Calculation of Power Losses in Thyristor Converters

This paper shows that the power loss in a thyristor and its commutation circuit can be adequately calculated from a detailed knowledge of the current waveforms and the use of a simple model for conducting thyristors and diodes. In some thyristor circuits, device switching losses can be neglected with little loss in accuracy. Snubber losses are included. The analytical technique described is verified.     

PWM开关变换器的建模方法综述

介绍了PWM开关变换器的主要建模方法:状态空间平均法、等效电路法、离散时域法、动态向量法以及等效小参量法,叙述了它们的理论依据,并分析了各自的优缺点。     

Current Source Optimization in AC-DC GTO Thyristor Converters

A digital interface for a three-phase PWM ac-dc GTO converter is described, and a microprocessor-based firing scheme for the PWM control system is proposed. Two modulation strategies, equal pulsewidth modulation (EPWM) and sinusoidal pulsewidth modulation (SPWM), are implemented and their efficiencies of operation considered. Applied as the inner current loop in a dc motor controller with constant-gain proportional-plus-integral (PI) control, a fast response to step reference input changes is obtained. The theoretical responses using an approximate z-transform analysis are used to obtain optimum operational parameters.     

Family of Zero-Current Transition PWM Converters

In this paper, a new auxiliary circuit is introduced for applying to buck, buck-boost, zeta, forward, and flyback converters. This auxiliary circuit provides a zero-current switching condition for all switching elements. The proposed zero-current transition (ZCT) pulsewidth-modulated buck converter is briefly described. Also, a ZCT flyback converter is analyzed, and its different operating modes are presented. Design considerations are explained, and a design example along with the experimental results of the ZCT flyback converter is presented.     

Low Frequency Characterization of PWM Converters

Low frequency components of states or outputs in pulse-width modulation (PWM) dc and ac converters can be characterized by differential equations called describing state-space equations. These equations are derived by inspection of converter topology and use of switching functions and duty ratios. Their steady-state and small-signal dynamic solutions show how energy-storage elements in a converter/load system shape the frequency response of conversion functions established by the switches.     

多电平PWM控制技术发展

多电平PWM控制技术一直是多电平变换器研究的核心内容之一。基于传统两电平PWM技术研究的经验，经过近十几年的发展，多电平PWM控制技术已形成了儿类不同的实现方法，同时新的控制方法还在涌现。与两电平相比，多电平PWM方法需要面对一些新出现的问题，并拓展PWM控制的内涵，进而形成新的PWM控制思路。按照目前的发展情况，多电平PWM控制方法一般有多电平载波PWM方法、多电平空间矢量PWM方法，以及其他优化的PWM方法。本文对已有多电平PWM控制技术进行了归纳和分析，最后指出多电平空间矢量法和载波调制法在一定条件下具有内在的一敛性。     

A Comparative Study of Zero-Current-Transition PWM Converters

Zero-current-transition pulsewidth-modulation (ZCT-PWM) boost converters are conventional boost converters that use an active auxiliary circuit to turn off the main power switch with zero-current switching; the operation and properties of these converters are the focus of this paper. In this paper, the general operating principles behind all ZCT-PWM converters are reviewed, and the operation and properties of specific converters are discussed. The strengths and weaknesses of each converter are stated, and a new and improved ZCT-PWM boost converter is proposed and discussed. Experimental results obtained from an experimental ZCT-PWM boost converter prototype implemented with several of the auxiliary circuits discussed in this paper are presented, and the results confirm the superior performance of the proposed converter     

PWM开关变换器的符号分析

本文将等效小参量法＾「６」，推广到继续电流模式工作的或多个开关拓扑的开关变换器的分析中，可获得全符号表示的直流解及纹波解。     

开关功率变换器符号分析方法的原理

本文介绍了ＰＷＭ开关功率变换器的一种符号分析方法，着重阐述了该方法的一般原理，这一方法容易得到输出纹波的解析表达式以及系统的小信号模型，兼有计算过程简单和准确度较高的优点，可望成为功率电子学领域比较通用的一种方法。     

Synthesis of Medium Voltage dc-to-dc Converters From Low-Voltage, High-Frequency PWM Switching Converters

Low-voltage dc-to-dc power conversion is a very mature industry which uses high-frequency pulsewidth modulation (PWM) switching techniques. The passive and active components needed to build low-voltage dc-to-dc converters are highly available, affordable and constantly improving. In this paper, a very simple and systematic method of using a large number of low-voltage, high-frequency PWM converters to synthesize highly redundant, medium voltage (4-40 kV) dc-to-dc converters is presented. Theoretical and practical considerations are discussed in necessary detail and test results of an actual 10-kW, 10 kV-to-400 V, converter built from 48 low-voltage forward converters are presented. Real-time and average reduced circuit models are derived to predict the dynamical behavior of the converter and to design the feedback control loop.     

硅锗基区异质结双极晶体管的研究进展

叙述了硅锗基区异质结双极晶体管的研究发展现状，分析了该晶体管的结构机理、特点及制造技术，并且阐述了该器件的发展前景。     

自主均流法在开关变换器并联系统中的研究

大功率电源系统为保证模块间电流应力和热应力的均匀分配,防止一台或多台模块运行在电流极限值,其变换器采用了并联的拓扑结构、均分电流技术和高性能控制策略。文中分析了自主均流法的工作原理和性能特点,介绍了两种改进式的均流方法,最后指出了自主均流法的不足。     

Family of Soft-Switching PWM Converters With Current Sharing in Switches

In this paper, a new family of soft-switching pulsewidth modulation (PWM) converters is introduced. In this family of converters, two switches operate out of phase and share the output current while providing soft-switching condition for each other. A buck converter, from this family of converters, is analyzed and its operating modes are discussed. The adoption of regular PWM control circuit to the proposed converters is presented. A prototype converter is implemented and its experimental results are illustrated.     

PWM DC-DC变换器功率级的采样数据模型

将PWM变换器按其工作状态,分别写出开关导通和截止时的数学模型,根据其周其工作的特点,写出其非线性采样数据模型,将该方法用于变换器功率级的建模。以连续导通电压型DC-DC变换器为例,给出了PWM变换器功率级的一种非线性和线性化的采样数据模型,并推导了考虑到控制作用延迟时由控制到输出的传递函数,满足了控制器设计的需要。     

有线电视县域总前端建设

结合广东省雷州市(县)域有线电视前端建设,探讨贫困地区电视网络如何既满足现有用户收看需求,避免重复投资,同时预留今后电视网络的发展空间,介绍雷州市区域总前端系统的组成、规划、传输及应遵循的原则。     

A New Family of Zero-Current-Switching (ZCS) PWM Converters

A new family of zero-current-switching (ZCS) pulsewidth-modulated (PWM) converters which uses a new ZCS-PWM switch cell is presented in this paper. The main switch and auxiliary switch operate at ZCS turn-on and turn-off, and all the passive semiconductor devices in the ZCS-PWM converter operate at zero-voltage-switching (ZVS) turn-on and turn-off. Besides operating at constant frequency and with reduced commutation losses, these new converters have no additional current stress in comparison to the hard-switching converter counterpart. The new family of ZCS-PWM converters is suitable for high-power applications using insulated gate bipolar transistors (IGBTs). The PWM switch model and state-space averaging approach is used to estimate and examine the steady-state and dynamic character of the system. The principle of operation, theoretical analysis, and experimental results of the new ZCS-PWM boost converter, rated 1 kW and operating at 30 kHz, are provided in this paper to verify the performance of this new family of converters.     

控制信号变化对PWM变换器谐波的作用模型

在频域内使用频率耦合矩阵（FCMs），用建模方法描述了控制信号变化对PWM变换器谐波的影响。该方法是建立在对变换器开关函数严格的数学分析基础上的，并在频域内产生了一个完整的分析式。本文提供了这种建模方法得到的结果并用时域内的仿真数据进行了校验。     

不连续导电模式PWM开关变换器闭环系统的符号分析法

本文将文献[11]提出的连续电流模式(CCM)PWM变换器闭环系统的符号分析法推广于不连续导电模式(DCM)PWM变换器闭环系统的稳态分析中,获得全符号表示的DCM PWM变换器闭环系统状态变量的直流解及纹波解.     

Effect of the Output Impedance in Multiphase Active Clamp Buck Converters

Passive current sharing in multiphase converters, where resistive losses are not dominant, is a quite complex goal. In this paper, an averaged model of an active clamp buck converter was obtained. It has been checked that this topology presents high output impedance. This property is used like a lossless passive equalization. The principle of operation, theoretical analysis, simulation, and experimental results are presented, taken from a three-stage laboratory prototype.      

Computer-Aided Dynamic Characterization of Fourth-Order PWM DC–DC Converters

Average-value modeling of dc–dc converters has been an area of active research for many years. Developing accurate average-value models of higher order converters is further complicated by the presence of parasitics and waveform nonlinearity. This paper extends the numerical state-space averaging to the fourth-order capacitor-based switching stages. The proposed model takes into account conduction losses associated with switching-stage components and is seamlessly functional in all operational modes. The proposed model is validated with a hardware prototype and detailed simulation and is shown to accurately predict large-signal time-domain transients as well as small-signal frequency-domain characteristics.