Integrated Power Electronic Converters and Digital Control

Ali Emadi, Alireza Khaligh, Zhong Nie, Young Joo Lee

• Publisher: CRC Press
• Year: 2017
• Print ISBN: 9781439800690
• eBook ISBN: 9781351834360
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Because of the demand for higher efficiencies, smaller output ripple, and smaller converter size for modern power electronic systems, integrated power electronic converters could soon replace conventional switched-mode power supplies. Synthesized integrated converters and related digital control techniques address problems related to cost, space, flexibility, energy efficiency, and voltage regulation—the key factors in digital power management and implementation.

Meeting the needs of professionals working in power electronics, as well as advanced engineering students, Integrated Power Electronic Converters and Digital Control explores the many benefits associated with integrated converters. This informative text details boost type, buck type, and buck-boost type integrated topologies, as well as other integrated structures. It discusses concepts behind their operation as well specific applications.

Topics discussed include:

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• Isolated DC-DC converters such as flyback, forward, push-pull, full-bridge, and half-bridge

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• Power factor correction and its application

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• Definition of the integrated switched-mode power supplies

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• Steady-state analysis of the boost integrated flyback rectifier energy storage converter

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• Dynamic analysis of the buck integrated forward converter

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• Digital control based on the use of digital signal processors (DSPs)

With innovations in digital control becoming ever more pervasive, system designers continue to introduce products that integrate digital power management and control integrated circuit solutions, both hybrid and pure digital. This detailed assessment of the latest advances in the field will help anyone working in power electronics and related industries stay ahead of the curve.

chapter one

Non-isolated DC-DC Converters

The DC-DC converters are widely used in regulated switched-mode DC power supplies and DC motor drive applications. The input to these converters is often an unregulated DC voltage, which is obtained by rectifying the line voltage, and therefore it will fluctuate due to changes in the line voltage magnitude. Switched-mode DC-DC converters are used to convert the unregulated DC input to a controlled DC output at a desired voltage level [1].

The converters are very often used with an electrical isolation transformer in the switched-mode DC power supplies and almost always without an isolation transformer in the case of DC motor drives [2].

Buck (step down), boost (step up) converters and buck-boost are the basic converter topologies. There is a very wide choice of topologies available; each one has its own particular advantages and disadvantages, making it suitable for special power supply application [1], [2], [3], [4], [5] and [6]. Basic operation, advantages, drawbacks, and most common area of use for the most common topologies are discussed in the following sections.

1.1 Buck Converter

This is one of the non-isolated, very basic switching power supply topologies [3], [4]. The output voltage in this topology is always less than the input voltage and thus it is considered a buck converter. The power stage circuit is shown in Figure 1.1.

Depending on the current through the inductor L, the converter can be operated in two basic operating modes. One of them is continuous conduction mode (CCM) and the other is discontinuous conduction mode (DCM). The converter is said to be in CCM when the current through the inductor never reaches zero (for example, i_L is always positive). On the other hand, if the inductor current reaches zero and stays zero for some time, the converter is said to be in DCM. The boundary between continuous and discontinuous conduction mode is known as critical continuous conduction mode (CCCM) or critical discontinuous conduction mode (CDCM).

When switch S is turned on, the input voltage is applied to inductor L and power is delivered to the output. Inductor current also builds up according to Faraday’s law. When the switch is turned off, the voltage across the inductor reverse and freewheel diode D becomes forward biased. This allows the energy stored in the inductor to be delivered to the output. This continuous current is then smoothed by output capacitor C.

Figure 1.1 Buck converter.

The LC filter has an averaging effect on the applied pulsating input, producing a smooth DC output voltage and current, with very small ripple components superimposed. The average voltage-second across the inductor over a completer switch cycle must equal zero in the steady state.

1.1.1 Buck Converter in Continuous Conduction Mode

The operating mode starts when the switch is turned on. Here it is assumed that the converter is in continuous conduction mode and thus, initially, the inductor current is holding some minimum value. When the switch is on, negative voltage appears across the diode and it turns to off. Therefore, the current goes through the inductor. The inductor current increases line...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Preface
• Authors
• Chapter 1 Non-isolated DC-DC Converters
• Chapter 2 Isolated DC-DC Converters
• Chapter 3 Power Factor Correction
• Chapter 4 Integrated Switched-Mode Power Converters
• Chapter 5 Boost-Type Integrated Topologies
• Chapter 6 Buck-Type Integrated Topologies
• Chapter 7 Buck-Boost Type Integrated Topologies
• Chapter 8 Other Types of Integrated Topologies
• Chapter 9 Steady-State Analysis
• Chapter 10 Dynamic Analysis
• Chapter 11 Synchronous Rectification
• Chapter 12 Synchronous Rectification with Flyback and Forward Converters
• Chapter 13 Synchronous Rectification for Integrated High-Quality Rectifier-Regulators
• Chapter 14 Integrated Switched-Mode Power Supplies Applications
• Chapter 15 Review of Digital Control Techniques in Power Electronics
• Chapter 16 Implementation of Digital Control Using Digital Signal Processors
• Index