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Dual Active Bridge Converter
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Constraints on Inductance
0 5 10 15 20 25 30
0.9
1
1.1
1.2
1.3
1.4
1.5
Tank Inductance Ll [H]
No
rmal
ized
Cu
rren
t
Io,avg
Io,rms
Io,pk
Io,ZVSmin
Non-ZVS• From previous analysis, smaller Ll results in smaller RMS currents in converter
• However, Ll must be large enough to store energy necessary for ZVS
• Near-optimal design at a single operating point by selecting Ll just large enough to obtain ZVS
DAB Operation Analysis• Phase-shifted DAB has four unique intervals per
half-period
• Primary dead time
• Phase shift
• Secondary dead time
• Main power delivery
• Begin by considering DCX operation, where
Vout = ntVg
• Even-numbered intervals, circuit reduces to
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• Resonant intervals have equivalent circuits of the form:
• Both of which can be simplified to:
Resonant Interval Analysis
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State Plane Analysis of DAB Converter
Primary Secondary
l
p
gbaseL
CVI
lt
sgbase
Ln
CVI
2
State Plane Analysis of DAB Converter
l
p
gbaseL
CVI
lt
sgbase
Ln
CVI
2
Primary Secondary