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This work presents a hybrid seven-level dual inverter scheme with increased linear modulation range. The hybrid inverter structure is formed by supplying the load from primary side by using a cascaded structure of a two-level inverter and H-bridge (HB) and secondary side of the load is supplied by a floating-capacitor-fed two-level inverter. The combination of primary two-level space vector structure (SVS) with secondary two-level SVS and primary three-level SVS of HB form a seven-level SVS that can further be extended to an eight-level hexagonal SVS. This structure then reduced to a 12-sided eight-level SVS to avoid exceeding motor phase voltage rating. Subsequently by using this eight-level SVS in an unique pulsewidth modulation mode, the proposed topology can increase the modulation range linearly from 0.577Vdc to 0.637Vdc peak phase fundamental voltage for any load power factor (pf), where dc-link voltage is Vdc . An 11 % increase in modulation range ( 0.637Vdc/0.577Vdc ) is possible devoid of lower order harmonics (predominantly 5th , 7th , 11th , 13th , etc.) in phase voltage for unity pf load in comparison to the conventional six-step operation of two-level and multilevel hexagonal SVS. To balance HB capacitors voltages in this work, a concept of indirect space vector redundancy is used. The efficacy of the proposed inverter scheme is verified through various experimental results at different steady-state and transient conditions.
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