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A New Class of EMI Filter IPEMs

Year: 2005
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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