Linearization of Overmodulation Region for 12 and 24-Sided Polygonal Space Vector-Based Inverters With Harmonic Filters

Two multisided space vector modulation (SVM) schemes, specifically 12-sided and 24-sided voltage polygons, are proposed in this article for an open-end wound induction machine using two, two-level inverters with a single dc source. The primary inverter will be connected to a dc source, while the secondary inverter will operate solely with a dc link capacitor. The dc link voltage of the second inverter is self-regulated without the need for any closed-loop voltage controller. A detailed mathematical derivation for the stability analysis of the capacitor voltage of the secondary inverter is presented, considering both transient and steady-state operation. The advantage of using multisided SVMs lies in their ability to eliminate lower order harmonics from the phase voltage in the overmodulation region, particularly at higher machine speeds. A linearization technique is implemented in this overmodulation region for 12-sided and 24-sided SVMs, creating a linear relationship between the fundamental component of the output voltage and the reference voltage. This leads to efficient utilization of the dc source at high speeds. Exhaustive experimental results are included to validate the proposed concepts.