Two-Phase Soft-Switching DC-DC Converter with …...Two-Phase Soft-Switching DC-DC Converter with...

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



•Two-phase DC-DC converter solution



•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






•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


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


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






•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


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


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






•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


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|)


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


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


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






•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


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


Load Current and Current Balance


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






•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.

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