ecen5817 lecture 44 - university of colorado...
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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*
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*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]
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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
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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