PhD student Arjit Bali with Advisor A. Stillwell

Electric vehicle and electric aviation applications demand lightweight electro-mechanical energy conversion, but passive components in the drive system can limit power density.  Slotless machine constructions offer high power density but result in very low per-phase inductance, necessitating additional filtering that diminishes the power density benefits.  Additionally, the dc-link capacitor significantly contributes to the inverter’s weight and volume.

My research explores the advantages of interleaving multilevel topologies and proposes an interleaved hybrid active neutral point clamped (I-HANPC) converter to reduce output filter size and minimize dc-link capacitor requirements.  A 7-level I-HANPC prototype demonstrates a peak efficiency of 98.8%, a ~25% reduction in dc-link capacitor RMS current, and total harmonic distortion below 5%.

Figure 9. Hardware prototype of 7-level I-HANPC converter that attains a peak efficiency of 98.8% with low output total harmonic distortion.