Estimation of Radiated EMI from an Inverter Unit in a Variable Speed Drive System Based on Radiation Model of Electric Dipole

This paper presents an estimation method for radiated EMI at far-field from an inverter unit in a variable speed drive (VSD) system. This method is based on the radiation model of an electric dipole and propagation properties in a semi-anechoic chamber for the 10-m standard test. Since the radiated emission test is conducted in a semi-anechoic chamber with a metal ground plane as the floor, the radiated EMI at far-field comprised direct and reflected waves from the equipment under test. To evaluate the pass/fail criteria in the EMC standard, the standard electric field intensity was introduced to determine the maximum radiated electric field as the receiving antenna height was varied. The estimation error of the proposed method was quantitatively analyzed by comparing the measured radiated EMI with the calculated value at the 10-m far-field from the inverter unit in the VSD system.