A Proposed Terminal-Ground EMI Filter for Reduction of Conducted Emissions Considering Cable Radiation and Safety

This article proposes an optimal design of a terminal-ground electromagnetic interference filter (TGEF) for reduction of common-mode (CM) conducted emissions (CEs) with considering cable radiations and safety. The TGEF is free from risks of magnetic saturation and heat problem. In experimental tests with a 3.3-kW air conditioner system, a prototype TGEF well reduced low-frequency CM CE noises, but increased disturbance power (DP) due to cable radiations. To investigate the principle of cable radiations, the impedance and parameters in the DP measurement setup are extracted by measurements using a vector network analyzer and validated with full-wave simulations. The effects of the TGEF on total CM DP currents at power cables are also experimentally demonstrated and modeled in simulations. Based on the analysis of DP measurement environments, a quantitative guideline for a TGEF design was proposed without increasing cable radiations while maintaining CE noise attenuation performances. The performances of the optimized TGEF are then validated by CE and DP measurements in the real product system. Moreover, safety of the optimized TGEF in a ground-fault condition was experimentally confirmed.