### 20110105_세미나3

```2010. 12. 28
Quasi-resonant Converters
& Design Example
Power Supply CookBook (2nd) – Marty Brown
윤자웅
BioMedical Instrumentation Lab., BME, Yonsei University
Contents
1. Quasi-resonant Converters
- Introduction of the Quasi-resonant Converter
- ZCS Quasi-resonant Converter
- ZVS Quasi-resonant Converter
2. The Design Example
- 10W Synchronous Buck Converter
BioMedical Instrumentation Lab., BME, Yonsei University
Introduction of the Quasi-resonant converters
• 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 !!!
BioMedical Instrumentation Lab., BME, Yonsei University
ZCS Quasi-resonant Converter
• Zero Current Switching quasi-resonant
Switching Power Supply (ZCS QR SMSP)
• Always switched when the Current is Zero
• Type L, Type M
BioMedical Instrumentation Lab., BME, Yonsei University
ZCS Quasi-resonant Converter
BioMedical Instrumentation Lab., BME, Yonsei University
ZCS Quasi-resonant Converter – Mode 1
•
•
•
•
•
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
BioMedical Instrumentation Lab., BME, Yonsei University
ZCS Quasi-resonant Converter – Mode 2
•
•
•
•
•
•
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
BioMedical Instrumentation Lab., BME, Yonsei University
ZCS Quasi-resonant Converter – Mode 3
• 0 ~ t3 까지의 동작
• IL = Io - Im*sin(wt) 로 주어진다.
• Vc(pk) = 2Vs * cos(wt)
• t3 
LC sin 1 (
Io  L
)
Vs  C
BioMedical Instrumentation Lab., BME, Yonsei University
ZCS Quasi-resonant Converter – Mode 4
• 0 ~ t4 까지의 동작
• Vc = V(c3) – (Io/C)*t
• t4 = V(c3) * C/Io
BioMedical Instrumentation Lab., BME, Yonsei University
ZCS Quasi-resonant Converter – Mode 5
• 0 ~ t5 까지의 동작
• t5 = T – (t1 + t2 + t3 + t4)
fr 
1
2
LC
BioMedical Instrumentation Lab., BME, Yonsei University
ZVS Quasi-resonant Converter
• Zero Voltage Switching quasi-resonant
Switching Power Supply (ZCS QR SMSP)
• Always switched when the Voltage is Zero
BioMedical Instrumentation Lab., BME, Yonsei University
ZVS Quasi-resonant Converter
BioMedical Instrumentation Lab., BME, Yonsei University
ZVS Quasi-resonant Converter – Mode 1
•
•
•
•
•
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
BioMedical Instrumentation Lab., BME, Yonsei University
ZVS Quasi-resonant Converter – Mode 2
•
•
•
•
•
•
0 ~ t2 까지의 동작
스위치 S1은 OFF 상태로 남아있고, 다이오드 Dm 은 ON
Vc = Vm*sin(wt) + Vs 로 주어진다.
이때 피크 스위치 전압은 I 0 L  Vs
C
인덕터 전류 IL = Io * cos(wt)
t2 =  LC
BioMedical Instrumentation Lab., BME, Yonsei University
ZVS Quasi-resonant Converter – Mode 3
• 0 ~ t3 까지의 동작
• Vc = Vs – Vm*sin(wt)
• IL = - Io * cos(wt)
• t3 
LC sin 1 (
Io  L
)
Vs  C
BioMedical Instrumentation Lab., BME, Yonsei University
ZVS Quasi-resonant Converter – Mode 4
•
•
•
•
0 ~ t4 까지의 동작
스위치 S1 -> On, 다이오드 Dm 은 On 상태 유지
IL = IL3 + (Vs/L) * t
t4 = (Io – IL3) / ( L/Vs )
BioMedical Instrumentation Lab., BME, Yonsei University
ZVS Quasi-resonant Converter – Mode 5
• 0 ~ t5 까지의 동작
• t5 = T – (t1 + t2 + t3 + t4)
BioMedical Instrumentation Lab., BME, Yonsei University
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
Thank you for your attention !
BioMedical Instrumentation Lab., BME, Yonsei University
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