Engineering design of lossless passive soft switching methods forPWM converters. I. With minimum voltage stress circuit cells

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     

一种新型软开关DC-DC PWM升压变换器设计

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%。     

高频软开关PWM功率变换技术的发展与现状

本文介绍了三类零电压软件开关ＰＷＭ变换器和两类零电流软件开关ＰＷＭ变换器的特点和工作原理。     

New conceptual three-phase current-fed soft switching pulse width modulation converter with switched capacitor type resonant dc link

This paper presents a novel prototype of three-phase current-fed PWM converter with a switched capacitor type resonant dc link snubber circuit, which can basically operate under a principle of zero current soft switching commutation. The optimum PWM pattern-based control scheme proposed by the authors is effectively applied for this active converter. In this paper, the steady-state operating principle of a new converter circuit treated here is described. The practical design procedure of this converter is discussed from a theoretical point of view. The feasible experiment to confirm zero current soft switching commutation of this converter is concretely implemented and evaluated herein.     

Resonant link bidirectional power converter. I. Resonant circuit

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     

一种新型ZVT—PWM软开关BOOST变换器

介绍一种带缓冲电路的新型零电压过渡PWM（ZVT－PWM）软件开关BOOST变换器,缓冲电路的加入,使主,辅助开关都能实现软化,减小了开关管的电压和电流应力,提高了整机效率,对电路的工作原理进行了详细分析,推导出了工作过程中各阶段的状态具体表达式,最后进行了仿真分析,并在此基础上进行实验验证,给出实验结果,实验证明,该电路结构简单,效率较高,具有一定的实用价值。     

New zero voltage switching DC converter with flying capacitors

A new soft switching converter is presented for medium power applications. Two full-bridge converters are connected in series at high voltage side in order to limit the voltage stress of power switches at V_in/2. Therefore, power metal–oxide–semiconductor field-effect transistors (MOSFETs) with 600 V voltage rating can be adopted for 1200 V input voltage applications. In order to balance two input split capacitor voltages in every switching cycle, two flying capacitors are connected on the AC side of two full-bridge converters. Phase-shift pulse-width modulation (PS-PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active MOSFETs can be turned on under zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. Two full-bridge converters are used in the proposed circuit to share load current and reduce the current stress of passive and active components. The circuit analysis and design example of the prototype circuit are provided in detail and the performance of the proposed converter is verified by the experiments.     

基于PWM变换器的新型无源无损软开关

详细分析了一种基于PWM变换器的新型无源无损软开关，并给出了其最优化设计步骤。通过一台满载输出功率为900w的带有该无源无损软开关的Boost变换器验证了其开关管实现零电流开通和零电压关断，并与传统的Boost变换器比较，验证其具有较高的效率。     

A study of active power filters using quad-series voltage-sourcePWM converters for harmonic compensation

An active power filter using quad-series voltage-source pulse-width-modulated (PWM) converters to suppress AC harmonics by injecting compensating currents into the AC system is described. The circuit used to calculate the compensating current references, the compensation characteristics, and the capability of the DC capacitor are discussed theoretically and experimentally. A control circuit for the DC capacitor voltage is proposed. The discussions focus on transient states, based on the instantaneous reactive power theory. A passive LC filter is designed to remove the switching voltage and current ripples caused by the PWM converters at the AC side. Some experimental results that illustrate the details of the study are shown     

Modeling of capacitor impedance in switching converters

Switched capacitor (SC) converters are gaining acceptance as alternatives to traditional, inductor-based switching power converters. Proper design of SC converters requires an understanding of all loss sources and their impacts on circuit operation. In the present work, an equivalent resistance method is developed for analysis, and equivalent resistance formulae are presented for various modes of operation. Quasiresonant converters are explored and compared to standard SC converters. Comparisons to inductor-based switching power converters are made. A number of capacitor technologies are evaluated and compared for applications to both SC converters and inductor-based converters. The resulting model can be used to accurately predict and optimize converter performance in the design phase.     

A zero-current-switching PWM flyback converter with a simpleauxiliary switch

A simple and effective approach of turning an isolated hard-switched converter design into a soft-switched one is presented. By adding an auxiliary winding, switch and small capacitor to the conventional pulsewidth modulation (PWM) isolated flyback converter, all switches and diodes are softly turned on and off. No extra active or passive voltage clamp circuit is needed to suppress voltage stress on the switching devices that were usually found in classical converters. A zero-current-switching (ZCS) PWM flyback converter topology with multiple outputs is analyzed and examined. The proposal inherently utilizes the leakage inductance of the “flyback” transformer to achieve ZCS of all switching devices. A complete steady-state DC analysis and the operating principle are described. The performance of an 80 W experimental converter prototype with dual-voltage outputs is included     

基于高频高压交流母线多组输出直流电源的研制

本电源是基于高频高压交流母线具有多组输出的直流电源，它具有高达200kHz的开关频率，后级的整流电路由于高频交流母线的存在，使得变压器和电感的设计变得简单，滤波电容的选择也更容易。本电源由PFC电路提供400V的高压直流输入，再由MOSFET组成全桥逆变电路，在固定额率的PWM发生电路和IR2110 MOSFET驱动电路作用下，只加—个谐振电感就可实现开关管的零电压开通，可在大大降低开关损耗和噪声的同时实现直流交流的变换。整流部分采用倍流整流电路以提高原边电压的利用率，可输出低压大电流。由于采用肖特基管，—方面可使得二板管的损耗可以接受，另外—方面还避免了采用同步整流电路所面临的电路结构复杂和驱动困难。     

A Multistage Interleaved Synchronous Buck Converter With Integrated Output Filter in 0.18 μm SiGe Process

The design and analysis of a fully integrated multistage interleaved synchronous buck dc-dc converter with on-chip filter inductor and capacitor is presented. The dc-dc converter is designed and fabricated in 0.18 mum SiGe RF BiCMOS process technology and generates 1.5 V-2.0 V programmable output voltage supporting a maximum output current of 200 mA. High switching frequency of 45 MHz, multiphase interleaved operation, and fast hysteretic controller reduce the filter inductor and capacitor sizes by two orders of magnitude compared to state-of-the-art converters and enable a fully integrated converter. The fully integrated interleaved converter does not require off-chip decoupling and filtering and enables direct battery connection for integrated applications. This design is the first reported fully integrated multistage interleaved, zero voltage switching synchronous buck converter with monolithic output filters. The fully integrated buck regulator achieves 64% efficiency while providing an output current of 200 mA.     

Design and Application for PV Generation System Using a Soft-Switching Boost Converter With SARC

In order to improve the efficiency of energy conversion for a photovoltaic (PV) system, a soft-switching boost converter using a simple auxiliary resonant circuit, which is composed of an auxiliary switch, a diode, a resonant inductor, and a resonant capacitor, is adopted in this paper. The conventional boost converter decreases the efficiency because of hard switching, which generates losses when the switches are turned on/off. During this interval, all switches in the adopted circuit perform zero-current switching by the resonant inductor at turn-on, and zero-voltage switching by the resonant capacitor at turn-off. This switching pattern can reduce the switching losses, voltage and current stress of the switching device. Moreover, it is very easy to control. In this paper, we have analyzed the operational principles of the adopted soft-switching boost converter, and it is designed for PV generation system. Simulation and experimental results are presented to confirm the theoretical analysis.      

Z-Source AC–AC Converters Solving Commutation Problem

A new family of Z-source ac-ac converters with buck-boost ability are proposed, including four switches single-phase structure and six switches three-phase structure. New commutation strategies for these converters are proposed and safe commutation can be achieved without snubber circuit. The commutation strategies are easily to realize by sampling only voltage signals, and two switches are always turned on, so switching loss can be reduced. Analysis based on state-space averaging reveals the relationship between Z-source inductor current and filter inductor current as well as voltage ratio. The design considerations of voltage-fed single-phase topology are given as an example. Simulation results on the voltage-fed topologies and experimental results on voltage-fed single-phase topology verified the unique features of Z-source ac-ac converters and the proposed commutation strategies. These converters have merits such as less conduction and switching loss, less devices, therefore high efficiency and reliability can be achieved.     

Novel zero-voltage and zero-current-switching full bridge PWMconverter using transformer auxiliary winding

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) pulse width modulation (PWM) converter is proposed to improve the demerits of the previously presented ZVZCS-FB-PWM converters, such as use of lossy components or additional active switches. A simple auxiliary circuit which includes neither lossy components nor active switches provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches. Many advantages including simple circuit topology, high efficiency, and low cost make the new converter attractive for high power (>2 kW) applications. The operation, analysis, features and design considerations are illustrated and verified on a 2.5 kW, 100 kHz insulated gate bipolar transistor (IGBT) based experimental circuit     

Multifunctional Grid-Connected Multimodule Power Converters Capable of Operating in Single-Pulse and PWM Switching Modes

Pulsewidth-modulated (PWM) techniques equip power converters with unique features such as input-output linearity and control flexibility. Nevertheless, frequent switching of semiconductor switching devices causes considerable switching loss, and therefore makes traditional two-level PWM converters inappropriate for high-power applications. Two alternatives for building modular structures, namely multipulse and multimodule PWM converters were introduced to provide not only voltage and current sharing among the semiconductor switching devices, but also a high-quality output voltage at a much lower switching frequency. While multipulse converters offer minimal switching losses, low-order harmonic neutralization, and the best utilization of the inverter, multimodule PWM converters give control flexibility and power structure simplicity. This paper combines these two, and preserves the advantages of both multipulse and multimodule PWM converters. This not only provides an additional degree of freedom for voltage control, but also enables the converter to operate in PWM mode during transient and in single-pulse mode during the steady state. For the PWM switching mode, a special space vector strategy of 3 p.u. switching frequency is presented to maximize the voltage utilization and maintain a linear transfer characteristic. The power structure and control methods are analyzed, and validated by simulation and experimentally.     

DC-DC converter: four switches V/sub pk/=V/sub in//2, capacitive turn-off snubbing, ZV turn-on

A new four-switch full-bridge dc-dc converter topology is especially well-suited for power converters operating from high input voltage: it imposes only half of the input voltage across each of the four switches. The two legs of a full-bridge converter are connected in series with each other, across the dc input source, instead of the usual topology in which each leg is connected across the dc source. The topology reduces turn-off switching losses by providing capacitive snubbing of the turn-off voltage transient, and eliminates capacitor-discharge turn-on losses by providing zero-voltage turn-on. (Switching losses are especially important in converters operating at high input voltage because turn-on losses are proportional to the square of the input voltage, and turn-off losses are proportional to the input voltage). The topology is suitable for resonant and nonresonant converters. It adds one bypass capacitor and one commutating inductor to the minimum-topology full-bridge converter (that inductor is already present in many present-day converters, to provide zero-voltage turn-on, or is associated with one or two capacitors to provide resonant operation), and contains a dc-blocking capacitor in series with the output transformer, primary winding, and some nonresonant converters (that capacitor is already present in resonant power converters). The paper gives a theoretical analysis, and experimental data on a 1.5-kW example that was built and tested: 600-Vdc input, 60-Vdc output at up to 25A, and 50-kHz switching frequency. The measured performance agreed well with the theoretical predictions. The measured efficiency was 93.6% at full load, and was a maximum of 95.15% at 44.8% load.     

基于状态空间法的非理想Boost电路开环建模

Boost变换器是组成高阶变换器的基本单元,故对其建模和仿真的研究有着理论和实际意义。状态空间平均法是DC-DC变换器建模的有力工具。在考虑了电感电容高频寄生电阻的条件下,应用状态空间平均法对非理想Boost变换器进行建模。为统一开关变换器不同工作状态下的状态方程,在此引入开关函数。开关函数的引入使得对状态方程平均化的问题转化为对开关函数平均化的问题,简化了建模过程,且平均化的开关函数具有明确的物理意义。最后将数学模型与电路模型的仿真结果以及实测数据加以对比,得出了较为一致的结论,为直流变换器的设计和分析提供参考。     

Novel zero-voltage and zero-current-switching (ZVZCS) full-bridge PWM converter using coupled output inductor

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge pulse-width-modulated (PWM) converter is proposed to improve the previously proposed ZVZCS full-bridge PWM converters. By employing a simple auxiliary circuit with neither lossy components nor active switches, soft-switching of the primary switches is achieved. The proposed converter has many advantages such as simple auxiliary circuit, high efficiency, low voltage stress of the rectifier diode and self-adjustment of the circulating current, which make the proposed converter attractive for the high voltage and high power applications. The principles of operation and design considerations are presented and verified on the 4 kW experimental converter operating at 80 kHz.