功率电感性能指标
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fswitch 200kHz Iout =1A VSW = 1V Vin=15V VD =0,6V Vout =5V
9
Inductance Value – Selection for a Buck
Fswitch = 200kHz Vin=15V VSW = 1V VD =0,6V Vout=5V Iout=1A
– – – – THT or SMT toroidal , solenoidal (Rod core), multilayer shielded or unshielded wire (round, rectangular flat, Litz,..)
core material
– – – NiZn MnZn Iron alloy • Superflux • WE-Perm • WE-Perm2 etc…
www.we-online.com
Agenda
Inductor Selection Power Inductor Specsheet Definitions The Fastest Way : Component Selector
2
Inductor Selection
shape & size : different constructions
14
Saturation Current
110
Definition Wurth Elektronik: e.g. WE-PD
inductance L/Lo [ %]
100 90 80 70 60 50 40 30 20 10 0 0 5 10 15 20 25 30 35
∆L= 10%
∆L= - 30%
Isat = 25 A Isat = 30 A
I [A]
Saturation Current
• the saturation current always refers to a certain inductance drop and differs in Inductor construction and varies by manufacturers ! check the specification !
choose additional: 744 771 147 (47µH)
+
744 771 168 (68µH)
11
POWER INDUCTOR SPECSHEET DEFINITIONS
12
Saturation Current ?
13
Saturation Current
=> Print in the data sheet and in the catalogue, drop of the inductance value
electrical parameters of application
3
Permeability – complex permeability
10000
Z = jωL0 µ − jµ = R + jX
| |
µr=350
(
)
1000
µ|
RS = ωL0 µ ||
X LS = ωL0 µ
|
100
reactance portion of inductance
50% 40% 30% 20% 10% 0% 0,01
XL(MnZn)
XL(NiZn)
„0“-400kHz
„0“-10MHz
„0“-40MHz
f/MHz
0,1 1 10 100 1000
6
INDUCTOR SELECTION - First step
7
INDUCTOR SELCTION - First step
R (MnZn)
R (NiZn)
200kHz4MHz
3-60MHz
202000MHz
0,1
1
10
100
1000
Frequency [MHz]
5
Core Material – power conversion application
100% 90% 80% 70%
Impedance
60%
XL(Fe)
23
stray field - shielded vs. unshielded
24
stray field - unshielded vs. shielded
unshielded shielded
25
COMPONENT SELECTOR
www.we-online.com/component-selector
10
µ ||
frequency dependent core losses
1 1 10 100 1000
f/MHz
10000
4
Core material – filtering application
100% 90% 80% 70% 60%
Impedance
R (Fe)
50% 40% 30% 20% 10% 0% 0,01
20
Rated current – Derating !
Example: at 100°C ambient temperature only 60% of the rated current can be permitted ~ derating of 40 %
the max operating temperature of the inductor is 125°C (Can be higher 155°C, like WE-HCI or WE-PDF series,…)
21
Shielded vs Unshielded Inductors • influence of an air gap
shielded unshielded
smaller
leff
bigger
leff
22
Shielded Power Inductors • e.g. WE-PD Series Advantage: • reduction of magnetic stray field • increased Rated Current • reduced DCR for same L-value compared to unshielded construction Disadvantage: • reduction of Saturation Current compared to same L-value unshielded
=> Rated Current describes the self generated heating of Power Inductor by DC-current flow (only) and is free to manufacturesr specification definitions !
COUPLED INDUCTOR
High current and High efficiency inductor - Flat Wire - Special material
8
Inductance Value – Buck Converter example
DC ⋅ (Vin − Vout ) L= f switch ⋅ r ⋅ I out
L (µH)
6,00 5,00 4,00 3,00 2,00 1,00 0,00 0 2 4 6 8 Current (A)
17
WE-HCI WE-SI
Material: NiZn AirGap: small
WE-PD
10 12 14
Rated Current ?
18
Rated Current ?
19
Rated Current: Measuring Standards ?
Similar measurements but different ratings
For measuring the rated current (e.g. 40K temperature rise) a DC current must be driven through the inductor. Contacting the inductor means to take heat energy away from the inductor (heatsinking) The most objective method does not cool down the inductor during measurement !
1
Vout 5V DC = = ≅ 0,33 Vin 15V
2
I rated ≅ I out = 1A
3
I ripple ≅ 20%...40% ⋅ I out = 0,2...0,4 A
4
(practical values)
DC ⋅ (Vin − Vout ) 0,33 ⋅ (15V − 5V ) s = L= 200 E 3 ⋅ 0,2 ⋅1A f switch ⋅ r ⋅ I out
Behind the Spec of Power Inductors
Wuerth Elektronik eiSos Alexander Gerfer, CTO
March 16 - 20, 2014 APEC Industrie Session
Behind the Spec of Power Inductors
I sat ≥ 1,2 A
WE-PD 1260 : 744 771 156 Irated=2,01A Isat=2,35A RECOMMENDATION:
- test different inductor values tolerance of L- values effect on the design (e.g. ripple current; DCR, ɳ)
15
Saturation current
16
Saturation Current vs Core Material
11,00 10,00 9,00 8,00 7,00
WE-SD
Material: NiZn AirGap: big
Material: WE-Perm AirGap: small Material: Iron AirGap: distributed
26
Component Selector
27
www.we-online.com/component-selector
27
源自文库
28
28
29
29
Component Selector
30
30
31
choose average value 56µH to begin optimization
10
L = 83....42 µH
r = 0,2 r = 0,4
Inductance Value – Example Buck
L = 56 µH
at
r = 0,3
I out = 1A
r = 0,4
I L max ≅ 1,2 A
© All rights reserved by Würth Elektronik, also in the event of industrial property rights. All rights of disposal such as copying and redistribution rights with us.
9
Inductance Value – Selection for a Buck
Fswitch = 200kHz Vin=15V VSW = 1V VD =0,6V Vout=5V Iout=1A
– – – – THT or SMT toroidal , solenoidal (Rod core), multilayer shielded or unshielded wire (round, rectangular flat, Litz,..)
core material
– – – NiZn MnZn Iron alloy • Superflux • WE-Perm • WE-Perm2 etc…
www.we-online.com
Agenda
Inductor Selection Power Inductor Specsheet Definitions The Fastest Way : Component Selector
2
Inductor Selection
shape & size : different constructions
14
Saturation Current
110
Definition Wurth Elektronik: e.g. WE-PD
inductance L/Lo [ %]
100 90 80 70 60 50 40 30 20 10 0 0 5 10 15 20 25 30 35
∆L= 10%
∆L= - 30%
Isat = 25 A Isat = 30 A
I [A]
Saturation Current
• the saturation current always refers to a certain inductance drop and differs in Inductor construction and varies by manufacturers ! check the specification !
choose additional: 744 771 147 (47µH)
+
744 771 168 (68µH)
11
POWER INDUCTOR SPECSHEET DEFINITIONS
12
Saturation Current ?
13
Saturation Current
=> Print in the data sheet and in the catalogue, drop of the inductance value
electrical parameters of application
3
Permeability – complex permeability
10000
Z = jωL0 µ − jµ = R + jX
| |
µr=350
(
)
1000
µ|
RS = ωL0 µ ||
X LS = ωL0 µ
|
100
reactance portion of inductance
50% 40% 30% 20% 10% 0% 0,01
XL(MnZn)
XL(NiZn)
„0“-400kHz
„0“-10MHz
„0“-40MHz
f/MHz
0,1 1 10 100 1000
6
INDUCTOR SELECTION - First step
7
INDUCTOR SELCTION - First step
R (MnZn)
R (NiZn)
200kHz4MHz
3-60MHz
202000MHz
0,1
1
10
100
1000
Frequency [MHz]
5
Core Material – power conversion application
100% 90% 80% 70%
Impedance
60%
XL(Fe)
23
stray field - shielded vs. unshielded
24
stray field - unshielded vs. shielded
unshielded shielded
25
COMPONENT SELECTOR
www.we-online.com/component-selector
10
µ ||
frequency dependent core losses
1 1 10 100 1000
f/MHz
10000
4
Core material – filtering application
100% 90% 80% 70% 60%
Impedance
R (Fe)
50% 40% 30% 20% 10% 0% 0,01
20
Rated current – Derating !
Example: at 100°C ambient temperature only 60% of the rated current can be permitted ~ derating of 40 %
the max operating temperature of the inductor is 125°C (Can be higher 155°C, like WE-HCI or WE-PDF series,…)
21
Shielded vs Unshielded Inductors • influence of an air gap
shielded unshielded
smaller
leff
bigger
leff
22
Shielded Power Inductors • e.g. WE-PD Series Advantage: • reduction of magnetic stray field • increased Rated Current • reduced DCR for same L-value compared to unshielded construction Disadvantage: • reduction of Saturation Current compared to same L-value unshielded
=> Rated Current describes the self generated heating of Power Inductor by DC-current flow (only) and is free to manufacturesr specification definitions !
COUPLED INDUCTOR
High current and High efficiency inductor - Flat Wire - Special material
8
Inductance Value – Buck Converter example
DC ⋅ (Vin − Vout ) L= f switch ⋅ r ⋅ I out
L (µH)
6,00 5,00 4,00 3,00 2,00 1,00 0,00 0 2 4 6 8 Current (A)
17
WE-HCI WE-SI
Material: NiZn AirGap: small
WE-PD
10 12 14
Rated Current ?
18
Rated Current ?
19
Rated Current: Measuring Standards ?
Similar measurements but different ratings
For measuring the rated current (e.g. 40K temperature rise) a DC current must be driven through the inductor. Contacting the inductor means to take heat energy away from the inductor (heatsinking) The most objective method does not cool down the inductor during measurement !
1
Vout 5V DC = = ≅ 0,33 Vin 15V
2
I rated ≅ I out = 1A
3
I ripple ≅ 20%...40% ⋅ I out = 0,2...0,4 A
4
(practical values)
DC ⋅ (Vin − Vout ) 0,33 ⋅ (15V − 5V ) s = L= 200 E 3 ⋅ 0,2 ⋅1A f switch ⋅ r ⋅ I out
Behind the Spec of Power Inductors
Wuerth Elektronik eiSos Alexander Gerfer, CTO
March 16 - 20, 2014 APEC Industrie Session
Behind the Spec of Power Inductors
I sat ≥ 1,2 A
WE-PD 1260 : 744 771 156 Irated=2,01A Isat=2,35A RECOMMENDATION:
- test different inductor values tolerance of L- values effect on the design (e.g. ripple current; DCR, ɳ)
15
Saturation current
16
Saturation Current vs Core Material
11,00 10,00 9,00 8,00 7,00
WE-SD
Material: NiZn AirGap: big
Material: WE-Perm AirGap: small Material: Iron AirGap: distributed
26
Component Selector
27
www.we-online.com/component-selector
27
源自文库
28
28
29
29
Component Selector
30
30
31
choose average value 56µH to begin optimization
10
L = 83....42 µH
r = 0,2 r = 0,4
Inductance Value – Example Buck
L = 56 µH
at
r = 0,3
I out = 1A
r = 0,4
I L max ≅ 1,2 A
© All rights reserved by Würth Elektronik, also in the event of industrial property rights. All rights of disposal such as copying and redistribution rights with us.