ECEN5817 Lecture 44 - University of Colorado Boulderecee.colorado.edu/~ecen5817/lectures/L44_ECEN5817_out1.pdf · Dual active bridge DC-DC converter summary • At V/nV g = 1 (DCX),

ECEN5817 Lecture 44

On-campus students: • Pick up final exam• Pick up final exam• Due by 2pm on Wednesday, May 9 in the instructor’s office

Off-campus students:• Pick up and submit the exam via D2L • Exam is due in 5 days from the start time but no work will be

accepted after 5pm MT on Wednesday, May 16

ECEN 58171

ECEN5817 Lecture 44

Dual-active-bridge converter*

Q1 Q3 Q5 Q7 +

Vg V+–

v2 v4 v6 v81:n

Q2 Q4Q6 Q8

_

ECEN 58172

* R.W.A.A. De Doncker, D.M. Divan, M.H. Kheraluwala, "A Three-phase Soft-Switched High-Power-Density DC-DC Converter for High-Power Applications," IEEE Tran. on Industry Applications, Jan/Feb 1991, Vol. 27, No. 1, pp. 63-73.

DCX (V/nVg = 1) waveforms neglecting resonant transitions

V V+

Q1

v2

Q3

v4

Q5

v6

Q7

v8

+

1:nLl

+ +

io

il

Vg V–

Q2 Q4Q6 Q8

_

vp_

vs_

dTs/2

0 < d < 1Phase shift

vp pko IdnI )1( 2

2 sg TdV

Ivs/n

22 s

l

gpk d

LI

sg dTVI

il2

s

l

gpk L

I

)1( ddTV

I sg

nioIpk

nIo

)1(2

ddnL

Il

o

Note how phase shift d controls the

ECEN 58173

o

Ts/2 Ts

shift d controls the DCX power flow

Dual Active Bridge (DAB) DC-DC Converter

Cp Cp Cs Cs

Q1 Q3 Q5 Q7

Ll 1:nt

io

+

–

+

–

+

–VoutCout

Q Q Q Q

il

t

Vg vp vs Rout

150-to-12 V, 100 W

Cp Cp Cs Cs

Q2 Q4 Q6 Q8

i• Zero-voltage switching of all

1 MHzEfficiency: 97.5%

ilvds6

vds2 vds4

transistors

• Relatively low peak and RMS current stresses

vds2 vds4 • Circuit design trade-offs driven by primary-side device Cp, and secondary-side device Ron

ECEN 58174

[1] D. Costinett, H. Nguyen, R. Zane, D. Maksimovic, “GaN-FET based dual active bridge DC-DC converter,” IEEE APEC 2011. [2] D. Costinett, R. Zane, D. Maksimovic, "Automatic voltage and dead time control for efficiency optimization in a dual active bridge

converter," IEEE APEC 2012.

Effects of primary-side device capacitance0 5

++ Poutil

Ll 1:nt

Vg v v

0

0.5

I l [A]

il

––

outlg vp vs

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-0.5

time [sec]

400 400 t 12 V 100 W

-200

0

200

V p [V]

Cp = 70 pF

Cp = 40 pF

Cp = 20 pF

vp

400-to-12 V, 100 W

1.35

1.4

16

18Ig,rmsntiout,rmsL

• Primary ZVS minimizes primary-side

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-400

time [sec]

vp

1.2

1.25

1.3

curr

ents

[A]

10

12

14L l [

μH]

Ll

switching losses

• A larger device Cp requires larger Ll, and longer transition times, which results in larger peak and RMS

1.05

1.1

1.15

RM

S c

4

6

8

L

ECEN 58175

results in larger peak and RMS currents, i.e. larger conduction loss on both primary and secondary sides

0 100 200 300 400 5001

0 100 200 300 400 5002

Cp [pF]

Device comparison for DAB application

Si vs. GaN Transistors, 20-40VSi vs. GaN Transistors, 200V

Ron

[pF

·Ω]

Ron

[pF

·Ω]

Cos

s·R

Cos

s·R

Data-sheet based comparison of Si and GaN (EPC 2011) devicesD t h t C t 100V 20V d Q t t d lt V

Qg·Ron [pC·Ω]Qg·Ron [nC·Ω]

Datasheet Coss at 100V or 20V, and Qg at rated voltage VGS

• DAB circuit design trade-offs decided by primary-side CossRon, and secondary-side device QgRon

ECEN 58176

y Qg on

Device Loss Comparison: 150-12 V DAB

Primary Gate Drive LossSecondary Gate Drive Loss

S C

W]

Secondary Conduction Loss

Primary Conduction Loss

Loss

[WP

ower

ECEN 58177

Efficiency optimization via control

0.97

0.98

il

vgs6100

W

150-to-(10-12) V conversion

0.93

0.94

0.95

0.96

cien

cy

vgs2 vgs4

W

0.9

0.91

0.92

0.93

Eff

ic

Manual Optimization

Constant Vout

Automatic Vout Regulation

80W

20 30 40 50 60 70 80 90 100 110 1200.88

0.89

Output Power [W]

out g

W20

W

Vout/Vg conversion ratio controlled to maximize efficiency over wider power

ECEN 58178

maximize efficiency over wider power range

Dual active bridge DC-DC converter summary

• At V/nVg = 1 (DCX), waveforms are close to ideal if F << 1

• ZVS of all semiconductors for loads greater than a minimum

• ZVS can be extended to lighter loads by adjusting conversion ratio

• Phase shift can be used to control the conversion ratio (non-DCX operation)

• High step-down, or high step-up conversion ratios feasible at high efficiencies (well above 90%).

• Bidirectional power flow is possible

• For standard unidirectional applications, the secondary-side bridge can be just diodes (operation is similar, but not the same)

• Half-bridge and push-pull variations are available

• Some DAB issues: • Transformer saturation (may require a series blocking capacitor)

• Switching frequency trade-offs (F << 1; transformer and inductor core and proximity losses)

• Significant new developments in Power Electronics based on emerging compound

ECEN 58179

• Significant new developments in Power Electronics based on emerging compound semiconductor (elements from 2 or more groups of the periodic table) devices (e.g. GaN, GaAs, SiC)

Application example:Automotive battery power management in a fuel-cell vehicle*

ECEN 581710

*F. Krismer, J.W.Kolar, “Accurate Power Loss Model Derivation of a High-Current Dual Active Bridge Converter for an Automotive Application, IEEE Trans. On Industrial Electronics, March 2010

Efficiency results

ECEN 581711

Power flow control in 3-phase AC power distribution*

• Purpose: control active and reactive power flow; increasingly important function in AC power distribution systems with distributed resources

• Solution above requires bulky 50/60 Hz transformers, e.g. for a 6.6 kV, 1 MVA unit, each transformer weights around 4,000 kg

ECEN 581712

* A. Inoue, H. Akagi, “A Bidirectional Isolated DC–DC Converter as a Core Circuit of the Next-Generation Medium-Voltage Power Conversion System,” IEEE Trans. on Power Elect., March 2007

Solution based on modular DCX

• Each cell can be switched as +E, -E, or 0

• With N = 9 cells, a total 19 levels are available to synthesize high-quality sine-wave

ECEN 581713

Converter realization

ECEN 581714

Spring 2013: ECEN 5807 Modeling and Control of Power Electronics

• Averaged switch modeling and simulation (Section 7.4 and Appendix B)

• Techniques of Design-Oriented Analysis, with Application to Switching q g y , pp gConverters

• Middlebrook's Extra Element Theorem (Appendix C)

• Input Filter Design (Chapter 10)p g ( p )

• The n-Extra Element Theorem

• Middlebrook's Feedback Theorem

• Dynamic modeling and simulation of converters operating in • Dynamic modeling and simulation of converters operating in discontinuous conduction mode (Chapter 11 and Appendix B)

• Introduction to sampled-data modeling

• Current Programmed Control (Chapter 12 and Appendix B)• Current Programmed Control (Chapter 12 and Appendix B)

• Introduction to Digital Control of Switching Converters

• Power-Factor Correction Rectifiers (Chapters 16-18)

ECEN 581715

Professional Certificate in Power Electronics

Awarded upon completion of ECEN5797, ECEN5807 and ECEN5817

Send a request to Adam Sadoff, ECEE graduate program [email protected]

ECEN 581716

New courses offered in Fall 2012 and Spring 2013ECEN5017 Power Electronics for Electric Drive Vehicles

Fall 2012

ECEN 581717

New courses offered in Fall 2012 and Spring 2013ECEN5737 Adjustable Speed AC Drives

Spring 2013

ECEN 581718

New DOE GATE Center: Innovative Drivetrains in Electric Automotive Technology Education (IDEATE)

Joint center between CU-Boulder and UC Colorado Springs campusesGraduate certificate in battery controls and electric drivetrains

http://mocha-java.uccs.edu/ideate/

Graduate certificate in battery controls and electric drivetrains

ECEN 581719

19

Th k f h d k d l k i h h fi lThank you for your hard work, good luck with the finals

ECEN 581720