1/46

DC-DC轉換器的基本觀念與定義

2008年1月8日

鄒 應 嶼 教 授

國立交通大學 電機與控制工程研究所

LAB808NCTU

Lab808: 電力電子系統與晶片實驗室Power Electronic Systems & Chips, NCTU, TAIWAN

台灣新竹•交通大學•電機與控制工程研究所

台灣新竹‧交通大學‧電機與控制工程研究所‧808實驗室電力電子系統晶片、數位電源、DSP控制、馬達與伺服控制

http://pemclab.cn.nctu.edu.tw/Lab-808: Power Electronic Systems & Chips Lab., NCTU, Taiwan

2/46

DC-DC Converters – Basic Concepts

Power Electronic Systems & Chips Lab., NCTU, Taiwan

電力電子系統與晶片實驗室Power Electronic Systems & Chips Lab.交通大學 • 電機與控制工程研究所

3/46

DC-DC Voltage Regulators

AC line voltage

(1-phase or 3 phase)

Uncontrolleddiode

rectifier filter

capacitor

(unregulated)

DC

(unregulated)

DC DC-DC converter

(regulated)

DCload

battery

A DC-DC converter system.

unregulated dc input regulated dc output

DC-DC converters are the most widely used power converters!

4/46

Functional Block Diagram of a Switching Power Supply

COMP

REF

Line input AC

PFC converterand filter

PWM Controller

Highfrequencyinverter

20-200 KHz Output DC

output rectifierand filter

LoadSource

120 Hz

Feedback Sensing,

Reference, and Isolator

PFC Controller

Input EMI filter

Output EMI filterDC-DC converter

A power supply is a power conversion and control processor.

PWM

OSC

5/46

Two-Stage AC/DC & DC/DC Converter

PFC ConverterDC-DC Converter

Q1

PFC Controller

CboostVLINE

85-260VAC

Vout-3

Vout-2

Vout-1

PWM Controller: Primary & Secondary

CRM PFC IC CCM PFC IC Voltage Mode IC Current Mode IC

6/46

Typical Block Diagram of an ATX Power Supply

PFCcontroller

PFC Diode

SMPScontroller

SMPSregulator

Biasoutput

MOSFET

Output circuitry12 Vout5 Vout3.3 Vout

Postregulator

Outputrectification

Supe

rvis

ory

EMIfilter

7/46

Power Conversion, Control, and Management

Power Conversion, Control, and Management

AC/DC Battery Charger DC/DCDC/DC

ApplicationsSMPSMonitor / CTVNotebookPC, ServerLamp ballast

Portable ApplicationsNotebookCell PhonePDA

ApplicationsMotherboardNotebookPower Supplies / VRMTelecom

DC

AC85

…26

5V

PFC Controller PWM Controller

DC/DCController

SMPS AC/DC

BatteryCharger

DC/DC Converter

DC/DCController

IC

8/46

DC/DC Converters for Mobile Phones

Battery Charger

LDO

Display

Audio

Vibrator

P/DSPcore

D/A

A/DI/O

Antenna

2.5V 2.5V

2.7-5.5V

3.6V 2.5V1.5V

Baseband digital

Power distribution: Vg = 2.8–5.5V

1-3.6V

Analog/RF

LO

2.5V

Switchingregulators

PA

LNA

LDO

DC-DC

DC-DC LDO

DC-DCDC-DC

LDO

3.6V

DC-DC

REF: Frank De Stasi & Mathem Jacob, “Magnetic Buck Converters for Portable Applications”, National Semiconductor.

9/46

Low-Power Low-Voltage Power Supplies

Good for the IC, bad for the power supply!

Vcc

year

5V

3.3V1.5V 0.8V

icc

year

samefunctionality

Increasedfunctionality

IC

icc

Vccpowersupply

Vbat

10/46

Battery-Based Power Converters for Portable IA

Vo = 1.2 V (+/- 2%)Io = 1 mA (idle)

500 mA (on)

LithiumIon Battery2.8-4.5V1000mAh

SwitchingRegulator

-Processor

Ig

Vg

Io

Vo

Is

Vs

Charger

Idc

Vdc

Battery Protection IC

11/46

Linear Voltage Regulator: Basic Principle

RO VRRRV

2

21

VINVCE

VO

CC

VR

R1

R2

RL

IO Efficiency

Output Impedance

Efficiency Analysis ( = Vout/Vin) Loop Gain of Error Amp for Output Impedance

OCELoss IVP CEL

L

RRR

電流注入頻率掃瞄量測

12/46

The Classical Linear Regulator TL431

CATHODE

REF

ANODE

SymbolPackage

Anode Cathode

REF

REF

Cathode

Anode

2.4k

7.2k

3.28k

800

1k

4k

800 800

150

10k

20pF

20pF

TL431 = Reference + OP Amp. + Driver

2.5V REF

13/46

TL431: Circuit Schematics and Device Model

(a)

(b)

(C) TL431 OPEN-LOOP VOLTAGE GAIN VERSUS FREQUENCY

14/46

State of the Art TL431: Schematics and IC Layout

11 x Tr. = Reference + OP + Driver

SymbolPackage

Anode Cathode

REF

15/46

A High Efficiency Step-Down Switching Converter

REF: TL431, A, B Series, NCV431A Programmable Precision References (datasheet, On-Semi)

TL431

2.5V REF

Cathode (K)Reference (R)

Anode (A)

2200F

1.0k

4.7k

0.1F2.2k

4.7k 4.7k

TIP115150F @2.0A

0.01F 100k

470F

51k

1N5823

NPSA20

VIN = 10~20V VOUT = 5.0VIOUT = 1.0A

TO-92 (TO-226)LP SUFFIX

case 29

Pin 1. Reference2. Anode3. Cathode

12 3

vo

16/46

Power Supplies: Efficiency, Size, Dynamic Response

Topologies

Thermal Management

HarmonicsControlLoss

EMC Design

SoftSwitching

Reliable, Size, Cost, EasyPackagingDynamicResponse

ControlArchitecture

Control Design

Control IC

PowerManagement

Efficiency Control

17/46

R

Switching Control of DC-DC Converters

VdVo

vo

tVo

Vd

ton toff

Ts

Pulsewidth Modulation (PWM) Switching (Hard Switching)Fixed Frequency (Duty Ratio Control)Variable Frequency (Fixed ON Time, Fixed OFF Time)

Resonant Switching (Quasi-Resonant, Multi-Resonant) Soft Switching

sTtD on

18/46

Operating Principle of a Switching Regulator

A switching regulator is a power processor in which the power handing devices are operated as switches in either ON or OFF positions.

The regulation process of a switch mode converter is performed via the pulse width modulator with a control voltage derived from the output of the converter.

+

+

R1

R2R3

R4

A2A1vd

R

vovi C

+ vCC

i

L

vm

vC

19/46

Pulse-Width Modulator

Amp comparator

repetitive waveform

switch control signal

vcontrolvo (desired)

vo (actual)

ton toffTs

on on

off off

switch control signal

stV̂

vst = sawtooth voltage vcontrol (amplified error)

vcontrol > vst

vcontrol < vst

(switch frequency fs = 1/Ts)

sts Vv

TtD ˆ

controlon

The carrier signal may be a nonlinear function to produce nonlinear PWM control signal.

Modulating signal

Carrier signal

Trailing-Edge PWM

Three Types of PWM Signals

Leading-Edge PWM

Central PWM

Trailing-Edge & Trailing-Edge PWM Control

Trailing-Edge Modulation (TEM) Leading-Edge Modulation (LEM)

Current flowing paths for LEM/TEM control scheme

COMP

EA

OSC CLK

RAMP

LB

ILVin

SWIO

VoCB

VrefVctrol

Q

S

R

Q

VSW

RAMP

TIME

TIME

COMP

EA

OSC CLKRAMP

LB

ILVin

SWIO

VoCB

Vref Vctrol

VSW

RAMP

TIME

TIME

Q

S Q

R

L1

SW1

L2

Vin VoSW2

C1 D1 C2

SW1

SW2

TS

22/46

PWM DC-DC Power Conversion and Regulation

Z i

Z f

vref

vo

v C

d

vg

vP

vP vC

d TTONT

TONError Amplifier

Comparator HF Sawtooth Generator

What is the BW requirement of the error amp?What is the design requirement for the comparator?

DC-DC Converters

Q

S

R

CLKOSC

23/46

The OP AMP 741

Pin Connection

No Frequency Compensation Required

Short Circuit Protection Offset Voltage Null Capability Wide Common Mode and

Differential Voltage Ranges Low Power Consumption No Latch Up

24/46

Major Function Circuit of 741

REFI3Q

4Qemitterfollower

ovA 1

high-gainamp

differentialinput

Intermediate stage

iv

Input stage Output stage

Small-Signal Equivalent Circuit

viRid Gm1vi Ro1

vi2 Ri2

Ro2

Ri3vi3 vo

Ro

2222 iomo vRGv

2ov RL

ICVCC

vO

Q8

D1D2

CC

Q6

Q5

R1Q4Q3

Q1 Q2

IA

vN vP

VEE

Q7

input stage secondstageoutputstage

25/46

Selection of CCGm1vid R1 vi2C1vid

Gm2vi2R2 vo

C2

CC

1221

1RCRG Cm

P

1pot A

oA

1p

0 dB

-20 dB/decade

-40 dB/decade

low-frequency dominant polehigh-frequency pole

t

unit-gain bandwidth

2p

tCm

mm RCRGRGRG

1222211

1)(

C

mt C

G 1

21 mmo GGA

26/46

A Typical Internally Compensated CMOS OP-AMP

Introduction to CMOS OP-AMPs and Comparators, Roubik Gregorian, John Wiley & Sons, Feb. 12, 1999.

inv

inv

1Q 2Q

3Q 4Q

5Qbiasv7Q

SSv

6Q8Q

9Q

cC 10Q

11Q

DDv

outv

voltagegain (dB)

log (f)

eqmom Rgrg 322

eqmomom Rgrgrg 32211

voltagegain (dB)

log (f)

2f 2f

3f1insert CC

3f

2f 2f

3f

3f 1f

1f2f

1insert CC

21 and insert CC CC

inv

inC inm vg 1 1C

1ov

1or 012vgm 2C 2or 023vgm LC eqR

03|| rRR Leq

2cC

1cC2ov ov

27/46

Second-Order Switched-Capacitor Filter

1 1

2 2inV 1C

AC

2 1

23C

BC

2

2C

1

oV

2

1

4C

Analog Filter Design, M. E. Van Valkenburg, Oxford University Press, USA, June 8, 1995.

CTR s

28/46

A Seventh-Order Switched-Capacitor Filter

inV

1C

3C

2C

4C13C

5C 7C 14C 16C

8C

29C 11C

3C

21C

22C

17C

12C 18C

6C 15C 23C

24C

25C

20C 26C

9C 10C 19C

28CoutV

HC

27C

29/46

Definition of DC-DC Converter

DC-DC converter is the Gate Way to all other power converters!

30/46

Basic Power Converters

DC-AC Converter

DC-DC Converter

AC-AC Converter

AC-DC Converter

31/46

Definition of “DC-DC Converter”

DC-DC Converter (Chopper)

A dc-to-dc converter is any network that can have as its sole source of energy a constant dc voltage VIN or a constant dc current IIN and can provide dc output power such that VOUT > VIN or IOUT > IIN.

VOUT, IOUTVIN, IIN

E. T. Moore and T. G. Wilson, “Basic considerations for dc to dc conversion networks,” IEEE Trans. Magn., vol. MAG-2, pp. 620–624, Sept. 1966.

According to this definition, A Linear Regulator is NOT A DC-DC Converter!

32/46

Converter Topology

The Issue:

A topology is the arrangement of the power devices and their magnetic elements. Each topology has its own merits within certain applications. Some of the factors which determine the suitability of a particular topology to a certain application, such as isolation, power ratings, component stress, number of output required, utilization factor, etc.

vo

d

vg

33/46

Development of Basic DC-DC Converters

vo

d

vg

The Problem:

Configure these four basic elements to devise a dc-dc voltage converter!

34/46

Two Basic Energy Switching Architectures

Switching Inductor Converter

vovgThe switching inductor as a switching current source!

ovvg

Switching Capacitor Converter

The switching capacitor as a switching voltage source!

35/46

Basic DC-DC Converters

Buck蹲

Boost Buck-Boost跳 可蹲可跳

要蹲不難，要蹲的很低，不容易！

要跳不難，要跳的很高，也不容易！

可蹲可跳，要蹲還是要跳呢？

36/46

Intrinsic Characteristics of Basic DC-DC Converters

vi vo

L

CBuck

Boost

Buck-Boost L C vovi

L

C vovi

Vdc

Vdc

Vdc

Switching Inductor

The inductor current must maintain its continuity!

The direction of the inductor current flow can not be changed!

The behavior of the inductor current determines the operating modes of the converter.

The average inductor current is the effective current!

37/46

Common One-Switch Power Converter Topologies

Buck

Boost

Buck-Boost

Non-Isolated Single-Ended Single-Switch Converter

vo

vo

vo

vi

vi

vi

ControlCircuit

T1

D1

D2 Co

VoD3

TR1

LoVin

resetting winding

n : n : 1

Forward Converter

n : 1 IL

VinCo R

Flyback Converter

vo

38/46

Basic Topologies of PWM DC-DC Converters

Buck

Boost

Buck-Boost L C

D

vovi

L

C

D

vovi

vi vo

L

CD

One Inductor, One Capacitor

　

　

　

C,uk

L1

C2D

L2C1

L1

C2

D

L2

C1

SEPIC

Zeta L1 C2D

L2C1

SEPIC: Single-Ended Primary Inductor Converter

Two Inductors, Two Capacitors

vi

vi

vi

vo

vo

vo

39/46

Switches in the Thee Basic PWM DC-DC Converters

vi vo

L

CD

Buck Converter

Boost Converter

Buck-boost Converter

L C

D

vovi

L

C

D

vovi

The switches must keep the continuity of the inductor current!

The buck-boost converter has an inverting output!

40/46

Basic Circuit Concept

This is not a workable circuit, unless V1 = V2.

This is not a workable circuit.

This is not a workable circuit. 1I

1I 2I

1V 2V

1V 1I This is not a workable circuit.

41/46

Basic Circuit Concept

This is a workable circuit.

This is a workable circuit. 1V 1I

1V

This is a workable circuit.

This is a workable circuit.

What is the common rule for the judgement?

42/46

At High Freq., The Inductor as A Current Source

The inductor as a current source and the capacitor as a voltage source!

Buck vi vo

L

CD

Boost

L

C

D

vovi

Buck-Boost L C

D

vovi

43/46

Switching Energy Transfer in a Cuk Converter

A switching capacitor converter (The CCM and DCM operation is determined by the continuity of the capacitor voltage)

Low input and low output current ripple Optimal DC-DC converter with ripple current free: if the input and

output inductor can be coupled to eliminate the input and outputcurrent ripples

C,uk Converter

L1

C2D

L2C1

Svi vo

44/46

Control of Basic PWM DC-DC Converters

PWMModulator

LoopCompensator

vg

vo

vR

Efficiency

Boost Converter Buck/Boost Converter Buck Converter

load

RL di~

Switching power converters

Output Impedance

GateDrive

osZ

sv~

sV

Current Injection Method

45/46

Example of Pulsewidth Modulator in a Buck Converter

R1

R2R3

R4

vd

R

vovi

C

+ vCCi

L

ramp voltage

vm

DT

PWM output

vC

vm

vC

The modulating signal vm compares with the carrier signal vC to generate a pulse width controlled digital vd.

The PWM modulation process can be of the following types:

constant frequency switchingfixed ON-time switchingfixed OFF-time switchingNonlinear carrier PWM/PFM with Skip Cycle PWM with Doube-Edge

2A1A

46/46

Loop Compensator

C3

R1

R2

e a

eo

v ref

C5R5

R4Rb

Ra

R3

-50

0

50

phase response

10 0 10 1 10 2 10 3 104 105

frequency(rad/sec)

10 0 10 1 10 2 10 3 104 10510

1

102

103

magnitude response

frequency(rad/sec)

The loop compensator is used to stabilize the closed-loop regulation of the converter and provide good disturbance rejection capability.The analog signal processor (loop compensator) is an analog realization of a control algorithm.The loop compensator processed the error signals (derived from the feedback and reference signals) and their derivative and/or integrals to produce a correcting signal such that the control loops are stabilized.

Type 3: Three poles and two zeros

47/46

Questions inspire effective learning!

Any Questions ???

Power Electronic Systems & Chips Lab., NCTU, Taiwan

電力電子系統與晶片實驗室Power Electronic Systems & Chips Lab.交通大學 • 電機與控制工程研究所

記筆記問問題

學習的關鍵