Study on filtering performance of soft magnetic composite inductors for switching harmonics in 3-phase 70 kW PWM converter systems

Soft magnetic composite (SMC) is considered as an alternative solution for core materials of inductors used in LCL filters in power converter applications. Performance of SMC inductors in damping a range of harmonics caused by voltage switching is an interesting topic. The method used in this paper is to test the inductors together with a 70 kW PWM inverter to examine the filtering effects for different harmonics and the harmonic losses as well as the temperature rise of the SMC inductors. The study is conducted with different inductor currents and switching frequencies (5 kHz, 10 kHz and 15 kHz). The harmonic spectra of voltages and currents as well as the harmonic losses calculated based on the measured values. A FE model is built to study distributions of magnetic fluxes, losses and temperature. The model is verified based on comparisons of computed and experimental results.