《EMI Filter Design》里一段没有理解

wzy962

小标题是
“THE 400-HZ FILTER COMPARED WITH THE 50- OR 60-HZ FILTER”


原文如下：
The problem with the 400-Hz power frequency is the voltage rise. Again, we are speaking of a system requiring substantial serious loss and load current. It is the
cutoff frequency of the EMI filter that creates the problem. There is always a
substantial voltage rise ahead of this cutoff frequency that pushes up the frequency
spectrum at 400 Hz. This creates a severe voltage rise at 400 Hz. At 60
or 50 Hz, the rise is so much smaller that other factors will compensate for it,
making the output voltage the same as the input or a slight voltage drop. This will
be handled later in the book, but the main answer is getting the cutoff frequency
as high as possible. This requires multistage filtering and impedance matching.
For the same amount of loss (80 dB at 100 kHz), as the number of stages grows,
the cutoff frequency increases, dropping the gain at 400 Hz. However, as the
current level decreases through the filter, this often enhances the voltage rise
problem. There is also a technique referred to as RC shunt that decreases resonant
rises, say here at 6000 Hz. The resonant rise could be 10 to 15 dB. The resistor
could be 10 ohms (covered later in the book) and the capacitive reactance at
6000 Hz would be 10 ohms. Would this lower the resonant rise? Of course it
would, but now you have 5 dB at 4000 Hz. So what is the gain at 400 Hz? About
the same as before, but I have seen cases where this fix made the condition worse.
The resonant frequency dropped in dB but was also moved to a lower frequency,
negating the fix.

有无达人曾经看过，或是理解了的，帮忙讲解一下！
谢谢：）

sysop

就是两个低频滤波器的比较。