Two-Phase Soft-Switching DC-DC Converter with Voltage-Mode Resonant Switch
Yi Xiong*, Yifei Sun, Nobukazu Tsukiji, Yasunori Kobori, Haruo Kobayashi
Gunma University
NA-L5: Circuits & Systems I
Thursday, November 9, 2017
08:30 – 08:50
2Research Objective
Development of power supply with
- Low noise
- Fast response
- High efficiency
- Soft-switching with voltage-mode resonant
- Multi-phase
Approach
Objective
3Contents
•Research background
•Voltage-mode resonant switch control
•Two-phase converter solution
•Simulation result
•Characteristics test
•Conclusion
4Contents
•Research background
•Voltage-mode resonant switch control
•Two-phase DC-DC converter solution
•Simulation result
•Characteristics test
•Conclusion
5What is Power Supply ?
100~240V AC
4.2V DC
Power supply is demanded everywhere to
provide appropriate voltage for electronic device
AC-DC Converter
DC-DC Converter
Power
Supply
6Classifications of DC-DC Converter
Buck Boost Buck-Boost
Basic configurationDC-DC converter
Vin<VoVin>Vo Vin Vo
Load
7Operation of Buck Converter
VinVo
Q L
CD
PWM
Buck Converter
Vo+
-
L
C
+
-
+-
Vo
+
-
Vin +
-
L+ -
C
Q VEO
VEO
DVin
On State: Q on D off
VQ
IL
IL
VQ
IL
VEO
Ton Toff
ΔIL+
ΔIL-
Off State: Q off D on
Volt-second
Balance
VLon = Vin-Vo= L・(⊿iL+/⊿ton)
VLoff =-Vo= L・(⊿iL-/⊿toff)
⊿iL+ = ⊿iL-
On State
Off State
Vo = Vin
Ts
𝑇𝑜𝑛
𝑇𝑠
8Demand for Power Supply
Low noiseHigh
efficiency
Soft-switchingVoltage-mode
control
Fast
response
Multi-phase
Two-phase voltage-mode soft switching
DC-DC converter
9Contents
•Research background
•Voltage-mode resonant switch control
•Two-phase DC-DC converter solution
•Simulation result
•Characteristics test
•Conclusion
10Normal Voltage-mode Control
PWM
ILo
SAW
ΔVo
Lr Lo
Co Ro
Vin
Vref
Do
VoIo
Saw tooth Wave Generator
VfbPWM
Driver
CompAmp
Clock
SW
ΔVo
Voltage-mode Converter
Saw-tooth signal is generated by external clock
PWM is generated by closed-loop control
Switching loss
Operation Waveform
Hard Switching
VSW
ISW
Turn off Turn on
Δton Δtoff
Slow respondΔPsw
11
V
-200
-50
100
-0
200
400
time/mSecs 200nSecs/div
2.0236 2.0238 2.024 2.0242 2.0244 2.0246 2.0248
PW
M1 /
V
0
2
4
V
-200
-50
100
-0
200
400
time/mSecs 200nSecs/div
2.0236 2.0238 2.024 2.0242 2.0244 2.0246 2.0248
PW
M1 /
V
0
2
4PWM
Ids
Vr
Vd
Operation WaveformT1 T2
Voltage-mode Resonant Switch
Db
DrLr Lo
Co Ro
Vin
Vr Vd
Vref
Do
Vo
Cr
Io
Saw tooth Wave Generator
VfbPWM
Driver
Vd
Vr
CompAmp
Ir
Ids
Vr
Voltage-mode Resonant Converter
Isw
Turn off Turn on
Δton Δtoff
Vsw
Resonant Inductor Lr & Resonant Capacitor Cr
Saw-tooth is generated without clock
Soft Switching
T1 The switch turns off when Vr is nearly 0
T2 The switch turns on when Ids is nearly 0
Soft-switching is achieved
≈ 0
ΔPsw ≈ 0Isw
+ -
T3
T1~T2
T2~T3 +-
Ta Tb
Ta~Tb
T1~Ta
Tb~T3
Ir
12Contents
•Research background
•Voltage-mode resonant switch control
•Two-phase DC-DC converter solution
•Simulation result
•Characteristics test
•Conclusion
13Demerit of Single-Phase Converter
One-phase converter
The whole output current
Io will flows only through
inductor Lo
Db
DrLr Lo
Co Ro
Vin
Vr Vd
Vref
Do
Vo
Cr
Io
Saw tooth Wave Generator
VfbPWM
Driver
Vd
Vr
CompAmp
Ir
Ids
Io
Lo will be large in size
PMW
ILo=Io
Large load on
Inductor Lo100A
Vo
14Merit of Two-Phase Converter
Two-phase converter
Inductor L1 and L2 will
go shares with the Io
L1 and L2 will be small
in size
180°phase difference
Load of each phase’s
inductor halved
Simulative frequency
multiplication
Db1
Dr1Lr1 L1
Co Ro
Vin
Vr Vd
Vref
Vr
VdPWM1
Do1
PWM2
Vo
Lr2Dr2
Db2
Cr1
Cr2
Do2L2
Amp
Comp2
Io
Multiphase controller
IL1
IL2
IoVo
IL1
IL2
ILo=IL1+IL2
PWM1
PWM2
50A
50A
100A
VoLow ripple by shifted
two-phase peak current
180°
15Difficult to get Multi-Phase without Clock
Voltage-mode resonant converter
No clock
Frequency & phase
swinging
Db
DrLr Lo
Co Ro
Vin
Vr Vd
Vref
Do
Vo
Cr
Io
Saw tooth Wave Generator
VfbPWM
Driver
Vd
Vr
CompAmp
Ir
Ids
Power supply for sever process
Vout
Clock inside
Four-phase or more is normal
Easy to get
multi-phase
PWM
PMW1
PMW2
PMW3
PMW4
Difficult to get
multi-phase PWM
PMW1
PMW2
PMW3
PMW4
Tracking PWM
with PWM1 is
demanded
without clock
Io Vo
16Proposed Two-Phase Converter Solution
PMW1
Peak Hold
Db1
Dr1Lr1 L1
Co Ro
Vin
Vr Vd
Vref
Vr
Vd
PWM1
Do1
PWM2
Vo
RR
SAW1
SAW2
Lr2Dr2
Db2
Cr1
Cr2
Do2L2
Amp
Comp1
Comp2Comp3Comp4
Io
I1
DC
I2
IoVo
Peak hold circuit
180° 180°
𝟏
𝟐Vp
Vp
t
IL1
IL2
SAW2 Generator
SAW1 Generator
Two-phase control Two-phase PWM simulation result
SAW1
PMW1
SAW2
PMW2
17Contents
•Research background
•Voltage-mode resonant switch control
•Two-phase DC-DC converter solution
•Simulation result
•Characteristics test
•Conclusion
18Parameters and Key Waveforms
𝑉𝒊𝒏 12V
𝑉𝑜 7V
𝐿𝑟1, 𝐿𝑟2 20uH
𝐶𝑜 200uF
𝐶𝑟1, 𝐶𝑟2 100pF
𝐼𝑜 500mA
𝐹𝑜𝑝 1.295MHz
Peak Hold
Db1
Dr1Lr1 L1
Co Ro
Vin
Vr Vd
Vref
Vr
Vd
PWM1
Do1
PWM2
Vo
RR
SAW1
SAW2
Lr2Dr2
Db2
Cr1
Cr2
Do2L2
Amp
Comp1
Comp2Comp3Comp4
Io
I1
DC
I2
IoVo
IL1
IL2
SAW2 Generator
SAW1 Generator
Two-phase control
VO
/ V
7.00022
7.00024
7.00026
SA
W2 /
V
0.5
2
SA
W1 /
V
0.5
2
PW
M2 /
V
0
2
4
PW
M1 /
V0
2
4
IL2 /
mA
235
250
265IL
1 /
mA
230
245
260
time/mSecs 500nSecs/div
2.8285 2.829 2.8295 2.83 2.8305 2.831 2.8315
Io /
mA
494
504
[t/ms]
Circuit parameters & simulation
Vo
Io
SAW1
SAW2
PMW1
PMW2
IL1
IL2
19Current Balance
Current balance offset ΔIL (ΔIL = |IL – Io/2|)
time/mSecs 500nSecs/div
2.829 2.8295 2.83 2.8305 2.831
mA
200
250
300
350
400
450
500
550
ILo mean = 500mA
IL2mean = 252.4mA
IL1mean = 247.6mA
I/
mA
ΔIL1 = IL1 - Io/2
= |247.6-500/2|=2.4mA
ΔIL2 = IL2 - Io/2
= |252.4-500/2|=2.4mA
ΔIL1 = ΔIL2
δ = 2.4/(500/2)×100% = 0.96% [t/ms]
time/mSecs 1mSecs/div
2 3 4 5 6 7 8 9 10
I /
A
0
0.5
1
1.5
2
2.5
IL2
IL1
ILo
I/A
[t/ms]
1.18ms
1.47ms
1.51ms
VO
/ V
6.984
6.988
6.992
6.996
7
7.004
time/mSecs 5uSecs/div
3 3.005 3.01 3.015 3.02 3.025 3.03 3.035
I /
mA
250
350
450
550
IL2 keeps pace with IL1 during the transient response
Current balance & transient response
20Comparison
VO
/ V
7
7.0001
7.0002
7.0003
7.0004
time/mSecs 5uSecs/div
2.905 2.91 2.915 2.92 2.925 2.93 2.935 2.94
VO
/ V
7.0001
7.0002
7.0003
7.0004
0.09mV
0.05mV
Conventional
Two-phase
Vo /
V
[t/ms]
VO
/ V
6.985
6.995
7.005
VO
/ V
6.985
6.995
7.005
time/mSecs 200uSecs/div
2.8 3 3.2 3.4 3.6 3.8 4
S8-C
P /
V
1
3
23.1mVpp
14.5mVpp
Conventional
Two-phase
1.0A 0.5A0.5A
Io/A
Vo
/V
[t/ms]
Conventional Two-phase
Output Voltage ripple
0.09mV 0.05mV
Conventional Two-phase
Overload Vpp 19.8mV 8.8mV
Underload Vpp 15.7mV 8.7mV
Recover time 0.27ms / 0.23ms 0.20ms / 0.18ms
Static State Characteristic
Dynamic Load Regulation
Output Voltage ripple 44.4% off
Transient response peak to peak
voltage 37.2% off
21Content
•Research background
•Voltage-mode resonant switch control
•Two-phase DC-DC converter solution
•Simulation result
•Characteristics test
•Conclusion
22Characteristics Test 1
2.2
2.25
2.3
2.35
2.4
2.45
2.5
-40 -30 -20 -10 0 10 20 30 40
ΔI L
2/[
mA
]
Δt/[ns]
ΔIL22.46mA
Maximum of ΔIL2 is 2.46 mA
deviating less than 1%
Relationship between
Phase Displacement & Current Balance
-1.0%
-0.8%
-0.5%
-0.3%
0.0%
0.3%
0.5%
0.8%
1.0%
-4
-3
-2
-1
0
1
2
3
4
Δt/
[ns]
Io/[A]
Δt phase deviation rate
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Phase displacement shifts less than ±1ns
even the load current is 4.0A
Relationship between
Load Current & Phase Displacement
Io= 0.5A
23Characteristics Test 2
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
0
5
10
15
20
25
30
35
40
45
50
0 0.5 1 1.5 2 2.5 3 3.5 4
σ/%
ΔI L
2/[
mA
]
Io/[A]
ΔIL2 current deviation ratio
2
2.1
2.2
2.3
2.4
2.5
2.6
0.833 0.876 0.926 0.987 1.063 1.161 1.295
I L2/[m
A]
Fop/[MHz]
ΔIL2 Io= 0.5A
Relationship between
Load Current and Current Balance
Relationship between
Load Current and Current Balance
ΔIL2 rises in proportion to
increasing load current
ΔIL2 changes a little by varying operation freq.,
getting little current offset ratio less than 1%
24Contents
•Research background
•Voltage-mode resonant switch control
•Two-phase DC-DC converter solution
•Simulation result
•Characteristics test
•Conclusion
25Conclusion
• We have proposed
two-phase DC-DC converter
with voltage-mode resonant switch.
• Low output voltage ripple, fast response
are achieved.
• Stable characteristic of current balance
is tested.
26
Thank you for listening
谢谢
27Q&A
Q:How many times did you do the simulation until the result coming out.
A:Actually, I did many times for the simulation. As for the voltage resonant switch, there is a necessary condition that Vrmax = IoZn to achieve the soft-switching. As for the characteristics of current balance, I also did many times for the simulation to get the necessary data to paint the graph.
Q:What is the difference between convectional and two-phase converter.
A:The output voltage ripple has get off by 44.4%. The voltage step-up and down during the transient response also low, so do the recovery time.