BOOK_CONTENT
From The Switching Function: Analysis of Power Electronic Circuits

Chapter List

Chapter 9: The Step Down Converter
Chapter 10: The Step Up or Boost Converter
Chapter 11: The Buck Boost dc to dc Converter
Chapter 12: The CUK dc to dc Converter
Chapter 13: The PWM Full Bridge dc to dc Converter

Part Overview

Fine common circuits are presented here for both continuous and discontinuous conduction. The dc to dc step down is a rather simple application of the technique. The rest of the circuits present a challenge because an impedance, an inductor, is inserted between the voltage source and the semiconductor switches. In this case the voltage equations for the loops are derived by considering the various modes of the circuit in order to derive the switching functions and the derived expressions.

9.1 Introduction

Figure 9.1 shows a simple circuit of the step down converter. The chopped voltage of a dc source is applied to a series inductor L and a parallel combination of a smoothing capacitor C and a resistor R. The resistor represents the power-consuming element of the load. The inductor has inductance L and ohmic resistance r. The switch is a MOSFET or an IGBT transistor. A control circuit, not shown in the diagram, generates the gate pulses to switch on and off the transistor. The switch opens and closes at a fixed frequency. The duty-cycle of the switch determines the level of the output voltage.


Figure 9.1: The step down converter

It is possible for this circuit to enter...

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Products & Services
Switching Power Supplies
Switching power supplies are DC sources that use a switching element (normally a power transistor) to generate the desired voltage. Switching power supplies are also called switch-mode products or switching mode power supplies (SMPS).
DC-DC Converter Chips
DC-DC converter chips provide a regulated DC voltage output from a different, unregulated input voltage. 
IC Switching Voltage Regulators
IC switching voltage regulators are integrated circuits (ICs) that store energy in an inductor, transformer, or capacitor and then use this storage device to transfer energy from the input to the output in discrete packets over a low-resistance switch.
Switch Mode Transformers
Switch mode transformers (switching transformers) are used mainly in switching power supplies and DC-DC converters. They provide a storage element for transferring energy from input to output in discrete packets as required in switching power supplies, regulators and converters.
DC Power Supplies
DC power supplies accept an input power and output the desired form of DC power. Common types of DC power supplies include linear power supplies, switching power supplies, DC-DC converters, and silicon controlled rectifier (SCR) type power supplies.

Topics of Interest

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