Carrier Modulation Schemes of Asymmetric, Multileveled, Switched Reluctance Machine Drives

Multilevel converter topologies are an ongoing research topic only recently extended to the asymmetric, switched reluctance machine drives. These topologies show potential in extending the operable speed range, reducing torque ripple and improving generation efficiency. However, due to the asymmetric, nonconventional nature of these topologies, traditional carrier modulation schemes have yet to be explored. This paper addresses a lack of available literature on the subject by proposing suitable carrier modulation strategies for the asymmetric flying capacitor, asymmetric neutral point clamped and asymmetric cascaded cell half bridge topologies. These strategies make use of interleaved carrier waveforms and can also be implemented with suitable capacitor balancing control strategies. The harmonic distortion of the input current waveform due to the modulation is also considered, providing a suitable criteria for comparing recently proposed topologies with their new modulation schemes.