Switchmode Power Supply Handbook
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Switchmode Power Supply Handbook

Switchmode Power Supply Handbook by Keith Billings and Taylor Morey | PDF Free Download.

Authors of Switchmode Power Supply Handbook

KEITH BILLINGS, President of DKB Power Inc. and engineering design consultant, has over 46 years of experience in switch-mode power supply design. He is a Chartered Electronics Engineer and a full member of former Great Britain’s Institution of Electrical Engineers (now the Institution of Engineering and Technology).

TAYLOR MOREY is a Professor of Electronics Engineering Technology at Conestoga College Institute of Technology and Advanced Learning in Kitchener, Ontario, and a design consultant with over 30 years of experience in power supplies.

Switchmode Power Supply Contents

  • Common Requirements: An Overview
  • Ac Powerline Surge Protection
  • Electromagnetic Interference (Emi) In Switchmode Power Supplies
  • Faraday Screens
  • Fuse Selection
  • Line Rectification And Capacitor Input Filters For “Direct-Off-Line” Switchmode Power Supplies 
  • Inrush Control
  • Soft Start And Low-Voltage Inhibit
  • Turn-On Voltage Overshoot Prevention
  • Overvoltage Protection
  • Undervoltage Protection
  • Overload Protection
  • Foldback (Reentrant) Output Current Limiting
  • Base Drive Requirements For High-Voltage Bipolar Transistors
  • Proportional Drive Circuits For Bipolar Transistors
  • Antisaturationtechniques For High-Voltagetransistors 
  • Cross Conduction
  • Output Filters
  • Power Failure Warning Circuits
  • Centering (Adjustment To Center) Of Auxiliary Output Voltages On Multiple-Output Converters
  • Auxiliary Supply Systems
  • Parallel Operation Of Voltage-Stabilized Power Supplies
  • Multiple-Output Flyback Switchmode Power Supplies
  • Flyback Transformer Design
  • Reducingtransistor Switching Stress
  • Selecting Power Components For Flyback Converters
  • The Diagonal Half-Bridge Flyback Converter
  • Self-Oscillating Direct-Off-Line Flyback Converters
  • Applying Current-Mode Control To Flyback Converters
  • Direct-Off-Line Single-Ended Forward Converters
  • Transformer Design For Forwarding Converters
  • Diagonal Half-Bridge Forward Converters
  • Transformer Design For Diagonal Half-Bridge Forward Converters 
  • Half-Bridge Push-Pull Duty-Ratio-Controlled Converters 
  • Bridge Converters
  • Low-Power Self-Oscillating Auxiliary Converters
  • Single-Transformertwo-Transistor Self-Oscillating Converters
  • Two-Transformer Self-Oscillating Converters 
  • The Dc-To-Dctransformer Concept 
  • Multiple-Output Compound Regulating Systems
  • Duty-Ratio-Controlled Push-Pull Converters
  • Dc-To-Dc Switching Regulators
  • High-Frequency Saturable Reactor Power Regulator (Magnetic Duty Ratio Control)
  • Constant-Current Power Supplies 
  • Variable Linear Power Supplies
  • Switchmode Variable Power Supplies
  • Switchmode Variable Power Supply Transformer Design
  • Inductors And Chokes In Switchmode Supplies

Preface to Switchmode Power Supply Handbook

When Keith Billings wrote the first edition of Switchmode Power Supply Handbook over twenty years ago, he was aware that many engineers had expressed the desire for a general handbook on the subject.

He responded to this need with a practical, easy-to-read explanation of many of the techniques in common use, together with some of the latest developments.

The author has drawn upon his own experience of the questions most often asked by students and junior engineers to address the subject in the most straightforward way, giving explicit design examples that do not assume any previous knowledge of the subject.

In particular, the design of the wound components is covered very fully, since these are critical to the final performance but tend to be rather poorly understood.

In the third edition, Keith continues the easily assimilated, nonacademic treatment, using the simplified theory and mathematical analysis that was so well received in the previous editions, waiving the fully rigorous approach in the interests of simplicity.

As a result, this latest edition should once again appeal to students, junior engineers, and interested nonspecialist users, as well as practicing professional power supply engineers.

The new edition covers the subject from simple system explanations (with typical specifications and performance parameters) to the final component, thermal, and circuit design and evaluation, and now includes new material related to resonant and quasi-resonant systems and highly efficient, high power, phase shift-modulated switching converters.

As before, to simplify the design approach, considerable use has been made of nomograms, many of which have been developed by the author, originally for his own use.

Some of the more academic supporting theory is covered in chapter appendixes, and those who wish to go further should read these and the many excellent specialized books and papers mentioned in the references.

Since the seventies, switchmode power supply design has developed from a somewhat neglected “black art” to precise engineering science.

The rapid advances in electronic component miniaturization and space exploration have led to an ever-increasing need for small, efficient, powder processing equipment.

In recent years this need has caught and focused the attention of some of the world’s most competent electronic engineers. As a result of intensive research and development, there have been many new innovations with a bewildering array of topologies.

As yet, there is no single “ideal” system that meets all needs. Each topology lays claim to various advantages and limitations, and the power supply designer’s skill and experience is still needed to match the specification requirements to the most suitable topology to define the preferred technique for a particular application.

The modern switchmode power supply will often be a small part of a more complex processing system.

Hence, as well as supplying the necessary voltages and currents for the user’s equipment, it will often provide many other ancillary functions, for example, power good signals (showing when all outputs are within their specified limits),

power failure warning signals (giving advanced warning of line failure), and overtemperature protection, which will shut the system down before damage can occur. Further, it may respond to an external signal demand for power on or power off.

The power limit and current limit circuitry will protect the supply and load from fault conditions. Overvoltage protection is often provided to protect sensitive loads from overvoltage conditions, and in some special applications, synchronization of the switching frequency to an external clock will be provided. Hence, the power supply designer must understand and meet many needs.

To utilize or specify a modern power processing system more effectively, the user should be familiar with the advantages and limitations of the many techniques available.

With this information, the system engineer can specify the power supply requirements so that the most cost-effective and reliable system may be designed to meet these needs.

Very often a small change in specification or rearrangement of the power distribution system will allow the power supply designer to produce a much more reliable and cost-effective solution to the user’s needs.

Hence, to produce the most reliable and cost-effective design, the development of the specification should be an interactive exercise between the power supply designer and the user. Very often, power supply specifications have inflexible, and often artificial boundaries and limitations.

These unrealistic specifications usually result in overspecified requirements and hence an overdesigned supply.

This, in turn, can entail a high cost, high complexity, and lower reliability. The power supply user who takes the trouble to understand the limitations and advantages of modern switchmode techniques will be in a far better position to specify and obtain reliable and cost-effective solutions to power supply requirements. The book is presented in four parts:

Part 1, “Functional Requirements Common to Most Direct-Off-Line Switchmode Power Supplies,” covers, in simple terms, the requirements which tend to be common to any supply intended for operation directly from the ac line supply.

It gives details of the various techniques in common use, highlighting their major advantages and limitations, together with typical applications.

In this new edition, Chapter 23 has been expanded to include a current-fed, self-oscillating, resonant sine wave inverter adapted to providing multiple distributed independently isolated auxiliary supplies for a large system.

The need for semi-stabilized outputs with very low noise is addressed by a linear regulator that also affords current limiting and the use of sine wave power distribution for low system noise.

Part 2, “Design, Theory, and Practice,” considers the selection of power components and transformer designs for many well-known converter circuits.

It is primarily intended to assist practicing power supply engineers in developing conservatively rated prototypes with more speed and minimum effort.

It provides examples, information, and design theory sufficient for a general understanding and the initial design of the more practical switchmode power supplies.

However, to produce fully optimized designs, the reader will need to become conversant with the more specialized information presented in Part 3 and the many references.

Part 3, “Applied Design,” deals with many of the more general engineering requirements of switchmode systems, such as transformer design, choke design, input filters, RFI control, snubber circuits, thermal design, and much more.

Part 4, “Supplementary,” looks at a number of selected topics that may be of more interest to power supply professionals. The first topic covers the design of an active power factor correction system.

The power distribution industry is becoming more concerned with the increasing level of harmonic content caused by non-corrected electronic equipment and in particular electronic ballasts for fluorescent lighting.

Active power factor correction is still a relatively new addition to the power supply designer’s tasks. It is difficult to display waveforms and design power inductors, due to the dynamic behavior of the boost topology, with its low- and high-frequency requirements.

This part should help remove some of the mystery regarding this subject. In most switchmode power supplies, it is the wound components that mainly control the efficiency and performance. Switching devices will work efficiently only if leakage inductances are small and good coupling is provided between input and output windings.

The designer has considerable control over the wound components, but it requires considerable knowledge and skill to overcome the many practical and engineering problems encountered in their design.

The author has therefore concentrated on the wound components and provided many worked examples.

To develop a full working knowledge of this critical area, the reader should refer to the more rigorous transformer design information given in Part 3, and the many references. The advances in resonant and semi-resonant converters have focused much attention on these promising techniques.

An examination of the pros and cons of a fully resonant technique is demonstrated by the design of a resonant fluorescent ballast. The principles demonstrated are applicable to many other fully resonant systems.

A quasi-resonant system is demonstrated by the design of a high-power, full-bridge converter that uses both semi-resonant techniques and phase shift modulation to achieve very high efficiency and low noise.

This section includes a step-by-step analysis of each stage of operation of the circuit during the progress of the switching cycle.

In Part 4 Chapters 4 and 5, co-author Taylor Morey shows a current fed, self-oscillating, fully resonant inverter using power MOSFETs.

This version has the advantage of near-ideal zero voltage switching transitions that result in harmonic free waveforms of high purity. He also shows a variable frequency sine wave oscillator, implemented with operational transconductance amplifiers.

In this design, the frequency can be adjusted with a single manual control, or electronically swept over a wide range from milliHertz to hundreds of kiloHertz. No single work can do full justice to this vast and rapidly developing subject.

The reader’s attention is directed to the Reference section where many related books and papers will be found that extend the range of knowledge well beyond the scope of this book.

It is hoped that this new edition will at least partly fill the need for a more general handbook on the subject.

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