A Novel Leg-Integrated Switched Capacitor Inverter Topology for Three-Phase Induction Motor Drives

This article presents an optimized leg-integrated switched capacitor inverter topology for 3-phi induction motor driven home appliance applications where a switched capacitor (SC) network, used for voltage boosting, is integrated with one of the inverter legs (phase-A leg). This results in a reduced semiconductor requirement as the voltage ratings of the phase-A switches are reduced by half. Moreover, due to the unique structure of the proposed topology, it can produce three-level pole voltage corresponding to phase-A, even though the pole voltages of phases B and C remain two-level. This kind of performance, referred to as quasi three-level performance, results in an unusual space vector (SV) hexagon with 12 SVs, which is implemented by using a novel pulsewidth modulation method. A comparison study of the proposed topology with the existing SC based 3-phi inverter topologies reveals that the former has the lowest semiconductor requirement, highly improved harmonic performance and very low losses. All the claims are supported by experimental validations performed on a 3 phi induction motor (3 phi IM) drive.