Analysis and implementation of power management and control strategy for six-phase multilevel ac drive system in fault condition

• Main Authors: Sanjeevikumar Padmanaban, Gabriele Grandi, Frede Blaabjerg, Patrick William Wheeler, Joseph Olorunfemi Ojo
• Format: Article
• Language: English
• Published: Elsevier 2016-03-01
• Series: Engineering Science and Technology, an International Journal
• Subjects: Dual three-phase motor; Multilevel inverter; Multi-phase motor drive; Open-end winding; Post-fault tolerance; Multilevel PWM; Level-shifted PWM
• Online Access: http://www.sciencedirect.com/science/article/pii/S2215098615001081

This research article exploits the power management algorithm in post-fault conditions for a six-phase (quad) multilevel inverter. The drive circuit consists of four 2-level, three-phase voltage source inverter (VSI) supplying a six-phase open-end windings motor or/impedance load, with circumstantial failure of one VSI investigated. A simplified level-shifted pulse-width modulation (PWM) algorithm is developed to modulate each couple of three-phase VSI as 3-level output voltage generators in normal operation. The total power of the whole ac drive is shared equally among the four isolated DC sources. The developed post-fault algorithm is applied when there is a fault by one VSI and the load is fed from the remaining three healthy VSIs. In faulty conditions the multilevel outputs are reduced from 3-level to 2-level, but still the system propagates with degraded power. Numerical simulation modelling and experimental tests have been carried out with proposed post-fault control algorithm with three-phase open-end (asymmetrical induction motor/R-L impedance) load. A complete set of simulation and experimental results provided in this paper shows close agreement with the developed theoretical background.