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Single-Inductor Dual-Output Soft-Switching Converter with Voltage-mode Resonant Switch
Yasunori Kobori*, Nobukazu Tsukiji, Yoshiki Sunaga, Takuya Arafune, Nobukazu Takai, Haruo Kobayashi
( Gunma University )
( IEEE ICSICT 2016 )
1
Outline 1. Introduction 2. Conventional Soft Switching Converter 2-1 Half-wave type Converter 2-2 Full-wave type Converter
3. Proposed Soft Switching Converters 3-1 Voltage-mode Converter with Clamp Circuit 3-2 Simulation Results 4. Single-Inductor Dual-Output (SIDO) Converters 4-1 Soft Switching SIDO Converter with Clamp 4-2 Simulation Results
5. Conclusion
SIDO : Single-Inductor Dual-Output
Fig.1 Our Research for Switching Converters
Functions
[Single Output]
[Dual/Multi
Output]
Low Cost
Buck/Boost Converters
SIDO Serial
(Standard type)
(Reduce Inductor)
Hysteretic Converters
(High Speed)
SIDO (Synchronizing)
Resonant Converter
(Soft Switching)
SIDO (Resonant Level)
2
●Our Research
1. Introduction
3
Outline 1. Introduction 2. Conventional Soft Switching Converters 2-1 Half-wave type Converter 2-2 Full-wave type Converter
3. Proposed Soft Switching Converters 3-1 Voltage-mode Converter with Clamp Circuit 3-2 Simulation Results 4. Single-Inductor Dual-Output (SIDO) Converters 4-1 Soft Switching SIDO Converter with Clamp 4-2 Simulation Results
5. Conclusion
SIDO : Single-Inductor Dual-Output
4
Fig.3 Major Signals
PWM
SAW
IL Io
⊿Vo
2. Conventional Soft Switching Converter
● Normal Buck Converter * Clock pulse generates Saw-tooth(SAW) signal. * SW is controlled by PWM signal, * PWM is generated by comparing ⊿Vo and SAW signal.
Fig.2 Standard Buck Converter
SW Lo Vi Vo
PWM
SAW
AMP
Co RL Do
Clock
COMP1
⊿Vo
PWM: Pulse Width Modulation
Fig.4 Half-wave Converter 5 Fig.5 Major Signals
2-1 Voltage-mode Soft Switching Converter 【Half-wave type converter】 ・Resonant Inductor Lr & Resonant Capacitor Cr are added. ・When SW is OFF, resonant voltage Vr goes up & down. ・ No clock, so SAW is triggered & PWM turns [H], when Vr = VD. ⇒ Zero-Voltage Switching (ZVS) ⇒ Reduce Switching Loss
PWM
SAW
Ir
IL
Vr GND
Io
Vi
Trigger
Vo
PWM
SAW
AMP
Co RL
Vr COMP2
COMP1
SW
Lo
Vi
Cr
Lr
Do
Vr Ir IL VD
VD
⊿Vo
6 Fig.8 Simulation Results Fig.5 Major Signals
PWM
SAW
Ir
IL
Vr GND
Io
Vi
● Simulation Results (SIMPLIS 7.0) * Simulation Conditions: ・Vi=10V, Vo=5V, Io=0.25A Lr=20uH, Cr=100pF * Simulation Results: FOP = 380kHz, Vr = 125V Ir = -0.25A, ID = 0.50A
[ms]
125V
V
-0
20
40
60
80
100
120
time/mSecs 500nSecs/div
7.9995 8 8.0005 8.001 8.0015 8.002 8.0025 8.003
?
Y3
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
mA
Y2
-200
-100
0
100
200
300
400
500
To=2.62 us
VD
Vr
I D I L
I r -270mA
540mA
Fig.6 Full-wave Converter 7 Fig.7 Major Signals
Vo
PWM
SAW
AMP
Co RL
Vr COMP2
COMP1
Lo
Vi
Cr
Lr
Do
Vr Ir IL VD
VD
【Full-wave type converter】
・Only Diode is added to Half-wave type converter.
・The resonant voltage Vr goes positive & negative. ⇒ Diode blocks conduction of Body-Diode BD, when Vr < 0.
PWM
SAW
Ir
IL
Vr GND
Io
Vi
BD
⊿Vo
Trigger
8 Fig.9 Simulation Results Fig.7 Major Signals
●Simulation Results ・Simulation Conditions are same. ・Resonant Results: Fop=830 kHz, Vr=Vi±115V, Ir = -0.25A, Id = 0.50A
PWM
SAW
Ir
IL
Vr GND
Io
Vi [ms]
-260mA
V
-150
-100
-50
0
50
100
150
time/mSecs 200nSecs/div
3.8994 3.8996 3.8998 3.9 3.9002 3.9004 3.9006 3.9008 3.901
mA
-300
-200
-100
-0
100
200
300
400
500
125V
To=1.2 us
Vr
Vd
Ir
Id Io 500mA
-105V
9
Outline 1. Introduction 2. Conventional Soft Switching Converters 2-1 Half-wave type Converter 2-2 Full-wave type Converter 3. Proposed Soft Switching Converters 3-1 Voltage-mode Converter with Clamp Circuit 3-2 Simulation Results 4. Single-Inductor Dual-Output (SIDO) Converters 4-1 Soft Switching SIDO Converter with Clamp 4-2 Simulation Results
5. Conclusion
SIDO : Single-Inductor Dual-Output
Fig.10 Proposed Half-wave Converter 10
3-1 Voltage-mode Converter with Clamp Circuit
【Half-wave type converter】
・Add clamp circuit with Zener Diode. (Vz is 40V.) ・Peak voltage of Vr is suppressed from at 125V to 44V. (35%) ・ Resonant current Ir is suppressed from 250mA to 70mA. (30%) ・ Operating period Top is changed from 2.62us to 2.02us. (77%)
Vo SW Vi
Cr
Lr Vr
IL VD
ZD
Fig.11 Simulation Results
Vr / V
-60
-40
-20
0
20
40
60
time/mSecs 500nSecs/div
7.799 7.7995 7.8 7.8005 7.801 7.8015 7.802
mA
-200
-100
0
100
200
300
400
500
Vr
Id
Ir
2.04us
3. Proposed Soft-Switching Converter
Fig.12 Full-wave Converter 11
【Full-wave type converter】
・Clamp circuit like Half-wave type.
・Peak voltage of Vr is suppressed from at 125V to 44V. (35%) ⇒ Low break-voltage BVDS MOSFETs can be used. ・ Resonant current Ir is suppressed from 250mA to 90mA. (35%) ・ Operating period Top is changed from 1.2us to 3.7us. (X3.1)
Vo SW Vi
Cr
Lr Vr
IL VD
ZD
Fig.13 Simulation Results
Vr
Vc / V
-60
-40
-20
0
20
40
60
time/mSecs 1uSecs/div
4.898 4.899 4.9 4.901 4.902 4.903
mA
-200
-100
0
100
200
300
400
500
44V
Id
Ir
3.7us -20V
0.33A
-0.09A
Fig.14 Ripple of Half-wave Converter 12
3-2 Simulation Results
【Output Voltage Ripples】
* Vo=5.0V (Half-wave), Vo=7.0V (Full-wave) ・Stable output ripples are less than 2 mVpp @ Io=0.50A. ・Over/Under-shoots are less than ±15mV @⊿Io=0.25A.
time/mSecs 200uSecs/div
3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4
V
4.97
4.98
4.99
5
5.01
5.02
5.03
With Clamp
W/O Clamp 13mV
12mV
0.25A 0.25A 0.50A
Fig.15 Ripple of Full-wave Converter
12mV
time/mSecs 200uSecs/div
3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4
V
6.97
6.98
6.99
7
7.01
7.02
7.03
W/O Clamp
12mV
With Clamp
0.25A 0.25A 0.50A
13
Outline 1. Introduction 2. Conventional Soft Switching Converters 2-1 Half-wave type Converter 2-2 Full-wave type Converter
3. Proposed Soft Switching Converters 3-1 Voltage-mode Converter with Clamp Circuit 3-2 Simulation Results 4. Single-Inductor Dual-Output (SIDO) Converters 4-1 Soft Switching SIDO Converter with Clamp 4-2 Simulation Results
5. Conclusion
SIDO : Single-Inductor Dual-Output
OP amp1 Power
Stage
OP amp2
VD
Vr
Fig.16 SIDO Converter with Clamp 14
4-1 Soft Switching SIDO Converter with Clamp ・It consists of Power stage, Two sub-converters and controller. ・SEL signal is decided by comparing ⊿V1 and ⊿V2. ・Each period is different. SEL & SAW are synchronized with PWM.
★Reduce Lo, Lr, Cr, ZD.
Fig.17 Simulation Results (Full-wave)
4. Single-Inductor Dual-output Converter
SEL
PWM
Vr IL S
EL / V
0
1
2
3
4
PW
M / V
0
1
2
3
4
5
time/mSecs 5uSecs/div
4.5 4.505 4.51 4.515 4.52
IL / A
0.4
0.6
0.8
1
1.2
1.4
V
Y1
-20
0
20
40
60
15
4-2 Simulation Results A) Output Voltage Ripples (Vo1=5.0V, Vo2=4.0V, Vz=40V) ・Current step: Io1= 0.50A ⇔ 0.75A, Io2= 0.25A ⇔ 0.50A ・Stable Ripples : < 5mVpp (<0.2%) @ Io=0.75A ・Overt/Under-shoots: ≒±12mV (≒0.25%) @⊿Io=0.25A (Blue Arrows show Self-Regulation, Red Arrows do Cross-Regulation. )
Fig.19 Ripple of Half-wave Converter
±9 mV
[ms]
Vo1 / V
4.97
4.98
4.99
5
5.01
5.02
5.03
time/mSecs 1mSecs/div
5 6 7 8 9
VO
2 / V
3.97
3.98
3.99
4
4.01
4.02
4.03
±9 mV
1 ms
V2=4V
V1=5V
I1=0.50A 0.50A 0.75A
I2=0.25A 0.25A 0.50A
Cross-Regulation
±9 mV
Fig.18 Ripple of Full-wave Converter
Vo1 / V
4.97
4.98
4.99
5
5.01
5.02
5.03
time/mSecs 1mSecs/div
4 5 6 7 8 9
VO
2 / V
3.97
3.98
3.99
4
4.01
4.02
4.03V2=4V
V1=5V 1 ms ±12 mV
±10 mV
I1=0.50A 0.50A 0.75A
I2=0.25A 0.25A 0.50A
Self-Regulation
V2=4V
V1=5V 1 ms ±12 mV
±10 mV
I1=0.50A 0.50A 0.75A
I2=0.25A 0.25A 0.50A
16
5. Conclusion 1. Proposed Soft Switching Converters with Zener Clamp
* Conditions: Vo=5.0V, Io=0.25A, Vz=40V
1) Suppress resonant voltage from 125V to 44V (35%).
⇒ MOSFETs with Low BVDS can be used.
2) Suppress resonant current from 260mA to 90mA (35%).
3) Stable output ripples : < 2mVpp @ Io = 0.50A.
4) Over/Under-shoots : ±15mV @⊿Io = 0.25A.
2. SIDO Soft Switching Converters with Clamp
* Conditions: Vo1=5.0V, Vo2=4.0V, Io1=0.5A, Io2=0.25A
1) Stable output ripples : < 5mVpp @ Io = 0.75A.
2) Over/Under-shoots : ±12mV @⊿Io = 0.25A.
17
Thank you for your attention!
謝 謝
18
3-2 Simulation Results
【Operation Period Top vs. Output Current Io 】
・ In Full-wave converter, Top changes from 1.7us to 13.2us. (X7.5) ・ In Half-wave converter, Top is reduced from 10us to 6.2us. (62%) ・ Clamp method is good for Half-wave converter. [TF: Full-wave, TH: Half-wave] [Tw: with Clamp, To: without Clamp]
Fig.16 Operating Period Top vs. Output current Io
[us]
[A]
THo
THw
TFo
TFw
Half-wave
Fig.21 Power Loss of SISO (SISO: Single-Inductor Single-Output) 19
Fig.22 Power Loss of SIDO
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 0.25 0.5 0.75 1
Psw(SISO*2) Psw(SIDO) ⊿Po
SIDO
SISO*2
Difference
0.0
0.5
1.0
1.5
2.0
2.5
0 0.5 1 1.5 2 2.5
Psw(従来) Psw(ソフトSW) ⊿Po [W]
[A]
B) Power Loss vs. Output Current Io ・Power loss of W/O clamp is better than that of with clamp. ・It is difficult to improve the efficiency in Soft Switching. But ・・・
Psw(Soft SW) Psw(Conv.)
Conventional
Soft Switching
Difference
Fig.23 Spectrum of Voltage of SW 20
C) Spread Spectrum of Vsw ・Spectrum of Voltage between Switching element. ・More than 50MHz, spectrum level of soft switching converter is better than that of the conventional one. ・Soft switching converter may be good for EMI reduction.
Frequency/MHertz 20MHertz/div
-0 20 40 60 80 100 120 140 160 180 200
V
10u
100u
1m
10m
100m
1
10
Soft Switching Converter Conventional Converter
50MHz
SW Vi Vo
V
21
【 Operating 0】 * State 0: ・First, PWM=[H] & SW=ON ・VD = Vi, Do = OFF ⇒ Ir = IL (Increasing)
【Conditions】 * Resonant Condition:Vi<Vr = Io・Zr (Zr=√(Lr/Cr) Characteristics Z
* Resonant Frequency:Fr= 1/2π√(Lr・Cr) ( ≠ Operating Frequency)
Vi Vo
PWM=H
VD
IL Ir
Vr
Lo Lr
PWM
SAW
Ir
IL
Vr GND
Io
Vi
Fig.4-1 Half-wave Converter Fig.5-1 Major Signals
SW=ON
22
IL
PWM
SAW
Ir
IL
Vr GND
Io
Vi
Vi Vo
PWM=L
Vr Ir
VD
Cr
Lr
ID
【 Operating 1】 * State 1: ・Vo is increasing & Vo > Vref, then PWM turns [L] & SW=OFF ・L & C start resonating. ⇒ Ir is charging C and Vr goes up. Diode turns ON and VD is -VF. ・After Ir=0, Ir direction turns reverse and Vr lowers to 0V. ・Finally, Vr reaches to VD =-VF.
Fig.4-2 Half-wave Converter Fig.5-2 Major Signals
23
Vi Vo
PWM=H
Vr Ir
VD
PWM
SAW
Ir
IL
Vr GND
Io
Vi
ID
Fig.4-3 Half-wave Converter Fig.5-3 Major Signals
【 Operating 2】 * State 2: ・When detect VD =-VF, SAW is reset & PWM turns [H] & SW=ON ・L & C resonance stops. ⇒ ・After Ir=0, Ir direction turns reverse and Vr lowers to 0V. ・Finally, Vr reaches to VD =-VF.
Io=0.25 A
[V]
[ms]
Io=0.25 A
Io=0.50 A
±15mV
24
* Step Response: Io = 0.25A ⇔ 0.50A
・Stable output ripples <2mVpp @ Io= 0.5A
・Step Responses (Over/Under shoots)<±15mV
Fig.10 Step Responses
2-2 Simulation Results 【 Output Voltage Ripples 】
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