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 Lab-808: Power Electronic Systems & Chips Lab., NCTU, Taiwan http://pemclab.cn.nctu.edu.tw/ DC-DC 轉換器的基本觀念與定義 鄒應嶼 教授 國立交通大學 電機與控制工程研究所 2008 年 1 月 8 日 LAB808 NCTU 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 1/46
Power Electronic Systems & Chips Lab., NCTU, Taiwan DC-DC Converters Basic Concepts 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 2/46
DC-DC Voltage Regulators battery AC line voltage Uncontrolled diode rectifier DC filter capacitor DC DC-DC converter DC load (1-phase or 3 phase) (unregulated) (unregulated) (regulated) A DC-DC converter system. unregulated dc input regulated dc output DC-DC converters are the most widely used power converters! 3/46
Functional Block Diagram of a Switching Power Supply Line input AC 120 Hz 20-200 KHz Output DC High frequency inverter Source Load Input EMI filter PFC converter and filter DC-DC converter output rectifier and filter Output EMI filter PFC Controller PWM OSC COMP REF Feedback Sensing, Reference, and Isolator PWM Controller A power supply is a power conversion and control processor. 4/46
Two-Stage AC/DC & DC/DC Converter PFC Converter DC-DC Converter Vout-1 VLINE 85-260VAC Q1 Cboost Vout-2 Vout-3 PFC Controller PWM Controller: Primary & Secondary CRM PFC IC CCM PFC IC Voltage Mode IC Current Mode IC 5/46
Typical Block Diagram of an ATX Power Supply Output circuitry EMI filter PFC controller PFC Diode SMPS controller 12 V out 5 V out 3.3 V out Post regulator MOSFET Supervisory Bias output Output rectification SMPS regulator 6/46
Power Conversion, Control, and Management Power Conversion, Control, and Management AC/DC Battery Charger DC/DC DC/DC AC 85 265V DC/DC Controller DC DC/DC Controller IC PFC Controller PWM Controller SMPS AC/DC DC/DC Converter Charger Battery Applications SMPS Monitor / CTV Notebook PC, Server Lamp ballast Applications Motherboard Notebook Power Supplies / VRM Telecom Portable Applications Notebook Cell Phone PDA 7/46
DC/DC Converters for Mobile Phones Power distribution: V g = 2.8 5.5V Battery Charger DC-DC DC-DC DC-DC Switching regulators LDO 3.6V 2.5V 1.5V 1-3.6V Antenna LDO 2.7-5.5V Display Audio P/DSP core I/O D/A A/D LO PA LNA DC-DC Vibrator Baseband digital Analog/RF 3.6V 2.5V 2.5V 2.5V DC-DC LDO LDO REF: Frank De Stasi & Mathem Jacob, Magnetic Buck Converters for Portable Applications, National Semiconductor. 8/46
Low-Power Low-Voltage Power Supplies i cc V bat power supply V cc IC V cc 5V i cc Increased functionality 3.3V 1.5V 0.8V same functionality year year Good for the IC, bad for the power supply! 9/46
Battery-Based Power Converters for Portable IA Battery Protection IC I dc Charger I s Lithium Ion Battery 2.8-4.5V 1000mAh I g Switching Regulator I o -Processor V dc V s V g V o V o = 1.2 V (+/- 2%) I o = 1 ma (idle) 500 ma (on) 10/46
Linear Voltage Regulator: Basic Principle V IN V CE V O I O Efficiency C C R 1 R L V R R 2 Output Impedance 電流注入頻率掃瞄量測 V R R 1 2 O V R R2 P Loss V CE I O R L RL R CE Efficiency Analysis ( = V out /V in ) Loop Gain of Error Amp for Output Impedance 11/46
The Classical Linear Regulator TL431 CATHODE 800 800 Cathode REF 20pF REF 150 2.4k 3.28k 20pF 4k 10k 2.5V REF 7.2k Anode 1k ANODE Package 800 Symbol TL431 = Reference + OP Amp. + Driver REF Anode Cathode 12/46
TL431: Circuit Schematics and Device Model (b) (a) (C) TL431 OPEN-LOOP VOLTAGE GAIN VERSUS FREQUENCY 13/46
State of the Art TL431: Schematics and IC Layout Package Symbol REF 11 x Tr. = Reference + OP + Driver Anode Cathode 14/46
A High Efficiency Step-Down Switching Converter V IN = 10~20V 1.0k TIP115 4.7k 4.7k 150 F @2.0A 1N5823 V OUT = 5.0V I OUT = 1.0A 2200 F NPSA20 4.7k 0.01 F 100k 470 F 0.1 F 2.2k 51k TO-92 (TO-226) LP SUFFIX case 29 Reference (R) Cathode (K) 1 2 3 Pin 1. Reference 2. Anode 3. Cathode TL431 2.5V REF REF: TL431, A, B Series, NCV431A Programmable Precision References (datasheet, On-Semi) Anode (A) 15/46
Power Supplies: Efficiency, Size, Dynamic Response Efficiency Control Soft Switching Topologies Control Architecture Control IC Loss Harmonics Control Control Design Thermal Management EMC Design Power Management Packaging Reliable, Size, Cost, Easy Dynamic Response 16/46
Switching Control of DC-DC Converters V d R V o V d V o t t on T s t off D t on T s 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 17/46
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. L v i C R + v CC v d A 1 + v C v m A 2 + R 3 i R 1 R 2 R 4 18/46
Pulse-Width Modulator (desired) (actual) Amp Modulating signal v control comparator switch control signal Carrier signal v st = sawtooth voltage Vˆst repetitive waveform v control (amplified error) D t T on v control ˆ s V st v control > v st The carrier signal may be a nonlinear function to produce nonlinear PWM control signal. switch control signal on off on off t on t off v control < v st T s (switch frequency f s = 1/T s ) 19/46
Three Types of PWM Signals Trailing-Edge PWM Leading-Edge PWM Central PWM
L B Trailing-Edge & Trailing-Edge PWM Control L B V in I L SW I O C B V o RAMP V in I L SW I O C B V o RAMP V ref EA V ctrol VSW TIME V ref EA V ctrol VSW TIME OSC RAMP CLK COMP R S Q Q OSC RAMP CLK COMP R S Q Q Trailing-Edge Modulation (TEM) TIME L1 Leading-Edge Modulation (LEM) L2 TIME SW1 SW2 V in SW1 SW2 C1 D1 C2 V o T S Current flowing paths for LEM/TEM control scheme
PWM DC-DC Power Conversion and Regulation DC-DC Converters v g What is the BW requirement of the error amp? What is the design requirement for the comparator? R Q d S Z f v P v C Z i v C v ref OSC CLK Comparator v P HF Sawtooth Generator Error Amplifier T ON T d TON T 22/46
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 23/46
Major Function Circuit of 741 V CC I C I REF Q 3 I A Q 7 D 1 v i differential input A 1 v N v P C C D 2 v O high-gain amp emitter follower Q 4 Q 1 Q 2 Q 5 Q 8 Input stage Intermediate stage Output stage Q 3 Q 4 R 1 Q 6 Small-Signal Equivalent Circuit input stage second stage output stage V EE R o2 R o v i R id G m1 v i R o1 v i2 R i2 v i3 R i3 2 R L v G R v o2 m2 o2 i2 24/46
C C Selection of C C Gm1vid G m2 v i2 v R1 id C 1 vi2 R 2 C 2 A G o G m1 m2 A o -20 db/decade ( G m1 R G 1 m2 R 2 ) G m2 1 R C 2 C R 1 t 0 db p2 p1 t -40 db/decade t m G 1 C C P 1 G m 2 1 R C 2 low-frequency dominant pole C R 1 t A o p1 high-frequency pole unit-gain bandwidth 25/46
A Typical Internally Compensated CMOS OP-AMP C c2 v DD v in 1 vo2 C c1 R eq R L r 03 vo Q3 Q4 Q 8 Cin g v m1 in C1 r g v o1 m2 01 C r g v 2 o2 m3 02 CL Req Q 6 v in Q1 Q2 v in C c Q 10 Q 11 ut voltage gain (db) gm2ro 2gm3 R eq Q 9 f 2 f 2 v bias Q 5 Q 7 insert CC1 f 3 v SS f 3 log (f) voltage gain (db) gm 1ro 1gm2ro 2gm3 f 2 R eq f 2 f 2 f 1 insert CC1 f 3 insert C C and C 1 C 2 Introduction to CMOS OP-AMPs and Comparators, Roubik Gregorian, John Wiley & Sons, Feb. 12, 1999. f 1 f 3 log (f) 26/46
Second-Order Switched-Capacitor Filter C 2 1 Ts R C C A C 4 2 C B V 2 C 2 in 1 1 C 3 2 2 V o 1 1 2 1 Analog Filter Design, M. E. Van Valkenburg, Oxford University Press, USA, June 8, 1995. 27/46
A Seventh-Order Switched-Capacitor Filter C6 C15 C23 C H C5 C7 C14 C16 C 22 C 24 V out C 13 C 21 C 28 C 4 C 3 C 8 C 3 C 17 C 25 C 27 C 1 C 2 C29 C11 C12 C18 C20 C26 C9 C10 C19 V in 28/46
Definition of DC-DC Converter DC-DC converter is the Gate Way to all other power converters! 29/46
Basic Power Converters DC-DC Converter DC-AC Converter AC-DC Converter AC-AC Converter 30/46
Definition of DC-DC Converter DC-DC Converter (Chopper) V IN, I IN V OUT, I OUT A dc-to-dc converter is any network that can have as its sole source of energy a constant dc voltage V IN or a constant dc current I IN and can provide dc output power such that V OUT > V IN or I OUT > I IN. According to this definition, A Linear Regulator is NOT A DC-DC Converter! 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. 31/46
Converter Topology v g d 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. 32/46
Development of Basic DC-DC Converters v g d The Problem: Configure these four basic elements to devise a dc-dc voltage converter! 33/46
Two Basic Energy Switching Architectures Switching Inductor Converter v g The switching inductor as a switching current source! Switching Capacitor Converter v g The switching capacitor as a switching voltage source! 34/46
Basic DC-DC Converters Buck 蹲 Boost 跳 Buck-Boost 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? 35/46
Intrinsic Characteristics of Basic DC-DC Converters L Switching Inductor Buck V dc v i C The inductor current must maintain its continuity! Boost V dc v i L C The direction of the inductor current flow can not be changed! The behavior of the inductor current determines the operating modes of the converter. V dc v i Buck-Boost L C The average inductor current is the effective current! 36/46
Common One-Switch Power Converter Topologies n : 1 I L Buck v i V in C o R Flyback Converter Boost v i Vin D3 D1 Lo Vo T1 n : n : 1 D2 Co Buck-Boost v i Control Circuit TR1 resetting winding Non-Isolated Single-Ended Single-Switch Converter Forward Converter 37/46
Basic Topologies of PWM DC-DC Converters One Inductor, One Capacitor L Two Inductors, Two Capacitors L 1 C 1 L 2 Buck v i D C C, uk v i D C 2 L D L 1 C 1 D Boost v i C SEPIC v i L 2 C 2 D SEPIC: Single-Ended Primary Inductor Converter C 1 L 2 v i Buck-Boost L C v i Zeta L C 2 1 D 38/46
Switches in the Thee Basic PWM DC-DC Converters L D v i D C v i L C Buck Converter Buck-boost Converter v i L D C The switches must keep the continuity of the inductor current! The buck-boost converter has an inverting output! Boost Converter 39/46
Basic Circuit Concept V1 V2 This is not a workable circuit, unless V 1 = V 2. I1 I 2 This is not a workable circuit. I 1 This is not a workable circuit. V1 I1 This is not a workable circuit. 40/46
Basic Circuit Concept V 1 This is a workable circuit. V1 I1 This is a workable circuit. This is a workable circuit. This is a workable circuit. What is the common rule for the judgement? 41/46
At High Freq., The Inductor as A Current Source The inductor as a current source and the capacitor as a voltage source! L Buck v i D C L D Boost v i C D v i Buck-Boost L C 42/46
Switching Energy Transfer in a Cuk Converter L 1 C 1 L 2 v i S D C 2 C, uk 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 output current ripples 43/46
Control of Basic PWM DC-DC Converters Switching power converters Z os v g v~s V s Boost Converter Buck/Boost Converter Buck Converter R L ~ id load Gate Drive PWM Modulator Loop Compensator v R Efficiency Output Impedance Current Injection Method 44/46
Example of Pulsewidth Modulator in a Buck Converter v i L C R The modulating signal v m compares with the carrier signal v C to generate a pulse width controlled digital v d. A 1 v C + v CC i R 1 The PWM modulation process can be of the following types: constant frequency switching v d v m A 2 fixed ON-time switching R 3 R 2 fixed OFF-time switching R 4 Nonlinear carrier ramp voltage PWM/PFM with Skip Cycle v C v m PWM with Doube-Edge PWM output DT 45/46
Loop Compensator 10 3 magnitude response 10 2 Type 3: Three poles and two zeros C 3 e o R a 10 1 10 0 10 1 10 2 10 3 10 4 10 5 50 phase response frequency(rad/sec) e a R 3 R 1 0 R 4 v ref R 2 R b -50 10 0 10 1 10 2 10 3 10 4 10 5 frequency(rad/sec) R 5 C 5 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. 46/46
Power Electronic Systems & Chips Lab., NCTU, Taiwan Any Questions??? Questions inspire effective learning! 學習的關鍵 記筆記 問問題 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 47/46