Christoph Haederli - Les thèses en ligne de l'INP - Institut National ...
Christoph Haederli - Les thèses en ligne de l'INP - Institut National ...
Christoph Haederli - Les thèses en ligne de l'INP - Institut National ...
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ML Converter Topologies 41<br />
f<br />
C<br />
sw<br />
= k f<br />
(12)<br />
I<br />
f _ sw<br />
*<br />
NT<br />
sw _ base<br />
I<br />
N<br />
I<br />
FC _ max SP FC _ max<br />
FC _ max<br />
0<br />
= =<br />
=<br />
(13)<br />
Mk1U<br />
DC<br />
Mk1U<br />
DC<br />
fsw<br />
Mk1U<br />
DC<br />
f<br />
sw _ basek<br />
f _ sw<br />
I<br />
FC _ max<br />
IFC<br />
_ maxN<br />
Mk<br />
f _ sw<br />
Mk<br />
f _ sw<br />
C1 = =<br />
= C0<br />
(14)<br />
k U f Mk U f N N<br />
1<br />
DC sw _ base<br />
1<br />
DC<br />
sw<br />
N<br />
C = 0<br />
C1<br />
(15)<br />
Mk f _ sw<br />
N<br />
C 0 refers to the actual capacitance required, taking into account the level over interleaving and<br />
the applied switching frequ<strong>en</strong>cy. C 1 is a g<strong>en</strong>eric value <strong>de</strong>p<strong>en</strong>ding on maximum curr<strong>en</strong>t, maximum<br />
voltage ripple and base switching frequ<strong>en</strong>cy. It can be se<strong>en</strong> from (15) that a reduction of the<br />
number of cells can be comp<strong>en</strong>sated with higher switching frequ<strong>en</strong>cy. With a total number of k<br />
flying capacitors, we get the total <strong>en</strong>ergy in the flying capacitors:<br />
E<br />
tot<br />
=<br />
k<br />
∑<br />
x=<br />
1<br />
C0U<br />
2<br />
2<br />
x<br />
=<br />
k<br />
∑<br />
C1NU<br />
2Mk<br />
2<br />
x<br />
x=<br />
1 f _ sw<br />
(16)<br />
A constant shall be <strong>de</strong>fined as follows to compare differ<strong>en</strong>t topologies without taking into<br />
account any absolute values from a giv<strong>en</strong> operating point.<br />
E<br />
tot<br />
I<br />
U<br />
2<br />
C1U<br />
DC<br />
FC _ max DC<br />
= K<br />
E _ cap<br />
= K<br />
E _ cap<br />
(17)<br />
2<br />
2k1<br />
f<br />
sw _ base<br />
(18) follows directly from (16) and (17).<br />
2<br />
k<br />
2E<br />
⎛ ⎞<br />
tot<br />
N U<br />
x<br />
K<br />
_<br />
= =<br />
2 ∑<br />
⎜<br />
⎟<br />
E cap<br />
(18)<br />
C1U<br />
Mk<br />
DC<br />
f _ sw x=<br />
1 ⎝U<br />
DC ⎠<br />
In the case of p groups of flying capacitors with each group forming a MC, this can also be<br />
writt<strong>en</strong> as (k/p is the number of flying capacitors per group):<br />
∑∑<br />
− 2<br />
p 1 k / p<br />
N ⎛U<br />
y+<br />
x*<br />
k / p ⎞<br />
K<br />
E _ cap<br />
=<br />
⎜<br />
⎟<br />
(19)<br />
Mk<br />
f _ sw x= 0 y=<br />
1 U<br />
DC<br />
⎝<br />
⎠<br />
With p id<strong>en</strong>tical groups of flying capacitors this results in:<br />
2<br />
k / p<br />
pN ⎛ U<br />
y ⎞<br />
K<br />
_<br />
= ∑<br />
⎜<br />
⎟<br />
(20)<br />
E cap<br />
Mk<br />
f _ sw y=<br />
1 ⎝U<br />
DC ⎠