Application Note
36 of 53
V 1.0
2019-04-01
IM393 Application note
IM393 IPM Technical Description
Bootstrap circuit
Figure 29
Bootstrap capacitance as a function of the switching frequency
Figure 29 shows the curve for a continuous sinusoidal modulation. If the voltage ripple is 0.1 V, the
recommended bootstrap capacitance is therefore in the range of 4.7 µF for most switching frequencies. In case
of other PWM method like a discontinuous sinusoidal modulation, the t
charge
must be set to the longest period of
the low-side IGBT off-state.
Note that this result is only an example. It is recommended that the system design considers the actual control
pattern and lifetime of the used components.
0
1
2
3
4
5
0
5
10
15
20
f
PWM
[kHz]
C
B
S
[
u
F
]
