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for the World Application太阳风翻译
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Note Semiconductor and Electronics Company
For further information contact:
eupec
Marketing Department
Tel:+49 2902 764-0Max Planck Str. 5
Fax:+49 2902-764-1256D-59581 Warstein Internet::
Measurement of the circuit stray inductance L σ
Fig.1 shows the principle circuit of a half-bridge and the resulting voltage and current wave-forms when switching IGBT1. The circuit stray inductance L σ, shown as a concentrated ele-ment, reprents all distributed inductances (of capacitors, busbars and IGBT modules)within the commutation loop (striped area).
00V D2
I I 0V V GE Fig.1: Half-bridge circuit with current and voltage waveforms when switching IGBT1
Due to the changing current a voltage drop of L σ * di off /dt occurs across the stray inductance L σ. It is overlayed to the DC link voltage V CC and en as a voltage spike across the turning-off IGBT1. According to the RBSOA diagram, this spike must be limited to the blocking volt-age V CES of the IGBT module (measured at the chip, means measured at the CE auxiliary terminals). Also a derated curve is given in the data-sheet for measurements at the power terminals, taking into account the internal module stray inductance between main and auxil-iary terminals of the module.
The stray inductance of the commutation loop can be derived from the voltage drop across IGBT at turn-on: while the IGBT is still blocking and the current is already rising, you can measure di/dt and voltage drop ∆V and calculate the inductance according to
L σ = ∆V / di/dt.
Application Note p age 2 of 2For further information contact:
eupec
Marketing Department Tel:+49 2902 764-0
高考英文作文Max Planck Str. 5Fax:+49 2902-764-256
D-59581 Warstein Internet::
Fig.2: Switching curves of current and voltage when turning on an IGBT
Example:
i: 400A / div (green)v: 200V / div. (black)
dearfriendsThe voltage drop happens at a point of time, where the diode still has no blocking capability.Therefore the voltage drop can only be caud be the stray inductances. No other effects have to be considered.
wholesalerThe circuit stray inductance is calculated according to the above shown formula at zero crossing of current. We get the following values:
哈尔滨雅思培训∆V ≈ 230V
di/dt ≈ 3200A/800ns
shabby什么意思>livÅ L σ ≈
58nH
>四六级准考证号忘了怎么查分
