Soft‐switching converter with low circulating current and wide range of ZVS turn‐on

In this paper, a new hybrid dc–dc converter with low circulating current within the freewheeling interval, wide range of zero‐voltage switching and reduced output current ripple is presented. The proposed hybrid circuit includes two three‐level pulse‐width modulation converters and a series resonant converter with the shard lagging‐leg switches. Series resonant converter is operated at fixed switching frequency (close to series resonant frequency) to extend the zero‐voltage switching range of lagging‐leg switches. The output of series resonant converter is connected to the secondary sides of three‐level converters to produce a positive rectified voltage instead of zero voltage. Hence, the output inductances can be reduced. The reflected positive voltage is used to decrease the circulating current to zero during the freewheeling interval. Therefore, the circulating current losses in three‐level converters are improved. Finally, experiments are presented for a 1.44 kW prototype circuit converting 800 V input to an output voltage 24 V/60A. Copyright © 2015 John Wiley & Sons, Ltd.     

550kV超长距离GIS电压互感器现场校验用工频谐振升压电源研究

在巨型水力发电站550kV超长距离GIS电压互感器现场误差校验中,升压是较难解决的问题,其关键技术是工频谐振电源系统的选用、组合与控制。介绍了一种550 kV超长距离GIS电压互感器现场误差校验用组合式工频谐振电源系统,其谐振电抗器采用小型固定电抗器与可调电抗器组合的方式,可实现对电容量范围为1000 pF~40 000 pF的550 kV GIS一次回路的工频谐振升压,为电压互感器现场校验或其他试验提供了升压电源。实际应用结果表明,这种电源系统灵活、轻便,组合与控制及适应性能强,具有较高的实用价值。     

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.     

Realization of the powering/regenerative operation of the induction motor by the parallel resonant power converter and proposal of a novel circuit topology

A resonant power converter for the low switching loss power conversion must be achieved for high-frequency zero voltage switching or zero current switching. The important matters of the continuation of resonant phenomena are the control strategy of resonant initial current and the clamp circuit for suppressing the resonant link voltage. The control strategy of the resonant initial current is discussed and the powering and regenerative operation are shown successfully in the steady state and transient state by experimental test. Finally, a new resonant dc link dual converter system is proposed and it is confirmed that the voltage stress of the resonant capacitor and the rms value of electrolytic capacitor current are decreased with experimental test also.     

Series resonant ZCS‐PFM DC‐DC power converter with high‐frequency high‐voltage transformer link for high‐power magnetron drive

This paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20126     

LLC谐振式磁控管供电电源的研究

研制了一台零电压软开关电源,其目的是代替微波炉中工频变压器和半波倍压整流电路,为磁控管供电。用LLC谐振变换器作为电源主电路,以dsPIC单片机为核心设计了电源的控制系统,并通过改变主电路开关变频率控制法实现了电源输出电压和输出功率的调节。实验结果表明开关频率变动范围内,该电源可安全可靠地实现软开关控制,输出电压完全满足磁控管运行需求,磁控管输出功率可实现连续可调。     

创新型基于软开关的X射线电源系统

介绍了一种最新研制的可调高压电源,其创新的主电路拓扑结构由功率因数校正(PFC)模块、Buck模块、逆变电路、高频变压器和倍压电路组成.电源利用变压器的寄生参数谐振工作;利用软开关技术实现了ZCS的低损耗.PFC模块能使该电源系统用于国内外市场,并减小其对电网的谐波污染.电源的控制电路采用基于DSP的PI调解器,并基于RS232实现了与PC的通信,从而实现了本地控制和远程管理.     

创新型的基于软开关的X射线电源系统

介绍了一种最新研制的可调高压电源,创新的主电路的拓扑结构由PFC(功率因数校正)模块、Buck模块、逆变电路、高频变压器和倍压电路组成。此电源利用变压器的寄生参数谐振工作,利用软开关技术实现了ZCS低损耗。同时,PFC模块能使此电源系统适用于国内和国外市场,并且减小对电网的谐波污染。     

变频微波炉电源用LLC谐振变换器

研制了一款专为变频微波炉中磁控管供电的高频软开关电源。采用倍压输出式LLC谐振变换器作为该电源的主电路,并用基波分析法建立了其稳态基波等效电路模型;对其直流增益、谐振电流及零电压导通条件等进行了分析,并对高频变压器的电压比、品质因数、励磁电感、谐振电感及谐振电容等核心参数进行了优化设计。仿真和实验表明所建立的稳态电路模型及其理论分析是正确的,给出的谐振网络参数及其优化设计是正确的,这对于分析、研究和改进变频微波炉电源的设计及指导生产具有现实意义。     

Analysis, Design, and Control of a Transcutaneous Power Regulator for Artificial Hearts

Based on a generic transcutaneous transformer model, a remote power supply using a resonant topology for use in artificial hearts is analyzed and designed for easy controllability and high efficiency. The primary and secondary windings of the transcutaneous transformer are positioned outside and inside the human body, respectively. In such a transformer, the alignment and gap may change with external positioning. As a result, the coupling coefficient of the transcutaneous transformer is also varying, and so are the two large leakage inductances and the mutual inductance. Resonant-tank circuits with varying resonant-frequency are formed from the transformer inductors and external capacitors. For a given range of coupling coefficients, an operating frequency corresponding to a particular coupling coefficient can be found, for which the voltage transfer function is insensitive to load. Prior works have used frequency modulation to regulate the output voltage under varying load and transformer coupling. The use of frequency modulation may require a wide control frequency range which may extend well above the load insensitive frequency. In this paper, study of the input-to-output voltage transfer function is carried out, and a control method is proposed to lock the switching frequency at just above the load insensitive frequency for optimized efficiency at heavy loads. Specifically, operation at above resonant of the resonant circuits is maintained under varying coupling-coefficient. Using a digital-phase-lock-loop (PLL), zero-voltage switching is achieved in a full-bridge converter which is also programmed to provide output voltage regulation via pulsewidth modulation (PWM). A prototype transcutaneous power regulator is built and found to to perform excellently with high efficiency and tight regulation under variations of the alignment or gap of the transcutaneous transformer, load and input voltage.     

新型HID灯电子镇流器电路拓扑的研究

提出一种基于非对称半桥结构的新型电子镇流器电路,南提供高频方波电压的半桥逆变电路和将电流波形滤波成准正弦波的谐振电路组成.通过非对称PWM控制驱动,能有效调节灯功率,实现软开关,并保持放电灯的稳定工作和电子镇流器的可靠性,实现了电了镇流器在高强度放电(High Intensity Discharging.简称HID)灯中应用的一些关键技术.最终研制出一套300 W的样机用于验证所提电路拓扑和控制方法的正确性.     

Control of the output voltage of a controlled rectifier based on a transformer with rotating magnetic field

A new control method for a rectifier based on a transformer with a rotating magnetic field (TRMF) containing an even number of sections of circular winding (CW), which makes it possible to double the number of ripples of rectified voltage in the supply-voltage period, is considered. It leads to a reduction in the ripple amplitude and improves the quality of rectified voltage. The geometrical similarity of the CW of a TRMF making it possible to implement the new control method is analyzed. Switching algorithms of power switches for the classical and new control methods for any quantity of an even number of CW sections are presented. As an example, a switching queue of power switches for a CW with ten sections is considered. The output-voltage shapes for different depths of control are shown. The calculating procedure of the control characteristic for the classical and new control methods, as well as corresponding diagrams, are presented. For the presented example with ten sections of CW, the efficiency of the new control method was evaluated and the dependences of the voltage-ripple ratio on the RMS of rectified voltage are presented. A comparative analysis of the number of ripples for different quantity of CW sections was conducted, and the harmonic composition of output voltage spectrum for the example under consideration is determined. It has been concluded that, in the case of using the new control method for achieving the desired quality of rectified voltage, the number of CW sections may be halved compared with the classical control method, which will simplify the manufacture of a transformer magnetic conductor, halve the number of pairs of power switches switching the CW taps, and decrease the mass, dimension, and cost factors of a semiconductor switch and the TRFM itself as a whole. Using the new control method makes it possible to make a controlled rectifier with an even number of sections of a CW transformer almost as efficient as using a transformer with an uneven number of CW sections and the classical control method. The new control method ensures the fulfillment of the requirements for the available value of the ripple ratio of the output voltage of a controlled rectifier based on a transformer with a rotating magnetic field set out by State Standard YuST 13109-97 at a lower RMS of rectified voltage.     

高压变压器寄生电容对串联谐振变换器特性的影响

高压串联谐振变换器广泛应用于电容器充电、静电除尘等系统中。然而,高压变压器寄生电容的存在,使得客观上并不存在理想的高压串联谐振变换器。定量分析了高压高频变压器的寄生电容对工作于断续谐振电流模式(discontinuous current mode,DCM)的串联谐振变换器特性的影响,这些特性包括临界断续谐振频率、归一化输出电流和软开关。当考虑高压变压器寄生电容后,串联谐振变换器实际上已经演变为LCC串并联谐振变换器。通过对DCMLCC谐振变换器在不同工作阶段的数学分析、推导和归一化处理,得到了具有封闭形式的电路特性的表达式。通过分析发现,随着等效电压增益的增加,DCM LCC谐振变换器的正向和反向谐振过程均由两元件谐振向三元件谐振过程转变,临界断续频率升高。以图形曲线的方式给出了量化的分析结果。通过比较两类典型的控制方法可知,第二类典型控制方法具有更高的电流输出能力和能量传输效率,是一种优化的控制方法。所得分析结果可为工作于断续谐振电流模式的高压串联谐振变换器的设计提供参考,特别对电容充电和静电除尘电源具有工程应用价值。     

200°C operation of a 500-W DC-DC converter utilizing powerMOSFETs

This paper presents results from the operation of the power stage of a 500-W DC-DC converter at an ambient temperature of 200°C. This converter is designed to provide an output voltage of 12-Vdc from a 28-Vdc input. It utilizes an H-bridge configuration composed of eight International Rectifier power MOSFETs (parallel connections of two MOSFETs) and four Motorola diodes to convert the DC input voltage to a high-frequency square wave which can then be stepped up with a transformer. The transformer output voltage is then rectified and filtered to produce the DC output voltage. A phase-shifted pulse-width modulation (PWM) switching scheme is utilized to control the MOSFETs in the H bridge. This scheme allows zero-voltage turn-on of the MOSFETs to improve the efficiency. The efficiency of this converter when operated on the laboratory bench was measured to be 89%. The H bridge and transformer were then placed in an oven and operated over an ambient temperature range of 20°C-200°C. The efficiency varied from 86.1% to 85.4% over this temperature range. The long feedthroughs for oven operation caused the efficiency to decrease from 89% to 86.1%     

创新型的基于软开关的X射线电源系统

自动X射线检测(AXI)已经成为检测和评估复杂微机电系统(MEMS)和微光电子机械系统(MOEMS)的基本方法,在医疗、考古等领域也有了广泛应用,而稳定可靠高效的直流高压电源是AXI的核心组件。一般的高压直流电源为定值输出,它们在X射线管这样的宽负载变化范围下的稳态和暂态响应不能满足AXI的要求。基于AXI的需要,本文介绍了一种最新研制的可调高压电源,创新型的主电路拓扑结构由PFC(功率因数校正)模块、Buck模块、逆变电路、高频变压器和倍压电路组成。电源利用变压器的寄生参数谐振工作,利用软形状技术实现了ZCS低损耗。PFC模块能使此电源系统适用于国内外市场并且可减小对电网的谐波污染。电源的控制电路采用基于DSP的PI调解器,并基于RS232实现与PC的通信,从而实现本地控制和远程管理。     

Application of Power Transistors to Residential and Intermediate Rating Photovoltaic Array Power Conditioners

An investigation into power conditioners that interface with photovoltaic arrays and utilities has been recently completed. The ratings for this investigation include residential systems (5-30 kW) that interface with a 240-V single-phase utility connection and intermediate systems (30-200 kW) that interface with a 480-V three- phase utility connection. Both systems mandated that an isolation transformer be provided between the array and the utility interface. A trade-off study was performed for many transistor and thyristor circuits and configurations. The weighting criteria included full- and part-load efficiency, size, weight, reliability, ease of control, injected harmonics, reactive power requirements, and parts cost. As the result of this study, a 10-kW high-frequency PWM transistor inverter feeding a high-frequency isolation transformer with a sinusoidally shaped current wave was selected. The output of the transformer is rectified with a diode bridge rectifier. Four thyristors, used as 60-Hz switches, reverse the polarity of the rectified current on every other half-cycle of the utility voltage. This reversal is accomplished slightly before the natural zero crossing of the voltage, thereby providing commutation for the thyristors. The results in the intermediate rating study targeted on a 100-kW design using power transistors in a full-bridge circuit connected to a 60-Hz three-phase transformer. Three bridge circuits are provided to interface with the polyphase utility. The switching strategy for the power transistors is based on a sine wave shape of current with a controlled deadband.     

有源箝位正激式高频脉冲直流环节逆变器大信号特性

有源箝位正激式高频脉冲直流环节逆变器具有优良的综合性能。然而 ,当输入电源电压或负载大信号瞬变时 ,有源箝位电路的动态特性严重影响了变压器最大磁化电流和功率开关承受的最大峰值电压。本文采用平均状态轨迹法深入分析了闭环反馈控制、输入电压前馈控制有源箝位正激式高频脉冲直流环节逆变器瞬态大信号特性 ,获得了瞬态大信号特性与系统控制带宽、箝位支路谐振频率参数间的关系。     

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.     

高压电容器充电电源谐振变换器的定频控制

为有效控制高压电容器高频恒流充电电源谐振变换电路的开关频率,研制了定频控制(占空比为50%,开关频率在整个充电过程中保持不变)的20 kW高压电容器充电装置逆变电路开关电路。通过提出的充电电源电路的并联负载谐振(PLR)DC-DC变换电路的等效电路模型,研究了充电电源装置的恒流充电原理,找出了电容充电初始阶段谐振电流和开关频率的数值关系。实验研究结果表明,当谐振变换电路开关频率接近于等效电路固有谐振频率的奇数分之一时,产生较大的谐振电流;为了实现谐振变换电路开关器件的零电流开通和关断,开关频率的大小始终可控制在小于等效电路固有谐振频率的1/2的范围之内。     

一种CC/CV平滑切换的宽输出电压充电电路

目前多种动力蓄电池凭借着能量密度高、续航里程长和可循环使用等优势,在新能源汽车领域得到了广泛应用。针对当前以谐振电路为基础构建复合变换器应用于蓄电池充电存在输出电压范围、模式间切换、效率等不同问题,提出了一种四开关Buck-Boost与电容钳位LLC级联复用式变换器作为充电电路。该电路增益曲线的容性区和感性区均可工作,宽调频范围的容性区具有恒流特性,感性区的最佳谐振点具有恒压特性,利于实现蓄电池恒流恒压充电控制。频率与占空比的解耦控制拓宽了变换器的输出电压范围,且负载阻抗连续变化下电压增益连续,利于实现蓄电池恒流恒压平滑切换及满足不同电池充电控制方案,宽增益下的宽调控范围可减少输出纹波。拥有桥臂间移相软开关、复用桥臂增强软开关能力和降低通态电流、变压器低磁链及最终移动于最佳谐振点工作等电路特性,利于实现电能高效传输。仿真与实验结果验证了充电电路全程满足ZVS、ZCS的恒流恒压控制及充电模式间平滑切换特性。