Formula Sheets: Power Semiconductor Diodes & Transistors | Power Electronics - Electrical Engineering (EE) PDF Download

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P o w er Electronics: P o w er Semiconductor Dio des &
T ransistors F orm ula Sheet for Electrical GA TE
P o w er D io des
• Dio de V-I Characteristics : F orw ard v oltage drop and rev erse blo c king.
I
D
= I
S
(
e
V
D
nV
T
-1
)
where I
D
is dio de curren t, I
S
is saturation curren t, V
D
is dio de v oltage, n is idealit y
factor (1–2 for p o w er dio des), V
T
=
kT
q
˜25mV at ro om temp erature.
• P o w er Loss : Conduction loss in forw ard bias.
P
cond
= V
F
I
a vg
where V
F
is forw ard v oltage drop (V ), I
a vg
is a v erage forw ard curren t (A ).
• Rev erse Reco v ery Time : Time to switc h from conducting to blo c king state.
t
rr
= t
a
+t
b
where t
rr
is rev erse reco v ery time, t
a
is time to p eak rev erse curren t, t
b
is time for
curren t to deca y .
• Rev erse Reco v ery Charge :
Q
rr
=
?
trr
0
I
rr
(t)dt
where Q
rr
is rev erse reco v ery c harge, I
rr
is rev erse reco v ery curren t.
Bip olar Junction T ransistors (BJT)
• Curren t Gain : Ratio of collector to base curren t.
ß =
I
C
I
B
where I
C
is collector curren t, I
B
is base curren t.
• Collector Curren t :
I
C
= I
S
(
e
V
BE
V
T
-1
)
where V
BE
is base-emitter v oltage, I
S
is saturation curren t.
• P o w er Dissipation :
P = V
CE
I
C
where V
CE
is collector-emitter v oltage.
• Switc hing Times : T urn-on and turn-off times.
t
on
= t
d
+t
r
, t
off
= t
s
+t
f
where t
d
is dela y time, t
r
is rise time, t
s
is storage time, t
f
is fall time.
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P o w er Electronics: P o w er Semiconductor Dio des &
T ransistors F orm ula Sheet for Electrical GA TE
P o w er D io des
• Dio de V-I Characteristics : F orw ard v oltage drop and rev erse blo c king.
I
D
= I
S
(
e
V
D
nV
T
-1
)
where I
D
is dio de curren t, I
S
is saturation curren t, V
D
is dio de v oltage, n is idealit y
factor (1–2 for p o w er dio des), V
T
=
kT
q
˜25mV at ro om temp erature.
• P o w er Loss : Conduction loss in forw ard bias.
P
cond
= V
F
I
a vg
where V
F
is forw ard v oltage drop (V ), I
a vg
is a v erage forw ard curren t (A ).
• Rev erse Reco v ery Time : Time to switc h from conducting to blo c king state.
t
rr
= t
a
+t
b
where t
rr
is rev erse reco v ery time, t
a
is time to p eak rev erse curren t, t
b
is time for
curren t to deca y .
• Rev erse Reco v ery Charge :
Q
rr
=
?
trr
0
I
rr
(t)dt
where Q
rr
is rev erse reco v ery c harge, I
rr
is rev erse reco v ery curren t.
Bip olar Junction T ransistors (BJT)
• Curren t Gain : Ratio of collector to base curren t.
ß =
I
C
I
B
where I
C
is collector curren t, I
B
is base curren t.
• Collector Curren t :
I
C
= I
S
(
e
V
BE
V
T
-1
)
where V
BE
is base-emitter v oltage, I
S
is saturation curren t.
• P o w er Dissipation :
P = V
CE
I
C
where V
CE
is collector-emitter v oltage.
• Switc hing Times : T urn-on and turn-off times.
t
on
= t
d
+t
r
, t
off
= t
s
+t
f
where t
d
is dela y time, t
r
is rise time, t
s
is storage time, t
f
is fall time.
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MOSFET s
• Drain Curren t (Linear Region) :
I
D
= K
[
2(V
GS
-V
th
)V
DS
-V
2
DS
]
where K =
µnCoxW
2L
, V
GS
is gate-source v oltage, V
th
is threshold v oltage, V
DS
is drain-
source v oltage.
• Drain Curren t (Saturation Region) :
I
D
= K(V
GS
-V
th
)
2
• On-State Resistance :
R
DS( on)
=
V
DS
I
D
• P o w er Loss :
P = I
2
D
R
DS( on)
• Gate Charge :
Q
g
=
?
I
G
dt
where Q
g
is total gate c harge, I
G
is gate curren t.
Insulated Gate Bip olar T ransistors (IGBT s)
• Collector Curren t : Similar to MOSFET in saturation.
I
C
˜ K(V
GE
-V
th
)
2
where V
GE
is gate-emitter v oltage.
• Conduction Loss:
P
cond
= V
CE( sat)
I
C
where V
CE( sat)
is collec tor-emitter saturation v oltage.
• Switc hing Loss : Energy loss during switc hing.
E
on/off
=
?
V
CE
I
C
dt
Key Notes
• T ypical V alues : V
F
˜ 0.7V –2V for p o w er dio des, V
th
˜ 2V –4V for MOSFET s,
V
CE( sat)
˜1V –3V for IGBT s.
• Safe Op erating Area (SO A) : Ensure op eration within v oltage and curren t ratings.
• Thermal Considerations : P o w er dissipation m ust b e managed with heatsinks.
• Units : Use SI units for GA TE (e.g., V , A , s ).
• Applications : Dio des for rectification, BJT s/MOSFET s/IGBT s for switc hing in con-
v erters/in v erters.
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