改进型移相全桥ZVS PWMDC/DC变换器。该箝位网络减小了移相全桥变换器续流状态时的初级环流,在宽负载范围内实现了滞后桥臂的ZCS开关,并可有效减小次级整流二极管上的振荡尖峰。详细分析了变换器的工作原理及各个工作模态;研制了一台输出功率为3kW(360V/8.5A)的DC/DC变换器样机。实验结果表明,该箝位网络可以减小初级续流环流,并可减小整流二极管上的振荡尖峰,且变换器的整机变换效率高。     

采用次级辅助网络的零压零流PWM三电平变换器

该文提出一种新型的ZVZCSPWMTL直流变换器，在变压器的次级侧增加一个辅助绕组，其辅助电压为滞后管创造零电流条件，较好地解决了滞后管轻载下软开关难的问题。新的主电路拓扑减小了功率器件的电压应力。辅助电路没有使用有源开关和有损元件，具有简单高效低成本的优点，特别适用于高电压大功率的场合。该文分析了该变换器各时段的工作原理，并提供了设计参考和实验结果(4kw实验样机)。     

A novel prototype of auxiliary edge resonant bridge leg link snubber‐assisted soft‐switching sine‐wave PWM inverter

This paper proposes a new circuit topology of the three‐phase soft‐switching PWM inverter and PFC converter using IGBT power modules, which has the improved active auxiliary switch and edge resonant bridge leg‐commutation‐link soft‐switching snubber circuit with pulse current regenerative feedback loop as compared with the typical auxiliary resonant pole snubber discussed previously. This three‐phase soft‐switching PWM double converter is more suitable and acceptable for a large‐capacity uninterruptible power supply, PFC converter, utility‐interactive bidirectional converter, and so forth. In this paper, the soft‐switching operation and optimum circuit design of the novel type active auxiliary edge resonant bridge leg commutation link snubber treated here are described for high‐power applications. Both the main active power switches and the auxiliary active power switches achieve soft switching under the principles of ZVS or ZCS in this three‐phase inverter switching. This three‐phase soft‐switching commutation scheme can effectively minimize the switching surge‐related electromagnetic noise and the switching power losses of the power semiconductor devices; IGBTs and modules used here. This three‐phase inverter and rectifier coupled double converter system does not need any sensing circuit and its peripheral logic control circuits to detect the voltage or the current and does not require any unwanted chemical electrolytic capacitor to make the neutral point of the DC power supply voltage source. The performances of this power conditioner are proved on the basis of the experimental and simulation results. Because the power semiconductor switches (IGBT module packages) have a trade‐off relation in the switching fall time and tail current interval characteristics as well as the conductive saturation voltage characteristics, this three‐phase soft‐switching PWM double converter can improve actual efficiency in the output power ranges with a trench gate controlled MOS power semiconductor device which is much improved regarding low saturation voltage. The effectiveness of this is verified from a practical point of view. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 64–76, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20207     

一种PWM软开关变流器实现及损耗分析

零电流转换（ZCT）技术通过控制辅助电路的谐振,为开关器件创造零电流的开关条件.辅助电路的引入不会对主电路的控制算法产生影响,使得传统PWM控制策略能够直接应用在软开关变流器上.在分析ZCT软开关工作原理的基础上,引入的辅助电路损耗小于减少的开关损耗,ZCT技术提高变流器的整机效率.通过一台500 kVA三相ZCT软开关PWM软开关变流器互馈试验平台,完成了功率、软开关试验及不同谐振参数下的效率对比试验.试验结果表明,PWM变流器基本实现了开关器件的零电流转换,且谐振过程与理论分析基本相同,验证了谐振电流峰值与谐振周期对整机效率的影响.     

Zero-current Switching Series Resonant High-voltage DC-DC Converter with Series-connected Primary Windings of Center-tapped Transformer

Abstract—This article proposes a novel zero-current switching series resonant inverter-fed voltage multiplier based high-voltage DC-DC converter. The series resonant inverter in the proposed topology has two power switches (insulated-gate bipolar transistors), two resonant capacitors, and only one high-voltage transformer with center-tapped primary windings. The power switches are connected in the form of a half-bridge network. The leakage inductances of the transformer's primary windings together with resonant capacitors form two series resonant circuits. The series resonant circuits are fed alternately by operating power switches with an interleaved half-switching cycle. The secondary winding of the high-voltage transformer is connected to a voltage multiplier circuit to rectify and boost the voltage. The converter operates in discontinuous conduction mode, and its output voltage is regulated by pulse-frequency modulation. Therefore, all the power switches turn ON and OFF at the zero-current switching condition. The main features of the proposed converter are lower power loss, less cost, and smaller size compared to previously proposed series resonant high-voltage DC-DC converters. The experimental results of a 130-W prototype of the proposed converter are presented both for dynamic and steady-state operation. The results confirm the excellent operation and performance of the converter.     

A fully soft switched high step-up SEPIC-boost DC-DC converter with one auxiliary switch

This paper proposed a new single-ended primary inductor converter (SEPIC)-boost DC-DC converter that uses only one auxiliary switch to create soft switching condition for all semiconductor devices. The auxiliary circuit comprises one power switch (S_a), one resonant inductor (L_r), one resonant capacitor (C_r), and one diode (D_o2). The auxiliary switch (S_a) controls the resonance during switching instants. The converter has simple structure and its control circuit remains pulse width modulation (PWM). Besides, the proposed converter has high voltage gain without using any transformer or coupled inductors. In addition, the auxiliary switch is not located in the main power path. Moreover, using soft switching techniques is the best way for reducing the size, weight, and volume of the converter. Furthermore, reduction of input inrush current and voltage stress for the main switch is obtained by using SEPIC-boost structure. A laboratory prototype converter is designed and implemented. The experimental results presented confirm the theoretical and features of the proposed converter.     

一种基于FAN6754A的PWM反激式开关电源的设计

介绍了新款峰值电流型PWM控制芯片FAN6754A的工作特性和原理,分析了反激式开关电源的设计原理以及工作过程.针对次级电路结构,设计了一种新型反激式开关稳压电源.着重介绍了反激式开关电源的变压器设计过程,包括电感值的计算、磁芯的选择、绕组匝数的确定以及气隙等.利用三端稳压器TL431配合FAN6754A实现了对电源电...     

一种采用无源钳位电路的新型零电压零电流开关变换器

针对传统的全桥移相PWM零电压零电流(ZVZCS)DC-DC变换器存在的缺点,提出了一种在副边采用无源钳位电路的新型全桥移相PWMZVZCSDC-DC变换器。这种变换器可以有效实现超前桥臂开关管的零电压开关,以及滞后桥臂开关管的零电流开关。这里详细分析了此变换器的工作原理以及变换器各个阶段的工作模态,并且分析了此变换器实现软开关的条件。理论分析表明这种变换器具有副边电压应力低,实现软开关负载范围大,辅助电路损耗小等优点。通过一台0.8kW,60kHz的样机进行了实验,验证了理论分析的正确性。实验结果证明该变换器能够在较宽的负载范围内实现滞后桥臂的零电流关断,适用于大功率应用IGBT的场合。     

多级串联高压大功率矩阵变换器的研究

提出和采用载波移相调制原理,仿真分析一种降压变压器次级绕组功率平衡的多级串联高压变频器,即一个次级变压器承担对称的3个三相-单相矩阵变换器输出,输出相位相同的三相-单相矩阵变换器通过升压变压器次级串联,构成一相高压交流输出。整个电路由网侧工频降压变压器、单相矩阵变换器阵列、载侧高频升压变压器以及滤波电路构成。仿真结果表明,所提出的多级串联高压变频器具有可行性和低成本特征。     

双绕组反激式单级PFC变换器及功率因数改善措施研究

为改善功率变换器的功率因数,提出一种双绕组反激式单级功率因数校正PFC(Power Factor Correction)变换拓扑。该拓扑由Boost PFC电路和具有串并联结构的双绕组反激变换电路组合而成,利用2个中间储能电容吸收变压器初级绕组的漏感能量,有效地抑制功率器件的电压应力,提高变换器的可靠性。详细分析了变换器的工作原理和稳态特性,并在传统的单电压环控制方法的基础上,将整流电压引入到控制电路,提出了一种简单的电压补偿控制方法来提高变换器的功率因数、降低输入电流的总谐波畸变率。设计制作了一台150 W/24 V实验样机,实验结果验证了所提出电路原理的正确性和采用电压补偿控制方法改善输入电流波形质量的有效性。