"A New PWM Scheme to Improve the Input Power Quality of 18-Pulse Rectif" by Sharmin Shila, Shuvra Prokash Biswas et al.
Distorted line current is always a common issue of induction motor drive (IMD) driven by an 18-pulse rectifier fed multilevel inverter (MLI). The basic 18-pulse diode bridge rectifier (DBR) used in IMD does not comply with the IEEE-519 standard. A 3-level neutral point clamped (NPC) MLI operating at low switching frequency is utilized on the motor side to provide compactness and good performance. Inverter switching uses pulse width modulation (PWM) technique which is largely affected by the tota...
Source: uow.edu.au