AN-3008 RC Snubber Networks for Thyristor Power Control and ...
AN-3008 RC Snubber Networks for Thyristor Power Control and ...
AN-3008 RC Snubber Networks for Thyristor Power Control and ...
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APPLICATION NOTE<br />
<strong>AN</strong>-<strong>3008</strong><br />
Critical Damping<br />
6.0<br />
6.1<br />
6.2<br />
6.3<br />
e = E– V OL<br />
( 1 – αt )e – αt + ξte – αt<br />
de<br />
----- = [ αV<br />
dt OL<br />
( 2 – αt) + ξ( 1 – αt)<br />
]e – αt<br />
ξ<br />
2 + -------------<br />
2V<br />
t OL<br />
PK = -----------------------<br />
ξ<br />
α + ---------<br />
V OL<br />
V PK = E–<br />
[ V OL<br />
( 1 – α t PK )–<br />
ξ t PK ]e – α t PK<br />
6.4<br />
Average dV ------<br />
dt<br />
=<br />
V<br />
---------- PK<br />
t PK<br />
When I = 0,<br />
R S = 0M , = 0<br />
e(t) rises asymptotically to E. t PK <strong>and</strong> average dV ------ do not exist.<br />
dt<br />
6.5<br />
3αV OL<br />
+ 2ξ<br />
t max = -----------------------------<br />
α 2 V OL<br />
+ αξ<br />
When I = 0,<br />
t max = 0<br />
For R S<br />
------ ≥ 3⁄<br />
4<br />
R T<br />
6.6<br />
then dV dV<br />
------ = ⎛------<br />
⎞<br />
dt max ⎝ dt ⎠0<br />
⎛dV<br />
------ ⎞<br />
⎝ dt ⎠max<br />
–<br />
[ αV OL<br />
( 2 – α t max ) + ξ ( 1–<br />
α t max )]e αt max<br />
=<br />
Appendix E<br />
<strong>Snubber</strong> Discharge<br />
Overdamped<br />
dI<br />
dt<br />
Derivations<br />
1.0<br />
i<br />
=<br />
V<br />
---------- CS<br />
α – αt sinh( ωt)<br />
ωL S<br />
1.1<br />
1.2<br />
C<br />
i PK = V S<br />
CS<br />
------ e – α t<br />
L PK<br />
S<br />
1<br />
t PK = --- tanh – 1 ω ω ᾱ --<br />
Critical Damped<br />
2.0<br />
i<br />
=<br />
V CS<br />
-------- te – αt<br />
L S<br />
2.1<br />
V CS<br />
i PK = 0.736--------<br />
R S<br />
REV. 4.01 6/24/02 23
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