BioMedical Instrumentation Lab., BME, Yonsei University

윤 자 웅

2010. 12. 28

Quasi-resonant Converters & Design Example

Power Supply CookBook (2nd) – Marty Brown

Contents

BioMedical Instrumentation Lab., BME, Yonsei University

1. Quasi-resonant Converters- Introduction of the Quasi-resonant Con-

verter- ZCS Quasi-resonant Converter

- ZVS Quasi-resonant Converter2. The Design Example

- 10W Synchronous Buck Converter

Introduction of the Quasi-resonant converters

BioMedical Instrumentation Lab., BME, Yonsei University

• Purpose : Reduction & Elimination Switching loss in P.S

• Resonant tank circuit• Disadvantage : Voltage & Current Stresses on Power

Components More RFI/EMI noise

• Design time & Product Cost = Very high

Not Recommended !!!

ZCS Quasi-resonant Converter

BioMedical Instrumentation Lab., BME, Yonsei University

• Zero Current Switching quasi-resonant Switching Power Supply (ZCS QR

SMSP)• Always switched when the Current is Zero• Type L, Type M

ZCS Quasi-resonant Converter

BioMedical Instrumentation Lab., BME, Yonsei University

ZCS Quasi-resonant Converter – Mode 1

BioMedical Instrumentation Lab., BME, Yonsei University

• 0 ~ t1 까지의 동작• 스위치 SW 가 턴온 , 인덕터에 흐르는 전류 Isw 가 선형적으로 증가• IL = ( Vs / L ) * t • 이 모드는 IL = I0 일 때 끝나게 된다 . • 즉 t = t1 이고 , t1 = (I0*L) / Vs

• 0 ~ t2 까지의 동작• 스위치 SW 는 ON 상태로 남아있으나 다이오드 Dc 는 OFF 된다 .• IL = Im*sin(wt) + Io 로 주어진다 .• 이때 피크 전류는 Ip = Im + Io • 피크 전압 Vc(pk) = 2Vs• t2 = LC

ZCS Quasi-resonant Converter – Mode 2

BioMedical Instrumentation Lab., BME, Yonsei University

)(sin 13 CVs

LIoLCt

ZCS Quasi-resonant Converter – Mode 3

BioMedical Instrumentation Lab., BME, Yonsei University

• 0 ~ t3 까지의 동작• IL = Io - Im*sin(wt) 로 주어진다 .• Vc(pk) = 2Vs * cos(wt)

•

ZCS Quasi-resonant Converter – Mode 4

BioMedical Instrumentation Lab., BME, Yonsei University

• 0 ~ t4 까지의 동작• Vc = V(c3) – (Io/C)*t• t4 = V(c3) * C/Io

ZCS Quasi-resonant Converter – Mode 5

BioMedical Instrumentation Lab., BME, Yonsei University

• 0 ~ t5 까지의 동작• t5 = T – (t1 + t2 + t3 + t4)

LCfr 2

1

ZVS Quasi-resonant Converter

BioMedical Instrumentation Lab., BME, Yonsei University

• Zero Voltage Switching quasi-resonant Switching Power Supply (ZCS QR

SMSP)• Always switched when the Voltage is Zero

ZVS Quasi-resonant Converter

BioMedical Instrumentation Lab., BME, Yonsei University

ZVS Quasi-resonant Converter – Mode 1

BioMedical Instrumentation Lab., BME, Yonsei University

• 0 ~ t1 까지의 동작• 스위치 S1 , 다이오드 Dm 모두 OFF• Vc = (Io/C) * t• 이 모드는 Vc = Vs 일 때 끝나게 된다 . • 즉 t = t1 이고 , t1 = Vs*C/I

• 0 ~ t2 까지의 동작• 스위치 S1 은 OFF 상태로 남아있고 , 다이오드 Dm 은 ON• Vc = Vm*sin(wt) + Vs 로 주어진다 .• 이때 피크 스위치 전압은 • 인덕터 전류 IL = Io * cos(wt)• t2 =

sVCLI 0

ZVS Quasi-resonant Converter – Mode 2

BioMedical Instrumentation Lab., BME, Yonsei University

LC

)(sin 13 CVs

LIoLCt

ZVS Quasi-resonant Converter – Mode 3

BioMedical Instrumentation Lab., BME, Yonsei University

• 0 ~ t3 까지의 동작• Vc = Vs – Vm*sin(wt)• IL = - Io * cos(wt)

•

ZVS Quasi-resonant Converter – Mode 4

BioMedical Instrumentation Lab., BME, Yonsei University

• 0 ~ t4 까지의 동작• 스위치 S1 -> On, 다이오드 Dm 은 On 상태 유지• IL = IL3 + (Vs/L) * t• t4 = (Io – IL3) / ( L/Vs )

ZVS Quasi-resonant Converter – Mode 5

BioMedical Instrumentation Lab., BME, Yonsei University

• 0 ~ t5 까지의 동작• t5 = T – (t1 + t2 + t3 + t4)

Quasi-resonant Switching Power Supply Topologies

BioMedical Instrumentation Lab., BME, Yonsei University

The Design Example – 10W Synchronous Buck Converter

BioMedical Instrumentation Lab., BME, Yonsei University

The Design Example – 10W Synchronous Buck Converter

BioMedical Instrumentation Lab., BME, Yonsei University

The Design Example – 10W Synchronous Buck Converter

BioMedical Instrumentation Lab., BME, Yonsei University

Epilogue – Q&A

BioMedical Instrumentation Lab., BME, Yonsei University

Thank you for your attention !