A Comparison of Solar-Cell and Battery-Type Power System for Spacecraft

The electrical power systems of orbiting unmanned spacecraft generally consist of energy-conversion devices in combination with energy-storage and conditioning components. The development of efficient pulse-duration modulation regulators suggests configurations smaller, lighter, and cheaper than conventional dissipative voltage regulators. These savings may or may not be realizable, depending upon the system reliability design goal and amount of redundancy required to meet the goal. Three spacecraft electrical power systems, each containing a solar-cell energy converter and using different voltage regulation schemes, are compared for a common mission specification. Each system is made to meet a given reliability goal by a technique that adds redundant components in a manner that minimizes a system design characteristic such as weight. The reliability design goal is kept constant as mission length is increased, permitting system comparison in terms of weight and cost as a function of time.     

一种应用于超小型无人机的定高系统设计方案

作者使用PC104计算机和美国ICSENSOR公司的压阻硅式绝压传感器,设计出适合超小型无人机使用的新型定高系统。这种定高系统具有灵敏度高、质量轻、耗电少、一体化板式结构、可靠性高、重复性好的特点,是一种全新的尝试。     

Portable computer power sources

The designers of any portable computer face a dilemma when choosing the power source for their product. The product can be either smaller and lighter than the competition-and possibly suffer from shorter run-time-or it may have superior run-time at the expense of added weight and volume. The balance between these options is a delicate one that impacts product acceptance and ultimately the manufacturer's revenue stream. Of course a high energy density power source represents only half of the run-time equation. The use of lower power hardware to achieve a given level of functionality can have an equally differentiating effect; and much work is currently underway to improve hardware power efficiency (Fadel, 1993). As levels of circuit integration increase emphasis upon power reduction is critical to achieve reliable operation at a reasonable temperature without some form of active cooling. These diametrically opposed design requirements, small size and light weight versus longer run-time, are set against the backdrop of a quickly changing electronics industry and a battery industry that is inherently slower to develop new products     

一种应用于超小型无人机的新型定高传感器

使用美国ICSENSOR公司的压阻硅式绝压传感器，对静压进行测量，并设计出适合超小型无人机使用的新型定高传感器，这种定高传感器具有灵敏度高，重量轻，单电源供电，板式结构。可靠性高，重复性好的特点，填补了应用于超小型无人机的定高传感器产品的空白。     

基于多电飞机的先进供电技术研究

阐述了多电飞机的特征,对多电飞机供电系统先进技术进行了研究,探讨了基于多电飞机的电气系统结构、电源系统、配电系统、负载自动管理技术等。     

Modern microwave power sources

The primary advantages of electron tubes over solid-state devices are that they are usually more efficient and will operate at higher temperature. Therefore, they can be smaller, tighter and still dissipate the waste heat that, unavoidably, goes along with the production of high output power. It is no accident that a one-megawatt cw microwave tube (1340 horsepower) is about the same size as a 1250 horsepower internal combustion engine. An assemblage of transistors or integrated circuits would be a much larger maze of circuit boards, power busses, cables, combiners, fuses, heat sinks, and, probably, water pipes. Unlike the situation that pertains for signal and data processing in which Moore's law applies, and complexity and performance increase while size and cost decrease in secular fashion, the transmitter built one hundred years from now will be no smaller and no lighter than the one you build today, unless the active elements are more efficient or run hotter than present-day microwave tubes. At ultra-high frequencies and above, solid-state technology has little hope of providing either advantage. The laws of thermodynamics are not man-made and cannot be broken. Many signals, including both analog and digital TV, digital communications, and EW, have high ratios of peak to average power. The poor efficiency of some microwave solid-state devices in class-A or class-AB operation when compared to that of class-AB gridded electron tubes and TWTs with multistage depressed collectors has interfered with their acceptance as amplifiers of such signals in both commercial and military service at UHF and higher frequencies. In this paper, new data on the new kinds of microwave tubes will be presented with emphasis on their suitability for application in economical, high-reliability, high-performance satellites, and communications, electronic warfare, and radar systems     

高效率模块化航空静止变流器的研制

基于通用化、系列化和模块化的研制思想,致力于研究提高航空静止变流器(ASI)的变换效率、减轻系统重量、提高可靠性和维护性等核心技术问题。从总体研制方案、核心技术和系列化基础模块3个层面出发,采用功率扩展性能好、变换效率高、可靠性高的推挽正激电路和双降压式逆变器研制了DC-DC变换模块、DC-AC变换模块等单元模块,组合成4种航空静止变流器基础模块。研制的系列化基础模块,整机变换效率均比国外同类产品提高4.5%以上,并且在体积、重量、可靠性和可维护性等方面均具有明显优势。     

Integration of Large Power Systems into Manned Space Stations

Essential design factors and system characteristics are explored for integration of large power systems into manned space stations. The impact of the type of power system selected upon the space station is outlined, as is the impact of the mission requirements upon the selection of power systems. Criteria for resolving the selection/application/ integration problems are provided. Comparisons between systems are based on recently defined space-station models for 90-day to five-year mission durations in the 1970' s, with four-to nine-man crews. Power systems encompass power levels from 3 to 50 kWe and include solar cell/battery. fuel cell, hybrid fuel cell/solar cell, radioisotope, and nuclear reactor systems. Thermoelectric, Brayton cycle, organic Rankine, and liquid-metal Rankine power conversion systems are considered for the nuclear energy sources. Both rigid and roll-out photovoltaic array configurations are analyzed with respect to the solar energy source.     

船舶混合动力系统与智能能量管理控制策略研究进展

开发新型动力系统和智能控制策略是解决节能减排的重要技术方向。本文首先对混合动力系统的配置和拓扑结构进行归类与比较，对控制策略中涉及的智能算法进行归纳和总结；其次，对新型动力船舶在动力系统和控制算法使用情况进行阐释；最后，从不同角度对混合动力系统以及能量管理系统的发展趋势进行展望，为绿色船舶混合动力系统开发以及能量管理系统的研发提供了参考依据。     

Energy and power

Energy sources for aerospace systems include electrochemicals, mechanical rotation, solar illumination, radioisotopes, and nuclear reactors. Energy is converted to power with engines, turbines, photovoltaics, thermoelectric and thermionic devices, and electrochemical processes. Although some early spacecraft flew with battery power, for longer flights the choice has been either solar or nuclear. Manned spacecraft must have power for the total mission duration including boost into orbit, on-orbit, and subsequent re-entry. Batteries are too heavy for extended manned space missions; tradeoff study alternatives range from radioisotope heated thermionic converters to hyperbolic-fueled engines. Arrays of solar cells are the obvious choice for powering space stations and for other extended-duration missions. This article emphasizes developments for space and airplane power systems. Enabling technologies are described along with significant spin-offs and future systems     

Radioisotope powered AMTEC systems

Alkali Metal Thermal to Electric Converter (AMTEC) systems are being developed for high performance spacecraft power systems, including small, General Purpose Heat Source (GPHS) powered systems. Several design concepts have been evaluated for the power range from 75 W to 1 kW. The specific power for these concepts has been found to be as high as 18-20 W/kg and 22 kW/m³. The projected area, including radiators, has been as low as 0.4 m²/kW. AMTEC power systems are extremely attractive, relative to other current and projected power systems, because AMTEC offers high power density, low projected area, and low volume. Two AMTEC cell design types have been identified. A single-tube cell is already under development and a multi-tube cell design, to provide additional power system gains, has undergone proof-of-principle testing. Solar powered AMTEC (SAMTEC) systems are also being developed, and numerous terrestrial applications have been identified for which the same basic AMTEC cells being developed for radioisotope systems are also suitable     

客机复合材料APU舱门结构设计及分析

按照结构布局、适航要求及APU门载荷水平,对复合材料APU舱门结构进行设计研究.为满足防火要求和闪电防护要求,选择先进碳纤维复合材料和泡沫芯材,设计了一种复合材料夹层结构.利用有限元模型对夹层结构在气动载荷和风载作用下进行应力和位移分析,得到应变云图和变形云图,分析说明该夹层结构设计满足设计要求.通过对B737飞机APU舱门结构研究和重量提取,进行重量等效对比分析,结果表明该复合材料夹层结构比金属结构重量轻25.8％,减重效果明显.     

The use of closed cycle coolers on space based observatories

Many proposed space based observations will rely on the use of closed cycle and passive cooling systems to provide the thermal environment for high sensitivity. The use of closed cycle mechanical coolers on space telescopes poses particular integration problems; some of these difficulties are discussed in this paper.One of the major problems envisaged is that of exported vibration. This problem, and that of the heat sinking required, can be alleviated by siting the compressors of the Stirling cycle precooler further from the displacer unit. The effect of the separation between the compressors and the displacer on the performance of the Stirling cycle precooler has been measured. Increasing the separation from 170 mm to 565 mm decreases the cooling power at 25 K from 220 mW to 180 mW. In most applications this would be acceptable.The pre-cooler provides cooling at a single point. In situations where refrigeration of extended objects (e.g. telescope mirrors) is required, some distribution method has to be found. A scheme for achieving this is presented together with preliminary calculations on such a system.Temperatures in the region of 2.5 to 4K are required to meet the requirements for long wavelength detectors. We have demonstrated how these temperatures can be achieved in a continuously operating closed cycle cooler that has been engineered for space applications. This cooler consists of a two-stage Stirling cycle precooling a closed cycle Joule-Thomson (JT) stage. Temperatures in the region of 4K are achieved by the use of helium-4 in the JT system. The lighter isotope of helium is used to obtain temperatures down to 2.5 K. Under no-load conditions the precooler reaches a base temperature of 11.3K. The JT system achieves 4.3 K with a 10 mW heat load and 2.5 K with a heat load of over 3 mW. The input power to the cooler is approximately 126 W.The temperature stability of the cooler at low temperatures is important to keep detector drift to a minimum. The temperature of the JT stage has been measured in uncontrolled laboratory conditions and found to vary by only 30 mK over a seventy hour period. The pre-cooler temperature varied by approximately 0.6 K during these measurements.     

First Mars outpost power systems

Research into potential power systems for the First Mars Outpost (FMO) was performed. The author examined a representative mission architecture which was developed by NASA to determine power system requirements. Power system options including nuclear, isotope, photovoltaic (PV), chemical heat engine, and regenerative fuel cell (RFC) concepts were identified for potential Mars surface applications. A top-level characterization study was conducted to determine power system mass and area for each application. It is seen that PV systems are generally not suited for Mars surface applications due to the large surface area required and higher mass than a closed Brayton cycle SP100 reactor system. A reactor is currently being considered by NASA Lewis Research Center to provide power for base architectures including an ISRU (in situ resource utilization). An oxygen/methane powered heat engine would provide 40 kWe of emergency power for the habitat. A dynamic isotope power system (DIPS) is the current choice for a long-duration pressurized rover due to the excessive size of a PV/RFC system and higher mass of a heat engine system. DIPS has advantages for other low power systems due to its neatly immediate availability and flexibility (night or day power; no recharging required)     

Fuel mass penalty due to generators and fuel cells as energy source of the all-electric aircraft

The paper presents the results of an assessment of the fuel mass penalty due to generators and fuel cell systems. Based on the simulation tool SysFuel, fuel mass penalties for different mission ranges and fuel cell architectures are calculated and compared to a conventional reference architecture. Different fuel cell architectures using ram air or cabin exhaust air and different options of energy recovery are considered. As a result of the studies, target values are presented for the mass to power ratio of fuel cell systems to achieve fuel mass reductions compared to conventional generator and auxiliary power unit systems.     

High efficiency dynamic radioisotope power systems for spaceexploration-a status report

Background on the space exploration program is discussed, and the currently identified NASA exploration missions are contrasted with the missions that were being planned a year ago. Developments in high-efficiency dynamic radioisotope power systems are discussed: and Brayton and Stirling power conversion cycles are compared for the missions planned for the next decade. Issues related to the use of high-efficiency radioisotope (HER) power systems are identified. It is noted that HER power systems are approximately three times as efficient as current radioisotope thermoelectric generators(RTGs) and are therefore significantly cheaper. Additionally, the world's supply of ²³⁸Pu is extremely limited. Currently discussed missions would cut deeply into this supply if powered by RTGs     

大功率离子推力器和流动控制单元验证现状 及其2000小时寿命试验

为了发展基于电推进的大功率空间运输系统,需要开发和验证功率达数十千瓦的电推进系统,深空任务电推进系统优化的比冲要求高达10⁵s。凯尔迪什研究中心（KeRC）正在开发这样的电推进部件。本文概述了 35kW离子推力器 IT-500及其流动单元FCU-500的验证现状。作为其验证的一部分,完成了IT-500 和 FCU-500的2000h寿命试验。其中,离子推力器大部分验证条件是：输入功率17.8kW,使用了40kg氙,2018h寿命试验。本文介绍了磁场和离子光学以及石墨格栅开发现状。     

Power Conditioning Systems for High-Power, Airborne, Pulsed Applications

The power conditioning portion of the high-power study that was performed for the Air Force Aeropropulsion Laboratory by the State University of New York at Buffalo is summarized. This effort defines the power conditioning system and critical component developments which will be required to interface the airborne 10-MW to 50-MW sources defined under separate study efforts with certain loads. Power conditioning systems are considered for use with magnetohydrodynamic generators and turbine driven alternators, both conventional and superconducting. The critical components required for each of the power conditioning systems are identified and then analyzed. The component analyses include estimations of development efforts necessary and of specific weights and volumes for components. The primary components considered are transformers (for alternator as well as for inverter use), switches, capacitors, and inductors. Weight algorithms are developed for each of the components. Following the component analyses, subsystems such as inverters and rectifier and filter packages are considered. The data for the various components and subsystems are then utilized for a comparison of the power conditioning techniques to be used with the various power sources. The weights and volumes of power conditioning systems for 8-point designs (8 variations of power, voltage, duty cycle, and total run time) are derived.     

Performance enhancement using power beaming for electric propulsionEarth orbital transporters

Power requirements for an electric propulsion Earth orbital transport vehicle (EOTV), which can effectively deliver large payloads using much less propellant than chemical transfer methods, are addressed. The power beaming concept is described. Arcjets, magnetoplasmadynamic (MPD) thrusters, and ion engines are covered. Power supply characteristics are discussed for nuclear, solar and power-beaming systems. Operational characteristics are given for each, as are the effects of the power supply alternative on the overall craft performance. Because of its modular nature, the power beaming can meet the power requirements of all three electric propulsion types. Commonality of approach allows different electric propulsion approaches to be powered by means of a single power supply approach. Power beaming exhibits better flexibility and performance than onboard nuclear or solar power systems     

同步发电机整流系统带恒功率负载的稳定性分析

 在现代飞行器电源系统负载中,功率变换器和电动机驱动装置大量增加,所表现出的负阻抗特性对系统稳定性产生十分重要的影响。采用状态空间平均法对同步发电机整流系统带恒功率负载(CPL)的稳定性进行了分析研究。建立了同步发电机整流系统同时带阻性负载和恒功率负载时的小信号数学模型,通过讨论负载参数对系统稳定性的影响,得到系统带恒功率负载时的极限值和稳定工作区域,所设计的串联校正环节在一定程度上改善系统响应快速性的同时,使系统的相角裕度增加了53°,有效地提高了系统的稳定性。