switching power theory

johnson_zhan

【文件名】:0691@52RD_开关原理[1].pdf
【格　式】:pdf
【大　小】:93K
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【目　录】:switching power introduction

flymsik

亏大了，不值钱的

mwo1974

DC-DC Power Converters
Robert W. Erickson
Department of Electrical and Computer Engineering
University of Colorado
Boulder, CO 80309-0425
......Dc-dc power converters are employed in a variety of applications, including power supplies for
personal computers, office equipment, spacecraft power systems, laptop computers, and
telecommunications equipment, as well as dc motor drives. The input to a dc-dc converter is an unregulated
dc voltage Vg. The converter produces
a regulated output voltage V, having a
magnitude (and possibly polarity) that
differs from Vg. For example, in a
computer off-line power supply, the
120 V or 240 V ac utility voltage is
rectified, producing a dc voltage of
approximately 170 V or 340 V,
respectively. A dc-dc converter then
reduces the voltage to the regulated 5 V
or 3.3 V required by the processor ICs.
High efficiency is invariably
required, since cooling of inefficient
power converters is difficult and
expensive. The ideal dc-dc converter
exhibits 100% efficiency; in practice,
efficiencies of 70% to 95% are
typically obtained. This is achieved
using switched-mode, or chopper,
circuits whose elements dissipate negligible power. Pulse-width modulation (PWM) allows control and
regulation of the total output voltage. This approach is also employed in applications involving alternating
current, including high-efficiency dc-ac power converters (inverters and power amplifiers), ac-ac power
converters, and some ac-dc power converters (low-harmonic rectifiers).
A basic dc-dc converter circuit known as the buck converter is illustrated in Fig. 1. A single-pole
double-throw (SPDT) switch is connected to the dc input voltage Vg as shown. The switch output voltage........
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