Integrated magnetics and dielectrics for EMI filter (2005)
The CPES team continued with the new research program on integrated EMI filters as passive IPEMs. EMI filter design is critical for power electronics equipment to be in compliance with the EMI/EMC standard. A good filter design is to realize high frequency attenuation effectively. Such a design is often achieved empirically, with good common sense, and deemed, by and large, as an art rather than science. It is well known that the filter parasitics are detrimental to its ability to attenuate high frequency noises. While reduction of certain critical parasitics such as, parasitic inductance of filter capacitors and certain mutual couplings can be realized relatively easily in the conventional discrete filter design practice, reduction of the winding capacitors of the inductor can best be implemented in an integrated filter design. The internal electromagnetic parameters in the three-dimensional structure can be controlled to enhance the attenuation of high frequency noise. This is done through the use of different interleaved materials and a three-dimensional geometrical configuration in order to cancel the undesired electrical field coupling to achieve near ideal behavior in the frequency band of interest. These properties cannot be achieved by construction techniques with discrete components. The integrated EMI filters have been demonstrated to be superior to their discrete counterparts in terms of filter behavior, profile and power density.