Computer Simulations of Optimum Boost and Buck-Boost Converters

The development of mathematical models suitable for minimum weight boost and buck-boost converter designs are presented. The facility of an augumented Lagrangian (ALAG) multiplier-based nonlinear programming technique is demonstrated for minimum weight design optimizations of boost and buck-boost power converters. ALAG-based computer simulation results for those two minimum weight designs are discussed. Certain important features of ALAG are presented in the framework of a comprehensive design example for boost and buck-boost power converter design optimization. The study provides refreshing design insight of power converters and presents such information as weight and loss profiles of various semiconductor components and magnetics as a function of the switching frequency.     

Unified approach to developing single-stage power converters

A unified approach to developing single-stage power converters which can fulfil multiple functions is presented. Four synchronous switches corresponding to the four common node types of two active switches are introduced. The approach is then to replace the active switches in multistage converters (in cascade or cascode connection) with one or several of the synchronous switches and their degenerated versions to form a single-stage converter. Illustrations of using these switches to develop single-stage converters are presented. These are started with the development of the well-known single-stage switch-mode converters (SMCs), buck-boost, Cuk, sepic, and Zeta (also named dual sepic), from the basic converters, buck and boost. Then, synthesis and applications of other single-stage converters are addressed. Due to increased component stresses, the developed single-stage converters are primarily suitable for applications with moderate power levels     

Resonant power supplies: their history and status

The various types of converter are described, and the history of resonant power supplies is briefly sketched. The differences between pulse-width-modulated (PWM) switch mode power supplies and resonant power supplies are discussed. Single-switch, multiple-switch, and series and parallel resonant converters are examined. The control of resonant converters is addressed. Hardware is briefly considered     

Aircraft Power System Harmonics Involving Single-Phase PFC Converters

AC-DC converters with active power factor correction (PFC) are replacing uncontrolled diode rectification circuits on commercial jet airplanes in order to meet harmonic distortion limits imposed by new airborne electrical system power quality standards. The high line frequency of airborne AC power systems presents a major challenge for the design of PFC converters capable of meeting these standards. This paper investigates a new source of harmonic current distortion and the resulting system power quality problems related to dynamic interactions between PFC converters and the AC source. Experimental results are first presented to demonstrate the existence of such interactions and their effects on system power quality. Analytical and numerical simulation results are then presented to explain why such dynamic interactions can lead to significantly increased harmonic current distortion in steady state operation. Elimination of undesirable system interactions through proper damping of the PFC converter input filter is also presented and its effectiveness experimentally validated.     

Optimal topologies of resonant DC/DC converters

Generalized and optimal topologies of zero-voltage-switching and zero-current-switching resonant DC/DC power converters are presented. It is shown that many equivalent topologies of the converters can be derived from each of the generalized topologies. The generalized topologies of the converters show clearly which of the parasitic capacitances and inductances can be absorbed into the LC resonant circuit. Utilizing this fact, optimal topologies that are the most suitable for high-frequency operation are derived. In the optimal topologies, the greatest possible number of parasitic reactances is included harmlessly in the resonant circuit. Optimum layout and component selection guidelines for the converters are given. High-order resonant converters are also developed     

CIECA: Application to Current Programmed Switching Dc-Dc Converters

Sundstrand Advanced Technology Corporation The current injection equivalent circuit approach (CIECA) to modeling switching converter power stages is extended to model the current programmed converter power stages operating in fixed frequency, continuous inductor conduction mode. To demonstrate the method, modeling is carried out for the buck, boost, and buckboost converters to obtain small-signal linear equivalent circuit models which represent both input and output properties. The results of these analyses are presented in the form of linear equivalent circuit models as well as transfer functions. Though current programmed converters exhibit single-pole response, the addition of artificial ramp changes converters to exhibit well damped two-pole response. This has been investigated for the first time using CIECA. The results of these analyses are presented in the form of linear equivalent circuit models as well as transfer functions.     

应用电流控制脉宽调制技术的功率变换器

介绍和分析了 A.G.Bose等提出的 PWM控制技术——电流控制脉宽调制技术 ,以及它在功率变换器中的应用 ,分析了电流控制脉宽调制系统的稳定性问题。实验表明 ,这种功率变换器具有重量轻、体积小、静态精度高、动态响应快等优点 ,有十分重要的应用价值。     

Single-stage ZVS PWM full-bridge converter

A new soft-switched ac-dc single-stage pulse width modulation (PWM) full-bridge converter is proposed. The converter operates with zero-voltage switching (ZVS), fixed switching frequency, and with a continuous input current that is sinusoidal and in phase with the input voltage. This is in contrast with other ac-dc single-stage PWM full-bridge converters that are either resonant converters operating with variable switching frequency control and high conduction losses, converters whose switches cannot operate with ZVS, or converters that cannot perform power factor correction (PFC) unless the input current is discontinuous. All converter switches operate with soft-switching due to a simple auxiliary circuit that is used for only a small fraction of the switching cycle. The operation of the converter is explained and analyzed, guidelines for the design of the converter are given, and its feasibility is shown with results obtained from an experimental prototype.     

Design and technology of compact high-power converters

New material technologies such as Silicon Carbide (SiC) are promising in the development of compact high-power converters for next-generation power electronics applications. This paper presents an optimized converter design approach that takes into consideration non-linear interactions among various converter components, source and load. It is shown that with the development of high-temperature, high-power SiC power module technology, magnetic components and capacitors become important technology challenges, and cannot be ignored. A 50% improvement in power density is calculated for a 100 V-2 kV, 7 kW SiC DC-DC power converter operating at 150°C compared to a silicon power converter. The SiC power converter can be operated at junction temperatures in excess of 300°C (as compared to 150°C for a silicon power converter) with reasonable efficiency that potentially leads to a significant reduction in thermal management     

分布式电推进飞机电力系统研究综述

继飞机二次能源逐步统一为电能形成多电/全电飞机之后,电推进技术成为飞机动力系统电气化的重要发展方向,有望进一步提高飞机动力系统能量转换效率、降低燃油消耗和排放,代表了航空电气化的高级阶段。飞机电力系统及相关技术是支撑电推进技术发展的重要基础。系统总结了电推进飞机的类型与发展现状,论述了飞机混合动力系统及分布式电推进系统的基本概念、特点与意义。阐述了航空电推进系统的基本结构,比较了适用于分布式电推进系统的电力系统架构,系统分析了实现电推进技术所需的高效高功率密度电机、高效大容量功率变换器和综合热管理等关键技术。小型纯电动飞机正在逐步迈向实用化,而分布式混合电推进技术是中大型飞机电气化的重要方向,仍然需要航空机电和动力系统等交叉融合与创新发展。     

Table-Aided Design of the Energy-Storage Reactor in DC-to-DC Converters

A new procedure for the selection of magnetic cores for use in energy-storage dc-to-dc power converters that eliminates the need for an automated computer search algorithm and stored data file is presented. The converter configurations included in the procedure are the three commonly encountered single-winding converters for voltage stepup, for current stepup and voltage stepup/current stepup, and for the two-winding converter for voltage stepup/current stepup. For each converter configuration, three types of controllers are considered: constant-frequency, constant on-time, and constant off-time. Using concepts developed from analyses of these converters by considering the transfer of energy by means of an energystorage inductor or transformer, a special table of parameters calculated from magnetic core data is constructed, which leads to a considerably simplified design procedure.     

并联交错式有源箝位正激变换器研究

深入分析研究了并联交错式有源箝位正激变换器的原理与设计 ,获得了功率开关实现零电压 ZVS开通的条件和关键电路参数选取准则 ,仿真与试验结果均证实了理论分析的正确性。研究结果表明 ,并联交错式有源箝位正激变换器具有优良的电气性能 ,特别适用于大功率分布式电源系统     

Mathematical Modeling of a VSCF Aircraft Generating System

DC-link converters having a variable input frequency but a constant output frequency now provide a viable alternative to the constant-speed mechanical drive as a means of providing a constant frequency power supply from an aircraft generator. The ease of replacement and repair, the reduction in servicing needs, and the ability to locate the components of the electrical system throughout the aircraft all combine to bring about a considerable reduction in the maintenance time which is required. A computationally efficient technique for the mathematical modeling of a typical electrical system, in which the overall power network is torn initially into a set of convenient subnetworks, is described. Connection matrices are employed to combine the equations computed for the various subnetworks with the equations for the overall network. Typical results are presented for the overall system. The performance detail enables many important design considerations to be investigated prior to manufacture.     

A State-Trajectory Control Law for DC-to-DC Converters

Mathematical representations of a state-plane switching boundary employed in a state-trajectory control law for dc-to-dc converters are derived. Several levels of approximation to the switching boundary equations are presented, together with an evaluation of the effects of nonideal operating characteristics of converter power stage components on the shape and location of the boundary and the behavior of a system controlled by it. Digital computer simulations ions of d-to-dc converters operating in conjunction with each of these levels of control are presented and evaluated with respect to changes in transient and steady-state performance.     

Series of radiation-hardened, high efficiency converters for high voltage bus

A review of common switching techniques for dc/dc power conversion is presented. The evolution of the forward converter is discussed, leading naturally to the introduction of the double forward converter. Technical details for a series of radiation-hardened converters are then provided. This series was designed for space power management and distribution (PMAD) applications. The successful development of the PMAD converter demonstrated the viability of high voltage bus.     

Megahertz power converters for specific power systems

Some of the problems in the development of pulsewidth power converters when the switching frequency is increased from hundreds of kilohertz to tens of megahertz are highlighted. The major goal is the establishment of a ten megahertz power chain designed to operate in a distributed system from a DC power bus of 24 to 48 V. Available components and materials are discussed, and possible topologies-flyback, forward, push-pull forward, and buck converters-are examined. The performance criteria chosen for this analysis are, in the order of preference, output requirements, size and weight, efficiency, and cost     

Robust model following control of parallel buck converters

A robust model-following (RMF) control technique for average current mode controlled (ACC) parallel buck dc-dc converters, RMFACC, is presented. RMFACC achieves that the loop gain of the voltage loop is little sensitive to the variation of power stage parameters: number of modules, input voltage, load, and component tolerances. The design of the voltage loop is 'decoupled' from the design of the disturbance rejection transfer functions in an important degree, so that the output impedance and audio susceptibility are greatly reduced without the need of high loop gain crossover frequencies. A comparative study between conventional ACC and RMFACC is shown.     

A new high rate lead acid battery

A new approach to the design of lead acid batteries has been developed based on the use of very thin lead foil current collectors. The basic cell construction and the performance characteristics for the new cell are described. Spiral wrap cells based on this electrode concept exhibit extremely high power output with excellent capacity maintenance. Additionally, these cells exhibit very flat voltage at all currents, and are capable of very rapid recharge. Applications for this high power technology cover a broad spectrum such as portable power tools, UPS systems, electrically heated catalytic converters, military pulse power applications and electric and hybrid vehicles     

AMTEC cells challenge energy converters

Sodium-base alkali-metal-thermal-to-electric conversion (AMTEC) cells have been receiving attention. Recently they were selected for the next generation deep-space missions, which need a converter that makes electricity from radioisotope heat. The AMTEC cell, being an electrochemical converter of heat to electricity, has no moving parts and is not limited to Carnot-cycle efficiency. However, its heat source and sink have to be near each other, so the challenge in AMTEC design is to minimize thermal losses and maximize electricity production. This required clever thermal designs. By 1991, high-temperature materials and computer modeling became available. The important AMTEC application was generating power from radioisotope heat in deep space missions. These spacecraft power needs had previously been supplied by inefficient thermoelectric converters     

Analysis of a parallel resonant converter with secondary-sideresonance

A high-frequency (HF) link parallel resonant DC/DC converter operating in the lagging power factor mode with the resonating capacitor on the secondary side of the HF transformer is analyzed using a state-space approach. Closed-form solutions (except for the duration of diode conduction) are obtained for steady-state conditions, and design curves are obtained. A method of obtaining optimum operating point under certain constraints is developed and is used as the basis of a simple design procedure. A theoretical study comparing the performance of three MOSFET-based 1-kW converters with different transformer turn ratios under load changes from rated-load to 10% load is carried out. Experimental results obtained with these converters with different transformer turn ratios are also presented