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

Abstract

A B S T R A C TThis 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.

A novel five-level optimized carrier multilevel PWM quad-inverter six-phase AC drive

“…Mostly suffers with power parts and survey reveals 31-37 % of faults is occurred by power parts with IGBT devices and also due to capacitors and gate control methods [1,[6][7][8]. On the other hand, the technology development in multiphase ac drives make them candidates to replace standard three-phase drives in configurations with limited rating (MOSFET/IGBT) devices [9][10][11][12][13][14][15][16][17][18][19]. Many topologies are addressed for multiphase versions, but dual three-phase (sixphase) drives have shown good reliability, redundant structure, limited dc link ripples, high power density, and fault tolerant capabilities [13][14][15][16][17].…”

“…On the other hand, the technology development in multiphase ac drives make them candidates to replace standard three-phase drives in configurations with limited rating (MOSFET/IGBT) devices [9][10][11][12][13][14][15][16][17][18][19]. Many topologies are addressed for multiphase versions, but dual three-phase (sixphase) drives have shown good reliability, redundant structure, limited dc link ripples, high power density, and fault tolerant capabilities [13][14][15][16][17]. Usually configured by two adjacent phases spatially shifted by 600 (symmetrical type) [9,13] or by 300 (asymmetrical one) [14][15][16][17] on applications.…”

“…Many topologies are addressed for multiphase versions, but dual three-phase (sixphase) drives have shown good reliability, redundant structure, limited dc link ripples, high power density, and fault tolerant capabilities [13][14][15][16][17]. Usually configured by two adjacent phases spatially shifted by 600 (symmetrical type) [9,13] or by 300 (asymmetrical one) [14][15][16][17] on applications. Advantages include easy splitting the phases as two standard sets of threephases driven by multiple classical VSIs as multiphase converter [14][15][16][17][18].…”

“…Usually configured by two adjacent phases spatially shifted by 600 (symmetrical type) [9,13] or by 300 (asymmetrical one) [14][15][16][17] on applications. Advantages include easy splitting the phases as two standard sets of threephases driven by multiple classical VSIs as multiphase converter [14][15][16][17][18]. Generally, addressed with terminology as dual-, triple-and quadruple three-phase ac drives are applicable to low-voltage/high-current ac traction, electric vehicles and 'More-Electric Aircraft' propulsion systems (MEA) [18][19].…”

“…Moreover, multiphase ac drives perform motoring/generator action during start and flight mode. It is evident that the grouping multi-phase and multi-level inverter could be effective to obtain the high power ratings configurations with limited voltage/current semiconductor devices [14][15][16][17][18][22][23][24][25][26][27][28][29][30].…”