TRANSISTOR CIRCUITS FOR SPACECRAFT POWER SYSTEM

Transcription

1 TRANSISTOR CIRCUITS FOR SPACECRAFT POWER SYSTEM

2 Transistor Circuits for Spacecraft Power System KengC. Wu Lockheed Martin Naval Electronics & Surveillance Systems Moorestown, NJ, USA.., ~ SPRINGER SCIENCE+BUSINESS MEDIA. LLC

3 Library of Congress Cataloging-in-Publication Data ISBN ISBN (ebook) DOI / Transistor Circuits for Spacecraft Power System KengC. Wu Springer Science+Business Media New York OriginaUy published by Kluwer Academic Publishers in 2003 Softcover reprint of the hardcover lst edition 2003 AII rights reserved. No part ofthis work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher, with the exception of any material supplied specificaliy for the purpose ofbeing entered and executed on a computer system, for exclusive use by the purchaser ofthe work. Permission for books published in Europe: permissions@wkap.nl Permissions for books published in the United States of America: permissions@wkap.com Printed on acid-free paper.

4 To My Mother, Hsue-yew (Snowy Moon) Tai. SHE instills in me the courage for facing life's torrents and challenges.

5 Table of Contents Preface I Part I 1 Junction Diode Circuits 1.1 Exponential Form Characteristics of p-n Junction Diode Resistor Diode Circuit Diode and RC Filter Diode and RL Load Single Phase Full-wave Rectifier and RL Load Three Phase Rectifier and RL Load 20 2 Discrete Transistor Circuits 2.1 Transistor Parameters Large Signal Amplifier- Class A, AB, and B Nonlinear Distortion Push-Pull Amplifier Current source Differential Amplifier Differential Amplifier with Current Output A Rudimentary Linear Integrated Circuit Inductive Load Switching Snubber Circuit Zero-voltage and Zero-current Switching 57 3 Operational Amplifiers 3.1 Open-loop Gain Limitation of Open-loop Gain Closed-loop Gain and Virtual Ground Type I Amplifier Type 2 Amplifier Type 3 Amplifier Current Mode Operation Voltage to Current Converter Precision Current Source Voltage Comparator Voltage Integrator RC Square Wave Generator RL Oscillator and DC Current Measurement Periodic, Large Signal Time-domain Studies 92

6 4 Transistors and Operational Amplifiers Combined- Medium Scale Circuit 4.1 Series Voltage Regulator with Bipolar Transistors Series Voltage Regulator with MOSFET Series Regulator in Other Configurations Linear Battery Charger Switching Battery Charger Switching DC-DC Power Converter Voltage-to-Frequency and Frequency-to-Voltage Converters 122 II Part II 5 Introduction of Spacecraft Power System 5.1 Overview Basic Architecture Management of Operation Mode Close Loop System System Dynamics Boost Converter - Battery Discharger 6.1 Mechanism of Operation Boundary Condition Sizing Inductor Output Ripple and Output Capacitor Sizing Parasitic Consideration Current Feedback Close Loop Output DC Regulation Control Loop Stability and Loop Gain Solar Array Shunt Regulators 7.1 Introduction Linear Shunts Nonlinear Shunt Linear Shunt 8.1 A Typical Linear Shunt Stage, DC Linear Shunt, AC Studies Sequential Linear Shunt Mode Control and Shunt Control Amplifier Sequential Linear Shunt in Close Loop, DC Linear Shunt in Close Loop - AC Studies Sequential Pulse Width Modulated Shunts 9.1 Pulse Width Modulation (PWM) The Sequencer 186

7 Steady State Free Running Switching Shunt --- Ripple Regulator 10.1 Introduction 10.2 Threshold Detection 10.3 Digital Sequencer loa Threshold Detector and Shift Register Gain 10.5 Loop Gain 10.6 Loop Stability Switching-mode Battery Charger 11.1 Operation of Boost (Step-up) Charger 11.2 Boost Charger at Steady State 11.3 Gate Drive 11.4 Lossless Snubber 11.5 Operation of Buck (Step-down) Charger 11.6 Buck Charger in Steady State Reference Appendix Index

8 Preface In the past two decades, the capability of space vehicles circling the globe has increased substantially with only reasonable increase in size and weight. This fact is made possible by the invention of transistors in 1948 and the subsequent miniaturization of large-scale circuits in 1960s. Without doubt, transistor circuits in various forms, be it discrete or integrated, play numerous irreplaceable roles in space-borne vehicles. Electrical systems in spacecraft can generally be partitioned by functions into four categories: command/control, communication, instrumentation, and power. This book aims to illuminate the last category, power system; which is omnipresent, but in the background and less visible. However, as a starting point, a clear distinction must be made between spacecraft's power electronics and power systems. Power electronics is a more general term. It encompasses both the generator (sources) and the load (users). Belonging to the source end, power systems concern power generation and regulation. In contrast, the load end focuses on power conversion. By this functional partition, power systems cover topics such as solar cells and array, fuel cells, thermal nuclear reactors, source characteristics, and their output management as a bus. Whereas power conversions on the user end concentrate instead on topics such as converters including DC-to-DC and DCto-AC; electromechanical apparatus including step motor drive (solar panel deployment and rotation), DC motor drive (momentum wheel control), and induction motor control (cooling system); peak power tracker; and so on. Given the vast subjects enunciated above and considering the author's limited exposures, a self-imposed boundary must be set. This current writing therefore covers only the source's electrical output management, solar array in particular, as a regulated bus for spacecraft consumption. Solar cell array and array characteristics that were well studied and reported [6] are not touched upon. Various batteries and their properties are also excluded from this writing since the author's lack of expertise in that field. As far as power conversions for end user are concerned, the author's other publication [5] and its soon-to-come second edition as a standing alone volume is a better source of reference. Moreover, electromechanical power conversions are better relegated to separate books, since those topics are both vast in breadth and enormous in depth; even though the author does have substantial knowledge in DC and AC motor control. By the same token, the author decides that countless issues such as material properties and component packaging be treated by other experts, because he does not have the appropriate background.

9 This book is divided into two parts. Part one, containing four chapters, presents transistor circuits in either discrete or integrated forms for applications pertaining to space vehicle power electronics. Chapter 1, Junction Diode Circuits, presents applications for diodes as power rectifiers. The powerful concept of continuity of states for circuits driven by periodic sources is introduced. Chapter 2, Discrete Transistor Circuits, reviews transistor amplifiers, differential amplifiers, and current sources. In-depth analytical treatments are given. Chapter 3, Integrated Operational Amplifiers, examines applications of operational amplifiers in integrated circuits (IC) forms. A more accurate approach in establishing closed-loop gain functions is introduced. Currentmode operation, precision current source, voltage comparators, oscillators, voltage-to-current converter, and so on are treated with mathematical rigors. Chapter 4, Transistors and Operational Amplifiers Combined, treats mediumscale combination of transistors and operational amplifiers, for instance linear (series) voltage regulator, voltage-to-frequency and frequency-to-voltage converters, and linear battery charger. Dealing with near-earth, solar-based satellites, part two constitutes the core of this book and consists of seven chapters. Chapter 5, Introduction to Space Power System, briefly introduces the evolution of spacecraft power system and issues involved in such a system. Chapter 6, Boost Converters - Battery Discharger, gives an extensive coverage for pulse-width-modulated (PWM) DC-to-DC power converters in boost configuration. Analytical equations extremely important for designers in component selections, in DC regulation, and in control loop stability are given in closed-form. Chapter 7, Solar Array Shunt Regulators, deals with the general view of current-shunt regulators for solar array. A configuration tree is presented. Chapter 8, Linear Shunts, covers as the chapter title indicates the linear shunt regulator. Both DC and AC studies for simple linear shunts and sequential linear shunts are given. Chapter 9, Sequential Pulse Width Modulated Shunts, examines PWM shunts; which dissipate less power than do linear shunts because they operate in nonlinear switch-mode. Chapter 10, Free-running Switching Shunts, shows how both analog and digital circuits can be used in a very innovative configuration in which systematic ripple serves as clock and its amplitude is in turn regulated. A patented concept giving adjustable control loop gain and consequently improved stability is also revealed. Chapter 11, Switching-mode Battery Charger, presents nonlinear PWM switching charger.

10 The book is intended for professional engineers and senior college students, who have already been exposed to the complexity of mid-level electronic networks and circuits and are searching for avenues to expand their expertise. Finally, a special thanks is due Lou Diana (Lockheed Martin, Communications and Power Center, Newtown, PA) for his extensive editing of the manuscript.