Three-Level Converters – A New Approach for High Voltage ...ruanxb.nuaa.edu.cn/Home/Ruan Xinbo_Home_files/PE-tutorial_A_Famil… · Buck/Boost Cuk Sepic Zeta. 2012-12-10 11 A Family

2012-12-10 1

Three-Level Converters – A New Approach for High Voltage and High Power DC-DC Conversions

Presented by

Xinbo Ruan

College of Electrical and Electronic EngineeringHuazhong University of Science and Technology

2012-12-10 2

Outlines

1. Backgrounds

2. Derivation of a Family of Three-Level Converters

3. Improved and Simplified Three-Level Converters

4. Buck TL Converter

5. ZVZCS PWM Hybrid Full-Bridge Three-Level

Converter

6. Possible of Three-Level Voltage

7. Conclusions

2012-12-10 3

Outlines

1. Backgrounds





Converter


7. Conclusions

2012-12-10 4

Vin

D1

D2

AB

Cd2

Q3

Q4

D3

D4

D6

Tr

DR1

DR2

Q1

Q2

Cd1D5

Lf

Cf

RLd

Vo

+

-

C

D

3-phase 380V±20% ac input is rectified

to a dc voltage:

w/o PFC: Vdcmax = 630V

with PFC: Vdc = 800-1000V

Backgrounds

Three-Level Converter

☺ The voltage stress of the power

switch is half of the input voltage.

In order to reduce the voltage stress of the switches

2012-12-10 5

Vin

D1

D2

AB

Cd2

Q3

Q4

D3

D4

D6

Tr

DR1

DR2

Q1

Q2

Cd1D5

Lf

Cf

RLd

Vo

+

-

C

D

- The voltage stress of the switches is the half of the input voltage;

- It is attractive for high voltage and high power dc/dc conversions

Vin

D1

D2

AB

Cd2

Q3

Q4

D3

D4

Tr

DR1

DR2

Q1

Q2

Cd1Lf

Cf

RLd

Vo

+

-

C

DVin

D1

AB

Cd2 Q2 D2

Tr

DR1

DR2

Q1Cd1

Lf

Cf

RLd

Vo

+

-

C

D

Derivation of Half-Bridge TL Converter

2012-12-10 6

Motivation

Extend the derivation of Half-Bridge Three-Level

converter to all the DC-DC converters

To reduce the voltage stress

of the switches.

2012-12-10 7

Outlines

1. Backgrounds





Converter


7. Conclusions

2012-12-10 8

TL Switch Cells

Vin

D1

D2

AB

Cd2

Q3

Q4

D3

D4

D6

Tr

DR1

DR2

Q1

Q2

Cd1D5

Lf

Cf

RLd

Vo

+

-

C

D

Q1

Q2

Dc

a

bc

Vcl /2

Vcl /2

Anode Cell

Q1

Q2

Dc

a

b

c

Vcl /2

Vcl /2

Cathode Cell

- Two series switches;- Clamping voltage source splitting

into two equally;- Clamping diode.

2012-12-10 9

Derivation of Buck TL Converter

Lf

Vin Cf

RLd

Vo

+

-D1

Q Lf

Vin Cf

RLd

Vo

+

-D1

Q1 Q2

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D1

Q1 Q2Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D1Dc

Q1 Q2

2012-12-10 10

A Family of TL Converters

BuckBoost

Buck/Boost Cuk

Sepic Zeta

2012-12-10 11


Forward Flyback

Push-Pull

2012-12-10 12

Full-Bridge

Half-Bridge


Vin

D1

D2

AB

Cd2

Q3

Q4

D3

D4

Dc2

TrDR1

DR2

Q1

Q2

Cd1

Dc1

Lf

Cf

RLd

Vo

+

-*

**

2012-12-10 13

Outlines

1. Backgrounds





Converter


7. Conclusions

2012-12-10 14

Output Waveform

v

0

VinVo

Vin /2

t

v

0

VinVo

t

Lf

Vin Cf

RLd

Vo

+

-D1

Q Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D1Dc

Q1 Q2

Buck Converter Buck TL Converter

2012-12-10 15

Problems of Buck TL Converter

v

0

VinVo

Vin /2

t

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D1Dc

Q1 Q2

VinCd2

Cd1

Cf

RLd

Vo

+

-D1Dc

Q1 Q2Cd2 provides moreenergy, which results in unbalance of voltage of the input divided capacitors

2012-12-10 16

D2

Q2

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D3

Q4

v

0

VinVo

Vin /2

t

D2

Q2

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D3

Q4

Cd1 provides moreenergy, which results in unbalance of voltage of the input divided capacitors

D2

Q2

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D3

Q4

Problems of Buck TL Converter

2012-12-10 17

Combined Buck TL Converter

D2

Q2

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D3

Q4

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D1Dc

Q1 Q2

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D3

D1

Q1

Q2

D2

Q3

Q4B

A

2012-12-10 18

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D3

D1

Q1

Q2

D2

Q3

Q4B

A

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D3

D1

Q1

Q2

D2

Q3

Q4B

A

vAB

0

t

Q2

Q1

Vo

Vin /2

t

t

Vin

t

t

Q3

Q4

Ts 3Ts' '2Ts'

Ts Ts

4Ts'

The voltage of the divided capacitors are Balanced.

Combined Buck TL Converter

2012-12-10 19

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

Improved Buck TL Converter

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D3

D1

Q1

Q2

D2

Q3

Q4B

A

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-D3

D1

Q1

Q2

D2

B

A

vAB

0

t

Q2

Q1

Vo

Vin /2

t

t

Vin

t

t

Q3

Q4

Ts 3Ts' '2Ts'

Ts Ts

4Ts'

2012-12-10 20

vAB

0

t

Q2

Q1

Vo

Vin /2

t

t

Vin

t

t

Q3

Q4

Ts 3Ts' '2Ts'

Ts Ts

4Ts'

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

vAB

0

t

Q2

Q1

Vo

Vin /2

t

t

Vin

t

t

Q3

Q4

Ts 3Ts' '2Ts'

Ts Ts

4Ts'

1. The voltage of the divided capacitors are balanced;

2. The ripple frequency of vAB is twice the switching frequency;

3. Q1 and Q2 are interleaving switched.

Improved Buck TL Converter

2012-12-10 21

Improved TL Converters

Lf

Cf

RLd

Vo

+

-

D1

D2

Q2

VinCd2

Cd1

Q1

Lb

Vin

Cf1

RLd

Vo

+

_

D1

D2

Q1

Q2Cf2

BuckBoost

Buck/Boost Cuk

Sepic

LfCf1

RLd

Vo

_

+

D1

D2Q2

VinCd2

Cd1

Cf2

Q1

L1

Vin

Q1

Q2

Cb1

Cb2

Cf1

RLd

Vo

+

_

D1

D2

Cf2

L2 L1

Q2

VinCd2

Cd1

Q1

Cf

RLd

Vo

+

-

D1

D2

Cb1

Cb2

Zeta

2012-12-10 22

Simplified Forward TL Converter

Vin

Q1

**

Q2

*

Tr1

DR1 RLd

Vo

+

-

Lf

DFW

D1Dc

Vin

Q1

*

Q2

*

Tr1

DR1RLd

Vo

+

-

Lf

DFW

D1

D2

A

Vin

Q1

**

Q2

*

Tr1

DR1 RLd

Vo

+

-

Lf

DFW

D1Dc

Vin

Q1

**

Q2

*

Tr1

DR1 RLd

Vo

+

-

Lf

DFW

D1

Dc

Q1 and Q2 conduct Q1 on, Q2 off

Q1 off, Q2 off

2012-12-10 23*

Q1 Q2

D1Cd1

Cd2

TrVin

Derivation of Hybrid Full-Bridge TL Converter

*

Q3 Q4

D2

Cd1

Cd2

TrVin

Cd1Q1

Cd2

D7

D8Vin

Q5

Q6

Q2

Q3

Q4

A

B

Tr

*

2012-12-10 24

Outlines

1. Backgrounds





Converter


7. Conclusions

2012-12-10 25

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_3L

ILfmax_3L

Vin/2

Vin

ToffTon

t

t

t

0

Ts

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_2L

ILfmax_2L

Vin/2

ToffTon

t

t

t

0

Ts

Key Waveforms

D > 0.5 D < 0.5

2012-12-10 26

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_3L

ILfmax_3L

Vin/2

Vin

ToffTon

t

t

t

0

Ts

D > 0.5

Operation of Buck TL Converter: D>0.5 (1)

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

2012-12-10 27

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_3L

ILfmax_3L

Vin/2

Vin

ToffTon

t

t

t

0

Ts

D > 0.5


2012-12-10 28

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_3L

ILfmax_3L

Vin/2

Vin

ToffTon

t

t

t

0

Ts

D > 0.5

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A


2012-12-10 29

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_3L

ILfmax_3L

Vin/2

Vin

ToffTon

t

t

t

0

Ts

D > 0.5


2012-12-10 30

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_2L

ILfmax_2L

Vin/2

ToffTon

t

t

t

0

Ts

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

D < 0.5

Operation of Buck TL Converter: D<0.5 (1)

2012-12-10 31

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_2L

ILfmax_2L

Vin/2

ToffTon

t

t

t

0

Ts

D < 0.5


2012-12-10 32

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_2L

ILfmax_2L

Vin/2

ToffTon

t

t

t

0

Ts

D < 0.5


2012-12-10 33

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_2L

ILfmax_2L

Vin/2

ToffTon

t

t

t

0

Ts

D < 0.5


2012-12-10 34

1.0

0.8

0.6

Vo / Vin

A

D=1.0

D=0.9

D=0.7

D=0.8

D=0.6

D=0.5

AD=0.4

D=0.2

D=0.3

D=0.1

D=0.0

0.2

0.4

0.01.0 2.0 Io / IoGmax

Voltage Conversion Ratio

Vo / Vin = D

2012-12-10 35

Output Filter Inductance

The output inductance of Buck TL converter

reduces to 1/4 ofthat of Basic Buck converter

*_Lf BuckIΔ

*_ _Lf Buck TLIΔ

2012-12-10 36

Output Filter Capacitor

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_3L

ILfmax_3L

Vin/2

Vin

ToffTon

t

t

t

0

Ts

The output capacitor in Buck TL

converter reduces to 1/2 of that in Basic Buck converter

2012-12-10 37

Q2

iLf

Q1

vAB

t0 t1 t2 t3 t4

t

IoILfmin_3L

ILfmax_3L

Vin/2

Vin

ToffTon

t

t

t

0

Ts

Unbalanced capacitor voltage

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

ASlight difference of 1) control signal and 2) drive circuit

Slight difference of duty cycle of the two switches

Unbalanced voltage of the divided capacitors

2012-12-10 38

Divided Capacitor Voltage Sharing

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

Kf_in

infK _21

Opti-Isolated

Kf_vo

-1_

+Kp

PI

_

+Vref

Comp_1

Comp_2

Q1

Q2

2012-12-10 39

Experimental Results

vDS(Q1):[100V/div]

vDS(Q2):[100V/div]

vAB:[100V/div]

Time:[5us/div]

vDS(Q1):[100V/div]

vDS(Q2):[100V/div]

vAB:[100V/div]

Time:[5us/div]

Without Feed-Forward control With Feed-Forward control

2012-12-10 40

vDS(Q1):[100V/div]

vDS(Q2):[100V/div]

vAB:[100V/div]

Time:[5us/div]

iLf:[5A/div]

vDS(Q1):[100V/div]

vDS(Q2):[100V/div]

vAB:[100V/div]

Time:[5us/div]

iLf:[5A/div]

D > 0.5 D < 0.5


2012-12-10 41

Outlines

1. Backgrounds





Converter


7. Conclusions

2012-12-10 42

ZVZCS PWM Hybrid Full-Bridge TL Converter

2012-12-10 43

Main Circuit and Key Waveforms

Vcbp

Vcbp

I I Kp o0 = /

t

t

t

t

t

t

Q1 Q1Q4

Q2 Q2Q3

Q6 Q6Q5

vAB Vin

Vin

Vin/2Vin/2

t

Vin/2KVin/K

t0 t1 t2 t3 t4 t5 t7t6 t8 t10t9 t14t13t12t11

ip

vcb

vrect

Treset

2012-12-10 44

The Secondary Rectified Voltage

t

vrect

0Ton

Ts/2

Vin/KVo

t

vrect

0Ton Treset

Ts/2

Vin/2K

Vin/KVo

Full-Bridge Converter Full-Bridge Three-Level Converter

2012-12-10 45

424 477 530 583 6362

4

6

8

10

12

Input Voltage (V)

Lf (u

H)

Lf_FB Vin( )

Lf_hybrid Vin( )

Vin

The Filter Inductance

Full-Bridge Converter

Full-Bridge Three-Level Converter

2012-12-10 46

Parameters for Prototype Converter

-Vin=530VDC (rectified and filtered from 3 phase 380VAC/50Hz)

-Vo = 54 VDC;- Io = 50 A;- Q1(D1&C1) - Q4(D4&C4): IRF460;- Q5 and Q6: CT60AM-20;- D5 - D8: DSEI30-06A;- Rectifier diode: MEK95-06 DA;- Ratio of windings : K=19:3;- Leakage inductance Llk=6uH; - Blocking capacitor: Cb=1uF; - Output filter inductance Lf=6uH; - Output filter capacitor Cf=6600uF; - Switching frequency: fs=50kHz.

2012-12-10 47


vAB: [1000V/div]

vcb: [100V/div]

ip: [20A/div]

Time: [5us/div]

vrect: [50V/div]

iD (Q1): [5A/div]

vGS (Q1): [25V/div]

Time: [2us/div]

vDS (Q1): [250V/div]

ZVS for Chopping Switches

ZV turn-on ZV turn-off

ip reduce to zero

2012-12-10 48

ZVS for lagging SwitchesZVS for leading Switches

iD (Q2): [5A/div]

vGS (Q2): [25V/div]

Time: [2us/div]

vDS (Q2): [250V/div]

ic (Q6): [5A/div]

vBE (Q6): [25V/div]

Time: [2us/div]

vCE (Q6): [500V/div]

Zero-Currentturn-off

Zero-Current turn-onZV turn-on ZV turn-off


2012-12-10 49

vAB: [1000V/div]

vcb: [100V/div]

ip: [20A/div]

Time: [5us/div]

vrect: [50V/div]

vAB: [500V/div]

vcb: [100V/div]

ip: [20A/div]

Time: [5us/div]

vrect: [50V/div]

Two-Level ModeThree-Level Mode


2012-12-10 50

Conversion Efficiency

87

89

91

93

95

0 10 20 30 40 50Output current (A)

Effic

ienc

y (%

)

2012-12-10 51

Conversion Efficiency

290 320 350 380 410 440 470Input voltage (V)

Effic

ienc

y (%

)

93.0

93.2

93.4

93.6

93.8

94.0

94.2

2012-12-10 52

Several ZVZCS Hybrid FB TL Converters

Cb

Cd1Q1 D1

C1

Css

Cd2

D7

D8

Q2 D2C2

Q3 D3C3

Q4 D4C4

A

Tr

Llk

*

Ls

DR2

DR1Lf

Cf

RLd

*

*

Q6

B

D6

Q5 D5

Qb

Cd1Q1 D1

C1

Css

Cd2

D7

D8Vin

Q2 D2C2

Q3 D3C3

Q4 D4C4

A

TrDR1

Llk

*

DR2

*

*

Lf

Cf

Cb

Db

RLd

Q6

B

D6

Q5 D5

2012-12-10 53

Cd1Q1 D1

C1

Css

Cd2

D7

D8Vin

Q2 D2C2

Q3 D3C3

Q4 D4C4

A

TrDR1

Lf RLd

Llk

*

DR2

Cb1

Db2

Db1

Cf

*

*

Q6

B

D6

Q5 D5

Cb1 Db2

Db1Cb2

Db3

Lf

Cf

RLd

Cd1Q1 D1

C1

Css

Cd2

D7

D8Vin

Q2 D2C2

Q3 D3C3

Q4 D4C4

A

TrDR1

Llk

*

DR2

*

*

Q6

B

D6

Q5 D5

Several ZVZCS Hybrid FB TL Converters

2012-12-10 54

Outlines

1. Backgrounds





Converter


7. Conclusions

2012-12-10 55

Availability of Three-Level Voltage Waveforms

Lf

VinCd2

Cd1

Cf

RLd

Vo

+

-

D1

Q1

Q2

D2

B

A

In order to achieve three-level voltage waveform, 1) there should be two divided capacitors. 2) The two divided capacitors could power the load simultaneously or alternatively.

vAB = Vin, Vin/2 and 0

2012-12-10 56

Possibility of Three-Level Voltage Waveforms

Lf

Cf

RLd

Vo

+

-

D1

D2

Q2

VinCd2

Cd1

Q1

Lb

Vin

Cf1

RLd

Vo

+

_

D1

D2

Q1

Q2Cf2

BuckBoost

Buck/Boost Cuk

Sepic

LfCf1

RLd

Vo

_

+

D1

D2Q2

VinCd2

Cd1

Cf2

Q1

L1

Vin

Q1

Q2

Cb1

Cb2

Cf1

RLd

Vo

+

_

D1

D2

Cf2

L2 L1

Q2

VinCd2

Cd1

Q1

Cf

RLd

Vo

+

-

D1

D2

Cb1

Cb2

Zeta

Non-isolated TL Converters

2012-12-10 57


Vin

D1

D2A

B

Cd2

Q3

Q4

D3

D4

D10

Q1

Q2

Cd1D9

D5

D6

Q7

Q8

D7

D8

D12

Q5

Q6D11

Tr

DR1

DR2

Lf

Cf

RLd

Vo

+

_

C

D

**

*

FB TL Converter

H-FB TL Converter

2012-12-10 58


Vin

DR2

TrDR1

* *

**

Q1

Q3

Q2

Q4

D1

D2

D3

D4D6

D5

RLd

Vo

+

_

Lf

Cf

Flyback TL Converter

HB TL Converter

Forward TL Converter

Push-Pull TL Converter

2012-12-10 59

Conclusions

1. Three-Level Converters- A-TLSC and C-TLSC are extracted;- A family of TL converters are proposed;- The non-isolated TL converters are improved;- Forward TL converter is further simplified;- A hybrid FB TL converter are proposed.

2. The advantages of the TL converters- Reduction of the voltage stress of the switches;- some TL converters obtain TL waveform, which can

significantly reduce the filter.

3. Method to ensure the voltage sharing of the divided capacitorsis proposed.

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Three-Level Converters – A New Approach for High Voltage ...ruanxb.nuaa.edu.cn/Home/Ruan Xinbo_Home_files/PE-tutorial_A_Famil… · Buck/Boost Cuk Sepic Zeta. 2012-12-10 11 A Family