Reduced switch count multiple three-phase ac machine drive systems

In this paper, two three-phase ac drive systems with reduced number of components, named configurations S and H, are investigated. Configuration S uses multiple two-leg voltage source inverters in which all inverters share an extra-leg. Configuration H also employs multiple two-leg inverters but in this case the inverters share the midpoint of a capacitor bank in the dc-link, instead. These configurations are compared to configuration F that employs multiple three-leg inverters. The main characteristics of the machine drive systems are presented together with selected experimental results that demonstrate the feasibility of the proposed configurations.