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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