Carrier-Based Modulation Techniques for Five-Phase Open-End Winding Drive Topology

The paper discusses implementation of level-shifted and phase-shifted carrier-based modulation methods, in conjunction with a multiphase open-end winding drive topology. The considered drive is supplied using two five-phase two-level voltage source inverters (VSIs), with input provided from two isolated dc sources of equal dc voltages. The topology is known to yield the same space vector pattern as a corresponding three-level inverter in single-sided supply mode. It is shown in the paper that, with the application of a simple logic, the same phase voltage waveforms result as those obtainable with the appropriate carrier-based modulation scheme applied to the three-level VSI in single-sided supply mode. While the outcomes of the modulation techniques are the same, the open-end winding topology offers certain advantages, such as modularity and absence of capacitor voltage balancing requirements. The analysis is conducted for selected modulation methods using voltage and current waveforms, spectra and total harmonic distortion (THD) as figures of merit. Theoretical considerations are verified by means of simulation and experimental results.