In the past two years, CPES has made a major advance
in integrating EMI filters into a low profile, small volume integrated
power electronics module (IPEM) with characteristics superior to an
EMI filter constructed from discrete components. However, these integrated
filters share the following functionality limits with their discrete
counterparts: the filters have to pass the full power of the system
and have to be designed as such; and as frequency increases, parasitics
will always limit the operational bandwidth.
CPES has now booked a major breakthrough by pioneering a totally new
type of filter, based on transmission line principles. This filter has
already been shown to be effective between 1MHz and 100MHz for filtering
both common mode and differential mode interference-a range where parasitics
are already killing performance of other filters. As shown in the figure,
the filter consists of transmission line absorbing elements stacked
between the busbars feeding the active power electronics module (IPEM).
The filter thus avoids the first disadvantage of the “classic”
generation, since it only handles the small absorbed interference power-
a negligible fraction of the main power. The total system power passes
through the busbars around the filter. The second disadvantage based
on the effect of parasitics is avoided, since as the frequency increases,
the absorber works better as a transmission line, improving the absorption.
This new technology will greatly simplify high frequency interference
filters, reduce volume and profile, improve manufacturability, and match
perfectly with the planar active IPEM technology (Embedded Power) developed
by CPES.
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