Harmonics mitigation and stability analysis of DTC motor drives in MVDC systems

This paper analyzes the harmonics emission, propagation, and mitigation issues in an MVDC distribution system. Specifically, the DC current harmonics from a high power NPC DTC motor drive is analyzed. It is found that DC network resonance is a major cause of DC current harmonics amplification and propagation in the MVDC system. As a result, adding a DC-side input filter inductor is proposed to attenuate current harmonics from NPC DTC drives. A dc-side filter design method based on system impedance models, with consideration on stability and DC network resonance, is presented and verified by simulations.