Active Common Mode EMI Filter for Eliminating Conducted Electromagnetic Interference

摘要

The present invention relates to an active common-mode EMI filter which is capable of using low-voltage amplifier devices by using a separate amplifier dc source unrelated to the system operating voltage and also is capable of circulating the leakage current within the system by coupling capacitors that operate for the filter circuit to be separated at low frequency and form the closed circuit with the main circuit of the system at high frequency. As a result, it is possible to use fast active devices than the filter circuit of prior arts regardless of the operating voltage of the target system. The present invention can solve the prior art's problem that transistors with higher voltage rating should be used in order for bipolar transistors to withstand the total dc voltage of the system while using a method for detecting and compensating the high-frequency common-mode current.