Preliminary hardware implementation of a six-phase quad-inverter induction motor drive

A hardware implementation of a quad-inverter configuration for multi-phase multi-level induction motor drives is presented in this paper. The scheme is based on four conventional 2-level three-phase voltage source inverters, able to supply the open-end windings of a dual three-phase motor (asymmetric six-phase machine), quadrupling the power capability of a single VSI with given voltage and current ratings. By a proper control algorithm the proposed converter is able to generate multi-level voltage waveforms, equivalent to the ones of a 3-level inverter, and to share the total motor power among the four dc sources within each switching period. A full-scale prototype of the whole power system has been realized utilizing six balanced impedances as six-phase load. A complete set of experimental results is given with reference to both balanced and unbalanced operating conditions.