High power AC drives based on stacking of standard low power AC drives

Adjustable speed drives (ASDs) are used in industry, among others, in pumps, compressors, and fans. Standard low power ASDs are based on a rectifier, a voltage DC link, and an inverter. The selection of an ASD depends upon the voltage and power rating of the load. For low power levels there are standard topologies that use standard semiconductors and thus with high availability and low cost. However, for high power rating, the ASD is mostly a more sophisticated power topology. Recent approaches include NPC, multi-cell, and H-bridge base topologies. This work proposes to stack standard low power ASDs to achieve higher operating power levels. The operation of the resulting configuration is done synchronized in order to take advantage of the higher number of power valves and thus achieve higher power quality indexes in both the load and AC mains.