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## Über dieses Buch

As a stand-alone volume, Transistor Circuits For Spacecraft Power System presents numerous transistor circuits and building blocks associated with power electronics in general, and examines the major subsystem components for solar-based spacecraft power systems. The technique and concept, of "continuity of states" for nonlinear circuits handling power transfer under cyclic excitation is introduced in Part I and further developed throughout the book. This powerful technique employing matrix formulation bypasses eigen-transients and yields steady-state responses rapidly. Closed-loop treatments are also given for large-scale linear circuits, many closed-form solutions for control loop-gain, conducted susceptibility, output impedance, etc. are covered. Extensive mathematical procedures are retained to highlight the importance of analytical flows.

The author also reviews the evolution of solar-based spacecraft power systems; introduces modes of operations: discharge (boost), shunt, and charge; and covers pulse-width-modulated (PWM) boost power converter for both DC and AC conditions. A configuration tree for shunt mode operation is conceived. Based on the configuration tree, the best topologies, sequential PWM shunt and ripple-regulated free-running shunt, are intensively examined and formulated.

Transistor Circuits For Spacecraft Power System provides important information for understanding the relationship between earthbound semiconductor circuits and space borne vehicles.

## Inhaltsverzeichnis

### Chapter 1. Junction Diode Circuits

Abstract
Most of us, since high school days, encounter quite often one of the most fundamental functions in science: the exponential function ex. This function can be placed in a more general form aebx. In this general form, the function then exhibits more interesting and useful properties that are hidden from its basic form. As shown in the general form, there are two scale factors, parameters a and b, and one variable, x. By also considering the parameter sign and magnitude, many nonlinear curves can be obtained. For instance 5e2x gives Fig. 1-1a, -5e2x produces Fig. 1-1b, 5e-2x generates Fig. 1-1c, 2e5x yields Fig. 1-1d, 2e-x/5 creates Fig. 1-1e, and so on. Evidently, by changing either a or b, or both, varieties of curves reflecting various functional dependency can be generated. The above exercise, in addition to presenting the spatial beauty of mathematical forms, also reveals several important views of parameter operations. Obviously, parameter “a” serves as a scale factor for functional magnitude and sign while parameter “b” compresses or expands the independent variable. In other words, “a” plays the role of amplification, or shrinking, and polarity indicator, while “b” either accelerate, or decelerate, the rate of “x”.
Keng C. Wu

### Chapter 2. Discrete Transistor Circuits

Abstract
Thousands of books have been written covering the basics of transistors and their applications since their invention in 1948. The need for one more book dealing with the same topics is therefore not justified. With this in mind, this chapter attempts to provide coverage of techniques that are less conventional. In what follows, we shall first sort out transistor parameters that are more or less beyond the device designers and the circuit engineers. We then try to identify those that are to a very large extent controllable by the device engineers. This step surely leaves us, the circuit designers, with some constraints that should be considered.
Keng C. Wu

### Chapter 3. Operational Amplifiers

Abstract
Section 2.6 and 2.8 of chapter two briefly discussed the core building block, and an early version, of a linear operational amplifier. A discussion of this nature is geared more toward integrated circuit designers. As application designers and engineers, our attentions focus more on the external terminal behavior of the block than the internal working of the device. We therefore direct our main theme of the current chapter to many key concepts regarding the former.
Keng C. Wu

### Chapter 4. Transistors and Operational Amplifiers Combined---Medium Scale Circuits

Abstract
With every single passing day, the complexity of electronic circuits is inching higher. This fact certainly holds for both the analog and digital circuits; though the latter may advance at a steeper slope. But advancement in complexity for both shares a common trait: they are all built by integrating ever more basic, small scale blocks. In the case of integrated operational amplifiers, they all contain without exception differential amplifiers, current sources, level shifters, protection circuits, output drivers, and so on. Eventually, the operational amplifiers are itself considered basic blocks and used extensively in building newer, and more sophisticated high level circuits. For instance, in the recent past, the application specific integrated circuits (ASICs) are speeding ahead in creating new market and demand. Not only are signal sensing and processing circuits included in the ASICs, the decision making blocks are also included. The latter even recruits digital circuits. Therefore mixed mode ICs are born. The trend in effect underscores the importance of building a solid base of medium scale analog circuits on which consolidated, or miniaturized, large-scale systems can be further implemented.
Keng C. Wu

### Chapter 5. Introduction of Spacecraft Power System

Abstract
Depending on the distance, and trajectory, a spacecraft travels from the earth, satellites are generally placed in two groups: 1) near-earth/sun and 2) deep space. Meteorological spacecraft and geosynchronous communication satellites in operation circling the earth either in polar orbit or in equator with 300 miles to 23,000 miles apogee are considered near earth. However, from the viewpoint of solar insolation, space vehicles in the vicinity of Venus, Mercury, Mars also belong to the first group. By this standard, space probes which move through the outer reach, e.g. Jupiter, Saturn, of the solar system fall into the second group.
Keng C. Wu

### Chapter 6. Boost Converter — Battery Discharger

Abstract
In Fig. 6-1, a simple, non-isolated DC-DC boost converter is shown. The converter employs peak current, current-mode control in regulating the main switch’s on/off duty cycle, which in turn regulates the output voltage V0.
Keng C. Wu

### Chapter 7. Solar Array Shunt Regulators

Abstract
Shunt regulation can be implemented in many ways. Because of these numerous possibilities, evaluating and ranking their performance superiority is not an easy task. In order not to be bogged down by the inability of assigning a pecking order, we instead attempt to present all known configurations without any preference, implied or otherwise. This approach leads us immediately to the proposed shunt configuration tree given by Fig.7-1.
Keng C. Wu

### Chapter 8. Linear Shunt

Abstract
While chapter 5 justifies the need of a shunt stage, chapter 7 briefly examines the basic capability various shunt architectures posses. It is therefore logical starting with this chapter on linear shunt to give a complete treatment for the subject matter. We will first establish the steady state for the shunt power stage. Then, if applicable, small-signal considerations follow. Studies of circuit behaviors under closed loop condition may also be included.
Keng C. Wu

### Chapter 9. Sequential Pulse Width Modulated Shunts

Abstract
In the previous chapter, a major concern was raised regarding the power dissipation of linear shunt dissipation elements; shunt transistors and resistors. Basically, it is the thermal environment those elements generate that is the main concern. It was also mentioned in section 7.3 that by taking the advantage of the short circuit operating point of solar cell characteristics, power dissipation and thermal issues are mitigated.
Keng C. Wu

### Chapter 10. Free Running Switching Shunt --- Ripple Regulator

Abstract
The sequential PWM shunt scheme as presented in the previous chapter requires multiple triangle wave oscillators. In theory, one oscillator is sufficient to support the system. But reliability considerations dictate the choice of configurations with multiple oscillators.
Keng C. Wu

### Chapter 11. Switching-mode Battery Charger

Abstract
It was mentioned in section 4.5 that the switching-mode charger will be treated in a standing alone chapter. The reason of doing so was also given. Without wasteful verbiage, we shall treat first a boost charger, then a charger in buck mode. For both chargers, some circuit blocks are given detailed analytical expressions and their derivations, considering their respective degree of importance. Others are omitted, or given only their end results, if doing so will not create misunderstanding or ambiguity. By covering most mathematical basis first, then steady state closed-loop formulation follows. The goal of the second step obviously is aiming at providing insight for steady-state charge (current) regulation. The performance merit in this regard basically resides in the quantitative study of charge current sensitivities against control loop parameters including active device characteristic and passive part values. Time domain study concludes the chapter.
Keng C. Wu

### Backmatter

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